%0 Conference Proceedings
%T Physical forcing affecting circulation and residence time in an estuary off Georgia
%D 2024
%B Ocean Sciences meeting
%9 Poster
%Z accepted
%M GCE.1322
%A Agonsi, Mitchelle
%A Sheldon, Joan E.
%A Castelao, Renato
%K Modeling, estuarine circulation, residence time

%0 Journal Article
%T Multivariate Analysis of the Community Composition of Tidal Freshwater Forests on the Altamaha River, Georgia
%D 2024
%V 15
%N 1
%B Forests
%S Coastal Forest Dynamics and Coastline Erosion—Series II
%9 Article
%Z published
%M GCE.1346
%R 10.3390/f15010200
%X Situated in the transitional zone between non-tidal forests upstream and tidal freshwater marshes downstream, tidal freshwater forests (TFF) occupy a unique and increasingly precarious habitat due to the threat of saltwater intrusion and sea level rise. Salinization causes tree mortality and forest-to-marsh transition, which reduces biodiversity and carbon sequestration. The Altamaha River is the longest undammed river on the United States East Coast and has extensive TFF, but there have been only limited field studies examining TFF along the entire gradient of salinity and flooding. We surveyed thirty-eight forest plots on the Altamaha River along a gradient of tidal influence, and measured tree species composition, diameter, and height. Hierarchical clustering and indicator species analysis were used to identify TFF communities. The relationship of these communities to elevation and river distance was assessed using non-metric multidimensional scaling (NMDS). We identified six significantly different forest communities: Oak/Hornbeam, Water Tupelo, Bald Cypress/Tupelo, Pine, Swamp Tupelo, and Bald Cypress. Both elevation and river distance were significantly correlated with plot species composition (p = 0.001). Plots at the downstream extent of our study area had lower stem density, basal area, and species diversity than those further upstream, suggesting saltwater intrusion. This study demonstrates the importance of and need for thorough and robust analyses of tidal freshwater forest composition to improve prediction of TFF response to sea level rise.
%U https://doi.org/10.3390/f15010200
%A Costomiris, Galen
%A Hladik, Christine M.
%A Craft, Christopher B.
%K tidal freshwater forests, community composition, flooding, salinity, Altamaha River, Georgia, Student Publication

%0 Journal Article
%T Canopy Heterogeneity and Environmental Variability Drive Annual Budgets of Net Ecosystem Carbon Exchange in a Tidal Marsh
%D 2024
%B JGR Biogeosciences
%9 Article
%Z published
%M GCE.1348
%R 10.1029/2023JG007866
%X Tidal salt marshes are important ecosystems in the global carbon cycle. Understanding their net carbon exchange with the atmosphere is required to accurately estimate their net ecosystem carbon budget (NECB). In this study, we present the interannual net ecosystem exchange (NEE) of CO2 derived from eddy covariance (EC) for a Spartina alterniflora salt marsh. We found interannual NEE could vary up to 3‐fold and range from − 58.5 ± 11.3 to − 222.9 ± 12.4 g C m− 2 year− 1 in 2016 and 2020, respectively. Further, we found that atmospheric CO2 fluxes were spatially dependent and varied across short distances. High biomass regions along tidal creek and estuary edges had up to 2‐fold higher annual NEE than lower biomass marsh interiors. In addition to the spatial variation of NEE, regions of the marsh represented by distinct canopy zonation responded to environmental drivers differently. Low elevation edges (with taller canopies) had a higher correlation with river discharge (R2 = 0.61), the main freshwater input into the system, while marsh interiors (with short canopies) were better correlated with in situ precipitation (R2 = 0.53). Lastly, we extrapolated interannual NEE to the wider marsh system, demonstrating the potential underestimation of annual NEE when not considering spatially explicit rates of NEE. Our work provides a basis for further research to understand the temporal and spatial dynamics of productivity in coastal wetlands, ecosystems which are at the forefront of experiencing climate change induced variability in precipitation, temperature, and sea level rise that have the potential to alter ecosystem productivity.
%U doi.org/10.1029/2023JG007866
%A Hawman, Peter
%A Cotten, David L.
%A Mishra, Deepak
%K tidal marsh, net ecosystem exchange

%0 Journal Article
%T Blue Carbon and Wetlands Compensatory Mitigation: Fitting a Climate-Sized Peg into a Watershed-Sized Hole
%D 2024
%V 13
%P 31
%B Sea Grant Law and Policy Journal
%9 Article
%Z published
%M GCE.1349
%X This Article seeks to provide policymakers and coastal resource managers with detailed insights into the challenges and opportunities for incorporating considerations of “blue carbon” into compensatory mitigation required under Clean Water Act Section 404. As our understanding of blue carbon systems deepens, so too does the urgency of responding to the global climate crisis. Commentators have encouraged the inclusion of blue carbon into existing domestic policies, including Clean Water Act Section 404. It is the authors’ hope that focused articles such as this can shine a light on which approaches might be most tenable under existing law, directing efforts towards workable solutions.
%U https://nsglc.olemiss.edu/sglpj/vol13no1/sglpj13.1-hill-spivak.pdf
%A Hill, Katie
%A Spivak, Amanda C.
%K blue carbon, clean water act

%0 Journal Article
%T A global database of dissolved organic matter (DOM) concentration measurements in coastal waters (CoastDOM v1)
%D 2024
%V 16
%P 1107-1119
%B Earth System Science Data
%9 Article
%Z published
%M GCE.1351
%R 10.5194/essd-16-1107-2024
%X Measurements of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) concentrations are used to characterize the dissolved organic matter (DOM) pool and are important components of biogeochemical cycling in the coastal ocean. Here, we present the first edition of a global database (CoastDOM v1; available at https://doi.org/10.1594/PANGAEA.964012, Lřnborg et al., 2023) compiling previously published and unpublished measurements of DOC, DON, and DOP in coastal waters. These data are complemented by hydrographic data such as temperature and salinity and, to the extent possible, other biogeochemical variables (e.g. chlorophyll a, inorganic nutrients) and the inorganic carbon system (e.g. dissolved inorganic carbon and total alkalinity). Overall, CoastDOM v1 includes observations of concentrations from all continents. However, most data were collected in the Northern Hemisphere, with a clear gap in DOM measurements from the Southern Hemisphere. The data included were collected from 1978 to 2022 and consist of 62 338 data points for DOC, 20 356 for DON, and 13 533 for DOP. The number of measurements decreases progressively in the sequence DOC > DON > DOP, reflecting both differences in the maturity of the analytical methods and the greater focus on carbon cycling by the aquatic science community. The global database shows that the average DOC concentration in coastal waters (average ± standard deviation (SD): 182±314 µmolC L−1 ; median: 103 µmolC L−1 ) is13-fold higher than the average coastal DON concentration (13.6 ± 30.4 µmol N L−1 ; median: 8.0 µmol N L−1 ), which is itself 39-fold higher than the average coastal DOP concentration (0.34 ± 1.11 µmol P L−1 ; median: 0.18 µmol P L−1). This dataset will be useful for identifying global spatial and temporal patterns in DOM and will help facilitate the reuse of DOC, DON, and DOP data in studies aimed at better characterizing local biogeochemical processes; closing nutrient budgets; estimating carbon, nitrogen, and phosphorous pools; and establishing abaseline for modelling future changes in coastal waters.
%A Lonborg, Christian
%A Carreira, Catia
%A Abril, Gwenael
%A Agusti, Susana
%A Amaral, Valentina
%A Medeiros, Patricia M.
%K Dissolved organic matter, DOC concentration, Database, Coastal DOC

%0 Journal Article
%T Large grazers suppress a foundational plant and reduce soil carbon concentration in eastern US saltmarshes
%D 2024
%B Journal of Ecology
%9 Article
%Z published
%M GCE.1319
%R 10.1111/1365-2745.14407
%X 1. Large grazers modify vegetated ecosystems and are increasingly viewed as keystonespecies in trophic rewilding schemes. Yet, as their ecosystem influencesare context-dependent,a crucial challenge is identifying where grazers sustain,versus undermine, important ecosystem properties and their resilience.2. Previous work in diverse European saltmarshes found that, despite changingplant and invertebrate community structure, grazers do not suppress below-groundproperties, including soil organic carbon (SOC). We hypothesised that,in contrast, eastern US saltmarshes would be sensitive to large grazers as extensiveareas are dominated by a single grass, Spartina alterniflora. We predicted thatgrazers would reduce above-andbelow-groundSpartina biomass, suppress invertebratedensities, shift soil texture and ultimately reduce SOC concentration.3. We tested our hypotheses using a replicated 51-monthlarge grazer (horse) exclusionexperiment in Georgia, coupled with observations of 14 long-termgrazedsites, spanning ~1000 km of the eastern US coast.4. Grazer exclusion quickly led to increased Spartina height, cover and flowering,and increased snail density. Changes in vegetation structure were reflected inmodified soil texture (reduced sand, increased clay) and elevated root biomass,yet we found no response of SOC. Large grazer exclusion also reduced drought-associatedvegetation die-off.5. We also observed vegetation shifts in sites along the eastern US seaboard wheregrazing has occurred for hundreds of years. Unlike in the exclusion experiment,long-termgrazing was associated with reduced SOC. A structural equation modelimplicated grazing by revealing reduced stem height as a key driver of reduced soilorganic carbon.6. Synthesis: These results illustrate the context dependency of large grazer impactson ecosystem properties in coastal wetlands. In contrast to well-studiedEuropean marshes, eastern US marshes are dominated and structured by a singlefoundational grass species resulting in vegetation and soil properties being moresensitive to grazing. Coastal systems characterised by a single foundation speciesmight be inherently vulnerable to large grazers and lack resilience in the faceof other disturbances, underlining that frameworks to explain and predict largegrazer impacts must account for geographic variation in ecosystem structure.
%A Sharp, Sean
%A Davidson, Kate
%A Angelini, Christine
%A Fischman, Hallie
%A Pennings, Steven C.
%A Fowler, M. S.
%A Griffin, John
%K herbivory, horses, cattle

%0 Journal Article
%T Long-term data reveal that grazer density mediates climatic stress in salt marshes
%D 2024
%B Ecology
%9 Article
%Z published
%M GCE.1320
%R 10.1002/ecy.4323
%X Understanding how climate and local stressors interact is paramount for predicting future ecosystem structure. The effects of multiple stressors are often examined in small-scale and short-term field experiments, limiting understanding of the spatial and temporal generality of the findings. Using a 22-year observational dataset of plant and grazer abundance in a southeastern US salt marsh, we analyzed how changes in drought and grazer density combined to affect plant biomass. We found: (1) increased drought severity and higher snail density both correlated with lower plant biomass; (2) drought and snail effects interacted additively; and, (3) snail effects had a threshold, with additive top-down effects only occurring when snails were present at high densities. These results suggest that the emergence of multiple stressor effects can be density dependent, and they validate short-term experimental evidence that consumers can augment environmental stress. These findings have important implications for predicting future ecosystem structure and managing natural ecosystems.
%U https://doi.org/10.1002/ecy.4323
%A Smith, Carter S.
%A Zhang, Stacy
%A Hensel, Marc Simon
%A Pennings, Steven C.
%A Silliman, Brian R.
%K herbivory, snails, Littoraria, drought, Spartina, SINERR Publication, UGAMI Publication

%0 Journal Article
%T The resistance of Georgia coastal marshes to hurricanes
%D 2024
%V 15
%N 4
%B Ecosphere
%9 Article
%Z published
%M GCE.1347
%R 10.1002/ecs2.4821
%X Ecosystems vary broadly in their responses to disturbance, ranging from highly impacted to resilient or resistant. We conducted a large-scale analysis of hurricane disturbance effects on coastal marshes by examining 20 years of data from 10 sites covering 100,000 ha at the Georgia Coastal Ecosystems Long-Term Ecological Research site distributed across gradients of salinity and proximity to the ocean. We analyzed the impacts of Hurricanes Matthew (in 2016) and Irma (in 2017) on marsh biota (plants, crabs, and snails) and physical attributes (erosion, wrack deposition, and sedimentation). We compared these variables prior to the storms (2000–2015) to years with storms (2016, 2017) to those after the storms (2018–2020). Hurricanes generated storm surges that increased water depth and salinity of oligotrophic areas for up to 48 h. Biological variables in the marsh showed few effects of the hurricanes. The only physical variable affected was creek bank slumping; however, slumping had already increased a year before the hurricanes, suggesting that slumping could have a different cause. Thus, our study uncovered only minor, ephemeral impacts on Georgia coastal marshes, highlighting their resistance to hurricane disturbance of the lower magnitude that typically confronts this region of coastline.
%U https://doi.org/10.1002/ecs2.4821
%A Smith, Rachel S.
%A Pennings, Steven C.
%A Alber, Merryl
%A Craft, Christopher B.
%A Byers, James
%K climate change, coastal protection, disturbance ecology, GCE-LTER, resilience, salt marshes, storm surge, Signature Publication

%0 Journal Article
%T Resistance and resilience: Tidal freshwater marsh response and recovery to acute and chronic saltwater intrusion
%D 2024
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.1352
%R 10.1016/j.ecss.2024.108911
%X The ability to both resist and recover from disturbances like storm surge and saltwater intrusion plays a key role in shaping the structure and function of tidal marshes. In this study, porewater chemistry, vegetation, and soil elevation change were measured in field plots of a tidal freshwater marsh exposed to four years of experimental press (chronic) and pulse (acute) brackish water additions followed by five years of recovery to assess their resistance and resilience to saltwater intrusion. Press additions produced significant, widespread changes in marsh structure and function including increased porewater N and P, reduced macrophyte cover and species richness, and loss of soil surface elevation whereas pulse additions had little effect. Once dosing ceased, porewater chemistry, vegetation and soils in press plots recovered at differing rates, with porewater N and P declining to background levels after one year, plant cover and species richness increasing within two to four years, and soil surface elevation increasing to similar levels found in control plots after five years. The plant community in the press treatment converged with the other treatments after 3–4 years, though macrophyte species exhibited varying rates of recovery. Ground cover (Ludwigia repens) and soft stem species (Persicaria) that declined first, recovered faster than Zizaniopsis miliacea that was more resistant but less resilient to brackish water intrusion. While tidal freshwater marshes are resistant and resilient to pulses such as those that stem from hurricanes and storm surges, continued long-term intrusion events like sea level rise (SLR) will likely lead to conversion into brackish marsh. Understanding long-term responses and tradeoffs in resistance and recovery as shown in this experiment offers insight into the future trajectory of tidal freshwater marshes as well as broader ecosystem responses to disturbance and recovery crucial to management and restoration.
%U https://doi.org/10.1016/j.ecss.2024.108911
%A Thompson, Madeleine
%A Pennings, Steven C.
%A Schubauer-Berigan, Joseph P.
%A Herbert, Ellen
%A Costomiris, Galen
%A Craft, Christopher B.
%K Disturbance, Sea level rise, Saltwater intrusion, Tidal freshwater marsh, Biological resistance, Ecosystem resilience, Student Publication, UGAMI Publication

%0 Journal Article
%T Variance reflects resilience to disturbance along a stress gradient: experimental evidence from coastal marshes
%D 2024
%V 2024
%P e4241
%B Ecology
%9 Article
%Z published
%M GCE.1317
%R 10.1002/ecy.4241
%X Quantifying ecosystem resilience to disturbance is important for understanding the effects of disturbances on ecosystems, especially in an era of rapid global change. However, there are few studies that have used standardized experimental disturbances to compare resilience patterns across abiotic gradients in real-world ecosystems. Theoretical studies have suggested that increased return times are associated with increasing variance during recovery from disturbance. However, this notion has rarely been explicitly tested in field, in part due to the challenges involved in obtaining long-term experimental data. In this study, we examined resilience to disturbance of 12 coastal marsh sites (five low-salinity and seven polyhaline (=salt) marshes) along a salinity gradient in Georgia, USA. We found that recovery times after experimental disturbance ranged from 7 to >127 months, and differed among response variables (vegetation height, cover and composition). Recovery rates decreased along the stress gradient of increasing salinity, presumably due to stress reducing plant vigor, but only when low-salinity and polyhaline sites were analyzed separately, indicating a strong role for traits of dominant plant species. The coefficient of variation of vegetation cover and height in control plots did not vary with salinity. In disturbed plots, however, the CV was consistently elevated during the recovery period and increased with salinity. Moreover, higher CV values during recovery were correlated with slower recovery rates. Our results deepen our understanding of resilience to disturbance in natural ecosystems, and point to novel ways that variance can be used either to infer recent disturbance, or, if measured in areas with a known disturbance history, to predict recovery patterns.
%U https://doi.org/10.1002/ecy.4241
%A Wang, J.
%A Guo, Hongyu
%A Alber, Merryl
%A Pennings, Steven C.
%K disturbance, salt marsh, Spartina, Juncus, Zizaniopsis, resistance, resilience, Signature Publication, SINERR Publication, UGAMI Publication

%0 Journal Article
%T The dynamics of marsh-channel slump blocks: an observational study using repeated drone imagery
%D 2024
%V 21
%P 1757-1772
%B Biogeosciences
%9 Article
%Z published
%M GCE.1350
%R 10.5194/bg-21-1757-2024
%X Slump blocks are widely distributed features along marsh shorelines that can disturb marsh edge habitats and affect marsh geomorphology and sediment dynamics. However, little is known about their spatial distribution patterns or their longevity and movement. We employed an unoccupied aerial vehicle (UAV) to track slump blocks in 11 monthly images (March 2020–March 2021) of Dean Creek, a tidal creek surrounded by salt marsh located on Sapelo Island (GA, USA). Slump blocks were observed along both convex and concave banks of the creek in all images, with sizes between 0.03 and 72.51m2. Although the majority of blocks were categorized as persistent, there were also new blocks in each image. Most blocks were lost through submergence, and both decreased in area and moved towards the center of the channel over time. However, some blocks reconnected to the marsh platform, which has not been previously observed. These blocks were initially larger and located closer to the marsh edge than those that submerged, and they increased in area over time. Only 13 out of a cohort of 61 newly created blocks observed in May 2020 remained after 5 months, suggesting that most blocks persist for only a short time. When taken together, the total area of new slump blocks was 886m2, and that of reconnected blocks was 652m2. This resulted in a net expansion of the channel by 234m2 over the study period, accounting for about 66% of the overall increase in the channel area of Dean Creek, and this suggests that slump block processes play an important role in tidal creek channel widening. This study illustrates the power of repeated UAV surveys to monitor short-term geomorphological processes, such as slump block formation and loss, to provide new insights into marsh eco-geomorphological processes.
%U https://doi.org/10.5194/bg-21-1757-2024
%A Yang, Zhicheng
%A Alexander, Clark R., Jr.
%A Alber, Merryl
%K drone imagery, marsh channel, slump blocks

%0 Journal Article
%T Practical guide to measuring wetland carbon pools and fluxes.
%D 2023
%V 43
%P 105
%B Wetlands
%9 Article
%Z published
%M GCE.1315
%R 10.1007/s13157-023-01722-2
%X Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions.
%U https://doi.org/10.1007/s13157-023-01722-2
%A Bansal, S.
%A Creed, Irena F.
%A Tangen, Brian A.
%A Bridgham, Scott D.
%A Desai, Ankur R.
%A Krauss, Ken W.
%A Neubauer, S. C.
%A Noe, G.
%A Rosenberry, Donald O.
%A Trettin, Carl
%A Wickland, Kimberly P.
%A Allen, Scott T.
%A Arias-Ortiz, Ariane
%A Armitage, Anna R
%A Baldocchi, Dennis
%A Banerjee, Kakoli
%A Bastviken, David
%A Berg, Peter
%A Bogard, Matthew J.
%A Chow, Alex T.
%A Conner, William H.
%A Craft, Christopher B.
%A Creamer, Courtney
%A DelSontro, Tonya
%A Duberstein, Jamie A.
%A Eagle, M.
%A Fennessy, M. Siobhan
%A Finkelstein, Sarah A.
%A Gockede, Mathias
%A Grunwald, Sabine
%A Halabisky, Meghan
%A Herbert, Ellen
%A Jahangir, Mohammad M.R.
%A Johnson, Olivia F.
%A Jones, Miriam C.
%A Kelleway, Jeffrey J.
%A Knox, Sara
%A Kroeger, Kevin D.
%A Kuehn, Kevin A.
%A Lobb, David
%A Loder, Amanda L.
%A Ma, Shizhou
%A Maher, Damien T.
%A McNicol, Gavin
%A Meier, Jacob
%A Middleton, Beth A.
%A Mills, Christopher
%A Mistry, Purbasha
%A Mitra, Abhijit
%A Mobilian, Courtney
%A Nahlik, Amanda M.
%A Newman, Sue
%A O'Connell, Jessica L.
%A Oikawa, Patty
%A van der Berg, Max Post
%A Schutte, Charles
%A Song, Changchun
%A Stagg, Camille L.
%A Turner, Jessica
%A Vargas, Rodrigo
%A Waldrop, Mark P.
%A Wallin, Marcus B.
%A Wang, Zhaohui Aleck
%A Ward, Eric J.
%A Willard, Debra A.
%A Yarwood, Stephanie
%A Zhu, Xiaoyan
%K Wetland carbon, field methods, lab methods

%0 Conference Proceedings
%T Detecting causal relationships in salt marsh productivity
%D 2023
%C San Francisco CA
%B AGU Fall meeting
%8 Dec 11-15, 2023
%9 Presentation
%Z presented
%M GCE.1323
%A Bice, Kadir
%A Hawman, Peter
%A Momani, A.A.
%A Mishra, Deepak
%A Bollt, E.
%A Meile, C.
%K NEE, causality

%0 Journal Article
%T Temporal patterns and causal drivers of aboveground plant biomass in a coastal wetland: insights from time-series analyses 
%D 2023
%V 10
%N 1130958
%B Frontiers of Marine Sciences
%9 Article
%Z published
%M GCE.1272
%R 10.3389/fmars.2023.1130958
%X Salt marshes play a crucial role in coastal biogeochemical cycles and provide unique ecosystem services. Salt marsh biomass, which can strongly influence such services, varies over time in response to hydrologic conditions and other environmental drivers. We used gap-filled monthly observations of Spartina alterniflora aboveground biomass derived from Landsat 5 and Landsat 8 satellite imagery from 1984-2018 to analyze temporal patterns in biomass in comparison to air temperature, precipitation, river discharge, nutrient input, sea level, and drought index for a southeastern US salt marsh. Wavelet analysis and ensemble empirical mode decomposition identified month to multi-year periodicities in both plant biomass and environmental drivers. Wavelet coherence detected cross-correlations between annual biomass cycles and precipitation, temperature, river discharge, nutrient concentrations (NOx and PO43–) and sea level. At longer periods we detected coherence between biomass and all variables except precipitation. Through empirical dynamic modeling we showed that temperature, river discharge, drought, sea level, and river nutrient concentrations were causally connected to salt marsh biomass and exceeded the confounding effect of seasonality. This study demonstrated the insights into biomass dynamics and causal connections that can be gained through the analysis of long-term data.
%U https://doi.org/10.3389/fmars.2023.1130958
%A Bice, Kadir
%A Sheldon, Joan E.
%A Schalles, John F.
%A Alber, Merryl
%A Meile, Christof
%K biomass, environmental driver, causal connections, wavelet, coherence, Student Publication

%0 Journal Article
%T Salt marsh nitrogen cycling: where land meets sea
%D 2023
%P 12
%B Trends in Microbiology
%9 Article
%Z published
%M GCE.1329
%R 10.1016/j.tim.2023.09.010
%X Salt marshes sit at the terrestrial–aquatic interface of oceans around the world. Unique features of salt marshes that differentiate them from their upland or offshore counterparts include high rates of primary production from vascular plants and saturated saline soils that lead to sharp redox gradients and a diversity of electron acceptors and donors. Moreover, the dynamic nature of root oxygen loss and tidal forcing leads to unique biogeochemical conditions that promote nitrogen cycling. Here, we highlight recent advances in our understanding of key nitrogen cycling processes in salt marshes and discuss areas where additional research is needed to better predict how salt marsh N cycling will respond to future environmental change.
%U https://doi.org/10.1016/j.tim.2023.09.010
%A Bowen, Jennifer L.
%A Spivak, Amanda C.
%A Bernhard, Anne E.
%A Fulweiler, Robinson, W.
%A Giblin, Ann E.
%K salt marshes, redox gradients, nitrogen cycle, global change

%0 Journal Article
%T Tidal Marsh Restoration on Sapelo Island: A Legacy of R.J. Reynolds, Jr., Eugene Odum and the University of Georgia Marine Institute
%D 2023
%B Ecological Engineering
%S Wetlands30
%9 Article
%Z published
%M GCE.1284
%R 10.1016/J.ecoeng.2022.106875
%X Restoration of tidal marshes throughout the 20th century have attempted to bring back important functions of natural tidal systems. In this study, vertical accretion, organic carbon (C) sequestration, and nitrogen burial were compared between a natural, never diked tidal salt marsh and a hydrologically restored tidal salt marsh on Sapelo Island, Georgia to examine the impacts of restoration years later. 64 years after hydrologic restoration in 1956, the restored marsh studied had higher rates of accretion based on 137Cs and 210Pb (4.8–5.1 mm/yr), C sequestration (118–125 g C/m2/yr) and N burial (8.3–8.8.g N/m2/yr) than the never diked marsh (2.9–3.4 mm/yr, 75–85 g C/m2/yr, 4.8–5.6 g N/m2/yr).Since maximum 137Cs deposition in 1964, approximately 30 cm of accretion has occurred in the restored marsh while the never diked marsh had approximately 10–30 cm of new soil deposited. The accumulated soil in the restored marsh was comparable to the natural marsh soil in terms of bulk density, percent C and N. However, below this depth, legacy effects from diking could be found through the higher soil bulk density and lower percent organic C and N relative to soils of the natural marsh.Vertical accretion in the natural marsh appears to be keeping pace with the current rate of sea level rise (SLR) (3.4 mm/yr) while accretion in the restored marsh exceeds SLR as the marsh compensates for subsidence that occurred when it was diked. Under current SLR and accretion rates, ecosystem functions of continual sequestration of C and burial of N will be supported. However, as SLR accelerates, the ability of both marshes to sequester C and bury N will depend on their ability to keep pace. If not, the marshes will eventually convert to mudflats or open water with a concurrent loss of these and other ecosystem services.
%U https//doi.org/10.1016/J.ecoeng.2022.106875
%A Craft, Christopher B.
%K diked marsh, hydrologic restoration, subsidence, accretion, carbon sequestration, nitrogen burial, UGAMI Publication

%0 Journal Article
%T Faunal engineering stimulates landscape-scale accretion in southeastern US salt marshes
%D 2023
%V 14
%N 881
%B Nature Communications
%9 Article
%Z published
%M GCE.1305
%R 10.1038/s41467-023-36444-w
%X The fate of coastal ecosystems depends on their ability to keep pace with sealevel rise—yet projections of accretion widely ignore effects of engineering fauna. Here, we quantify effects of the mussel, Geukensia demissa, on southeastern US saltmarsh accretion. Multi-season and -tidal stage surveys, in combination with field experiments, reveal that deposition is 2.8-10.7-times greater on mussel aggregations than any other marsh location. Our Delft-3DBIVALVES model further predicts that mussels drive substantial changes to both the magnitude (±<0.1 cm·yr&#8722;1) and spatial patterning of accretion at marsh domain scales. We explore the validity of model predictions with a multi-year creekshed mussel manipulation of >200,000 mussels and find that this faunal engineer drives far greater changes to relative marsh accretion rates than predicted (±>0.4 cm·yr&#8722;1). Thus, we highlight an urgent need for empirical, experimental, and modeling work to resolve the importance of faunal engineers in directly and indirectly modifying the persistence of coastal ecosystems globally.
%U https://doi.org/10.1038/s41467-023-36444-w
%A Crotty, Sinead M.
%A Pinton, Daniele
%A Canestrelli, Alberto
%A Fischman, Hallie
%A Ortals, Collin
%A Dahl, Nicholas R.
%A Williams, Sydney Laine
%A Bouma, Tjeerd J.
%A Angelini, Christine
%K salt marshes, accretion, faunal engineering, UGAMI Publication

%0 Thesis
%T Remote Sensing of Georgia Tidal Marsh Habitats Using Aerial Photography and Planetscope Satellite Imagery
%D 2023
%P 137
%I Georgia Southern University
%C Statesboro, GA
%9 M.S. Thesis
%Z published
%M GCE.1335
%X Globally, tidal marshes cover about 90,800 km. Within the state of Georgia tidal marshes are primarily located behind the barrier islands and total 1,619 km2 . The combination of high salinity environments and daily inundation, and being dependent on river output, make these dynamic systems. Tidal marshes provide numerous ecosystem services such as carbon and nitrogen sequestration, flood control, coastal protection, and numerous biogeochemical processes. Due to their unique position, tidal marshes are under threat from sea level rise, drought, coastal development, and large-scale disturbance events. Tidal freshwater marshes are especially susceptible to these threats due to their geographic location and small extent which have been historically understudied. By mapping tidal marshes, species composition is better understood and can be used to scale up ecosystem services, biogeochemical processes, and above ground biomass using remote sensing imagery. This study uses aerial orthoimagery along with a digital elevation model, National Wetland Inventory, and vegetation indices to map salt, brackish, and tidal freshwater marshes along the entire coast of Georgia. Higher spectral and spatial resolution PlanetScope 4- and 8-band satellite imagery was also used to map salt, brackish, and tidal freshwater marshes of the three main watersheds in coastal Georgia which include the Ogeechee, Altamaha, and Satilla Rivers. The aerial orthoimagery classification had an accuracy of 86.3% with salt marshes making up 67.8%, brackish 28.7%, and tidal freshwater 3.5% of the classified image and showed the importance of using a DEM and NWI for tidal marsh mapping. The PlanetScope classifications were comparable to the aerial classification with an accuracy of 86.5% (Ogeechee), 88.1% (Altamaha), and 75.9% (Satilla). Differences between the 4-band and 8-band PlanetScope imagery proved to be minimal. Due to the vulnerability of salt marshes to climate change, this study aims to contribute and expand upon current remote sensing studies on tidal marsh mapping.
%U https://digitalcommons.georgiasouthern.edu/etd/2643/
%A Currin, Harrison
%K Georgia coast, remote sensing, aerial imagery, satellite imagery, tidal marshes, habitat mapping, random forest, PlanetScope, Student Publication

%0 Journal Article
%T Differential impact of two major polychaete guilds on microbial communities in marine sediments: a microcosm study
%D 2023
%V 10
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1273
%R 10.3389/fmars.2023.1119331
%X Even though sediment macrofauna are widespread in the global seafloor, the influence of these fauna on microbial communities that drive sediment biogeochemical cycles remains poorly understood. According to recent field investigations, macrofaunal activities control bacterial and archaeal community structure in surface sediments, but the inferred mechanisms have not been experimentally verified. Here we use laboratory microcosms to investigate how activities of two major polychaete guilds, the lugworms, represented by Abarenicola pacifica, and the clamworms, represented by Nereis vexillosa, influence microbial communities in coastal sediments. A. pacifica treatments show >tenfold increases in microbial cell-specific consumption rates of oxygen and nitrate, largely due to the strong ventilation activity of A. pacifica. While ventilation resulted in clearly elevated percentages of nitrifying archaea (Nitrosopumilus spp.) in surface sediments, it only minorly affected bacterial community composition. By comparison, reworking – mainly by deposit-feeding of A. pacifica – had a more pronounced impact on microorganismal communities, significantly driving down abundances of Bacteria and Archaea. Within the Bacteria, lineages that have been linked to the degradation of microalgal biomass (e.g., Flavobacteriaceae and Rhodobacteraceae), were especially affected, consistent with the previously reported selective feeding of A. pacifica on microalgal detritus. In contrast, N. vexillosa, which is not a deposit feeder, did not significantly influence microbial abundances or microbial community structure. This species also only had a relatively minor impact on rates of oxygen and nitrogen cycling, presumably because porewater exchanges during burrow ventilation by this species were mainly restricted to sediments immediately surrounding the burrows. Collectively our analyses demonstrate that macrofauna with distinct bioturbation modes differ greatly in their impacts on microbial community structure and microbial metabolism in marine sediments.
%U https://doi.org/10.3389/fmars.2023.1119331
%A Deng, L.
%A Fiskal, A.
%A Boelsterli, D.
%A Meier, D.
%A Meile, C.
%A Lever, M.A.
%K bioturbation, microbial community

%0 Journal Article
%T Collective action and shellfish harvesting practices among Late Archaic villagers of the South Atlantic Bight
%D 2023
%V 69
%P 10
%B Journal of Anthropological Archaeology
%9 Article
%Z published
%M GCE.1324
%R 10.1016/j.jaa.2022.101483
%X Indigenous coastal communities across the globe sustainably harvested oysters and other shellfish species for millennia. European colonialism and the emergence of market-based institutions, however, lead to the eventual demise of many oyster reefs and fisheries beginning in the late 1800 s. Circular shell rings situated on Georgia’s South Atlantic coast are the preserved remnants of Native American village communities during the Late Archaic (5000–3000 cal. BP). Mollusk shells from these archaeological contexts hold chemical clues into past human-environmental interactions and thus give insight into Indigenous histories and sustainable shellfish harvesting practices. In this paper, we interpret shellfish geochemistry data (oxygen isotopes, &#948;18O) from the Sapelo Island Shell Ring Complex within a theoretical framework of cooperation and collective action to understand the ways in which Ancestral Muskogean people of Sapelo Island, Georgia, effectively managed and sustained oyster reefs and other coastal fisheries during the Late Archaic. More specifically, &#948;18O values from 18 oysters and 57 clams were used to determine season of harvest and to estimate salinity values of the habitats from which the shells were harvested. Results demonstrate considerable variation in estimated salinity values and some statistically significant differences in &#948;18O and salinity values between shells harvested in different seasons. This indicates that the sedentary villagers who lived at the Sapelo Shell Ring Complex were moving around seasonally and using an array of habitats. We argue that this suggests the presence of social institutions or rules that governed the use of coastal estuaries so that mollusks were not overexploited.
%U doi.org/10.1016/j.jaa.2022.101483
%A Garland, Carey J.
%A Thompson, Victor, D.
%K Shell isotope geochemistry, Late Archaic shell rings, Cooperation and collective action, Indigenous shell fishing practices

%0 Thesis
%T Ecological and Biogeochemical Responses to a Shifting Salinity Gradient in Tidal Marshes of the Satilla River Estuary, GA
%D 2023
%P 73
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.1327
%X The location of salinity gradients in coastal wetlands, from tidal freshwater sourced from riverine inputs to polyhaline sourced from saline ocean water, is subject to natural and unnatural shifts due to climactic patterns such as changes in discharge, sea-level rise (SLR), and alterations to hydrology. Increased inundation of saltwater in the Satilla River has resulted in conversions of plant communities from fresh or brackish to salt tolerant species that has implications for belowground soil biogeochemistry. I explored the translation of aboveground properties to soil properties in transitional wetlands in poly-, meso-, and oligohaline regions and across elevation gradients from levee to platform in the Satilla River Estuary, GA by characterizing the ecological communities and soil size fractionation, total organic carbon content (TOC) and composition (d13C). Natural and man-made alterations to river hydrology altered the aboveground plant communities and the soil carbon pools across the salinity gradient and with distance from creekbank.
%A Giordano, Gabriella Bliss
%K Tidal Marsh, Sea-Level Rise, Salinity Intrusion, Vegetation, Soil Organic Carbon, Student Publication

%0 Journal Article
%T Flood risk as legacy vulnerability: Reading the past into the present for environmental justice
%D 2023
%V 142
%P 10
%B Geoforum
%9 Article
%Z published
%M GCE.1310
%R 10.1016/j.geoforum.2023.103757
%X Decades of environmental justice research has focused on identifying existing patterns of disproportionate burdens to environmental harms across social difference. However, relatively few studies examine the “legacy effect” of historical patterns. In flood risk studies specifically, several scholars have highlighted the role of systemic processes in historically shaping and producing observed disparities in flood risk patterns. These studies reveal that such relations are tied to histories of racialized land struggles and territorial dispossessions. In this paper, I argue that scholars need to do more than quantify today’s disproportionate burdens across social difference or explain the systemic processes causing those disparities. I suggest that “legacy vulnerability” helps identify how the potential for harm from flood risk to marginalized groups may reside in events of the past that have imprinted a spatially hidden, but spatiotemporally revealed unjust pattern upon today’s landscape. In a flood risk assessment of Sapelo Island, the initial results suggest that when comparing contemporary flood risk of Sapelo’s Geechee descendant (Black and mostly low-to-middle income) to non-descendant newcomer owners (mostly white and affluent) an environmental justice disparity in proportional flood risk burden does not exist. However, results of a counterfactual flood risk assessment show that approximately one-third of historically owned, Geechee property is located outside the contemporary 100-year flood zone compared to zero percent outside of it today. In other words, roughly one-third of Geechee property’s flood risk today is a legacy vulnerability directly tied to racialized land dispossessions that unfolded in the middle twentieth century.
%U https://doi.org/10.1016/j.geoforum.2023.103757
%A Hardy, Dean
%K environmental justice, flood risk, historical geography, Gullah Geechee, UGAMI Publication

%0 Journal Article
%T Dynamic emergent leaf area in tidal wetlands: Implications for satellite-derived regional and global blue carbon estimates
%D 2023
%V 290
%N 15
%B Remote Sensing of Environment
%9 Article
%Z published
%M GCE.1304
%R 10.1016/j.rse.2023.113553
%X The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate highlights the importance of blue carbon in tidal wetlands in combating climate change. In this study, we highlight the uncertainty associated with leaf area index (LAI) estimations in tidal wetlands, specifically salt marshes, a key vegetation parameter for productivity models and Earth System Models (ESM). LAI, derived from satellite reflectance data, is linked to atmospheric carbon exchange and gross primary production (GPP) across vegetative ecosystems. However, estimating salt marsh LAI is challenging because canopy height and density vary across short distances, and tidal flooding alters the atmosphere-exposed leaf area, hereafter called emergent leaf area index (ELAI), at short time scales. Further, in tidal wetlands dominated by species such as Spartina alterniflora, canopy height and density vary across short distances. We present a novel approach for measuring spatiotemporal dynamics in tidal wetland ELAI. We modeled ELAI from vertical LAI profiles and created spatial estimates across tidal periods. We then linked ELAI with eddy covariance carbon (C) fluxes through footprint modeling and revealed correlations between emergent leaf area and C fluxes. Next, we demonstrated that ELAI can be readily estimated across 10-m spatial scales using Sentinel-2 satellite data, even during high tides (R2 = 0.89; NRMSE = 10%). Finally, we showed a common product, MODIS MYD15A2H, underestimated (20%) LAI during dry conditions but overestimated (7–93%) during high flooding. Dynamic ELAI could reduce uncertainties in satellite-derived global GPP products when developing blue carbon budgets for ecosystems threatened by accelerated sea level rise.
%U https://doi.org/10.1016/j.rse.2023.113553
%A Hawman, Peter
%A Mishra, Deepak
%A O'Connell, Jessica L.
%K Blue carbon. Salt marshes. Tidal wetlands .Leaf ar, UGAMI Publication

%0 Journal Article
%T The Coastal Carbon Library and Atlas: Open source soil data and tools supporting blue carbon research and policy.
%D 2023
%V 30
%N 1
%B Global Change Biology
%9 Article
%Z published
%M GCE.1332
%R 10.1111/gcb.17098
%X Quantifying carbon fluxes into and out of coastal soils is critical to meeting greenhouse gas reduction and coastal resiliency goals. Numerous ‘blue carbon’ studies have generated, or benefitted from, synthetic datasets. However, the community those efforts inspired does not have a centralized, standardized database of disaggregated data used to estimate carbon stocks and fluxes. In this paper, we describe a data structure designed to standardize data reporting, maximize reuse, and maintain a chain of credit from synthesis to original source. We introduce version 1.0.0. of the Coastal Carbon Library, a global database of 6723 soil profiles representing blue carbon-storing systems including marshes, mangroves, tidal freshwater forests, and seagrasses. We also present the Coastal Carbon Atlas, an R-shiny application that can be used to visualize, query, and download portions of the Coastal Carbon Library. The majority (4815) of entries in the database can be used for carbon stock assessments without the need for interpolating missing soil variables, 533 are available for estimating carbon burial rate, and 326 are useful for fitting dynamic soil formation models. Organic matter density significantly varied by habitat with tidal freshwater forests having the highest density, and seagrasses having the lowest. Future work could involve expansion of the synthesis to include more deep stock assessments, increasing the representation of data outside of the U.S., and increasing the amount of data available for mangroves and seagrasses, especially carbon burial rate data. We present proposed best practices for blue carbon data including an emphasis on disaggregation, data publication, dataset documentation, and use of standardized vocabulary and templates whenever appropriate. To conclude, the Coastal Carbon Library and Atlas serve as a general example of a grassroots F.A.I.R. (Findable, Accessible, Interoperable, and Reusable) data effort demonstrating how data producers can coordinate to develop tools relevant to policy and decision-making.
%U https://doi.org/10.1111/gcb.17098
%A Holmquist, J.R.
%A Klinges, D.H.
%A Lonneman, M.
%A Wolfe, J
%A Boyd, B.
%A Eagle, M.
%A Sanderman, Jonathan
%A Todd-Brown, K.
%A Belshe, E.F.
%A Chapman, S.
%A Corstanje, R.
%A Janousek, C.
%A Morris, J.T.
%A Noe, G.
%A Rovai, A.
%A Spivak, Amanda C.
%A Vashen, M.
%A Windham-Myers, L.
%A Kroeger, Kevin D
%A Megonigal, P.
%K blue carbon, open source

%0 Journal Article
%T GLORIA - A globally representative hyperspectral in situ dataset for optical sensing of water quality
%D 2023
%V 10:1130958, 6 April 2023
%N 100 (2023)
%P 13 p
%B Nature - Scientific Data
%9 Article
%Z Abbreviated authors list was provided here - there are 78 authors total (2 are GCE PIs). The Schalles lab contributed about 10% of the 7,572 curated hyperspectral remote sensing reflectance measurements in this public database. Georgia estuaries, coastal and shelf waters are conspicuously represented in this global spectral library.
%M GCE.1344
%R 10.1038/s41597-023-01973-y
%X The development of algorithms for remote sensing of water quality (RSWQ) requires a large amount of in situ data to account for the bio-geo-optical diversity of inland and coastal waters. The GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments (GLORIA) includes 7,572 curated hyperspectral remote sensing reflectance measurements at 1&#8201;nm intervals within the 350 to 900&#8201;nm wavelength range. In addition, at least one co-located water quality measurement of chlorophyll a, total suspended solids, absorption by dissolved substances, and Secchi depth, is provided. The data were contributed by researchers affiliated with 59 institutions worldwide and come from 450 different water bodies, making GLORIA the de-facto state of knowledge of in situ coastal and inland aquatic optical diversity. Each measurement is documented with comprehensive methodological details, allowing users to evaluate fitness-for-purpose, and providing a reference for practitioners planning similar measurements. We provide open and free access to this dataset with the goal of enabling scientific and technological advancement towards operational regional and global RSWQ monitoring.
%U https://www.nature.com/articles/s41597-023-01973-y
%A Lehmann, Moritz K.
%A Gurlin, Daniela
%A Pahlevan, Nima
%A Binding, C.E.
%A Fichot, C.G.
%A Gitelson, A.A.
%A Mishra, Deepak
%A Schalles, John F.
%A Simis, S.G.
%A Smith, Brandon 
%A Spyrakos, E. 
%K remote sensing, spectral library, water quality, chlorophyll, CDOM, suspended matter, RSWQ monitoring, Cross-site Research

%0 Journal Article
%T A global database of dissolved organic matter (DOM) concentration measurements in coastal waters (CoastDOM v1) [dataset]
%D 2023
%B PANGAEA - Data Publisher for Earth & Environmental Science
%9 Article
%Z published
%M GCE.1353
%R 10.1594/PANGAEA.964012
%X Measurements of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) concentrations are used to characterize the dissolved organic matter (DOM) pool and are important components of biogeochemical cycling in the coastal ocean. Here, we present the first edition of a global database (CoastDOM v1; available at https://doi.org/10.1594/PANGAEA.964012, Lřnborg et al., 2023) compiling previously published and unpublished measurements of DOC, DON, and DOP in coastal waters. These data are complemented by hydrographic data such as temperature and salinity and, to the extent possible, other biogeochemical variables (e.g. chlorophyll a, inorganic nutrients) and the inorganic carbon system (e.g. dissolved inorganic carbon and total alkalinity). Overall, CoastDOM v1 includes observations of concentrations from all continents. However, most data were collected in the Northern Hemisphere, with a clear gap in DOM measurements from the Southern Hemisphere. The data included were collected from 1978 to 2022 and consist of 62 338 data points for DOC, 20 356 for DON, and 13 533 for DOP. The number of measurements decreases progressively in the sequence DOC > DON > DOP, reflecting both differences in the maturity of the analytical methods and the greater focus on carbon cycling by the aquatic science community. The global database shows that the average DOC concentration in coastal waters (average ± standard deviation (SD): 182±314 µmolC L&#8722;1 ; median: 103 µmolC L&#8722;1 ) is13-fold higher than the average coastal DON concentration (13.6 ± 30.4 µmol N L&#8722;1 ; median: 8.0 µmol N L&#8722;1 ), which is itself 39-fold higher than the average coastal DOP concentration (0.34 ± 1.11 µmol P L&#8722;1 ; median: 0.18 µmol P L&#8722;1). This dataset will be useful for identifying global spatial and temporal patterns in DOM and will help facilitate the reuse of DOC, DON, and DOP data in studies aimed at better characterizing local biogeochemical processes; closing nutrient budgets; estimating carbon, nitrogen, and phosphorous pools; and establishing abaseline for modelling future changes in coastal waters.
%A Lonborg, Christian
%A Carreira, Catia
%A Abril, Gwenael
%A Agusti, Susana
%A Amaral, Valentina
%A Medeiros, Patricia M.
%K Dissolved organic matter, DOC concentration, Global database, Coastal waters

%0 Journal Article
%T Utilizing Repeat UAV Imagery to Evaluate the Spatiotemporal Patterns and Environmental Drivers of Wrack in a Coastal Georgia Salt Marsh
%D 2023
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1308
%R 10.1007/s12237-023-01265-z
%X Wrack, comprised of dead marsh grass, occurs naturally in salt marshes. Wrack can reduce biomass in underlying vegetation and affect salt marsh function. Unmanned aerial vehicles (UAV) provide a more efficient and cost-effective method than traditional field sampling for characterizing the distribution of wrack at a fine spatial scale. We used a DJI Matrice 210 UAV with a MicaSense Altum to collect a total of 20 images from January 2020–December 2021 in a salt marsh on Sapelo Island, GA. Wrack was classified using principal component analysis. Classified images were then used to characterize the size-frequency distribution, landscape position, and potential environmental drivers of wrack. We observed&#8201;~&#8201;2100 wrack patches over the course of the study, most of which were present for only a single month. Wrack was found most frequently at the mean higher high water line (~&#8201;1 m), although the areas with the highest frequency of wrack as a proportion of available marsh area were at a higher elevation (>&#8201;1.3 m) and closer to creeks or shorelines (~&#8201;40–50 m). High tide events were found to decrease the distance to water of wrack and increase the standard deviation of wrack elevation. This study provides a methodology for understanding wrack dynamics at a landscape scale using frequent, high-resolution UAV data.
%U https://doi.org/10.1007/s12237-023-01265-z
%A Lynn, Tyler
%A Alber, Merryl
%A Shalack, Jacob
%A Mishra, Deepak
%K UAV, salt marsh, wrack, Sapelo Island

%0 Journal Article
%T Photosynthetic Performance of Tidally Flooded Spartina Alterniflora Salt Marshes
%D 2023
%V 128
%N 3
%B JGR Biogeosciences
%9 Article
%Z published
%M GCE.1303
%R 10.1029/2022JG007161
%X Spartina alterniflora has a distinct flood-adapted morphology, and its physiological responses are likely to vary with differences in tidal submergence. To understand these responses, we examined the impacts of tidal inundation on the efficiency of Photosystem II (&#966;PSII) photochemistry and leaf-level photosynthesis at different canopy heights through a combination of in situ chlorophyll fluorescence (ChlF), incident photosynthetically active radiation, and tide levels. Our result showed small declines (7%–8.3%) in &#966;PSII for air-exposed leaves when the bottom canopies were tidally submerged. Submerged leaves produced large reductions (30.3%–41%) in &#966;PSII. Our results suggest that when submerged, PSII reaction centers in S. alterniflora leaves are still active and able to transfer electrons, but only at &#8764;20% of the typical daily rate. We attribute this reduction in &#966;PSII to the decrease in the fraction of “open” PSII reaction centers (10% of the total) and the stomatal conductance rate caused by the tidal submergence. To our knowledge, this flooding induced leaf-level reduction of &#966;PSII for S. alterniflora in field settings has not been reported before. Our findings suggest that canopy-level &#966;PSII is dependent on the proportion of submerged versus emerged leaves and highlight the complexities involved in estimating the photosynthetic efficiency of tidal marshes.
%U https://doi.org/10.1029/2022JG007161
%A Mao, Lishen
%A Mishra, Deepak
%A Hawman, Peter
%A Narron, Caroline
%A O'Connell, Jessica L.
%A Cotten, David L.
%K Spartina alternifora, chlorophyll fluorescence, photosynthetically active radiation, PAR, Signature Publication, Student Publication

%0 Thesis
%T Transformation and transport of dissolved organic matter in coastal systems using molecular and ocean color approaches
%D 2023
%P 130
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.1306
%A Martineac, Rachel P.
%K Dissolved organic matter, DOM composition, Microbial degradation, FT-ICR MS, Ocean color, Coastal DOM, Student Publication, UGAMI Publication

%0 Journal Article
%T Global dataset of soil organic carbon in tidal marshes
%D 2023
%V 10
%N 797
%P 14
%B Scientific Data
%9 Article
%Z published
%M GCE.1334
%R 10.1038/s41597-023-02633-x
%X Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2&#8201;±&#8201;38.1 Mg SOC ha&#8722;1 in the top 30&#8201;cm and 231&#8201;±&#8201;134 Mg SOC ha&#8722;1 in the top 1&#8201;m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies.
%U https://doi.org/10.1038/s41597-023-02633-x
%A Maxwell, Tania L.
%A Rovai, A.
%A Adame, Maria Fernanda
%A Adams, Janie B
%A Alvarez-Rogel, Jose
%A Austin, William E.N.
%A Beasy, Kim
%A Boscutti, Francesco
%A Bottcher, Michael E.
%A Bouma, Tjeerd J.
%A Bulmer, Richard H.
%A Burden, Annette
%A Burke, Shannon A.
%A Camacho, Saritta
%A Chaudhary, Doongar R.
%A Chmura, Gail L.
%A Copertino, Margareth
%A Cott, Grace M.
%A Craft, Christopher B.
%A Day, John
%A de los Santos, Carmen B.
%A Denis, Lionel
%A Dint, Weixin
%A Ellison, Joanna C.
%A Ewers Lewis, Carolyn J.
%A Giani, Louise
%A Gispert, Maria
%A Gontharet, Swanne
%A Gonzalez-Perez, Jose A.
%A Gonzalez-Alcaraz, M. Nazaret
%A Gorhan, Connor
%A Graverson, Anna Elizabeth
%A Grey, Anthony
%A Guerra, Roberta
%A He, Qiang
%A Holmquist, J.R.
%A Jones, Alize R.
%A Juanes, Jose A.
%A Kelleher, Brian P.
%A Kohfeld, Karen E.
%A Krause-Jensen, Dorte
%A Lafratta, Anna
%A Lavery, Paul S.
%A Laws, Edward A.
%A Leiva-Duenas, Carmen
%A Loh, Pei Sun
%A Lovelock, Catherine E.
%A Lundquist, Carolyn J.
%A Macreadie, Peter I.
%A Mazarrasa, Ines
%A Megonigal, Patrick
%A Neto, Joao M.
%A Nogueira, Juliana
%A Osland, Michael J.
%A Pages, Jordi F.
%A Perera, Nipuni
%A Pfeiffer, Eva-Maria
%A Pollmann, Thomas
%A Raw, Jacqueline L.
%A Recia, Maria
%A Ruiz-Fernandez, Ana Carolina
%A Russell, Sophie K.
%A Rybczyk, John M.
%A Sammul, Marek
%A Sanders, Christian
%A Santos, Rui
%A Serrano, Oscar
%A Siewert, Matthias
%A Smeaton, Craig
%A Song, Zhaoliang
%A Trasar-Cepeda, Carmen
%A Twilley, Robert R.
%A Van de Broek, Marijn
%A Vitti, Stefano
%A Vittori Antisari, Livia
%A Voltz, Baptiste
%A Wails, Christy N.
%A Ward, Raymond D.
%A Ward, Melissa
%A Wolfe, Jaxine
%A Yang, Renmin
%A Zubrzycki, Sebastian
%A Landis, Emily
%A Smart, Lindsey
%A Spalding, Mark
%A Worthington, Thomas A.
%K soil organic carbon, tidal marshes

%0 Journal Article
%T Top ten priorities for global saltmarsh restoration, conservation and ecosystem service research
%D 2023
%V 898
%N 165544
%P 13
%B Science of The Total Environment
%9 Article
%Z published
%M GCE.1341
%R 10.1016/j.scitotenv.2023.165544
%X Coastal saltmarshes provide globally important ecosystem services including ‘blue carbon’ sequestration, flood protection, pollutant remediation, habitat provision and cultural value. Large portions of marshes have been lost or fragmented as a result of land reclamation, embankment construction, and pollution. Sea level rise threatens marsh survival by blocking landward migration where coastlines have been developed. Research-informed saltmarsh conservation and restoration efforts are helping to prevent further loss, yet significant knowledge gaps remain. Using a mixed methods approach, this paper identifies ten research priorities through an online questionnaire and a residential workshop attended by an international, multi-disciplinary network of 35 saltmarsh experts spanning natural, physical and social sciences across research, policy, and practitioner sectors. Priorities have been grouped under four thematic areas of research: Saltmarsh Area Extent, Change and Restoration Potential (including past, present, global variation), Spatio-social contexts of Ecosystem Service delivery (e.g. influences of environmental context, climate change, and stakeholder groups on service provisioning), Patterns and Processes in saltmarsh functioning (global drivers of saltmarsh ecosystem structure/function) and Management and Policy Needs (how management varies contextually; challenges/opportunities for management). Although not intended to be exhaustive, the challenges, opportunities, and strategies for addressing each research priority examined here, providing a blueprint of the work that needs to be done to protect saltmarshes for future generations.
%U https://doi.org/10.1016/j.scitotenv.2023.165544
%A Petillon, Julien
%A McKinley, Emma
%A Alexander, Meghan
%A Adams, Janie B
%A Angelini, Christine
%A Balke, Thorsten
%A Griffin, John
%A Bouma, Tjeerd J.
%A Hacker, Sally D.
%A He, Qiang
%A Hensel, Marc Simon
%A Ibanez, Carles
%A Macreadie, Peter I.
%A Martino, Simone
%A Sharps, Elwyn
%A Ballinger, Rhoda
%A de Battisi, Davide
%A Beaumont, Nicola
%A Burdon, Daryl
%A Daleo, P.
%A D'Alpaos, Andrea
%A Duggan-Edwards, Mollie
%A Garbutt, Angus
%A Jenkins, Stuart
%A Ladd, Cai J.T.
%A Lewis, Heather
%A Mariotti, Giulio
%A McDermott, Osgur
%A Mills, Rachael
%A Moller, Iris
%A Nolte, Stefanie
%A Pages, Jordi F.
%A Silliman, Brian R.
%A Zhang, Liquan
%A Skov, Martin W.
%K saltmarsh restoration, conservation, ecosystem service

%0 Thesis
%T Using Machine Learning Classification and ESA Sentinel 2 Multispectral Imager Data to Delineate Marsh Vegetation and Measure Ecotone Movement in Coastal Georgia
%D 2023
%P 94
%I Georgia Southern University
%C Statesboro, GA
%9 M.S. Thesis
%Z published
%M GCE.1336
%X Tidal marshes are unique communities that are subjected to environmental stressors including sea level rise, salinity change, and drought, resulting in constant change. It is important to monitor these changing areas because of the ecosystem services they provide to us, such as protection from storms and carbon sequestration. The Georgia coast is home to a large section of marsh on the Atlantic coast of the United States. This thesis project focused on the study of tidal marshes, and the dynamics between the vegetation species within them, on Broughton Island, Georgia. The aim of this project was to use geospatial technology and analyses, along with machine learning classification methods, to monitor change in these valuable ecosystems. The two objectives of this study are to 1) examine multiple machine learning algorithms to determine the best supervised classification method for the Broughton Island, Georgia, and 2) quantify the relationship between species-specific aboveground biomass of vegetation with ecotone movement between the three tidal marsh domains. Objective one of this study compared two different supervised classification methods, Random Forest and Artificial Neural Networks, to determine which supervised classification performs best in mapping vegetation species and ground cover within the study area. In objective 2, the most accurate classifier will be used to examine ecotone movement over time and quantify the relationship between aboveground biomass, using vegetation indices as a proxy, of vegetation and ecotone movement.
%U https://digitalcommons.georgiasouthern.edu/etd/2642/
%A Pudil, Thomas
%K Remote sensing, Machine learning, Tidal marshes, Satellite imagery, Temporal change, Ecosystem change, Habitat mapping, Student Publication

%0 Journal Article
%T Carbonate chemistry and the potential for acidification in Georgia coastal marshes and the South Atlantic Bight, USA
%D 2023
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1309
%R 10.1007/s12237-023-01261-3
%X In coastal regions and marginal bodies of water, the increase in partial pressure of carbon dioxide (pCO2) in many instances is greater than that of the open ocean due to terrestrial (river, estuarine, and wetland) influences, decreasing buffering capacity and/or increasing water temperatures. Coastal oceans receive freshwater from rivers and groundwater as well as terrestrial-derived organic matter, both of which have a direct influence on coastal carbonate chemistry. The objective of this research is to determine if coastal marshes in Georgia, USA, may be “hot-spots” for acidification due to enhanced inorganic carbon sources and if there is terrestrial influence on offshore acidification in the South Atlantic Bight (SAB). The results of this study show that dissolved inorganic carbon (DIC) and total alkalinity (TA) are elevated in the marshes compared to predictions from conservative mixing of the freshwater and oceanic end-members, with accompanying pH around 7.2 to 7.6 within the marshes and aragonite saturation states (&#937;Ar) <1. In the marshes, there is a strong relationship between the terrestrial/estuarine-derived organic and inorganic carbon and acidification. Comparisons of pH, TA, and DIC to terrestrial organic material markers, however, show that there is little influence of terrestrial-derived organic matter on shelf acidification during this period in 2014. In addition, &#937;Ar increases rapidly offshore, especially in drier months (July). River stream flow during 2014 was anomalously low compared to climatological means; therefore, offshore influences from terrestrial carbon could also be decreased. The SAB shelf may not be strongly influenced by terrestrial inputs to acidification during drier than normal periods; conversely, shelf waters that are well-buffered against acidification may not play a significant role in mitigating acidification within the Georgia marshes.
%U https://doi.org/10.1007/s12237-023-01261-3
%A Reimer, Janet J.
%A Medeiros, Patricia M.
%A Hussain, Najid
%A Gonski, Stephen F.
%A Xu, Yuan Y.
%A Huang, Ting H.
%A Cai, Wei-Jun
%K Carbonate chemistry, coastal acidification, pCO2, total alkalinity, dissolved inorganic carbon

%0 Journal Article
%T Coastal vegetation and estuaries are collectively a greenhouse gas sink
%D 2023
%V 13
%P 579-587
%B Nature Climate Change
%9 Article
%Z published
%M GCE.1342
%R 10.1038/s41558-023-01682-9
%X Coastal ecosystems release or absorb carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), but the net effects of these ecosystems on the radiative balance remain unknown. We compiled a dataset of observations from 738 sites from studies published between 1975 and 2020 to quantify CO2, CH4 and N2O fluxes in estuaries and coastal vegetation in ten global regions. We show that the CO2-equivalent (CO2e) uptake by coastal vegetation is decreased by 23–27% due to estuarine CO2e outgassing, resulting in a global median net sink of 391 or 444&#8201;TgCO2e&#8201;yr&#8722;1 using the 20- or 100-year global warming potentials, respectively. Globally, total coastal CH4 and N2O emissions decrease the coastal CO2 sink by 9–20%. Southeast Asia, North America and Africa are critical regional hotspots of GHG sinks. Understanding these hotspots can guide our efforts to strengthen coastal CO2 uptake while effectively reducing CH4 and N2O emissions.
%U https://doi.org/10.1038/s41558-023-01682-9
%A Rosentreter, Judith A.
%A Laruelle, Goulven G.
%A Bange, Hermann W.
%A Bianchi, Thomas S.
%A Busecke, Julius J.M.
%A Cai, Wei-Jun
%A Eyre, Bradley D.
%A Forbrich, Inke
%A Kwon, Eun Young
%A Maavara, Taylor
%A Moosdorf, Nils
%A Najjar, Raymond G.
%A Sarma, V.V.S.S.
%A Van Dam, Bryce
%A Regnier, Pierre
%K coastal vegetation, estuaries, greenhouse gas

%0 Thesis
%T Groundwater Flow and Salt Marsh Migration: The Forest/Marsh Boundary
%D 2023
%P 44
%I University of South Carolina
%C Columbia, South Carolina
%9 M.S. Thesis
%Z published
%M GCE.1326
%X Salt marshes migrate landward in response to sea level rise, but the rate of this migration is not constant and can be influenced by pulse disturbances. Long term observations at Sapelo Island, Georgia, show that salt marsh migration has occurred during droughts, but the mechanism for this migration is unclear. Drought is thought to influence salt marsh migration by reducing fresh groundwater discharge from the upland and direct infiltration of freshwater onto the marsh platform. Rising sea level also encroaches on the upland, which could cause a movement of the freshwater lens inland. A two-dimensional numerical model was built to simulate groundwater flow and solute transport based on the Marsh Landing marsh at Sapelo Island. The model is designed to estimate salinity changes in response to climatic factors, such as drought and sea level rise. After calibration against hydraulic head and salinity data from 2018-2020, the model was used to estimate salinity and movement of the freshwater lens through the forest/marsh boundary over a 25 year period from 1998-2022 that corresponds with plant community observations at the site. Simulation results suggest that seasonal variations in salinity can be amplified during drought periods due to reduced freshwater availability. Results also indicate sea level rise observed in 2018-2022 coincides with an overall increase in salinity near the forest/marsh boundary.
%A Rossiello, Camille
%K groundwater flow, salt marsh

%0 Conference Proceedings
%T Georgia Coastal Ecosystems LTER Hydrodynamic and Water Quality Models
%D 2023
%B SEERS 2023
%9 Presentation
%Z presented
%M GCE.1321
%A Sheldon, Joan E.
%A Castelao, Renato
%K Modeling, water quality, estuarine circulation

%0 Journal Article
%T Ephemeral microbial responses to pulses of bioavailable carbon in oxic and anoxic salt marsh soils
%D 2023
%V 185
%B Soil Biology and Biochemistry
%9 Article
%Z published
%M GCE.1307
%R 10.1016/j.soilbio.2023.109157
%X Roots of salt marsh grasses contribute to soil building but also affect decomposition by releasing bioavailable carbon exudates and oxygen. Disentangling exudate and oxygen effects on decomposition is difficult in the field but essential for marsh carbon models and predicting the impacts of global change disturbances. We tested how pulsed, simulated exudates affect soil metabolism under oxic and anoxic conditions, and whether carbon and oxygen availability facilitate mineralization of existing organic matter (i.e., priming). We conducted a laboratory experiment in flow-through reactors, adding carbon pulses weekly for 84 days and then following starvation under low carbon conditions. Oxygen consumption and sulfide production were inhibited under anoxic and oxic conditions and slowed by 21 ± 10% and 55 ± 8%, respectively, between 1- and 5- days following exudate pulses. Respiration rates immediately following and between pulses increased over time, suggesting that microbes capitalize on and may acclimate to patchy resources. Starvation caused oxygen consumption and sulfide production to fall 28% and 78% in oxic and anoxic treatments. Smaller decreases in oxygen consumption following pulses could suggest greater access to secondary carbon sources and that sulfate reducers were more reliant on exudates. Soil organic carbon was not the likely secondary source because porewater dissolved inorganic carbon &#948;13C values did not change during transit through the reactors, despite a &#8764;26‰ difference between the supplied seawater and marsh soil. Interpretation of oxygen consumption rates is complicated by non-respiratory oxidation of reduced inorganic compounds and possibly significant lithoautotrophy. Exudate pulses elicited rapid and ephemeral respiratory responses, particularly under anoxia, but non-respiratory oxidation of reduced compounds obscured the impact of oxygen availability in our experimental system. Despite this, greater aerobic respiration rates suggest that oxygen availability has more potential to regulate carbon mineralization in coastal wetlands than root exudates.
%U https://doi.org/10.1016/j.soilbio.2023.109157
%A Spivak, Amanda C.
%A Pinsonneault, Andrew J.
%A Hintz, Christopher
%A Brandes, J.
%A Megonigal, Patrick
%K Salt marsh, Rhizosphere, Organic carbon, Redox, Priming, Sulfur oxidation, Signature Publication

%0 Journal Article
%T Applying the core-satellite species concept: Characteristics of rare and common riverine dissolved organic matter
%D 2023
%V 5
%N 1156042
%B Frontiers in Water
%S Crowdsourced Understanding of Global River Organic Matter Composition through the Lens of Ecological Theory
%9 Article
%Z published
%M GCE.1271
%R 10.3389/frwa.2023.1156042
%X Introduction: Dissolved organic matter (DOM) composition varies over space and time, with a multitude of factors driving the presence or absence of each compound found in the complex DOM mixture. Compounds ubiquitously present across a wide range of river systems (hereafter termed core compounds) may differ in chemical composition and reactivity from compounds present in only a few settings (hereafter termed satellite compounds). Here, we investigated the spatial patterns in DOM molecular formulae presence (occupancy) in surface water and sediments across 97 river corridors at a continental scale using the “Worldwide Hydrobiogeochemical Observation Network for Dynamic River Systems—WHONDRS” research consortium.Methods: We used a novel data-driven approach to identify core and satellite compounds and compared their molecular properties identified with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS).Results: We found that core compounds clustered around intermediate hydrogen/carbon and oxygen/carbon ratios across both sediment and surface water samples, whereas the satellite compounds varied widely in their elemental composition. Within surface water samples, core compounds were dominated by lignin-like formulae, whereas protein-like formulae dominated the core pool in sediment samples. In contrast, satellite molecular formulae were more evenly distributed between compound classes in both sediment and water molecules. Core compounds found in both sediment and water exhibited lower molecular mass, lower oxidation state, and a higher degree of aromaticity, and were inferred to be more persistent than global satellite compounds. Higher putative biochemical transformations were found in core than satellite compounds, suggesting that the core pool was more processed.Discussion: The observed differences in chemical properties of core and satellite compounds point to potential differences in their sources and contribution to DOM processing in river corridors. Overall, our work points to the potential of data-driven approaches separating rare and common compounds to reduce some of the complexity inherent in studying riverine DOM.
%U https://doi.org/10.3389/frwa.2023.1156042
%A Stadler, M.
%A Bice, Kadir
%A Meile, Christof
%K organic matter, comparison, core-satellite, Student Publication

%0 Journal Article
%T Recent acceleration of wetland accretion and carbon accumulation along the U.S. East Coast.
%D 2023
%B Earth’s Future
%9 Article
%Z published
%M GCE.1314
%R 10.1029/2022EF003037
%X The long-term stability of coastal wetlands is determined by interactions among sea level, plant primary production, sediment supply, and wetland vertical accretion. Human activities in watersheds have significantly altered sediment delivery from the landscape to the coastal ocean, with declines along much of the U.S. East Coast. Tidal wetlands in coastal systems with low sediment supply may have limited ability to keep pace with accelerating rates of sea-level rise (SLR). Here, we show that rates of vertical accretion and carbon accumulation in nine tidal wetland systems along the U.S. East Coast from Maine to Georgia can be explained by differences in the rate of relative SLR (RSLR), the concentration of suspended sediments in the rivers draining to the coast, and temperature in the coastal region. Further, we show that rates of vertical accretion have accelerated over the past century by between 0.010 and 0.083 mm yr&#8722;2, at roughly the same pace as the acceleration of global SLR. We estimate that rates of carbon sequestration in these wetland soils have accelerated (more than doubling at several sites) along with accelerating accretion. Wetland accretion and carbon accumulation have accelerated more rapidly in coastal systems with greater relative RSLR, higher watershed sediment availability, and lower temperatures. These findings suggest that the biogeomorphic feedback processes that control accretion and carbon accumulation in these tidal wetlands have responded to accelerating RSLR, and that changes to RSLR, watershed sediment supply, and temperature interact to determine wetland vulnerability across broad geographic scales.
%U https://doi.org/10.1029/2022EF003037
%A Weston, Nathaniel B.
%A Rodriquez, E.
%A Donnelly, B.
%A Solohin, Elena
%A Jezycki, K.
%A Demberger, S.
%A Sutter, Lori
%A Morris, James
%A Neubauer, S. C.
%A Craft, Christopher B.
%K Carbon, accretion, sedimentation, U.S. east coast

%0 Journal Article
%T Herbivory limits success of vegetation restoration globally
%D 2023
%V 382
%P 589-594
%B Science
%9 Article
%Z published
%M GCE.1340
%R 10.1126/science.add2814
%X Restoring vegetation in degraded ecosystems is an increasingly common practice for promoting biodiversity and ecological function, but successful implementation is hampered by an incomplete understanding of the processes that limit restoration success. By synthesizing terrestrial and aquatic studies globally (2594 experimental tests from 610 articles), we reveal substantial herbivore control of vegetation under restoration. Herbivores at restoration sites reduced vegetation abundance more strongly (by 89%, on average) than those at relatively undegraded sites and suppressed, rather than fostered, plant diversity. These effects were particularly pronounced in regions with higher temperatures and lower precipitation. Excluding targeted herbivores temporarily or introducing their predators improved restoration by magnitudes similar to or greater than those achieved by managing plant competition or facilitation. Thus, managing herbivory is a promising strategy for enhancing vegetation restoration efforts.
%U https://doi.org/10.1126/science.add2814
%A Xu, C.
%A Silliman, Brian R.
%A Chen, Jianshe
%A Li, X.
%A Thomsen, Mads S.
%A Zhang, Qun
%A Lee, J.
%A Lefcheck, Jonathan S.
%A Daleo, P.
%A Hughes, Brent B.
%A Jones, Holly P.
%A Wang, Rong
%A Wang, Shaopeng
%A Smith, Carter S.
%A Xi, Xinqiang
%A Alteiri, A.
%A van de Koppel, Johan
%A Palmer, Todd M.
%A Liu, Lingli
%A Wu, Jihua
%A Li, Bo
%A He, Qiang
%K vegetation restoration, herbivory

%0 Journal Article
%T Variation in Densities of the Salt Marsh Katydid Orchelimum fidicinium over Space and Time
%D 2022
%V 45
%P 260-271
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1221
%R 10.1007/s12237-021-00953-y
%X Densities of Orthoptera typically vary greatly over space and time. The most important salt marsh orthopteran on the East Coast of the US is Orchelimum fidicinium, an omnivore that feeds on cordgrass (Spartina alterniflora) and arthropods. We examined spatial (34 sites) and temporal (4 sites, 17 years) variation in O. fidicinium density in coastal Georgia. Sites with considerable adjacent upland habitat had higher densities of O. fidicinium than sites with little adjacent upland. Grasshoppers fed S. alterniflora from both types of sites did not differ in growth rates, ruling out food quality as an explanation. We speculate instead that O. fidicinium require terrestrial habitat for reproduction or escape from predators during extreme high tides. At four sites where O. fidicinium was common, densities varied greatly among years. Regressionmodels indicated that current year plant biomass (three sites) or previous year plant biomass (one site) was the best predictor of O. fidicinium density. Relationships between O. fidicinium and current year plant biomass were typically negative (more grasshoppers in years with lower plant biomass). A possible explanation for this pattern is that plant nutrientsmay be diluted in years with high plant biomass.We found little evidence that density of animal prey (Prokelisia spp.) or abiotic factors affected O. fidicinium densities. Our study illustrates the value of examining population densities across multiple sites and years, because results from any one site or year would likely have mischaracterized the spatial and temporal distribution of this common salt marsh consumer.
%U https://link.springer.com/article/10.1007%2Fs12237-021-00953-y
%A Adams, Tianjiao
%A Vu, Huy
%A Pennings, Steven C.
%K insect, grasshopper, Orchelimum, population dynamics, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Intraspecific variation in the distribution, physiology, population traits, and consumer effects of the salt marsh periwinkle, Littoraria irrorata, across its geographic range
%D 2022
%P 170
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.1280
%X Eastern US salt marshes are productive ecosystems providing numerous benefits to coastal communities. Within marshes, the snail, Littoraria irrorata, is an abundant grazer feeding on the dominant marsh plant, Spartina alterniflora. Previous work has demonstrated that the sign and strength of Littoraria’s effect on Spartina depends on both the abundance and size structure of Littoraria populations. Both of these attributes have the potential to be influenced by processes acting at multiple levels of organization and across spatial and temporal scales. This dissertation aims to quantify several sources of intraspecific variability across Littoraria populations with the ultimate aspiration of informing variation in consumer effects across the entirety of this species’ geographic range. By first understanding latitudinal variation in consumer population traits, we may be better able to explain coarse intraspecific patterns in consumer effects and the conditions under which consumer populations stimulate vs. suppress resource biomass. Across southeastern and mid-Atlantic US salt marshes, we quantified variation in Littoraria’s population density, size structure, resulting population biomass, and its effects on aboveground Spartina biomass over two growing seasons. Results from this study point towards the importance of regional intraspecific trait variation within the broader context of macroecological clines in species interactions. Furthermore, the large amount of unexplained variance in Littoraria density, biomass, and consumer effects partitioned among our experimental and survey plots within individual sites suggest that there are valuable sources of variation to consider at even smaller spatial scales. Lastly, we show that variation in Littoraria thermal traits interact with sizestructure of the Littoraria population to generate divergent population-level (cross site) responses to temperature. For example, when site-specific thermal response parameters are applied to populations with varying size-structures, striking and unexpected patterns emerged in among-site performance. These results collectively highlight the importance of considering variation in population size structure, distribution, and physiological traits when scaling up from individual consumers to cross-population consumer-resource interactions. Future work should strive to more cohesively integrate and resolve the relative importance of these sources of intraspecific variation in such a way that consumer effects can be more seamlessly explained.
%A Atkins, Rebecca
%K Littoraria, Spartina, physiology, body size scaling, consumer effects, Student Publication

%0 Journal Article
%T Thermal Traits Vary with Mass and across Populations of the Marsh Periwinkle, Littoraria irrorata
%D 2022
%V 242
%N 3
%P 173-196
%B The Biological Bulletin
%9 Article
%Z published
%M GCE.1262
%R 10.1086/719850
%X Physiological processes influence how individuals perform in various environmental contexts. The basis of such processes, metabolism, scales allometrically with body mass and nonlinearly with temperature, as described by a thermal performance curve. Past studies of thermal performance curves tend to focus on effects of temperature on a single body size or population, rather than variation in the thermal performance curve across sizes and populations. Here, we estimate intraspecific variation in parameters of the thermal performance curve in the salt marsh gastropod Littoraria irrorata. First, we quantify the thermal performance curve for respiration rate as a function of both temperature and body size in Littoraria and evaluate whether the thermal parameters and body size scaling are interdependent. Next, we quantify how parameters in the thermal performance curve for feeding rate vary between three Littoraria populations that occur along a latitudinal gradient. Our work suggests that the thermal traits describing Littoraria respiration are dependent on body mass and that both the thermal traits and the mass scaling of feeding vary across sites. We found limited evidence to suggest that mass scaling of Littoraria feeding or respiration rates depends on temperature. Variation in the thermal performance curves interacts with the size structure of the Littoraria population to generate divergent population-level responses to temperature. These results highlight the importance of considering variation in population size structure and physiological allometry when attempting to predict how temperature change will affect physiological responses and consumer-resource interactions.
%U https://www.journals.uchicago.edu/doi/10.1086/719850
%A Atkins, Rebecca
%A Clancy, Kathleen
%A Ellis, William
%A Osenberg, Craig W.
%K periwinkle, marsh, Littoraria irrorata, populations, Student Publication

%0 Conference Proceedings
%T Potential drivers of saltmarsh dynamics in the Altamaha River Estuary
%D 2022
%B LTER All Scientists' Meeting
%9 Poster
%Z published
%M GCE.1264
%A Bice, Kadir
%A Sheldon, Joan E.
%A Alber, Merryl
%A Schalles, John F.
%A Meile, Christof
%K marsh dynamics, climatic drivers, time-series analysis

%0 Conference Proceedings
%T Hydrodynamic forcings and causal drivers of saltmarsh biomass in the Altamaha River estuary.
%D 2022
%C Eastonville WA
%B Graduate Climate Conference
%8 Oct 28-30
%9 Presentation
%Z presented
%M GCE.1275
%A Bice, Kadir
%A Sheldon, Joan E.
%A Alber, Merryl
%A Schalles, John F.
%A Meile, Christof
%K biomass, environmental driver, causal connections, wavelet, coherence, Student Publication

%0 Conference Proceedings
%T Spatial and temporal variations in riverine DOM: An analysis of FTICR-MS data from the WHONDRS program.
%D 2022
%C Penn State University, State College, PA
%B HydroML
%8 May 18-20
%9 Poster
%Z presented
%M GCE.1278
%A Bice, Kadir
%A Stadler, M.
%A de Melo, M.
%A Borton, M.
%A Meile, C.
%K DOM, river, core-satellite

%0 Thesis
%T Evaluation of tidal fresh forest distributions and tropical storm impacts using Sentinel-2 MSI imagery
%D 2022
%I Georgia Southern University
%C Statesboro, GA
%9 M.S. Thesis
%Z published
%M GCE.1283
%X Situated in the transitional zone between non-tidal forests upstream and tidal fresh marshes downstream, tidal fresh forests occupy a unique and increasingly precarious habitat. The threat of intensifying anthropogenic climate change, compounded by the effects of historical logging and drainage alterations, could reduce the extent of this valuable ecosystem. The overall goals of this project were to identify forest communities present in the Altamaha tidal fresh forest; develop satellite imagery-based classifications of tidal fresh forest and tidal marsh vegetation along the Altamaha River, Georgia; and to quantify changes in vegetation distribution in the aftermath of hurricanes Matthew and Irma. Based on vegetation data gathered during our field survey, we identified at least eight distinct forest communities with hierarchical clustering methods. Using Sentinel-2 Multispectral Imager (MSI) satellite imagery and a balanced random forest classifier, we mapped land cover for six anniversary images from 2016 to 2021 to examine changes in vegetation distributions. Overall classification accuracies ranged from 80 to 86%, and we were able to accurately discriminate between several classes at the species level. Over our six year study period we did not observe any substantial changes in land cover, including the forest-marsh transition, suggesting resilience to tropical weather impacts. We postulate that this stasis may be due to the large volume of freshwater delivered by the Altamaha River and the extensive tidal marshes of the Altamaha estuary, which protect freshwater wetlands from the short-term effects of saltwater intrusion by reducing salinity and buffering them from acute pulse events such as hurricane storm surges.
%U https://digitalcommons.georgiasouthern.edu/etd/2506/
%A Costomiris, Galen
%K Altamaha River, community analysis, climate change, habitat mapping, hurricanes, plant ecology, remote sensing, satellite imagery, tidal freshwater forests, temporal change, Student Publication

%0 Conference Proceedings
%T Satellite image-based monitoring of tidal forests on the Altamaha River, GA
%D 2022
%I Georgia Southern University
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Poster
%Z presented
%M GCE.1296
%A Costomiris, Galen
%K satellite, tidal forest, Altamaha

%0 Book
%T Creating and Restoring Wetlands: From Theory to Practice. Second Edition
%D 2022
%P 464
%I Elsevier
%7 2nd
%9 Book
%Z published
%M GCE.1288
%R 10.1016/C2020-0-01153-9
%X Creating and Restoring Wetlands: From Theory to Practice, Second Edition describes the challenges and opportunities relating to the restoration of freshwater and estuarine wetlands in natural, agricultural, and urban environments in the coming century. This second edition is structured by clearly defined chapters based on specific wetland types (e.g. Peatlands, Mangroves) and with a consistent and coherent organization for ease of discoverability. The table of contents is divided into four main subjects: Foundations, Restoration of Freshwater Wetlands, Restoration of Estuarine Wetlands, and From Theory to Practice, each with multiple chapters. Part 1, Foundations, contains chapters describing definitions of wetlands, ecological theory used to guide restoration, and considerations on where to implement restoration on the landscape. In Parts 2 and 3, restoration of specific freshwater (marshes, forests, peatlands) and estuarine (tidal marshes, mangroves) wetlands are described. Part 4, From Theory to Practice, contains chapters describing performance standards to gauge success of projects and case studies describing small-scale and large-scale restoration projects of various freshwater and estuarine wetlands. Each chapter contains clearly labeled sections which assist the reader to quickly and easily key in on the subject matter that they are seeking. The approach of Creating and Restoring Wetlands is unique in that, in each chapter, it links ecological theory important to ecosystem restoration with practical techniques to undertake and implement successful wetland restoration projects, including recommendations for performance standards to gauge success as well as realistic expectations and timescales for achieving success. Each chapter ends with a summary table describing keys to ensure success for a given wetland ecosystem.
%U https://doi.org/10.1016/C2020-0-01153-9
%A Craft, Christopher B.
%K wetlands, ecology

%0 Journal Article
%T From the Headwaters to the Sea: The Role of Riparian, Alluvial and Tidal Wetlands to Filter Nutrients and Ameliorate Eutrophication
%D 2022
%P 1-9
%B River
%9 Article
%Z published
%M GCE.1266
%R 10.1002/rvr2.20
%X Wetlands are known for their ability to trap sediment and eliminate pollutants from the surrounding catchment. However, less is known regarding the differential role of headwater, mid-catchment, and coastal wetlands in filtering these materials. Soil accretion, organic carbon (C), total nitrogen (N), and total phosphorus (P) were measured in wetlands from the headwaters to the mouth of the Altamaha River, Georgia, USA to assess how sediment deposition, C sequestration, and N and P burial vary along the waterway. Soil cores (n&#8201;=&#8201;2 per site) were collected from riparian, upper and lower alluvial, tidal freshwater forest and marsh, brackish marsh, and salt marsh. Two-centimeter depth increments were analyzed for 137Cs, to determine soil accretion, bulk density, and C, N, and P concentration. Accretion exhibited a bimodel distribution with the highest rates in riparian wetlands of the headwaters (3.9&#8201;mm/year) and in tidal fresh and brackish marshes (4.7–5.4&#8201;mm/year) of the estuary. Accretion rates were considerably lower in alluvial and tidal fresh forests and salt marshes (0.9–2.5&#8201;mm/year). Carbon sequestration and N burial followed a similar trend with the greatest accumulation in soils of tidal fresh and brackish marshes (102–150&#8201;g&#8201;C/m2/year, 7.1–9.5&#8201;g&#8201;N/m2/year) that had not only high accretion but also high organic matter content (11%–12% C). Riparian soils with their low C content, high bulk density, and high P content had much greater sediment deposition (3310&#8201;g/m2/year) and P burial (2.75&#8201;g&#8201;P/m2/year) than other wetlands along the waterway (180–1730&#8201;g sediment/m2/year, 0.23–0.90&#8201;g&#8201;P/m2/year). Results suggest that, in the Altamaha River, sediment deposition and P removal are maximized in the headwaters thereby protecting downstream freshwaters from the effects of P eutrophication. Tidal fresh and brackish marshes with their high rates of N burial can aid in protecting estuaries from N enrichment, many of which suffer from the effects of N eutrophication. Results from this study are scalable to other rivers of the southeastern U.S. piedmont and coastal plain and similar rivers of this size, topography, and geology.
%U https://doi.org/10.1002/rvr2.20
%A Craft, Christopher B.
%K Eutrophication, organic matter, soil accretion, topography, wetlands, UGAMI Publication

%0 Journal Article
%T Deposit-feeding worms control subsurface ecosystem functioning in intertidal sediment with strong physical forcing.
%D 2022
%V 1
%N 4
%P pgac146
%B PNAS Nexus
%9 Article
%Z published
%M GCE.1274
%R 10.1093/pnasnexus/pgac146
%U https://doi.org/10.1093/pnasnexus/pgac146
%A Deng, L.
%A Meile, C.
%A Fiskal, A.
%A Boelsterli, D
%A Han, X.
%A Gajendra, N.
%A Dubois, N.
%A Bernasconi, S.
%A Lever, M.A.
%K bioturbation, microbial community

%0 Journal Article
%T Long-term ecological research and the COVID-19 anthropause: A window to understanding social–ecological disturbance
%D 2022
%B Ecosphere
%9 Article
%Z published
%M GCE.1256
%R 10.1002/ecs2.4019
%X The period of disrupted human activity caused by the COVID-19 pandemic, coined the “anthropause,” altered the nature of interactions between humans and ecosystems. It is uncertain how the anthropause has changed ecosystem states, functions, and feedback to human systems through shifts in ecosystem services. Here, we used an existing disturbance framework to propose new investigation pathways for coordinated studies of distributed, long-term socialecological research to capture effects of the anthropause. Although it is still too early to comprehensively evaluate effects due to pandemic-related delays in data availability and ecological response lags, we detail three case studies that show how long-term data can be used to document and interpret changes in air and water quality and wildlife populations and behavior coinciding with the anthropause. These early findings may guide interpretations of effects of the anthropause as it interacts with other ongoing environmental changes in the future, particularly highlighting the importance of long-term data in separating disturbance impacts from natural variation and long-term trends. Effects of this global disturbance have local to global effects on ecosystems with feedback to social systems that may be detectable at spatial scales captured by nationally to globally distributed research networks.
%A Gaiser, E.E.
%A Kominoski, John S.
%A McKnight, Diane M.
%A Bahlai, Christie A.
%A Cheng, Chingwen
%A Record, Sydne
%A Wollheim, Wilfred M.
%A Christianson, Kyle R.
%A Downs, Martha R.
%A Hawman, Peter
%A Holbrook, Sally J.
%A Kumar, Abhishek
%A Mishra, Deepak
%A Molotch, Noah P.
%A Primack, Richard B.
%A Rassweiler, Andrew
%A Schmidt, Russell J.
%A Sutter, Lori
%K COVID-19, anthropause, LTER, ecosystems, Cross-site Research

%0 Journal Article
%T A Multi-proxy assessment of the impact of environmental instability on Late Holocene (4500-3800 BP) Native American villages of the Georgia Coast
%D 2022
%B PLOS One
%9 Article
%Z published
%M GCE.1258
%R 10.1371/journal.pone.0258979
%X Circular shell rings along the South Atlantic Coast of North America are the remnants of some of the earliest villages that emerged during the Late Archaic (5000-3000 BP). Many of these villages, however, were abandoned during the Terminal Late Archaic (ca 3800-3000 BP). We combine Bayesian chronological modeling with mollusk shell geochemistry and oyster paleobiology to understand the nature and timing of environmental change associated with the emergence and abandonment of circular shell ring villages on Sapelo Island, Georgia. Our Bayesian models indicate that Native Americans occupied the three Sapelo shell rings at varying times with some generational overlap. By the end of the complex’s occupation, only Ring III was occupied before abandonment ca. 3845 BP. Ring III also consists of statistically smaller oysters harvested from less saline estuaries compared to earlier occupations. Integrating shell biochemical and paleobiological data with recent tree ring analyses shows a clear pattern of environmental fluctuations throughout the period in which the rings were occupied. We argue that as the environment became unstable around 4300 BP, aggregation at villages provided a way to effectively manage fisheries that are highly sensitive to environmental change. However, with the eventual collapse of oyster fisheries and subsequent rebound in environmental conditions ca. post-3800 BP, people dispersed from shell rings, and shifted to non-marine subsistence economies and other types of settlements. This study provides the most comprehensive evidence for correlations between large-scale environmental change and societal transformations on the Georgia coast during the Late Archaic period.
%A Garland, Carey J.
%A Thompson, Victor D.
%A Sanger, Matt
%A Smith, Karen Y
%A Andrus,  C. F.T.
%A Lawres, Nathan R
%A Napora, Katharine
%A Colaninno, Carol E
%A Compton, J. Matthew
%A Jones, Sharyn
%A Hadden, Carla S
%A Cherkinsky, Alexander
%A Maddox, Thomas
%A Deng, Yi-Ting
%A Lulewicz, Isabelle H.
%A Parsons, Lindsey
%K Late Archaic, environmental instability, oyster paleobiology and geochemistry, radiocarbon

%0 Journal Article
%T “We’re still here”: An abolition ecology blockade of double dispossession of Gullah/Geechee land
%D 2022
%P 10
%B Annals of the American Association of Geographers
%9 Article
%Z published
%M GCE.1254
%R 10.1080/24694452.2021.1989282
%X Narratives of resilience to sea-level rise too often perpetuate social violence. An abolitionist climate justice praxis necessitates seeing beyond physical inundation to sea-level rise as the sole issue. We argue that sea-level rise is environmental racism, if not always in its racialized outcomes of disproportionate harms, then always in its racialized production of differential value. More than mitigating flood risk when developing Black land futures strategies, to mitigate coastal land loss in the face of rising seas necessitates dismantling “racial regimes of ownership” that are imbued in property relations. Recognizing such, we argue that land futures strategies in the face of rising seas must account for multiple capitalist modes of accumulation but specifically the primitive accumulation process connected to heirs’ property. Here, we argue that racial coastal formations are still underway in how sea-level rise and gentrification are leading to a double dispossession of land and displacing Gullah/Geechee people on Sapelo Island. Although such displacement precipitates loss through harm and violence, in this article we share strategies from abolition ecology praxis to “blockade” these double dispossession processes and, to a degree, even the narrative of loss. To situate the double dispossession narrative within a broader praxis that imagines alternative futures, we till the soil, trace the archives, and tread the marsh and drainage ditches with each other, and in solidarity with other residents, to work toward achieving agricultural revival, property retention, and flood risk mitigation.
%U https://www.tandfonline.com/doi/full/10.1080/24694452.2021.1989282
%A Hardy, Dean
%A Bailey, Maurice
%A Heynen, Nik
%K abolition ecology, heirs’ property, land dispossession, sea-level rise, UGAMI Publication

%0 Conference Proceedings
%T Dynamic emergent leaf area in tidal wetlands: Implications for Blue Carbon
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Poster
%Z presented
%M GCE.1297
%A Hawman, Peter
%K tidal wetlands, blue carbon

%0 Conference Proceedings
%T A random forest model of salt marsh aboveground biomass at multiple LTER sites on the eastern coast of the United States
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Poster
%Z presented
%M GCE.1299
%A Julien, Asa
%K random forest model, salt marsh, aboveground biomass, Cross-site Research

%0 Journal Article
%T Responses of a tidal freshwater marsh plant community to chronic and pulsed saline intrusion
%D 2022
%V 110
%P 1508-1524
%B Journal of Ecology
%9 Article
%Z published
%M GCE.1257
%R 10.1111/1365-2745.13885
%X 1. Climate change causes both chronic and pulsed environmental changes to ecosystems. In estuaries, tidal freshwater marshes experience both extended and episodic periods of elevated salinities due to sea level rise, reduced river discharge during drought and storm surge, but most research has focused on extended (press) perturbations.2. Over a 4-year period, we added diluted seawater to replicated plots in a tidal freshwater marsh in Georgia, USA to raise porewater salinities from freshwater to oligohaline. We assessed the ecosystem effects of press (continuous) and pulse (2 months per year) changes in salinity by measuring the responses of dominant angiosperms, benthic microalgae and dominant macro-invertebrates (fiddler crabs). We transplanted angiosperms typical of oligohaline and mesohaline conditions into plots as bioindicators (phytometers) to assess potential forvegetation changes over longer time periods.3. In the press treatment, the cover of all common plant species decreased. Ludwigia repens almost disappeared within the first month; Polygonum hydropiperoides nearly disappeared within the first growing season; Pontederia cordata and Zizaniopsis miliacea declined over the 4 years but did not completely disappear. The decline in the four most dominant plant species decreased total above-ground plant biomass, leading to an increase in light penetration and increased densities of benthic diatoms and cyanobacteria. The density of fiddler crab burrows was not significantly affected by the treatments, but was positively related to above-ground plant biomass across all replicates. Transplant experiments indicatedthat plants typical of higher salinity conditions (e.g. Schoenoplectus sp.) performed well under conditions prevalent in the press plots.4. In the pulse treatment, only L. repens declined, and there was no effect on community-level above-ground biomass or other community variables.5. Synthesis. Our results indicate that tidal freshwater marsh plant and animal communities are vulnerable to extended periods of salinization but resilient to short saline pulses. Although saline pulses did not impair most ecosystem functions, the decline in a single species (L. repens) in the pulse treatment was associated with reduced marsh accretion and no elevation gain—factors which must be positive for wetland survival in an era of rising seas. Thus, periodic salinization may threaten the long-term persistence of freshwater wetlands even before dramatic changes in community structure occurs.
%U https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.13885
%A Li, Fan
%A Angelini, Christine
%A Byers, James
%A Craft, Christopher B.
%A Pennings, Steven C.
%K brackish marsh, climate change, press, pulse, salinity, salinization, sea level rise, tidal freshwater marsh, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Sources of polyamines in coastal waters and their links to phytoplankton
%D 2022
%V 242
%B Marine Chemistry
%9 Article
%Z published
%M GCE.1259
%R 10.1016/j.marchem.2022.104121
%X Polyamines are key components of labile dissolved organic nitrogen in coastal waters. They are found in all living organisms, which are the sources of dissolved organic matter in marine environments. The concentrations of dissolved polyamines are generally low and are controlled as much by production as by consumption. Understanding the dynamics of intracellular pools of polyamines could provide insight to their dynamics in the environment and their potential contribution to ecosystem processes. We measured the concentrations of 6 common polyamines (putrescine, cadaverine, norspermidine, spermidine, norspermine and spermine) extracted from particles in water samples collected on the continental shelf of the South Atlantic Bight (SAB). The total concentrations of extractable polyamines (EPs) decreased from inshore to the shelf-break of the SAB, following a pattern similar to chlorophyll a and opposite to salinity. The composition of EPs was highly correlated with the distribution of phytoplankton species assessed as the abundance of diatom 18S rRNA genes, and with densities of picoeukaryote, Synechococcus and Prochlorococcus cells, suggesting that phytoplankton are the primary source of EPs, followed by a freshwater or nearshore source. Our data suggest that putrescine, norspermidine and spermidine are released primarily from diatoms and picoeukaryotes, while Synechococcus and dinoflagellates are the likely sources of norspermine and spermine.
%A Liu, Qian
%A Nishibori, Naoyoshi
%A Hollibaugh, James T.
%K Polyamines, Diatoms, Picoeukaryotes, cyanobacteria, Dissolved organic nitrogen, DON, DOC, Student Publication, UGAMI Publication

%0 Thesis
%T Grazers vs Grazers: Large Mammal Herbivores Influence Salt Marsh Invertebrate Communities
%D 2022
%I University of Houston
%C Houston
%9 M.S. Thesis
%Z published
%M GCE.1270
%X Large mammals cause disturbances in the environments in which they graze by dramaticallychanging the physical structure of habitats. The response of plant and animal communities tomegafaunal herbivory is highly variable among ecosystems, geographic location, and species ofinterest. Past research has often only focused on the response of a single taxa, and effects ofgrazing in North American salt marshes is understudied. I conducted field studies on threebarrier islands on the coast of Georgia, USA. Each island served as a site for one of three grazingtreatments (cattle, feral horses, and artificial grazing by clipping). Treatment and control plotsat the three sites were sampled for vegetation metrics and invertebrate abundance anddiversity. All three grazing types altered invertebrate community composition, and eachrepresented a different level of grazing intensity. Cattle grazing had a particularly negativeimpact, while artificial grazing produced some opposite effects. Some vegetation characteristicsand taxa had varied responses, but others responded similarly to all three grazing types. Plantheight and katydid density were consistently reduced by the three grazing types, indicating thatgrazed vegetation does not provide katydids with ideal conditions. To further investigate this, Iperformed two katydid feeding experiments and found that a more nutritious diet may notnecessarily be more palatable. The responses of different taxonomic groups and invertebratecommunities and the underlying mechanisms should be considered when making livestock andland management decisions that aim to promote ecosystem functioning.
%A Lugar, Kori
%K herbivory, megafauna, insects, horses, cattle

%0 Conference Proceedings
%T Using UAVs to Analyze Biomass and Wrack in Salt Marshes at the Georgia Coastal Ecosystems LTER
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%S Drone imagery for Vegetation and Habitat Studies
%8 September 21, 2022
%9 Presentation
%Z presented
%M GCE.1302
%A Lynn, Tyler
%K UAV, biomass, wrack, salt marsh

%0 Thesis
%T Impacts Of Tidal Channel Migration On Salt Marsh Ecology And Carbon Storage
%D 2022
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.1292
%A Manns, Tiandra
%K Marsh Ecology, Carbon Storage, Channel Migration

%0 Thesis
%T Impacts of Tidal Channel Migration on Salt Marsh Ecology and Carbon Storage
%D 2022
%P 40
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.1328
%X Salt marshes and the role these ecosystems play in local-to-global carbon budgets are an important factor in how these ecosystems play a part in the overall carbon budget. The generation and integration of how tidal channel migration processes affect marsh ecology and carbon storage is important in understanding how marshes change over time. This research evaluated ecosystem function by characterizing plant and animal communities, sediment pore water chemistry, sediment carbon storage, and vertical accretion rates in three marshes impacted by channel migration. Samples were collected from regions within three marshes that were present in the 18000’s, 1930’s, and 2000’s in Doboy Sound, GA. The prograding side consists of these three regions and samples were taken from each. The retreating side consisted of regions that were from the 1800’s and beyond. Results concluded that marshes are impacted by tidal channel migration over time, but marsh retreat is compensated by marsh progradation.
%A Manns, Tiandra
%K Saltmarsh, Tidal channel migration, Carbon, Sediment, Radioisotope, Student Publication

%0 Journal Article
%T The effects of hurricanes and storms on the composition of dissolved organic matter in a southeastern U.S. estuary
%D 2022
%V 9
%P 855720
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1260
%R 10.3389/fmars.2022.855720
%X Extreme events such as hurricanes and tropical storms often result in large fluxes of dissolved organic carbon (DOC) to estuaries. Precipitation associated with tropical storms may be increasing in the southeastern U.S., which can potentially impact dissolved organic matter (DOM) dynamics and cycling in coastal systems. Here, DOM composition at the Altamaha River and Estuary (Georgia, U.S.A.) was investigated over multiple years capturing seasonal variations in river discharge, high precipitation events, and the passage of two hurricanes which resulted in substantial storm surges. Optical measurements of DOM indicate that the terrigenous signature in the estuary is linearly related to freshwater content and is similar after extreme events with or without a storm surge and during peak river flow. Molecular level analysis revealed significant differences, however, with a large increase of highly aromatic compounds after extreme events exceeding what would be expected by freshwater content alone. Although extreme events are often followed by increased DOC biodegradation, the terrigenous material added during those events does not appear to be more labile than the remainder of the DOM pool that was captured by ultrahigh-resolution mass spectrometry analysis. This suggests that the added terrigenous organic matter may be exported to the coastal ocean, while a fraction of the organic matter that co-varied with the terrigenous DOM may contribute to the increased biomineralization in the estuary, with implications to carbon processing in coastal areas.
%U https://www.frontiersin.org/articles/10.3389/fmars.2022.855720/full
%A Medeiros, Patricia M.
%K Dissolved organic matter, Hurricanes, DOM composition, Microbial degradation, FT-ICR MS, Marsh-dominated estuary, Southeastern U.S., UGAMI Publication

%0 Conference Proceedings
%T Flooding in Landsat across tidal systems (FLATS)
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Poster
%Z presented
%M GCE.1298
%A Narron, Caroline
%K Landsat, flooding

%0 Journal Article
%T Flooding in Landsat across tidal systems (FLATS): An index for intermittent tidal filtering and frequency detection in salt marsh environments
%D 2022
%V 141
%P 109045
%B Ecological Indicators
%9 Article
%Z published
%M GCE.1261
%R 10.1016/j.ecolind.2022.109045
%X Remote sensing can provide critical information about the health and productivity of coastal wetland ecosystems, including extent, phenology, and carbon sequestration potential. Unfortunately, periodic inundation from tides dampens the spectral signal and, in turn, causes remote sensing-based models to produce unreliable results, altering estimates of ecosystem function and services. We created the Flooding in Landsat Across Tidal Systems (FLATS) index to identify flooded pixels in Landsat 8 30-meter data and provide an inundated pixel filtering method. Novel applications of FLATS including inundation frequency and pattern detection are also demonstrated. The FLATS index was developed to identify flooding in Spartina alterniflora tidal marshes. We used ground truth inundation data from a PhenoCam and Landsat 8 pixels within the PhenoCam field of view on Sapelo Island, GA, USA to create the index. The FLATS index incorporates a normalized difference water index (NDWI) and a phenology-related variable into a generalized linear model (GLM) that predicted the presence or absence of marsh flooding. The FLATS equation for predicting flooding is 1-1/e^-1.6+20*NDWI4,6+68.6*Pheno3,4, and we found that a cutoff 0.1 was the optimized value for separating flooded and non-flooded pixel classes. FLATS identified flooded pixels with an overall accuracy of 96% and 93% across training data and novel testing data, respectively. FLATS correctly identified true flooded pixels with a sensitivity of 97% and 81%, across training and testing data, respectively. We established the need to apply FLATS when conducting vegetation time-series analysis in coastal marshes in order to reduce the per-pixel reflectance variations attributed to tidal flooding. We found that FLATS identified 12.5% of pixels as flooded in Landsat 8 tidal marsh vegetation time-series from 2013 to 2020, after traditional quality control and preprocessing steps were conducted, which could then be filtered out or modeled separately in order to conduct remotely sensed vegetation assessments. Therefore, in tidal wetlands, we recommend incorporating FLATS into Landsat 8 preprocessing prior to vegetation analysis. We also demonstrated innovative applications for the FLATS index, particularly in detecting flooding frequency and flooding patterns relevant to the broader biophysical modeling framework, including mapping marsh vulnerability due to fluctuation in inundation frequency. The FLATS index represents advancements in the understanding and application of inundation indices for coastal marshes.
%U http://gce-lter.marsci.uga.edu/public/uploads/1-s2.0-S1470160X22005167-main_20220708T200751.pdf
%A Narron, Caroline
%A O'Connell, Jessica L.
%A Mishra, Deepak
%A Cotten, David L.
%A Hawman, Peter
%A Mao, Lishen
%K Tidal inundation, Salt marshes, Flooding, Sea level rise, Spartina alterniflora, Coastal wetland, Georgia Coastal Ecosystems Long Term Ecological Re, Google Earth Engine, Student Publication, UGAMI Publication

%0 Journal Article
%T Lessons from the invasion of Spartina alterniflora in coastal China
%D 2022
%V 104
%P e3874
%B Ecology
%9 Article
%Z published
%M GCE.1268
%R 10.1002/ecy.3874
%A Nie, Ming
%A Liu, Wenwen
%A Pennings, Steven C.
%A Li, Bo
%K spartina, salt marsh, invasive species, Cross-site Research, SINERR Publication, UGAMI Publication

%0 Thesis
%T Position in the tidal frame strongly influences decomposition in salt marshes.
%D 2022
%I University of Georgia
%C Athens, GA
%9 B.S. Thesis
%Z published
%M GCE.1289
%A Reddy, Satyatejas
%K decomposition, salt marshes

%0 Conference Proceedings
%T Position in the Tidal Frame Strongly Influences Decomposition in Salt Marshes
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Poster
%Z presented
%M GCE.1301
%A Reddy, Satyatejas
%K decomposition, salt marshes

%0 Journal Article
%T Responses of Coastal Ecosystems to Climate Change: Insights from Long-Term Ecological Research.
%D 2022
%V 72
%N 9
%P 871-888
%B BioScience
%9 Article
%Z published
%M GCE.1285
%R 10.1093/biosci/biac006
%X Coastal ecosystems play a disproportionately large role in society, and climate change is altering their ecological structure and function, as well as their highly valued goods and services. In the present article, we review the results from decade-scale research on coastal ecosystems shaped by foundation species (e.g., coral reefs, kelp forests, coastal marshes, seagrass meadows, mangrove forests, barrier islands) to show how climate change is altering their ecological attributes and services. We demonstrate the value of site-based, long-term studies for quantifying the resilience of coastal systems to climate forcing, identifying thresholds that cause shifts in ecological state, and investigating the capacity of coastal ecosystems to adapt to climate change and the biological mechanisms that underlie it. We draw extensively from research conducted at coastal ecosystems studied by the US Long Term Ecological Research Network, where long-term, spatially extensive observational data are coupled with shorter-term mechanistic studies to understand the ecological consequences of climate change.
%U https://doi.org/10.1093/biosci/biac006
%A Reed, Daniel
%A Schmitt, Russell
%A Burd, Adrian B.
%A Burkepile, Deron
%A Kominoski, John S.
%A McGlathery, Karen
%A Miller, Robert
%A Morris, James
%A Zinnert, Julie C.
%K coastal ecosystems, climate change

%0 Journal Article
%T Indigenous oyster fisheries persisted for millennia and should inform future management
%D 2022
%V 13
%N 2383
%B Nature Communications
%9 Article
%Z published
%M GCE.1263
%R 10.1038/s41467-022-29818-z
%X Historical ecology has revolutionized our understanding of fisheries and cultural landscapes,demonstrating the value of historical data for evaluating the past, present, and future ofEarth’s ecosystems. Despite several important studies, Indigenous fisheries generally receiveless attention from scholars and managers than the 17th–20th century capitalist commercialfisheries that decimated many keystone species, including oysters. We investigate Indigenousoyster harvest through time in North America and Australia, placing these data in thecontext of sea level histories and historical catch records. Indigenous oyster fisheries werepervasive across space and through time, persisting for 5000–10,000 years or more. Oysterswere likely managed and sometimes “farmed,” and are woven into broader cultural, ritual, andsocial traditions. Effective stewardship of oyster reefs and other marine fisheries around theworld must center Indigenous histories and include Indigenous community members to codevelopmore inclusive, just, and successful strategies for restoration, harvest, andmanagement.
%A Reeder-Myers, Leslie
%A Braje, Todd, J.
%A Hofman, Courtney, A.
%A Elliot Smith, Emma, A.
%A Garland, Carey J.
%A Grone, Michael
%A Hadden, Carla, S.
%A Hatch, Marco
%A Hunt, Turner
%A Kelley, Alice
%A LeFebvre, Michelle, J.
%A Lockman, Michael
%A McKechnie, Iain
%A McNiven, Ian, J.
%A Newsom, Bonnie
%A Pluckhahn, Thomas
%A Sanchez, Gabriel
%A Schwadron, Margo
%A Smith, Karen, Y.
%A Smith, Tam
%A Spiess, Arthur
%A Tayac, Gabrielle
%A Thompson, Victor, D.
%A Vollman, Taylor
%A Weitzel, Elic, M.
%A Rick, Torben, C.
%K Indigenous oyster fisheries management

%0 Journal Article
%T Shallow Water Estuarine Mapping in High-Tide-Range Environments: A Case Study from Georgia, USA
%D 2022
%V 45
%P 980-999
%B Estuaries and Coasts
%S Shallow Water Mapping
%9 Article
%Z includes updated bathymetric mapping for Sapleo Sound and Doboy Sound entrance
%M GCE.1282
%R 10.1007/s12237-021-01032-y
%X Efficient methods for shallow water data collection have been employed to create comprehensive bathymetric surfaces for 3 Georgia sounds. Survey areas were characterized using existing charted depths, aerial photographs, and lidar-derived elevation data to identify regions shallower than 3-m mean lower low water. Single-beam sonar missions were completed for these shallow areas using various marine platforms to constrain the existing 3-m isobath. Below 3 m, waters are deep enough, and swath width is wide enough, to use a larger vessel with an interferometric sonar system collecting swath bathymetry and sidescan imagery. The collected data were merged and gridded in a geographic information system environment to generate digital elevation models. The modern digital surfaces were compared with historic depth data to identify areas of shoaling and deepening. The mean overall change between the historic data and modern data was relatively small (0.7 m for Wassaw Sound, 0.4 m for Ossabaw Sound, and 0.1 m for Sapelo Sound); only the change in Wassaw was greater than the error in the analysis. However, each sound exhibited up to 20 m of shoaling and deepening associated with entrance channel migration, illustrating that a significant change occurs in specific geomorphic zones in each of these settings. Sediment grabs ground-truth sidescan sonar imagery to interpret environmental energy and bottom character. The mean sediment size for all sounds fell in the fine to very fine sand range (2–4 phi), reflecting the characteristics of the coastal sediment prism, although gravels and muds characterize areas of scour and quiescent conditions, respectively. These surveys led to the first identification of hard-bottom habitats of erosion-resistant, vertical cliffs up to 10 m high and 1000 m long in Southeastern US estuaries.
%A Robinson, Michael
%A Alexander, Clark R., Jr.
%A Venherm, Claudia
%K bathymetry, sounds, mesotidal, surveying, Wassaw, Ossabaw, St Catherines, Sapelo

%0 Journal Article
%T The core root microbiome of Spartina alterniflora is predominated by sulfur-oxidizing and sulfate-reducing bacteria in Georgia salt marshes, USA
%D 2022
%V 10
%N 37
%B Microbiome
%9 Article
%Z published
%M GCE.1290
%R 10.1186/s40168-021-01187-7
%X Background: Salt marshes are dominated by the smooth cordgrass Spartina alterniflora on the US Atlantic and Gulf of Mexico coastlines. Although soil microorganisms are well known to mediate important biogeochemical cycles in salt marshes, little is known about the role of root microbiomes in supporting the health and productivity of marsh plant hosts. Leveraging in situ gradients in aboveground plant biomass as a natural laboratory, we investigated the relationships between S. alterniflora primary productivity, sediment redox potential, and the physiological ecology of bulk sediment, rhizosphere, and root microbial communities at two Georgia barrier islands over two growing seasons.Results: A marked decrease in prokaryotic alpha diversity with high abundance and increased phylogenetic dispersion was found in the S. alterniflora root microbiome. Significantly higher rates of enzymatic organic matter decomposition, as well as the relative abundances of putative sulfur (S)-oxidizing, sulfate-reducing, and nitrifying prokaryotes correlated with plant productivity. Moreover, these functional guilds were overrepresented in the S. alterniflora rhizosphere and root core microbiomes. Core microbiome bacteria from the Candidatus Thiodiazotropha genus, with the metabolic potential to couple S oxidation with C and N fixation, were shown to be highly abundant in the root and rhizosphere of S. alterniflora.Conclusions: The S. alterniflora root microbiome is dominated by highly active and competitive species taking advantage of available carbon substrates in the oxidized root zone. Two microbially mediated mechanisms are proposed to stimulate S. alterniflora primary productivity: (i) enhanced microbial activity replenishes nutrients and terminal electron acceptors in higher biomass stands, and (ii) coupling of chemolithotrophic S oxidation with carbon (C) and nitrogen (N) fixation by root- and rhizosphere-associated prokaryotes detoxifies sulfide in the root zone while potentially transferring fixed C and N to the host plant.
%U https://doi.org/10.1186/s40168-021-01187-7
%A Rolando, Jose L.
%A Kolton, Max
%A Song, Tianze
%A Kostka, Joel
%K Spartina alternifora, Salt marsh, Rhizosphere, Microbiome, Root, Biogeochemical cycles, Sulfur oxidation, Sulfate reduction

%0 Conference Proceedings
%T Dynamic, Rule-based Quality Control for Sensor Data Using the GCE Toolbox
%D 2022
%I LTER
%C Asilomar, CA
%B LTER All Scientist Meeting
%S Techniques and Approaches for Improving LTER Data Quality
%8 September 21, 2022
%9 Presentation
%Z presented
%M GCE.1291
%A Sapp, Adam
%K sensors, quality control, GCE toolbox

%0 Conference Proceedings
%T Drone imagery for Vegetation and Habitat Studies
%D 2022
%I Creighton
%B LTER All Scientist Meeting
%8 September 22, 2022
%9 Presentation
%Z presented
%M GCE.1293
%A Schalles, John F.
%K Drone imagery, habitat, vegetation

%0 Journal Article
%T Remote Sensing of Surface and Subsurface Soil Organic Carbon in Tidal Wetlands: A Review and Ideas for Future Research
%D 2022
%V 14
%N 2940
%B Remote Sensing
%9 Article
%Z published
%M GCE.1330
%R 10.3390/rs14122940
%X Tidal wetlands, widely considered the most extensive reservoir of soil organic carbon (SOC), can benefit from remote sensing studies enabling spatiotemporal estimation and mapping of SOC stock. We found that a majority of the remote-sensing-based SOC mapping efforts have been focused on upland ecosystems, not on tidal wetlands. We present a comprehensive review detailing the types of remote sensing models and methods used, standard input variables, results, and limitations for the handful of studies on tidal wetland SOC. Based on that synthesis, we pose several unexplored research questions and methods that are critical for moving tidal wetland SOC science forward. Among these, the applicability of machine learning and deep learning models for predicting surface SOC and the modeling requirements for SOC in subsurface soils (soils without a remote sensing signal, i.e., a soil depth greater than 5 cm) are the most important. We did not find any remote sensing study aimed at modeling subsurface SOC in tidal wetlands. Since tidal wetlands store a significant amount of SOC at greater depths, we hypothesized that surface SOC could be an important covariable along with other biophysical and climate variables for predicting subsurface SOC. Preliminary results using field data from tidal wetlands in the southeastern United States and machine learning model output from mangrove ecosystems in India revealed a strong nonlinear but significant relationship (r2 = 0.68 and 0.20, respectively, p < 2.2 × 10&#8722;16 for both) between surface and subsurface SOC at different depths. We investigated the applicability of the Soil Survey Geographic Database (SSURGO) for tidal wetlands by comparing the data with SOC data from the Smithsonian’s Coastal Blue Carbon Network collected during the same decade and found that the SSURGO data consistently over-reported SOC stock in tidal wetlands. We concluded that a novel machine learning framework that utilizes remote sensing data and derived products, the standard covariables reported in the limited literature, and more importantly, other new and potentially informative covariables specific to tidal wetlands such as tidal inundation frequency and height, vegetation species, and soil algal biomass could improve remote-sensing-based tidal wetland SOC studies.
%U https://doi.org/10.3390/rs14122940
%A Sharma, Rajneesh
%A Mishra, Deepak
%A Levi, Matthew R.
%A Sutter, Lori
%K belowground soil organic matter, SOC stocks, soil bulk density, Coastal Blue Carbon Network, SSURGO, machine learning, salt marsh, mangroves

%0 Journal Article
%T Greater Consideration of Animals Will Enhance Coastal Restoration Outcomes
%D 2022
%V 72
%N 11
%P 1088-1098
%B BioScience
%9 Article
%Z published
%M GCE.1286
%R 10.1093/biosci/biac088
%X As efforts to restore coastal habitats accelerate, it is critical that investments are targeted to most effectively mitigate and reverse habitat loss and its impacts on biodiversity. One likely but largely overlooked impediment to effective restoration of habitat-forming organisms is failing to explicitly consider non-habitat-forming animals in restoration planning, implementation, and monitoring. These animals can greatly enhance or degrade ecosystem function, persistence, and resilience. Bivalves, for instance, can reduce sulfide stress in seagrass habitats and increase drought tolerance of saltmarsh vegetation, whereas megaherbivores can detrimentally overgraze seagrass or improve seagrass seed germination, depending on the context. Therefore, understanding when, why, and how to directly manipulate or support animals can enhance coastal restoration outcomes. In support of this expanded restoration approach, we provide a conceptual framework, incorporating lessons from structured decision-making, and describe potential actions that could lead to better restoration outcomes using case studies to illustrate practical approaches.
%U https://doi.org/10.1093/biosci/biac088
%A Sievers, Michael
%A Brown, Christopher
%A Buelow, Christina
%A Hale, Robin
%A Ostrowski, Andria
%A Saunders, Megan
%A Silliman, Brian R.
%A Swearer, Stephen
%A Turschwell, Mischa
%A Valdez, Stephanie
%A Connolly, Rod
%K coastal restoration

%0 Journal Article
%T Insights into Salt Marsh Plant Community Distributions Through Computer Vision and Structural Equation Modeling
%D 2022
%V 46
%P 431-449
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1331
%R 10.1007/s12237-022-01147-w
%X Community structure and dynamics are influenced by numerous abiotic and biotic factors requiring large datasets to disentangle, which are often difficult to obtain over the spatiotemporal scales necessary for meaningful analysis. The approach outlined here illustrates one potential solution to this problem by leveraging computer vision methods to gain accurate, in-depth community data from&#8201;~&#8201;10,000 photographs of salt marsh plants across an elevation gradient at Sapelo Island, GA, USA. A convolutional neural network (ResNext101) trained to detect the 6 dominant plant species achieved high accuracy for all species, allowing mapping of high-marsh plant communities over gradients in elevation and pore-water salinity. To statistically analyze the high-resolution mapping data, we constructed a structural equations model using the generated data as informed by prevailing ecological theory for salt marshes in the Southeastern United States. Model fit to data was strong, with R2 values for five of six plant species&#8201;>&#8201;0.7. The distribution of the rare understory perennial Limonium carolinianum, however, was not accurately predicted by the model. Modeled effects of abiotic factors elevation and soil salinity were commensurate with the literature. Biotic interactions also largely conformed to ecological understanding of Southeastern marshes, but a potentially novel positive interaction between Borrichia frutescens and Batis maritima was observed. Overall, this approach shows promise as a method of efficiently generating and statistically analyzing community data for sessile species at scales not previously possible. This study contributes to a growing body of work developing integrated computer vision and big data techniques for ecological field work.
%U https://link.springer.com/article/10.1007/s12237-022-01147-w
%A Simon, J.
%A Hopkinson, Brian M.
%A Pennings, Steven C.
%K Salt marsh, Computer vision, Community ecology, Structural equation modeling, Deep learning, Methodological pipeline, Student Publication

%0 Journal Article
%T Recovering wetland biogeomorphic feedbacks to restore the world's biotic carbon hotspots
%D 2022
%V 376
%N 6593
%B Science
%9 Article
%Z published
%M GCE.1287
%R 10.1126/science.abn1479
%X Biogeomorphic wetlands cover 1% of Earth’s surface but store 20% of ecosystem organic carbon. This disproportional share is fueled by high carbon sequestration rates and effective storage in peatlands, mangroves, salt marshes, and seagrass meadows, which greatly exceed those of oceanic and forest ecosystems. Here, we review how feedbacks between geomorphology and landscape-building vegetation underlie these qualities and how feedback disruption can switch wetlands from carbon sinks into sources. Currently, human activities are driving rapid declines in the area of major carbon-storing wetlands (1% annually). Our findings highlight the urgency to stop through conservation ongoing losses and to reestablish landscape-forming feedbacks through restoration innovations that recover the role of biogeomorphic wetlands as the world’s biotic carbon hotspots. 
%U https://doi.org/10.1126/science.abn1479
%A Temmink, Ralph J.
%A Lamers, L.P.M.
%A Angelini, Christine
%A Bouma, Tjeerd J.
%A Fritz, Christian
%A van de Koppel, Johan
%A Lexmond, Robin
%A Rietkerk, Max
%A Silliman, Brian R.
%A Joosten, Hans
%A van der Heide, Tjisse
%K wetlands, carbon, biogeomorphic

%0 Conference Proceedings
%T A faunal engineer, G. demissa, enhances nitrogen transport in SE salt marshes
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Poster
%Z presented
%M GCE.1300
%A Williams, Sydney Laine
%K nitrogen transport, salt marshes

%0 Journal Article
%T Annual Lateral Organic Carbon Exchange Between Salt Marsh and Adjacent Water: A Case Study of East Headland Marshes at the Yangtze Estuary
%D 2022
%V 8
%N 809618
%P 15
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1333
%R 10.3389/fmars.2021.809618
%X Blue carbon (C) ecosystems (mangroves, salt marshes, and seagrass beds) sequester high amounts of C, which can be respired back into the atmosphere, buried for long periods, or exported to adjacent ecosystems by tides. The lateral exchange of C between a salt marsh and adjacent water is a key factor that determines whether a salt marsh is a C source (i.e., outwelling) or sink in an estuary. We measured salinity, particulate organic carbon (POC), and dissolved organic carbon (DOC) seasonally over eight tidal cycles in a tidal creek at the Chongming Dongtan wetland from July 2017 to April 2018 to determine whether the marsh was a source or sink for estuarine C. POC and DOC fluxes were significantly correlated in the four seasons driven by water fluxes, but the concentration of DOC and POC were positively correlated only in autumn and winter. DOC and POC concentrations were the highest in autumn (3.54 mg/L and 4.19 mg/L, respectively) and the lowest in winter and spring (1.87 mg/L and 1.51 mg/L, respectively). The tidal creek system in different seasons showed organic carbon (OC) export, and the organic carbon fluxes during tidal cycles ranged from –12.65 to 4.04 g C/m2. The intensity showed significant seasonal differences, with the highest in summer, the second in autumn, and the lowest in spring. In different seasons, organic carbon fluxes during spring tides were significantly higher than that during neap tides. Due to the tidal asymmetry of the Yangtze River estuary and the relatively young stage, the salt marshes in the study area acted as a strong lateral carbon source.
%U https://doi.org/10.3389/fmars.2021.809618
%A Yuan, Y.
%A Li, Xiuzhen
%A Xie, Zuolun
%A Xue, L.
%A Yang, B.
%A Zhao, Wenzhen
%A Craft, Christopher B.
%K blue carbon, salt marsh, organic carbon fluxes, tide, tidal creek

%0 Conference Proceedings
%T Synthesizing LTER data to determine drivers of food webs; 
%D 2022
%I University of Georgia
%C Asilomar, CA
%B LTER All Scientist Meeting
%8 September 21, 2022
%9 Presentation
%Z presented
%M GCE.1294
%A Ziegler, Shelby
%K food webs, synthesis

%0 Book Section
%T Sustaining Long-Term Ecological Research: Perspectives from Inside the LTER Program
%D 2021
%I Springer Nature
%C Switzerland
%B The Challenges of Long Term Ecological Research:  Historical Analysis
%9 Article
%Z published
%M GCE.1196
%A Alber, Merryl
%A Blair, John M.
%A Driscoll, Charles
%A Ducklow, Hugh
%A Fahey, Timothy
%A Fraser, William R. 
%A Hobbie, John E. 
%A Karl, David M. 
%A Kingsland, Sharon E. 
%A Knapp, Alan
%A Rastetter, Edward
%A Seastedt, Timothy
%A Shaver, Gaius
%A Waide, Robert B.
%E Waide, Robert B. 
%E Kingsland, Sharon E.
%K LTER

%0 Journal Article
%T Plasticity and selection drive hump-shaped latitudinal patterns of flowering phenology in an invasive intertidal plant
%D 2021
%V 102
%B Ecology
%9 Article
%Z published
%M GCE.1230
%R 10.1002/ecy.3311
%X Patterns of flowering phenology can affect the success of plant invasions, especially when introduced species spread across a wide range of latitude into different climatic conditions. We combined a 4-yr field survey and a 3-yr common garden experiment with the invasive grass Spartina alterniflora that is now widespread along the coast of China to document the latitudinal pattern of flowering phenology, determine if phenology was related to cli-mate or oceanographic variables, and determine whether phenology patterns were fixed versus plastic. In the field, first flowering day displayed a hump-shaped relationship with latitude, with low- and high-latitude plants flowering 100 d and 10 d earlier than plants at middle latitudes, respectively. Peak flowering day showed a similar hump-shaped relationship with latitude, with the interval between first and peak flowering day decreasing with increasing latitude. First flowering day had a hump-shaped relationship with annual growing degree days but a linear positive relationship with tidal range. In the common garden, first flowering day decreased linearly with increasing latitude of origin, as did peak flowering day, and the interval between first and peak flowering day increased with increasing latitude. First flowering day in the common garden had weak or no relationships with abiotic variables at the sites of origin. In both the field and common garden, first flowering day was later in site years for which plants were taller. These results indicate a high degree of plasticity in flowering phenology, with plants flowering later in the field at sites with intermediate temperatures and high tide ranges. Common garden results indicate some selection for earlier flowering at sites with low temperatures, consistent with a shorter growing season. Consistent with life-history theory, plants flowered later under conditions favoring vigorous growth. Earlier flowering and smaller size of plants at high and low latitudes suggests that S. alterniflora has already occupied much of the geographic range favorable for it on the East Coast of Asia.
%U https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3311?af=R
%A Chen, Xincong
%A Liu, Wenwen
%A Pennings, Steven C.
%A Zhang, Yihui
%K adaptive evolution, biological invasion, common garden, flowering phenology, latitudinal gradient, Spartina alterniflora

%0 Journal Article
%T Transcriptional activity differentiates families of Marine Group II Euryarchaeota in the coastal ocean
%D 2021
%B Springer Nature
%9 Article
%Z published
%M GCE.1216
%R 10.1038/s43705-021-00002-6
%X Marine Group II Euryarchaeota (Candidatus Poseidoniales), abundant but yet-uncultivated members of marine microbial communities, are thought to be (photo)heterotrophs that metabolize dissolved organic matter (DOM), such as lipids and peptides. However, little is known about their transcriptional activity. We mapped reads from a metatranscriptomic time series collected at Sapelo Island (GA, USA) to metagenome-assembled genomes to determine the diversity of transcriptionally active Ca. Poseidoniales. Summer metatranscriptomes had the highest abundance of Ca. Poseidoniales transcripts, mostly from the O1 and O3 genera within Ca. Thalassarchaeaceae (MGIIb). In contrast, transcripts from fall and winter samples were predominantly from Ca. Poseidoniaceae (MGIIa). Genes encoding proteorhodopsin, membrane-bound pyrophosphatase, peptidase/proteases, and part of the ß-oxidation pathway were highly transcribed across abundant genera. Highly transcribed genes specific to Ca. Thalassarchaeaceae included xanthine/uracil permease and receptors for amino acid transporters. Enrichment of Ca. Thalassarchaeaceae transcript reads related to protein/peptide, nucleic acid, and amino acid transport and metabolism, as well as transcript depletion during dark incubations, provided further evidence of heterotrophic metabolism. Quantitative PCR analysis of South Atlantic Bight samples indicated consistently abundant Ca. Poseidoniales in nearshore and inshore waters. Together, our data suggest that Ca. Thalassarchaeaceae are important photoheterotrophs potentially linking DOM and nitrogen cycling in coastal waters.
%U https://www.nature.com/articles/s43705-021-00002-6
%A Damashek, Julian
%A Okotie-Oyekan, A.O.
%A Gifford, Scott
%A Vorobev, A.
%A Moran, Mary Ann
%A Hollibaugh, James T.
%K euryarchaeota, coast, coastal ocean, transcription, UGAMI Publication

%0 Report
%T Data Package Design for Special Cases
%D 2021
%I EDI
%9 Article
%Z published
%M GCE.1242
%R 10.6073/pasta/9d4c803578c3fbcb45fc23f13124d052
%X In these documents we consider special cases for archiving research data based on their datatype, format, or acquisition method, and recommend practices that ensure optimal re-usability ofthe data. Most recommendations here are aimed at improving documentation of data acquisitionand processing to avoid misinterpretation. This includes the recommendation to publish rawdata and/or processing code along with the data products. Others are aimed at usability in termsof data size/volume or connecting related data. Some recommendations involve including ametadata document formatted according to a new and emerging standard (e.g., codeMeta) or adata inventory table. Data inventory tables can cross the line between metadata and data andare intended to improve discoverability and navigation of archived data.
%A Gries, Corinna
%A Beaulieu, Stace
%A Brown, Renee F.
%A Elmendorf, Sarah
%A Garritt, Hap
%A Gastil-Buhl, Gastil
%A Hsieh, Hsun-Yi
%A Kui, Li
%A Martin, Mary
%A Maurer, Greg
%A Nguyen, An T.
%A Porter, John
%A Sapp, Adam
%A Servilla, Mark
%A Whiteaker, Timothy L.
%K data package design, non-tabular data, EML, best practices

%0 Journal Article
%T Optimal Planting Distance in a Simple Model of Habitat Restoration With an Allee Effect
%D 2021
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1223
%R 10.3389/fmars.2020.610412
%X Ecological restoration is emerging as an important strategy to improve the recovery ofdegraded lands and to combat habitat and biodiversity loss worldwide. One centralunresolved question revolves around the optimal spatial design for outplanted propagulesthat maximizes restoration success. Essentially, two contrasting paradigms exist: thefirst aims to plant propagules in dispersed arrangements to minimize competitiveinteractions. In contrast, ecological theory and recent field experiments emphasizethe importance of positive species interactions, suggesting instead clumped plantingconfigurations. However, planting too many propagules too closely is likely to wasterestoration resources as larger clumps have less edges and have relatively lower spreadrates. Thus, given the constraint of limited restoration efforts, there should be an optimalplanting distance that both is able to harness positive species interactions but at the sametime maximizes spread in the treated area. To explore these ideas, here we proposea simple mathematical model that tests the influence of positive species interactionson the optimal design of restoration efforts. We model the growth and spatial spreadof a population starting from different initial conditions that represent either clumped ordispersed configurations of planted habitat patches in bare substrate. We measure thespatio-temporal development of the population, its relative and absolute growth ratesas well as the time-discounted population size and its dependence on the presence ofan Allee effect. Finally, we assess whether clumped or dispersed configurations performbetter in our models and qualitatively compare the simulation outcomes with a recentwetland restoration experiment in a coastal wetland. Our study shows that intermediateclumping is likely to maximize plant spread under medium and high stress conditions(high occurrence of positive interactions) while dispersed designs maximize growth underlow stress conditions where competitive interactions dominate. These results highlightthe value of mathematical modeling for optimizing the efficiency of restoration efforts andcall for integration of this theory into practice.
%A Hammann, Liv
%A Silliman, Brian R.
%A Blasius, Bernd
%K restoration, restoration design, optimality, Allee effect, diffusion, mathematical modeling, coastal wetlands

%0 Journal Article
%T "I am Sapelo": Racialized Uneven Development and Land Politics within the Gullah/Geechee Corridor.
%D 2021
%V 5
%N 1
%P 401-425
%B Environment and Planning E: Nature and Space
%9 Article
%Z published
%M GCE.1214
%R 10.1177/2514848620987366
%X The history of land struggles in the United States demonstrates how ongoing patterns of uneven development depend upon and codify the legacies of white supremacy. In this article, we show how the histories of white supremacy continue to be embedded and institutionalized into contemporary land and property politics through the processes of racialized uneven development using the case of Sapelo Island, Georgia. We trace the history of property relations on Sapelo over four periods (covering 1802–2020) to reveal how Black, Saltwater Geechee descendants’ presence on the island has persisted despite manifold attempts to manipulate, control, and dispossess families of their land. We re-interpret Sapelo’s history through the lens of abolition ecology to articulate how the struggle for life through land consistently runs up against statesanctioned racial violence, which perpetuates and institutionalizes systemic racialized uneven development. We argue that the “racial state” is facilitating the dispossession of Geechee cultural heritage, which lies in having access to and ownership of the land and requires new political imaginaries to combat the persistence of these tactics.
%U https://doi.org/10.1177/2514848620987366
%A Hardy, Dean
%A Heynen, Nik
%K Sapelo, development, planning, UGAMI Publication

%0 Journal Article
%T Patterns and trends of organic matter processing and transport: Insights from the US long-term ecological research network
%D 2021
%V 2
%B Climate Change Ecology
%9 Article
%Z published
%M GCE.1265
%R 10.1016/j.ecochg.2021.100025
%X Organic matter (OM) dynamics determine how much carbon is stored in ecosystems, a service that modulates climate. We synthesized research from across the US Long-Term Ecological Research (LTER) Network to assemble a conceptual model of OM dynamics that is consistent with inter-disciplinary perspectives and emphasizes vulnerability of OM pools to disturbance. Guided by this conceptual model, we identified unanticipated patterns and long-term trends in processing and transport of OM emerging from terrestrial, freshwater, wetland, and marine ecosystems. Cross-ecosystem synthesis combined with a survey of researchers revealed several themes: 1) strong effects of climate change on OM dynamics, 2) surprising patterns in OM storage and dynamics resulting from coupling with nutrients, 3) characteristic and often complex legacies of land use and disturbance, 4) a significant role of OM transport that is often overlooked in terrestrial ecosystems, and 5) prospects for reducing uncertainty in forecasting OM dynamics by incorporating the chemical composition of OM. Cross-fertilization of perspectives and approaches across LTER sites and other research networks can stimulate the comprehensive understanding required to support large-scale characterizations of OM budgets and the role of ecosystems in regulating global climate.
%U https://www.sciencedirect.com/science/article/pii/S2666900521000253?via%3Dihub
%A Harms, Tamara K.
%A Groffman, Peter M. 
%A Aluwihare, Lihini I.
%A Craft, Christopher B.
%A Wieder, William R.
%A Hobbie, Sarah E.
%A Baer, Sara G.
%A Blair, John M.
%A Frey, Serita
%A Remucal, Christina K.
%A Rudgers, Jennifer A.
%A Collins, Scott L.
%A Kominoski, John S.
%A Ball, Becky A.
%K Organic matter storage, Coupled biogeochemical cycles, Transport, Organic matter composition, Stabilization, Cross-site synthesis, Cross-site Research

%0 Journal Article
%T Salt Marsh Light Use Efficiency is Driven by Environmental Gradients and Species-Specific Physiology and Morphology
%D 2021
%V 126
%B Journal of Geophysical Research: Biogeosciences
%9 Article
%Z published
%M GCE.1219
%R 10.1029/2020JG006213
%X Light use efficiency (LUE) of salt marshes has not been well studied but is central to production efficiency models (PEMs) used for estimating gross primary production (GPP). Salt marshes are typically dominated by a species monoculture, resulting in large areas with distinct morphologyand physiology. We measured eddy covariance atmospheric CO2 fluxes for two marshes dominated by a different species: Juncus roemerianus in Mississippi and Spartina alterniflora in Georgia. LUE for the Juncus marsh (mean = 0.160 ± 0.004 g C mol&#8722;1 photon), reported here for the first time, was on average similar to the Spartina marsh (mean = 0.164 ± 0.003 g C mol&#8722;1 photon). However, Juncus LUE had a greater range (0.073–0.49 g C mol&#8722;1 photon) and higher variability (15.2%) than the Spartina marsh (range: 0.035–0.36 g C mol&#8722;1 photon; variability: 12.7%). We compared the responses of LUE across six environmental gradients. Juncus LUE was predominantly driven by cloudiness, photosynthetically active radiation (PAR), soil temperature, water table, and vapor pressure deficit. Spartina LUE was driven by water table, air temperature, and cloudiness. We also tested how the definition of LUE (incident PAR vs. absorbed PAR) affected the magnitude of LUE and its response. We found LUE estimations using incident PAR underestimated LUE and masked day-to-day variability. Our findings suggest that salt marsh LUE parametrization should be species-specific due to plant morphology and physiology and their geographic context. These findings can be used to improve PEMs for modeling blue carbon productivity.
%U https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG006213
%A Hawman, Peter
%A Mishra, Deepak
%A O'Connell, Jessica L.
%A Cotten, David L.
%A Narron, Caroline
%A Mao, Lishen
%K salt marsh, physiology, morphology, light use efficiency

%0 Journal Article
%T Feral hogs control brackish marsh plant communities over time
%D 2021
%B Ecology
%9 Article
%Z published
%M GCE.1253
%R 10.1002/ecy.3572
%X Feral hogs modify ecosystems by consuming native species and altering habitatstructure. These invasions can generate fundamentally different post-invasion habitats whendisturbance changes community structure, ecosystem function, or recovery dynamics. Here, weuse multiple three-year exclusion experiments to describe how feral hogs affect hyper-productive brackish marshes over time. We find that infrequent yet consistent hog foragingand trampling suppresses dominant plants by generating a perpetually disturbed habitat thatfavors competitively inferior species and disallows full vegetative recovery over time. Alongborders between plant monocultures, trampling destroys dominant graminoids responsible formost aboveground marsh biomass while competitively inferior plants increase fivefold. Hogactivities shift the brackish marsh disturbance regime from pulse to press, which changes theplant community: competitively inferior plants increase coverage, species diversity is doubled,and live cover is lowered by 30% as large plants are unable to take hold in hog-disturbed areas.Release from disturbance does not result in complete recovery (i.e., dominant plant monocul-tures) because hog consumer control is a combination of both top-down control and broaderengineering effects. These results highlight how habitats are susceptible to invasive effects out-side of structural destruction alone, especially if large consumers are pervasive over time andchange the dynamics that sustain recovery.
%U https://doi.org/10.1002/ecy.3572
%A Hensel, Marc Simon
%A Silliman, Brian R.
%A Hensel, E.
%A Byrnes, J.K.
%K competition, feral  swine, Juncus  romerianus, marsh  grass, pigs, Schoenoplectus americanus, Spartina cynosuroides, Sus scrofa

%0 Journal Article
%T A large invasive consumer reduces coastal ecosystem resilience by disabling positive species interactions
%D 2021
%V 12
%N 1
%B Nature Communications
%9 Article
%Z published
%M GCE.1206
%R 10.1038/s41467-021-26504-4
%X Invasive consumers can cause extensive ecological damage to native communities but effects on ecosystem resilience are less understood. Here, we use drone surveys, manipulative experiments, and mathematical models to show how feral hogs reduce resilience in southeastern US salt marshes by dismantling an essential marsh cordgrass-ribbed mussel mutualism. Mussels usually double plant growth and enhance marsh resilience to extreme drought but, when hogs invade, switch from being essential for plant survival to a liability; hogs selectively forage in mussel-rich areas leading to a 50% reduction in plant biomass and slower post-drought recovery rate. Hogs increase habitat fragmentation across landscapes by maintaining large, disturbed areas through trampling of cordgrass during targeted mussel consumption. Experiments and climate-disturbance recovery models show trampling alone slows marsh recovery by 3x while focused mussel predation creates marshes that may never recover from large-scale disturbances without hog eradication. Our work highlights that an invasive consumer can reshape ecosystems not just via competition and predation, but by disrupting key, positive species interactions that underlie resilience to climatic disturbances.
%U https://www.nature.com/articles/s41467-021-26504-4
%A Hensel, Marc Simon
%A Silliman, Brian R.
%A von de Koppel, J.
%A Hensel, E.
%A Sharp, Sean
%A Crotty, Sinead M.
%A Byrnes, J.K.
%K megaconsumer, SINERR Publication

%0 Journal Article
%T Spatio-temporal changes in dissolved organic matter composition along the salinity gradient of a marsh-influenced estuarine complex
%D 2021
%V 66
%P 3040-3054
%B Limnology & Oceanography
%9 Article
%Z published
%M GCE.1238
%R 10.1002/lno.11857
%X The interconnected estuarine complex of the Altamaha River and adjacent sounds located in Georgia (USA) functions as a hotspot for organic matter transformation as it is transported to the Atlantic Ocean. Here, we investigated how dissolved organic matter (DOM) composition changes both spatially and seasonally along the estuary and how it influences bacterial processing. Surface samples were collected during high tide at fifteen stations throughout the estuary in April, July, October 2017, and January 2018. Bulk, optical, and molecular analyses were conducted on samples before and after dark incubations to assess DOM sources and transformation patterns in the system. The dominant driver of change in DOM composition was found to be the terrigenous-marine gradient in organic matter sources. Six distinct clusters were identified based on the terrigenous signature of the DOM pool, explaining 45% of the variance in DOM composition in the system. Bacterial consumption of dissolved organic carbon (DOC) was strongly influenced by DOM composition, with increased degradation rates for DOM with a larger terrigenous character. However, changes in optical properties suggested that less aromatic DOM that co-varied with the terrigenous material was preferentially degraded. The passage of Hurricane Irma in September 2017 resulted in a 27±7% increase in DOC content, likely due to inundation associated with storm surge and increased local precipitation, and DOC biodegradation was 17±8% higher than during summer. These effects lasted for at least one month after the storm, revealing that hurricanes can have a large impact on DOM composition and cycling in coastal systems.
%A Letourneau, Maria L.
%A Schaefer, Sylvia C.
%A Chen, Huan
%A McKenna, Amy M.
%A Alber, Merryl
%A Medeiros, Patricia M.
%K DOM composition, FT-ICR MS, Altamaha River, Hurricane Irma, Georgia Coastal Ecosystems LTER, Student Publication, UGAMI Publication

%0 Journal Article
%T Variation in synchrony of production among species, sites and intertidal zones in coastal marshes
%D 2021
%B Ecology
%9 Article
%Z published
%M GCE.1184
%R 10.1002/ECY.3278
%X Spatially synchronous population dynamics are important to ecosystem functioning and have several potential causes. By looking at synchrony in plant productivity over 18 years across two elevations in three types of coastal marsh habitat dominated by different clonal plant species in Georgia, USA, we were able to explore the importance of plant species and different habitat conditions to synchrony. Synchrony was highest when comparing within a plant species and within a marsh zone, and decreased across species, with increasing distance, and with increasing elevational differences. Abiotic conditions that were measured at individual sites (water column temperature and salinity) also showed high synchrony among sites, and in one case (salinity) decreased with increasing distance among sites. The Moran Effect (synchronous abiotic conditions among sites) is the most plausible explanation for our findings. Decreased synchrony between creekbank and mid-marsh zones, and among habitat types (tidal fresh, brackish and salt marsh) was likely due in part to different exposure to abiotic conditions and in part to variation in sensitivity of dominant plant species to these abiotic conditions. We found no evidence for asynchrony among species, sites or zones, indicating that one habitat type or zone will not compensate for poor production in another during years with low productivity; however, tidal fresh, brackish and salt marsh sites were also not highly synchronous with each other, which will moderate productivity variation among years at the landscape level due to the portfolio effect. We identified the creekbank zone as more sensitive than the mid-marsh to abiotic variation and therefore as a priority for monitoring and management.
%U https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3278
%A Liu, Wenwen
%A Pennings, Steven C.
%K climate change, salt marsh, Juncus, Spartina, Zizaniopsis, synchrony, Signature Publication, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Which biogeochemical drivers most impact DOM composition of a marsh-dominated estuary?
%D 2021
%C Atlanta, GA
%B American Chemical Society 2021 Fall Meeting
%8 August 2021
%9 Presentation
%Z presented
%M GCE.1240
%A Martineac, Rachel P.
%A Medeiros, Patricia M.
%K DOM composition, biogeochemical processes, marsh-dominated estuary, Student Publication, UGAMI Publication

%0 Journal Article
%T Assessing the contribution of seasonality, tides, and microbial processing to dissolved organic matter composition variability in a Southeastern U.S. estuary
%D 2021
%V 8
%P 781580
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1244
%R 10.3389/fmars.2021.781580
%X Uncovering which biogeochemical processes have a critical role controlling dissolved organic matter (DOM) compositional changes in complex estuarine environments remains a challenge. In this context, the aim of this study is to characterize the dominant patterns of variability modifying the DOM composition in an estuary off the Southeastern U.S. We collected water samples during three seasons (July and October 2014 and April 2015) at both high and low tides and conducted short- (1 day) and long-term (60 days) dark incubations. Samples were analyzed for bulk DOC concentration, and optical (CDOM) and molecular (FT-ICR MS) compositions and bacterial cells were collected for metatranscriptomics. Results show that the dominant pattern of variability in DOM composition occurs at seasonal scales, likely associated with the seasonality of river discharge. After seasonal variations, long-term biodegradation was found to be comparatively more important in the fall, while tidal variability was the second most important factor correlated to DOM composition in spring, when the freshwater content in the estuary was high. Over shorter time scales, however, the influence of microbial processing was small. Microbial data revealed a similar pattern, with variability in gene expression occurring primarily at the seasonal scale and tidal influence being of secondary importance. Our analyses suggest that future changes in the seasonal delivery of freshwater to this system have the potential to significantly impact DOM composition. Changes in residence time may also be important, helping control the relative contribution of tides and long-term biodegradation to DOM compositional changes in the estuary.
%A Martineac, Rachel P.
%A Vorobev, Alexey
%A Moran, Mary Ann
%A Medeiros, Patricia M.
%K Dissolved organic matter, DOM composition, Microbial degradation, FT-ICR MS, marsh-dominated estuary, GCE-LTER, Southeastern U.S., Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Environmental drivers controlling DOM composition variability in a marsh-dominated estuary
%D 2021
%B ASLO 2021 Aquatic Sciences Virtual Meeting
%8 June 2021
%9 Meeting
%Z presented
%M GCE.1239
%A Martineac, Rachel P.
%A Vorobev, Alexey
%A Moran, Mary Ann
%A Medeiros, Patricia M.
%K DOM composition, biogeochemical processes, marsh-dominated estuary, microbial processing, Student Publication, UGAMI Publication

%0 Journal Article
%T Can Nucleation Bridge to Desirable Alternative Stable States? Theory and Applications.
%D 2021
%B The Bulletin of the Ecological Society of America.
%9 Article
%Z published
%M GCE.1249
%R 10.1002/bes2.1953
%X Ecosystem recovery is full of wicked problems that result in nonlinear responses to management interventions. As the United Nation’s call for a Decade on Ecosystem Restoration highlights, there is an urgent need to identify and address restoration barriers and enhance the efficacy of our restoration strategies in a rapidly changing world (United Nations 2019, Aronson et al. 2020, Fischer et al. 2021). Ecological nucleation is an emerging framework that shows promise as a restoration strategy across a variety of ecosystems. Unlike many other restoration strategies, ecological nucleation recognizes that many vital ecological interactions occur at the local scale and that these local interactions can be leveraged to initiate desirable landscape-scale changes in ecosystem structure and function. Past applications of ecological nucleation have used it as an analogy to describe the growth of recently established patches of the desired state, which can accelerate that state’s spread (Yarranton and Morrison 1974, Corbin and Holl 2012, Hulvey et al. 2017, Shaw et al. 2020). More recently, autocatalytic nucleation has been more strictly defined in ecology as the process by which a critical patch size of the desired state can lower resistance thresholds and catalyze rapid growth through local positive feedback dynamics (Michaels et al. 2020). In this way, nucleation leverages local-scale interactions to facilitate transitions between alternate stable states at the landscape scale. This symposium served as a conversation between architects of the ideas and practice underlying the notion of “nucleation.”
%U https://esajournals.onlinelibrary.wiley.com/doi/10.1002/bes2.1953?af=R
%A Michaels, T. 
%A Eppinga, M.
%A Angelini, Christine
%A Holl, K.
%A Bever, J.
%K facilitation, vegetative growth, patch dynamics, disturbance

%0 Book Section
%T Marsh Equilibrium Theory:  Implications for Responses to Rising Sea Level
%D 2021
%P 157-177
%I Cambridge University Press
%B Salt marshes: Functions, dynamics, and stresses
%9 Article
%Z published
%M GCE.1243
%A Morris, J.
%A Cahoon, D.
%A Callaway, J.
%A Craft, Christopher B.
%A Neubauer, S. C.
%A Weston, Nathaniel B.
%E Fitzgerald, D.
%E Hughes, Z.
%K marsh, sea level

%0 Thesis
%T Refining cultural and environmental temporalities at the late Archaic-early woodland transition along the Georgia coast, UGA
%D 2021
%I University of Georgia
%9 Ph.D. Dissertation
%Z published
%M GCE.1228
%A Napora, Katharine
%K Georgia coast

%0 Journal Article
%T BERM: A belowground ecosystem resilience model for estimating Spartina alterniflora belowground biomass
%D 2021
%B New Phytologist
%9 Article
%Z published
%M GCE.1226
%R 10.1111/nph.17607
%X Spatiotemporal patterns of Spartina alterniflora belowground biomass (BGB) are importantfor evaluating salt marsh resiliency. To solve this, we created the BERM (Belowground EcosystemResiliency Model), which estimates monthly BGB (30-m spatial resolution) from freelyavailable data such as Landsat-8 and Daymet climate summaries.Our modeling framework relied on extreme gradient boosting, and used field observationsfrom four Georgia salt marshes as ground-truth data. Model predictors included estimatedtidal inundation, elevation, leaf area index, foliar nitrogen, chlorophyll, surface temperature,phenology, and climate data. The final model included 33 variables, and the most importantvariables were elevation, vapor pressure from the previous four months, Normalized DifferenceVegetation Index (NDVI) from the previous five months, and inundation.Root mean squared error for BGB from testing data was 313 g m&#8722;2 (11% of the field datarange), explained variance (R2) was 0.62–0.77. Testing data results were unbiased across BGBvalues and were positively correlated with ground-truth data across all sites and years (r =0.56–0.82 and 0.45–0.95, respectively).BERM can estimate BGB within Spartina alterniflora salt marshes where environmentalparameters are within the training data range, and can be readily extended through a reproducibleworkflow. This provides a powerful approach for evaluating spatiotemporal BGB andassociated ecosystem function.
%U https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/nph.17607
%A O'Connell, Jessica L.
%A Mishra, Deepak
%A Alber, Merryl
%A Byrd, K. B.
%K Spartina, belowground biomass, model, Signature Publication

%0 Journal Article
%T Flows, transport and form drag in intertidal salt marsh creeks.
%D 2021
%V 126
%N 11
%P e2021JC017357
%B Journal of Geophysical Research - Oceans
%9 Article
%Z published
%M GCE.1250
%R 10.1029/2021JC017357
%X .Intertidal creeks (channel width <5 m) weave through salt marshes, delivering water, nutrients, and sediments into the marsh interior and affecting spatial heterogeneity in plant and animal distributions. Despite their global prevalence, creek connectivity, and the mechanisms controlling cross-marsh hydrodynamics, remain poorly resolved. In this study, we measured flow and total suspended solids transport in three intertidal creeks within a confined drainage basin in a Georgia, USA salt marsh. We discovered that the effective drag is 3–12 times greater than bed drag, reaching levels similar to those observed in coral reefs. Furthermore, the drag between tidal flood and ebb phases differs, indicating an asymmetric drag. Analyses of along-channel momentum reveal that pressure gradient urn:x-wiley:21699275:media:jgrc24762:jgrc24762-math-0001 m/s2 and friction urn:x-wiley:21699275:media:jgrc24762:jgrc24762-math-0002 m/s2 dominate creek momentum balance. Divergence in tidal and suspended solids transport between adjacent creeks revealed contrasting tidal transport asymmetries (i.e., flood or ebb dominated) within this confined basin. We discuss how these differences may alter the eco-geospatial evolution of salt marshes and their response to sea-level rise.
%U https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021JC017357
%A Ortals, Collin
%K form drag, effective drag, tidal circulation, coastal wetland, cross-marsh exchange

%0 Journal Article
%T Estimation of Abundance and Distribution of Salt Marsh Plants from Images Using Deep Learning
%D 2021
%P 2635-2642
%B Proceedings of the 25th International Conference on Pattern Recognition (ICPR)
%9 Article
%Z published
%M GCE.1186
%R 10.1109/ICPR48806.2021.9412264
%X Recent advances in computer vision and machinelearning, most notably deep convolutional neural networks(CNNs), are exploited to identify and localize various plant speciesin salt marsh images. Three different approaches are exploredthat provide estimations of abundance and spatial distributionat varying levels of granularity defined by spatial resolution. Inthe coarsest-grained approach, CNNs are tasked with identifyingwhich of six plant species are present/absent in large patcheswithin the salt marsh images. CNNs with diverse topologicalproperties and attention mechanisms are shown capable of providingaccurate estimations with > 90% precision and recall forthe more abundant plant species and reduced performance forless common plant species. Estimation of percent cover of eachplant species is performed at a finer spatial resolution, wheresmaller image patches are extracted and the CNNs tasked withidentifying the plant species or substrate at the center of theimage patch. For the percent cover estimation task, the CNNsare observed to exhibit a performance profile similar to that forthe presence/absence estimation task, but with an  5%–10%reduction in precision and recall. Finally, fine-grained estimationof the spatial distribution of the various plant species is performedvia semantic segmentation. The DeepLab-V3 semantic segmentationarchitecture is observed to provide very accurate estimationsfor abundant plant species, but with significant performancedegradation for less abundant plant species; in extreme cases,rare plant classes are seen to be ignored entirely. Overall, a cleartrade-off is observed between the CNN estimation quality and thespatial resolution of the underlying estimation thereby offeringguidance for ecological applications of CNN-based approachesto automated plant identification and localization in salt marshimages.
%A Parashar, J
%A Bhandarkar, S. M. 
%A Simon, J.
%A Hopkinson, Brian
%A Pennings, Steven C.
%K salt marsh, neural network, deep learning, SINERR Publication, Student Publication, UGAMI Publication

%0 Book Section
%T Community ecology of salt marshes
%D 2021
%P 82-112
%I Cambridge University Press
%C New York
%B Salt marshes
%9 Article
%Z published
%M GCE.1241
%A Pennings, Steven C.
%A He, Qiang
%E Fitzgerald, D.
%E Hughes, Z.
%K salt marsh, community ecology, herbivory, predation, facilitation, Cross-site Research, SINERR Publication, UGAMI Publication

%0 Book Section
%T Community ecology of salt marshes
%D 2021
%P 82-112
%I Cambridge University Press
%C New York
%B Salt marshes
%9 Article
%Z published
%M GCE.1316
%A Pennings, Steven C.
%A He, Qiang
%E Fitzgerald, D.
%E Hughes, Z.
%K salt marsh, community ecology, Spartina, herbivory, predation, disturbance, facilitation, UGAMI Publication

%0 Journal Article
%T Mussels drive polychlorinated biphenyl (PCB) biomagnification in a coastal food web
%D 2021
%V 11
%P 9180
%B Nature - Scientific Reports
%9 Article
%Z published
%M GCE.1251
%R 10.1038/s41598-021-88684-9
%X Despite international regulation, polychlorinated biphenyls (PCBs) are routinely detected at levels threatening human and environmental health. While previous research has emphasized trophic transfer as the principle pathway for PCB accumulation, our study reveals the critical role that non-trophic interactions can play in controlling PCB bioavailability and biomagnification. In a 5-month field experiment manipulating saltmarsh macro-invertebrates, we show that suspension-feeding mussels increase concentrations of total PCBs and toxic dioxin-like coplanars by 11- and 7.5-fold in sediment and 10.5- and 9-fold in cordgrass-grazing crabs relative to no-mussel controls, but do not affect PCB bioaccumulation in algae-grazing crabs. PCB homolog composition and corroborative dietary analyses demonstrate that mussels, as ecosystem engineers, amplify sediment contamination and PCB exposure for this burrowing marsh crab through non-trophic mechanisms. We conclude that these ecosystem engineering activities and other non-trophic interactions may have cascading effects on trophic biomagnification pathways, and therefore exert strong bottom-up control on PCB biomagnification up this coastal food web.
%U https://www.nature.com/articles/s41598-021-88684-9
%A Prince, Kimberly
%A Cetta, A. 
%A Crotty, Sinead M.
%A Denslow, N.
%A Delfino, J. 
%A Angelini, Christine
%K salt marsh, persistant organic pollutant, Georgia, fiddler crab, spartina, benthic algae

%0 Journal Article
%T Increasing grazer density leads to linear decreases in Spartina alterniflora biomass and exponential increases in grazing pressure across a barrier island
%D 2021
%V 659
%P 49-58
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.1208
%R 10.3354/meps13569
%X Researchers now recognize that top-down as well as bottom-up forces regulate salt marsh primary production. However, how top-down forces vary with grazer density is still poorly resolved. To begin to address this void, we (1) surveyed grazing intensity in short-form Spartina alterniflora across Sapelo Island, Georgia (USA), and (2) removed varying densities of grazers from 13 sites over 2 yr. Our survey revealed a non-linear relationship between snail abundance and grazing intensity, with grazing scars per stem increasing exponentially with snail density. Further, there appeared to be a threshold at ~80 snails m-2, below which increasing snail density did not significantly increase grazing scars—potentially because snails target dead grass rather than live grass when competition with other snails is low. Increasing snail densities also exponentially reduced stem density within a plot, but only over 80 snails m-2. Our removal experiment showed that snails linearly decreased S. alterniflora biomass across a naturally representative range of snails (0-586 snails m-2) and that top-down control of short-form S. alterniflora was important at multiple sites across an island, with snail removal on average increasing primary production by 164%. Our results reveal that top-down control of short-form S. alterniflora is a common process across this intensively studied island, and that grazing scars increase non-linearly with snail density, while consumer effects on biomass increase linearly. Future models based on marsh plant growth (e.g. geomorphic evolution, primary production) should incorporate both the importance and functional form of grazer control to create more accurate carbon budgets and to better understand marsh network dynamics.
%U https://www.int-res.com/abstracts/meps/v659/p49-58/
%A Renzi, Julianna J.
%A Silliman, Brian R.
%K biomass

%0 Journal Article
%T Climate Change, Resilience, and the Fisher-Hunter-Gatherers of Late Holocene Georgia Coast.
%D 2021
%B Quaternary International
%9 Article
%Z published
%M GCE.1164
%R 10.1016/j.quaint.2020.08.030
%X The Georgia Coast of the eastern United States boasts some of the largest and spatially complex Late Archaic sites in North America, with the most famous of these being shell rings. The shell ring village phenomenon and its larger ceremonial landscapes did not, however, last throughout the Late Archaic. Climate shifts that led to local relative sea level change in the area at around 3800 cal. BP appears to have resulted in conditions that suppressed shellfish productivity and ultimately led to the uneven abandonment of shell ring sites. Our understanding of these changes along the Georgia Coast is limited by the fact that much of the research focuses exclusively on large shell midden sites. Investigations at several large terminal Late Archaic sites demonstrate continuity in the size of these occupations compared to earlier Late Archaic sites (i.e., shell rings), demonstrating a socio-ecological resiliency in these small-scale societies. We argue that, contrary to narratives of collapsing socio-ecological systems, the terminal Late Archaic was a time when displaced communities coalesced and forged new community bonds in the wake of a shifting resource base.
%A Ritchison, Brandon Tyler
%A Thompson, Victor D.
%A Lulewicz, Isabelle H.
%A Tucker, Bryan
%A Turck, John A.
%K climate change

%0 Thesis
%T Groundwater flow and transport at the forest-marsh boundary: A modeling study
%D 2021
%V 547
%P 50
%I University of South Carolina
%C Columbia SC USA
%B Journal of Hydrology
%9 M.S. Thesis
%Z   Sanders, S. C. (2021). Groundwater flow and transport at the forest-marsh boundary: A modeling study (Order No. 28544844). Available from Dissertations & Theses @ University of South Carolina. (2605303719). Retrieved from https://login.pallas2.tcl.sc.edu/login?url=https://www.proquest.com/dissertations-theses/groundwater-flow-transport-at-forest-marsh/docview/2605303719/se-2?accountid=13965  
%M GCE.1252
%X The forest-marsh boundary, where tidally influenced salt marshes meet a forested upland, is hydrologically complex due to its multiple water inputs. Groundwater flow and salinity transport at this boundary are not well understood. In order to make predictions about salinity at this boundary as it responds to climatic factors, a two-dimensional model was built to simulate groundwater flow and solute transport at a salt marsh on Sapelo Island, Georgia. After calibration based on observed data from wells at the study site, the model can be used to identify patterns in groundwater movement and solute transport that may influence the vegetation and consequently the migration of the forest-marsh boundary. Additionally, the model is designed to be a first step toward identifying the impacts of press and pulse disturbances, such as sea level rise or drought, on the marsh.
%U https://login.pallas2.tcl.sc.edu/login?url=https://www.proquest.com/dissertations-theses/groundwater-flow-transport-at-forest-marsh/docview/2605303719/se-2?accountid=13965
%A Sanders, Sophia C.
%K Groundwater, Freshwater-saltwater interface, high marsh, models, salinity, hydraulic head, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Integrating inland and coastal water quality data for actionable knowledge
%D 2021
%V 13; 23 July 2021
%N 15
%P 24 p
%B Remote Sensing
%S Big Earth Data and Remote Sensing in Coastal Environments
%9 Article
%Z Contribution of Group on Earth Observations / AquaWatch ((https://www.geoaquawatch.org/). John Schalles is a co-author, Deepak Mishra was a co-editor of this Special Issue.  
%M GCE.1345
%R 10.3390/rs13152899
%X Water quality measures for inland and coastal waters are available as discrete samples from professional and volunteer water quality monitoring programs and higher-frequency, near-continuous data from automated in situ sensors. Water quality parameters also are estimated from model outputs and remote sensing. The integration of these data, via data assimilation, can result in a more holistic characterization of these highly dynamic ecosystems, and consequently improve water resource management. It is becoming common to see combinations of these data applied to answer relevant scientific questions. Yet, methods for scaling water quality data across regions and beyond, to provide actionable knowledge for stakeholders, have emerged only recently, particularly with the availability of satellite data now providing global coverage at high spatial resolution. In this paper, data sources and existing data integration frameworks are reviewed to give an overview of the present status and identify the gaps in existing frameworks. We propose an integration framework to provide information to user communities through the the Group on Earth Observations (GEO) AquaWatch Initiative. This aims to develop and build the global capacity and utility of water quality data, products, and information to support equitable and inclusive access for water resource management, policy and decision making.
%U https://www.mdpi.com/2072-4292/13/15/2899
%A Schaeffer, B.A.
%A Neely, M.B.
%A Spinosa, A.
%A Serafy, E.
%A Odermatt, D.
%A Weathers, K.C.
%A Barracchini, T.
%A Bouffard, D.
%A Carvalho, L.
%A Comny, R.N.
%A De Keukelaere, P.D.
%A Hunter, P.D.
%A Jamet, C.
%A Joehnk, K.D.
%A Johnston, J.M.
%A Knudby, A.
%A Minaudo, C.
%A Pahlevan, Nima
%A Rose, K.C.
%A Schalles, John F.
%A Tzortziou, M.
%K water quality, remote sensing, lake, estuary, coastal, sensors, management, interoperability, integration, Cross-site Research

%0 Conference Proceedings
%T Satellite and drone remote sensing to study decadal scale and high resolution spatial-temporal patterns and declines of Spartina alterniflora above-ground biomass in Georgia, USA salt marshes
%D 2021
%I Coastal Ecosystems and Global Change (CoEco)
%C Xiamen University, Xiamen, China
%B 1st International Symposium on Coastal Ecosystems and Global Change (CoEco1)
%S Session 2
%8 April 18, 2021
%9 Presentation
%Z Virtual, pre-recorded presentatons and live question & answer session
%M GCE.1246
%X We are studying multi-decadal spatio-temporal biomass patterns of the keystone species Spartina alterniflora (Marsh Cordgrass) within ten tidal watersheds covering 990 square kilometers of Georgia, USA wetlands. Geospatial techniques were used to scale up in situ biomass measurements within the NSF Georgia Coastal Ecosystems LTER research domain to landscape scale using > 300 Landsat 5 TM and Landsat 8 OLI 30 m resolution scenes since 1984 and recent 10 m resolution Sentinel 2 scenes. Climate and hydrological variables explain much of the variation in biomass for each of three height classes of Spartina.  Higher river discharges with reduced marsh salinities, total precipitation, and mean sea level have positive relationships with, and best explain biomass variation for all dates. Higher frequencies and severities of droughts in the past two decades were a major stressor. Importantly, average Spartina productivity was greatest in areas closest to larger river discharges (Altamaha, Savannah, Satilla, and Ogeeechee Rivers) and was ~300% greater in high precipitation, moist periods compared to drought periods. We conclude that river-dominated areas of higher production are better buffered against marsh soil hyper-salinization and experience greater nitrogen loading. Since 1984, overall average biomass declines of almost 20% represent a reduction of ~81,000 MT in average annual above-ground, organic carbon biomass. This loss presumably affects valuable ecosystem services, including wetland soil carbon sequestration and organic matter export (particulate and dissolved) and commercial fish and shellfish production in Georgia’s coastal ecosystems. Ultra-high, (5 cm) resolution drone imagery in monitored Spartina communities at Sapelo Island allows detailed examinations of specific disturbances (periwinkle snail die-backs, mud crab root herbivory with creek-head erosion, accumulations of smothering wrack, and stream-bank soil and plant slumpage). We are now able to explore and resolve scaling issues from sub-m2 plots to a 100 km2 regional perspective.
%A Schalles, John F.
%A Hladik, Christine M.
%A O'Donnell, John
%A Miklesh, David Michael
%A Pudil, Thomas
%A Nealy, Nicholas
%K Spartina alterniflora, biomass, drone imagery, remote sensing, spatial-temporal patterns, Student Publication

%0 Conference Proceedings
%T Serious multidecadal declines in aboveground biomass of the keystone salt marsh species, Spartina alterniflora, are related to climate change in coastal Georgia, USA
%D 2021
%I International Association for Ecology (INTECOL)
%C Christchurch, New Zealand (virtual, prerecorded)
%B 11th INTECOL International Wetlands Conference
%S Wetlandscapes: Understanding the Large-scale Wetland Functions in the Landscape Symposium
%8 October 14, 2021,
%9 Meeting
%Z presented
%M GCE.1245
%X We studied multidecadal (35 y) above-ground biomass dynamics and spatial distributions of MarshCordgrass, Spartina alterniflora, covering 933 square kilometers within nine tidal watersheds (WassawSound to Cumberland Sound) in the coastal zone of Georgia, USA. This keystone species accounts for 98% of the aerial extent of salt marshes in Georgia and represents about 1/3rd of all salt marsh habitat on the U.S. Western Atlantic Coast. Geospatial techniques were used to scale up in situ biomass measurements within our Georgia Coastal Ecosystems LTER research domain in the Central Georgia Coast to broader landscape scale estimates using > 350 Landsat 5, Landsat 8, and Sentinel 2 imagery dates between 1984 to 2020. Climate and hydrological variables explained much of the plant biomass dynamics. Overall biomass declines were linked to increased drought severity and frequency (primarily since 2000). Importantly, S. alterniflorabiomass production was greatest in areas closest to larger discharges of freshwater. Nine of the watersheds had overall biomass declines of 11.0 - 28.5%, while the Altamaha River watershed, with by far the largest discharges, had an increase of 9.6%. Marsh pore-water salinization is the major stressor. Long-term declines averaged 20.6%, representing ~ 157,000 MT in average annual aboveground live carbon biomass. Root declines may be comparable. This decline in salt marsh production could significantly reduce nutritional support to food webs and carbon biogeochemical cycling, and commercial fish and shellfish harvests in adjacent estuarine and offshore waters. We conclude that protection of freshwater river discharges are vitalto salt marsh health.
%A Schalles, John F.
%A Hladik, Christine M.
%A O'Donnell, John
%A Miklesh, David Michael
%A Pudil, Thomas
%A Nealy, Nicholas
%A Currin, Harrison
%K Spartina alterniflora, biomass, climate change, salt marsh, spatial patterns, temporal patterns

%0 Journal Article
%T Drivers of litter mass loss and faunal composition of detritus patches change over time
%D 2021
%V 11
%P 9642-9651
%B Ecology and Evolution
%9 Article
%Z The data have been deposited with PANGAEA: https://doi.org/10.1594/PANGAEA.931664
%M GCE.498
%R 10.1002/ece3.7787
%X Decomposition of vegetal detritus is one of the most fundamental ecosystem processes. In complex landscapes, the fate of litter of terrestrial plants may depend onwhether it ends up decomposing in terrestrial or aquatic conditions. However, (1) towhat extent decomposition rates are controlled by environmental conditions or bydetritus type, and (2) how important the composition of the detritivorous fauna is inmediating decomposition in different habitats, remain as unanswered questions. Weincubated two contrasting detritus types in three distinct habitat types in CoastalGeorgia, USA, to test the hypotheses that (1) the litter fauna composition dependson the habitat and the litter type available, and (2) litter mass loss (as a proxy fordecomposition) depends on environmental conditions (habitat) and the litter type.We found that the abundance of most taxa of the litter fauna depends primarilyon habitat. Litter type became a stronger driver for some taxa over time, but theoverall faunal composition was only weakly affected by litter type. Decompositionalso depends strongly on habitat, with up to ca. 80% of the initial detrital mass lostover 25 months in the marsh and forest habitats, but less than 50% lost in the creekbank habitat. Mass loss rates of oak versus pine litter differed initially but convergedwithin habitat types within 12 months. We conclude that, although the habitat typeis the principle driver of the community composition of the litter fauna, litter type is asignificant driver of litter mass loss in the early stages of the decomposition process.With time, however, litter types become more and more similar, and habitat becomesthe dominating factor in determining decomposition of older litter. Thus, the majordriver of litter mass loss changes over time from being the litter type in the earlystages to the habitat (environmental conditions) in later stages.
%A Seer, Franziska
%A Putze, Gregor
%A Pennings, Steven C.
%A Zimmer, Martin
%K marine-terrestrial ecotone, saltmarsh, decomposition, detritivorous soil fauna, leaf litter, litter fauna, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Directional movement of consumer fronts associated with creek heads in salt marshes
%D 2021
%V 102
%N 9
%P e03447
%B Ecology
%9 Article
%Z published
%M GCE.1267
%R 10.1002/ecy.3447
%X Consumers often deplete local resources and aggregate along edges of remainingresources, forming “consumer fronts.” We examined the factors that promote Sesarma reticulatumcrab aggregations at saltmarsh creek heads to explain the directional but slow movementof these fronts. We also created artificial creek heads to test the hypothesis that hydrologicalconditions at creek heads create superior habitat for crabs. Soil temperatures were ~11–12%cooler, hydrogen sulfide concentrations lower (0.0 vs. ~0.58 mg/L), and dissolved oxygen concentrationstwofold higher at the creek head versus the marsh platform. In the artificial creekheadexperiment, altering hydrological conditions led to lower dissolved sulfide levels, higherdissolved oxygen levels, and increased densities of crab burrows and Sesarma crabs. Moreover,the elevation of the soil surface declined rapidly at artificial creek heads versus controls, suggestingthat crabs were increasing erosion. Our results suggest that abiotic conditions for crabsare better at the leading edge of the creek head than the trailing edge, explaining the directionalmovement of the front. Moreover, the speed at which the front propagates appears to be limitedby the rate at which the creekhead erodes, rather than by crab mobility. The directionaland slow movement of Sesarma fronts compared to consumer fronts of other invertebratesappears to result from the inextricable link between Sesarma and marsh geomorphology,whereas other consumer fronts are associated mostly with food resources.
%A Vu, Huy
%A Pennings, Steven C.
%K salt marsh, spartina, sesarma, crab

%0 Journal Article
%T Disturbance is complicated: headward-eroding saltmarsh creeks produce multiple responses and recovery trajectories
%D 2021
%V 67
%P S86-S100
%B Limnology & Oceanography
%9 Article
%Z published
%M GCE.1185
%R 10.1002/lno.11867
%X Disturbances are one of the most important processes affecting natural systems, but there is a gap between the simplicity of conceptual models of disturbance and the rich complexity of empirical studies. We studied the perturbation caused by the movement of headward-eroding creeks onto the marsh platform in southeastern USA salt marshes. We measured the disturbance responses of 19 variables in terms of both magnitude (the difference between perturbed areas and control areas located on the marsh platform) and recovery trajectory (evaluated using a space for time substitution design along a marsh transect that ran the length of the newly-formed creek). Some variables (shoot density, root biomass, herbivorous snail density, soil pH, soil strength, soil temperature and elevation) declined sharply, while other variables (crab burrow density, soil organic matter and soil redox) increased sharply, in response to the heavily burrowed and grazed conditions at the creek head; these then recovered over subsequent years or decades. Other variables (shoot height, aboveground biomass, rhizome biomass, and light interception) declined sharply in the creek head, then overshot control values before recovering. Some variables (benthic algae, soil salinity) did not appear to be disturbed by the creek head. As hypothesized, plants recovered before soils and before snails. Disturbance magnitude and time to recovery were often greater directly adjacent to the new creekbank than for the same variables in a parallel transect further away from the creekbank that experienced an initial perturbation at the creek head but was not subject to the ongoing influence of the newly-formed creek, and in some cases variables never recovered, indicating a state change. Reducing the dimensionality of the data set into one or two principal component axes obscured the diverse ways in which different aspects of the system responded to and recovered from the perturbation. Our study illustrates the challenges in moving from simple conceptual models of disturbance to empirical studies in which multiple variables are likely to be affected differently and follow different recovery trajectories.
%U https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.11867
%A Wu, Fengrun
%A Pennings, Steven C.
%A Ortals, Collin
%A Ruiz, Jennifer
%A Farrell, William Reilly
%A McNichol, Samuel M
%A Angelini, Christine
%A Spivak, Amanda C.
%A Alber, Merryl
%A Tong, Chunfu
%K crabs, creek, disturbance, salt marsh, secondary succession, Signature Publication, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Consistent pattern of higher lability of leaves from high latitudes for both native Phragmites australis and exotic Spartina alterniflora
%D 2021
%V 35
%P 2084-2093
%B Functional Ecology
%9 Article
%Z published
%M GCE.1220
%R 10.1111/1365-2435.13826
%X 1. Global variation in litter decomposition rates is driven by climate, decomposertaxa and litter quality. Most large-scalestudies of litter quality have made comparisonsacross species, rather than within a species sourced from different latitudes.Here, we aim to explore latitudinal variation in leaf litter decomposition rate andlitter quality within a species.2. We investigated whether the typical interspecific pattern of increased litter labilityat higher latitudes also holds within plant species, by comparing leaf litterdecomposition rates and litter traits from stands of native Phragmites australis andexotic Spartina alterniflora in Chinese coastal wetlands spanning 20° of latitudeusing parallel greenhouse and field transplant experiments.3. We found that leaf litter from high-latitudeplants decomposed 46.6 ± 5.1% fasterthan that from low-latitudeconspecifics, with similar patterns in both plant speciesin both decomposition experiments. Higher lability of leaves from high latitudeswas associated with lower levels of plant defensive compounds (phenolics and tannins)and higher levels of nutrients (Ca, Mg and Na). Litter from the exotic S. alternifloradecomposed faster than litter from the native P. australis, being consistentwith lower defences and higher nutrient concentrations in S. alterniflora litter.4. Our results show that individual species follow the same pattern of increasinglitter lability at higher latitudes previously reported in cross-speciesgeographicalcomparisons. Moreover, this pattern can develop rapidly (<4 decades) in anintroduced species, raising the question of whether it is caused by phenotypicplasticity or adaptation.
%U https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.13826
%A Zhang, Youzheng
%A Pennings, Steven C.
%A Liu, Zixia
%A Li, Bo
%A Wu, Jihua
%K latitude, decomposition, Spartina, Phragmites, Student Publication

%0 Journal Article
%T State Changes: Insights from the U.S. Long Term Ecological Research Network
%D 2021
%B Ecosphere
%9 Article
%Z published
%M GCE.1198
%R 10.1002/ecs2.3433
%X Understanding the complex and unpredictable ways ecosystems are changing and predicting the state of ecosystems and the services they will provide in the future requires coordinated, long-term research. This paper is a product of a U.S. National Science Foundation funded Long Term Ecological Research (LTER) network synthesis effort that addressed anticipated changes in future populations and communities. Each LTER site described what their site would look like in 50 or 100 yr based on long-term patterns and responses to global change drivers in each ecosystem. Common themes emerged and predictions were grouped into state change, connectivity, resilience, time lags, and cascading effects. Here, we report on the “state change” theme, which includes examples from the Georgia Coastal (coastal marsh), Konza Prairie (mesic grassland), Luquillo (tropical forest), Sevilleta (arid grassland), and Virginia Coastal (coastal grassland) sites. Ecological thresholds (the point at which small changes in an environmental driver can produce an abrupt and persistent state change in an ecosystem quality, property, or phenomenon) were most commonly predicted. For example, in coastal ecosystems, sea-level rise and climate change could convert salt marsh to mangroves and coastal barrier dunes to shrub thicket. Reduced fire frequency has converted grassland to shrubland in mesic prairie, whereas overgrazing combined with drought drive shrub encroachment in arid grasslands. Lastly, tropical cloud forests are susceptible to climate-induced changes in cloud base altitude leading to shifts in species distributions. Overall, these examples reveal that state change is a likely outcome of global environmental change across a diverse range of ecosystems and highlight the need for long-term studies to sort out the causes and consequences of state change. The diversity of sites within the LTER network facilitates the emergence of overarching concepts about state changes as an important driver of ecosystem structure, function, services, and futures.
%U https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3433
%A Zinnert, Julie C.
%A Nippert, Jesse B.
%A Rudgers, Jennifer A.
%A Pennings, Steven C.
%A Gonzalez, Grizelle
%A Alber, Merryl
%A Baer, Sara G.
%A Blair, John M.
%A Burd, Adrian B.
%A Collins, Scott L.
%A Craft, Christopher B.
%A Di Iorio, Daniela
%A Dodds, Walter K. 
%A Groffman, Peter M. 
%A Herbert, Ellen
%A Hladik, Christine M.
%A Li, Fan
%A Litvak, Marcy
%A Newsome, Seth
%A O'Donnell, John
%A Pockman, William T.
%A Schalles, John F.
%A Young, Donald R.
%K arid grassland, coastal grassland, coastal marsh, tallgrass prairie, shrub invasion, sea level rise, tropical mountain cloud forest, UGAMI Publication

%0 Report
%T Sweet (and sticky) redemption
%D 2020
%B Scalawag Magazine
%9 Article
%Z published
%M GCE.1236
%U https://scalawagmagazine.org/2020/09/gullah-geechee-crops-agriculture/
%A Bailey, Maurice
%A Heynen, Nik
%K Sapelo

%0 Conference Proceedings
%T Factors determining GA salt marsh biomass: A dynamical systems approach
%D 2020
%C Atlanta (online due to COVID-19)
%B 7th Annual Southeastern Biogeochemistry Symposium
%8 March 14-15
%9 Poster
%Z presented
%M GCE.1204
%A Bice, Kadir
%A Schalles, John F.
%A Meile, Christof
%K marsh productivity, timeseries, Student Publication

%0 Conference Proceedings
%T Investigating subsurface biogeochemistry in tide-impacted Altamaha River sediment using microbial metagenomics and metabolomics
%D 2020
%C San Francisco (online due to COVID-19)
%B AGU Fall meeting
%8 December 1-17, 2020
%9 Poster
%Z presented
%M GCE.1205
%A Bice, Kadir
%A Wrighton, K.C.
%A Daly, R.A.
%A Schopflin, L.
%A Danczak, R.
%A Song, H.-S.
%A Schalles, John F.
%A Meile, Christof
%K Altamaha, metagenome, FTICR-MS, timeseries, Student Publication

%0 Journal Article
%T Historical Changes in the Vegetated Area of Salt Marshes
%D 2020
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1180
%R 10.1007/s12237-020-00781-6
%X Salt marshes are valuable ecosystems, and there is concern that increases in the rate of sea level rise along with anthropogenic activities are leading to the loss of vegetated habitat. The area of vegetated marsh can change not only through advance and retreat of the open fetch edge, but also due to channel widening and contracting, formation and drainage of interior ponds, formation and revegetation of interior mud flats, and marsh migration onto upland areas, each of which is influenced by different processes. This study used historical aerial photographs to measure changes in the extent of vegetated marsh over approximately 70 years at study marshes located in three long-term ecological research (LTER) sites along the US East coast: Georgia Coastal Ecosystems (GCE), Virginia Coast Reserve (VCR), and Plum Island Ecosystems (PIE). Marsh features were categorized into vegetated marsh, ponds, interior mud flats, and channels for three time periods at each site. The three sites showed different patterns of change in vegetated marsh extent over time. At the GCE study site, losses in vegetated marsh, which were primarily due to channel widening, were largely offset by channel contraction in other areas, such that there was little to no net change over the study period. The study marsh at VCR experienced extensive vegetated marsh loss to interior mud flat expansion, which occurred largely in low-lying areas. However, this loss was counterbalanced by marsh gain due to migration onto the upland, resulting in a net increase in vegetated marsh area over time. Vegetated marsh at PIE decreased over time due to losses from ponding, channel widening, and erosion at the open fetch marsh edge. Digital elevation models revealed that the vegetated areas of the three marshes were positioned at differing elevations relative to the tidal frame, with PIE at the highest and VCR at the lowest elevation. Understanding the patterns of vegetation loss and gain at a given site provides insight into what factors are important in controlling marsh dynamics and serves as a guide to potential management actions for marsh protection.
%U https://link.springer.com/article/10.1007/s12237-020-00781-6?wt_mc=Internal.Event.1.SEM.ArticleAuthorOnlineFirst
%A Burns, Christine
%A Alber, Merryl
%A Alexander, Clark R., Jr.
%K Salt marsh, LTER, Image analysis, Ponding, Marsh Migration, Signature Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Assessing long-term trends in lateral salt-marsh shoreline change along a U.S. East Coast latitudinal gradient
%D 2020
%V 37
%N 2
%P 291-301
%B Journal of Coastal Research
%9 Article
%Z published
%M GCE.1194
%R 10.2112/JCOASTRES-D-19-00043.1
%X Marshes are valuable intertidal habitats that respond to changes in their environment, and their perimeters can rapidly advance or retreat over time. This study used the analyzing moving boundaries using R (AMBUR) tool kit to measure approximately 70 years of edge change at salt marshes within three Long-Term Ecological Research sites along the U.S. East Coast: Georgia Coastal Ecosystems (GCE), Virginia Coast Reserve (VCR), and Plum Island Ecosystems (PIE). At each site, changes were assessed at the open-fetch marsh outer perimeter as well as throughout interior channels of varying sizes. At the open-fetch marsh outer perimeter, both the PIE and VCR study marshes exhibited significant net retreat, with the fastest rates in areas exposed to high fetch where wave action is strong, whereas the GCE marsh exhibited significant net advance. Changes in the sinuous interior channels were smaller, with channels often retreating on one edge but were balanced by advance on the opposite bank. When advance and retreat in the interior channels were considered along with the outer perimeter, the GCE and VCR study marshes exhibited dynamic stability in which overall marsh edge showed no significant net change, and the overall rate of marsh retreat at PIE, although still significant with respect to the uncertainty of the analysis, was considerably reduced. This study demonstrates the importance of assessing shoreline changes throughout the marsh, as rates of retreat and advance at the open-fetch marsh perimeter may differ greatly from those in the interior, and not be indicative of the overall change in marsh edge.
%U https://doi.org/10.2112/JCOASTRES-D-19-00043.1
%A Burns, Christine
%A Alexander, Clark R., Jr.
%A Alber, Merryl
%K salt marsh, UGAMI Publication

%0 Journal Article
%T Geomorphology and species interactions hierarchically structure the self-organization and landscape effects of a salt marsh facilitation cascade.
%D 2020
%B Current Biology
%9 Article
%Z published
%M GCE.1157
%R 10.1016/j.cub.2020.02.031
%X Facilitation cascades are chains of positive interactions that occur as frequently as trophic cascades and are equally important drivers of ecosystem function, where they involve the overlap of primary and secondary, or dependent, habitat-forming foundation species [1]. Although it is well recognized that the size and configuration of secondary foundation species’ patches are critical features modulating the ecological effects of facilitation cascades [2], the mechanisms governing their spatial distribution are often challenging to discern given that they operate across multiple spatial and temporal scales [1, 3]. We therefore combined regional surveys of southeastern US salt marsh geomorphology and invertebrate communities with a predator exclusion experiment to elucidate the drivers, both geomorphic and biotic, controlling the establishment, persistence, and ecosystem functioning impacts of a regionally abundant facilitation cascade involving habitat-forming marsh cordgrass and aggregations of ribbed mussels. We discovered a hierarchy of physical and biological factors predictably controlling the strength and self-organization of this facilitation cascade across creekshed, landscape, and patch scales. These results significantly enhance our capacity to spatially predict coastal ecosystem function across scales based on easily identifiable metrics of geomorphology that are mechanistically linked to ecological processes. Replication of this approach across vegetated coastal ecosystems has the potential to support management efforts by elucidating the multi-scale linkages between geomorphology and ecology that, in turn, define spatially explicit patterns in community assembly and ecosystem functioning.
%A Crotty, Sinead M.
%A Angelini, Christine
%K geomorphology, species interactions, salt marsh

%0 Journal Article
%T Sea-level rise and the emergence of a keystone grazer alter the geomorphic evolution and ecology of southeast US salt marshes
%D 2020
%V 117
%P 17891-17902
%B PNAS
%9 Article
%Z published
%M GCE.1182
%R 10.1073/pnas.1917869117
%X Keystone species have large ecological effects relative to their abundance and have been identified in many ecosystems. However, global change is pervasively altering environmental conditions, potentially elevating new species to keystone roles. Here, we reveal that a historically innocuous grazer—the marsh crab Sesarma reticulatum—is rapidly reshaping the geomorphic evolution and ecological organization of southeastern US salt marshes now burdened by rising sea levels. Our analyses indicate that sea-level rise in recent decades has widely outpaced marsh vertical accretion, increasing tidal submergence of marsh surfaces, particularly where creeks exhibit morphologies that are unable to efficiently drain adjacent marsh platforms. In these increasingly submerged areas, cordgrass decreases belowground root:rhizome ratios, causing substrate hardness to decrease to within the optimal range for Sesarma burrowing. Together, these bio-physical changes provoke Sesarma to aggregate in high-density grazing and burrowing fronts at the heads of tidal creeks (hereafter, creekheads). Aerial-image analyses reveal that resulting “Sesarma-grazed” creekheads increased in prevalence from 10 ± 2% to 29 ± 5% over the past <25 y and, by tripling creek-incision rates relative to nongrazed creekheads, have increased marsh-landscape drainage density by 8 to 35% across the region. Field experiments further demonstrate that Sesarma-grazed creekheads, through their removal of vegetation that otherwise obstructs predator access, enhance the vulnerability of macrobenthic invertebrates to predation and strongly reduce secondary production across adjacent marsh platforms. Thus, sea-level rise is creating conditions within which Sesarma functions as a keystone species that is driving dynamic, landscape-scale changes in salt-marsh geomorphic evolution, spatial organization, and species interactions.
%U https://www.pnas.org/content/early/2020/07/09/1917869117
%A Crotty, Sinead M.
%A Ortals, Collin
%A Pettengill, Thomas M.
%A Shi, Luming
%A Olabarrieta, Maitane
%A Joyce, Matthew A.
%A Altieri, Andrew H.
%A Morrison, Elise
%A Bianchi, Thomas S.
%A Craft, Christopher B.
%A Bertness, Mark D.
%A Angelini, Christine
%K Biodiversity, Bioturbation, Ecosystem engineer, Herbivory, Morphodynamics, Student Publication, UGAMI Publication

%0 Journal Article
%T Tidal wetland Gross Primary Production across the continental United States, 2000-2019
%D 2020
%V 34
%B Global Biogeochemical Cycles
%9 Article
%Z published
%M GCE.1136
%R 10.1029/2019GB006349
%X We mapped tidal wetland gross primary production (GPP) with unprecedented detail for multiple wetland types across the continental United States (CONUS) at 16&#8208;day intervals for the years 2000–2019. To accomplish this task, we developed the spatially explicit Blue Carbon (BC) model, which combined tidal wetland cover and field&#8208;based eddy covariance tower data into a single Bayesian framework, and used a super computer network and remote sensing imagery (Moderate Resolution Imaging Spectroradiometer Enhanced Vegetation Index). We found a strong fit between the BC model and eddy covariance data from 10 different towers (r2 = 0.83, p < 0.001, root&#8208;mean&#8208;square error = 1.22 g C/m2/day, average error was 7% with a mean bias of nearly zero). When compared with NASA's MOD17 GPP product, which uses a generalized terrestrial algorithm, the BC model reduced error by approximately half (MOD17 had r2 = 0.45, p < 0.001, root&#8208;mean&#8208;square error of 3.38 g C/m2/day, average error of 15%). The BC model also included mixed pixels in areas not covered by MOD17, which comprised approximately 16.8% of CONUS tidal wetland GPP. Results showed that across CONUS between 2000 and 2019, the average daily GPP per m2 was 4.32 ± 2.45 g C/m2/day. The total annual GPP for the CONUS was 39.65 ± 0.89 Tg C/year. GPP for the Gulf Coast was nearly double that of the Atlantic and Pacific Coasts combined. Louisiana alone accounted for 15.78 ± 0.75 Tg C/year, with its Atchafalaya/Vermillion Bay basin at 4.72 ± 0.14 Tg C/year. The BC model provides a robust platform for integrating data from disparate sources and exploring regional trends in GPP across tidal wetlands.
%U https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GB006349
%A Feagin, R. A.
%A Forbrich, Inke
%A Huff, T. P. 
%A Barr, J. G.
%A Ruiz-Plancarte, J.
%A Fuentes, J. D.
%A Najjar, R.
%A Vargas, Rodrigo
%A Vazquez-Lule, A. L.
%A Windham-Myers, L.
%A Kroeger, Kevin D
%A Ward, E. J.
%A Moore, G. W. 
%A Leclerc, Monique Y.
%A Krauss, K. W.
%A Stagg, C. L. 
%A Alber, Merryl
%A Knox, S. H.
%A Schafer, K. V. R.
%A Bianchi, Thomas S.
%A Hutchings, J. A.
%A Nahrawi, Hafsah Binti
%A Noormets, A.
%A Mitra, B.
%A Jaimes, A.
%A Hinson, A. L.
%A Bergamaschi, B.
%A King, J. S.
%K tidal wetland, Gross Primary Production, Cross-site Research

%0 Journal Article
%T Megafauna in salt marshes
%D 2020
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1211
%R 10.3389/fmars.2020.561476
%X Megafauna shape ecosystems globally through trophic interactions, ecology of fear, and ecosystem engineering. Highly productive salt marshes at the interface of terrestrial and marine systems have the potential to support megafauna species, but a recent global meta-analysis of consumer-plant interactions in marshes found few studies investigated impacts of wild megafauna. We conducted a literature review to document the variety of megafauna in salt marshes and found that 34 species utilize salt marshes, including sharks, manatees, pinnipeds, crocodilians, sea otters, hippos, and large terrestrial animals, such as lions, bears and water buffalo. The use of salt marsh habitats by a variety of megafauna may have implications for both the conservation of these large consumers and for the resilience of coastal wetlands through stabilizing feedbacks on plant ecosystems. Future studies should quantify the occurrence and impacts of megafauna in salt marshes, and how their conservation can help restore these valuable ecosystems.
%A Gaskins, L.C.
%A Paxton, A.
%A Silliman, Brian R.
%K megafauna, salt marsh, ecosystem resilience, coastal wetland, restoration

%0 Journal Article
%T Consumer regulation of the carbon cycle in coastal wetland ecosystems
%D 2020
%B Philosophical Transactions of the Royal Society
%9 Article
%Z published
%M GCE.1210
%R 10.1098/rstb.2019.0451
%X Despite escalating anthropogenic alteration of food webs, how the carbon cycle in ecosystems is regulated by food web processes remains poorly understood. We quantitatively synthesize the effects of consumers (herbivores, omnivores and carnivores) on the carbon cycle of coastal wetland ecosystems, ‘blue carbon’ ecosystems that store the greatest amount of carbon per unit area among all ecosystems. Our results reveal that consumers strongly affect many processes of the carbon cycle. Herbivores, for example, generally reduce carbon absorption and carbon stocks (e.g. aboveground plant carbon by 53% and aboveground net primary production by 23%) but may promote some carbon emission processes (e.g. litter decomposition by 32%). The average strengths of these effects are comparable with, or even times higher than, changes driven by temperature, precipitation, nitrogen input, CO2 concentration, and plant invasions. Furthermore, consumer effects appear to be stronger on aboveground than belowground carbon processes and vary markedly with trophic level, body size, thermal regulation strategy and feeding type. Despite important knowledge gaps, our results highlight the powerful impacts of consumers on the carbon cycle and call for the incorporation of consumer control into Earth system models that predict anthropogenic climate change and into management strategies of Earth’s carbon stocks.
%A He, Qiang
%A Li, H.
%A Xu, C.
%A Sun, Q.
%A Bertness, Mark D.
%A Fang, C.
%A Li, B.
%A Silliman, Brian R.
%K blue carbon, ecosystem functioning, food webs, salt marsh, top-down control

%0 Journal Article
%T Effects of ten years of nitrogen and phosphorus fertilization on carbon and nutrient cycling in a tidal freshwater marsh
%D 2020
%V 65
%P 1669-1687
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.1153
%X Tidal freshwater marshes can protect downstream ecosystems from eutrophication by intercepting excess nutrient loads, but recent studies in salt marshes suggest nutrient loading compromises their structural and functional integrity. Here, we present data on changes in plant biomass, microbial biomass and activity, and soil chemistry from plots in a tidal freshwater marsh on the Altamaha River (GA) fertilized for 10 yr with nitrogen (+N), phosphorus (+P), or nitrogen and phosphorus (+NP). Nitrogen alone doubled aboveground biomass and enhanced microbial activity, specifically rates of potential nitrification, denitrification, and methane production measured in laboratory incubations. Phosphorus alone increased soil P and doubled microbial biomass but did not affect microbial processes. Nitrogen or P alone decreased belowground biomass and soil carbon (C) whereas +NP increased aboveground biomass, microbial biomass and N cycling, and N, P, and C assimilation and burial more than either nutrient alone. Our findings suggest differential nutrient limitation of tidal freshwater macrophytes by N and microbes by P, similar to what has been observed in salt marshes. Macrophytes outcompete microbes for P in response to long&#8208;term N and P additions, leading to increased soil C storage through increased inputs of belowground biomass relative to N and P added singly. The susceptibility of tidal freshwater marshes to long&#8208;term nutrient enrichment and, hence their ability to mitigate eutrophication will depend on the quantity and relative proportion of N vs. P entering estuaries and tidal wetlands.
%U https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.11411
%A Herbert, Ellen
%A Schubauer-Berigan, Joseph P.
%A Craft, Christopher B.
%K freshwater marshes, nitrogen, UGAMI Publication

%0 Journal Article
%T A plantation can be a commons: Re-Earthing Sapelo Island through Abolition Ecology
%D 2020
%V 0
%N 0
%P 20
%B Antipode
%9 Article
%Z published
%M GCE.1215
%R 10.1111/anti.12631
%X This paper is based on the 2018 Neil Smith Lecture presented at the University of St Andrews. It considers the plantation past/futures of Sapelo Island, Georgia, one of the Sea Islands forming an archipelago along the US Southeastern coast. I work through the abolitionist efforts of the Saltwater Geechee’s who have resided there since at least 1803 to better understand how we can mobilise an emancipatory politics of land and property and to produce commons that work to repair and heal the violence done through enslavement and ongoing displacement. I weave together a series of historical threads to better situate linked ideas of abolition democracy and abolition geography, and to extend the notion of abolition ecology as a strategic notion to connect Eurocentric based political ecologies with the emancipatory tradition of Black geographies.
%A Heynen, Nik
%K abolition ecology, land, the commons, Black geographics

%0 Journal Article
%T Beyond 2100: Elevation capital disguises salt marsh vulnerability to sea-level rise in Georgia, USA
%D 2020
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.1195
%X Salt marshes rely on sufficient sediment inputs and room for lateral migration to maintain vertical and lateral stability under sea-level rise. As the global rate of sea-level rise accelerates, marshes unable to keep pace become vulnerable to drowning. We evaluated the long-term response of a salt marsh in Georgia, USA, to historical (1935–2018) and future projected rates of sea-level rise. We expected the marsh to be resilient because it receives high sediment inputs and has room to migrate landward. However, sediment cores show marsh accretion (1.55 mm y&#8722;1) is lower than the historical rate of sea-level rise (3.25 mm y&#8722;1) and that rates are independent of elevation. Results from a vertical accretion model show that while marsh area is stable through 2100 under historical and high sea-level rise scenarios, the marsh relies on elevation capital to maintain its extent under a high rate of sea-level rise. The marsh rapidly loses area beyond 2100 as it depletes its elevation reserve. By 2160, only 12% of the initial marsh area remains. Our results demonstrate that while elevation capital can extend the period of time a marsh maintains its areal extent, it does not remove the long-term threat of drowning when marsh accretion cannot keep pace with sea-level rise.
%A Langston, A.K.
%A Alexander, Clark R., Jr.
%A Alber, Merryl
%A Kirwan, M.
%K Accretion, Long-term changes, Mathematical models, sediment sampling, Student Publication, UGAMI Publication

%0 Thesis
%T Dissolved organic matter dynamics in coastal aquatic systems
%D 2020
%P 188
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.1192
%X Dissolved organic matter (DOM) is a critical component of aquatic environments and global carbon cycling; it has multiple sources including terrestrial runoff, riverine input, phytoplankton excretion, viral lysis, among others. These inputs have varying levels of contribution depending on temporal and spatial scales as well as environmental variables, making the characterization of the DOM increasingly complex. This dissertation used bulk (dissolved organic carbon - DOC), optical (chromophoric DOM - CDOM), molecular (FT-ICR MS) analyses as well as microbial incubation experiments to investigate changes in DOC concentration, DOM composition, and lability in coastal ecosystems in the southeastern U.S. In CHAPTER 2, changes in DOC concentration and DOM composition were analyzed monthly over a year at the Altamaha River and at the head of Sapelo Sound in coastal Georgia, USA. Results showed that river discharge was the primary driver that changed the DOM composition in both locations. In October 2016, the Georgia coast was hit by Hurricane Matthew, which increased the average DOC concentration by ~ 4 times and strongly augmented the terrigenous signature of DOM. In CHAPTER 3, changes in DOM composition and bacterial processing were investigated at fifteen sites across a riverine-estuarine gradient system as part of the GCE-LTER domain over four seasons. The terrigenous-marine gradient in organic matter sources explained the most variation in DOM composition throughout the year. Increased microbial degradation rates were observed for DOM that had a stronger terrigenous character, especially for samples collected ~ 30 days after Hurricane Irma had impacted the studied area. Finally, in CHAPTER 4, changes in DOC concentration and DOM composition of ambient seawater were characterized after interaction with a loggerhead sponge, Spheciospongia vesparium, in the Florida Bay, USA. The sponge-microbial holobiont removed small, oxygen-depleted, nitrogen-rich compounds and the DOM composition was significantly different than that of the ambient seawater. Microbial incubations suggested that sponge exhalent seawater was less labile than ambient seawater, possibly due to holobiont removal of nitrogen-rich compounds. Overall, this dissertation illuminates the merits of combining different chemical analyses and microbial experiments to better uncover and understand the dynamics of different DOM pools across complex coastal environments.
%U https://esploro.libs.uga.edu/esploro/outputs/9949365957702959
%A Letourneau, Maria L.
%K Dissolved organic carbon, DOM composition, Degradation, FT-ICR MS, GCE-LTER, Student Publication, UGAMI Publication

%0 Journal Article
%T Molecular composition and biodegradation of loggerhead sponge Spheciospongia vesparium exhalent dissolved organic matter
%D 2020
%V 162
%P 105130
%B Marine Environmental Research
%9 Article
%Z published
%M GCE.1187
%R 10.1016/j.marenvres.2020.105130
%X Sponges are critical components of marine reefs due to their high filtering capacity, wide abundance, and alteration of biogeochemical cycling. Here, we characterized dissolved organic matter (DOM) composition in the sponge holobiont exhalent seawater of a loggerhead sponge (Spheciospongia vesparium) and in ambient seawater in Florida Bay (USA), as well as the microbial responses to each DOM pool through dark incubations. The sponge holobiont removed 6% of the seawater dissolved organic carbon (DOC), utilizing compounds that were low in carbon and oxygen, yet high in nitrogen content relative to the ambient seawater. The microbial community accessed 7% of DOC from the ambient seawater during a 5-day incubation but only 1% of DOC from the sponge exhalent seawater, suggesting a decrease in lability possibly due to holobiont removal of nitrogen-rich compounds. If this holds true for other sponges, it may have important implications for DOM lability and cycling in coastal environments.
%A Letourneau, Maria L.
%A Hopkinson, Brian M.
%A Fitt, William K.
%A Medeiros, Patricia M.
%K Dissolved organic carbon, DOM composition, Degradation, FT-ICR MS, Loggerhead sponge, Coastal zone, Florida Bay, Student Publication

%0 Journal Article
%T Climate and geographic adaptation drive latitudinal clines in biomass of a widespread saltmarsh plant in its native and introduced ranges
%D 2020
%V 65
%P 1399-1409
%B Limnology & Oceanography
%9 Article
%Z published
%M GCE.1179
%R 10.1002/lno.11395
%X Introduced plants provide a unique opportunity to examine how plants respond through plasticity and adaptationto changing climates. We compared plants of Spartina alterniflora from the native (United States, 27–43
N)and introduced (China, 19–40
N) ranges. In the field and greenhouse, aboveground productivity of Chineseplants was greater than that of North American plants. Aboveground biomass in the field declined with increasinglatitude in the native range, a pattern that persisted in the greenhouse, indicating a genetic basis. Abovegroundbiomass in the field displayed hump-shaped relationships with latitude in China, but this pattern disappeared infield and greenhouse common gardens, indicating phenotypic plasticity. Relationships in both geographic regionswere explained by temperature, which is probably the underlying environmental factor affecting abovegroundbiomass. S. alterniflora has evolved greater biomass in China, but in the four decades since it was introduced, ithas not yet evolved the genetic cline in biomass seen in its native range. By working at lower latitudes in theintroduced range than have been sampled in the native range, we identified an optimum temperature in theintroduced range above which aboveground productivity decreases.
%A Liu, Wenwen
%A Chen, Xincong
%A Strong, Donald R.
%A Pennings, Steven C.
%A Kirwan, Matthew Lynn
%A Chen, Xiaolin
%A Zhang, Yihui
%K Spartina alterniflora, introduced species, latitude, cline, productivity

%0 Journal Article
%T Contrasting plant adaptation strategies to latitude in the native and invasive range of Spartina alterniflora
%D 2020
%V 226
%P 623-634
%B New Phytologist
%9 Article
%Z published
%M GCE.1189
%R 10.1111/nph.16371
%X Biological invasions offer model systems of contemporary evolution. We examined trait differencesand evolution across geographic clines among continents of the intertidal grassSpartina alterniflora within its invasive and native ranges.
 We sampled vegetative and reproductive traits in the field at 20 sites over 20° latitude inChina (invasive range) and 28 sites over 17° in the US (native range). We grew both Chineseand US plants in a glasshouse common garden for 3 yr.
 Chinese plants were c. 15% taller, c. 10% denser, and set up to four times more seed thanUS plants in both the field and common garden. The common garden experiments showed astriking genetic cline of seven-fold greater seed set at higher latitudes in the introduced butnot the native range. By contrast, there was a slight genetic cline in some vegetative traits inthe native but not the introduced range.
 Our results are consistent with others showing that introduced plants can evolve rapidly inthe new range. S. alterniflora has evolved different trait clines in the native and introducedranges, showing the importance of phenotypic plasticity and genetic control of change duringthe invasion process
%A Liu, Wenwen
%A Zhang, Yihui
%A Chen, Xincong
%A Maung-Douglass, Keith
%A Strong, Donald R.
%A Pennings, Steven C.
%K Spartina, introduced species, exotic species, latitude, common garden experiment, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T What controls DOM composition variability in marsh-dominated estuaries?
%D 2020
%I American Geophysical Union
%C San Diego, CA
%B Ocean Sciences Meeting
%8 February 2020
%9 Poster
%Z presented
%M GCE.1193
%A Martineac, Rachel P.
%A Medeiros, Patricia M.
%K Dissolved organic carbon, DOM composition, Degradation, FT-ICR MS, GCE-LTER, Student Publication, UGAMI Publication

%0 Journal Article
%T Differential effects of press vs. pulse seawater intrusion on microbial communities of a tidal freshwater marsh
%D 2020
%B Limnology and Oceanography Letters
%9 Article
%Z published
%M GCE.1197
%R 10.1002/lol2.10171
%X Tidal freshwater marshes (TFMs) are threatened by seawater intrusion, which can affect microbial communities and alter biogeochemical processes. Here, we report on a long-term, large-scale manipulative field experiment that investigated continuous (press) and episodic (pulse, 2 months/yr) inputs of brackish water on microbial communities in a TFM. After 2.5 yr, microbial diversity was lower in press treatments than in control (untreated) plots whereas diversity in pulse plots was unaffected by brackish water additions. Sulfate reducer abundance increased in response to both press and pulse treatments whereas methanogens did not differ among treatments. Our results, along with other lab and field measurements that show reduced soil respiration and extracellular enzyme activity suggest that continuous seawater intrusion will decrease macrophyte C inputs that reduce bacterial diversity in ways that also diminish ecosystem carbon cycling.
%A Mobilian, Courtney
%A Wisnoski, Nathan
%A Lennon, Jay
%A Alber, Merryl
%A Widney, Sarah
%A Craft, Christopher B.
%K seawater intrustion, microbial, tidal freshwater, freshwater marsh, UGAMI Publication

%0 Journal Article
%T Parasites enhance resistance to drought in a coastal ecosystem
%D 2020
%B Ecology
%9 Article
%Z published
%M GCE.1209
%R 10.1002/ecy.2897
%X Parasites are more diverse and numerous than their hosts and commonly control population dynamics. Whether parasites also regulate key ecosystem processes, such as resistance to climate stress, is unclear. In southern U.S. salt marshes, drought interacts synergistically with keystone grazing to generate extensive ecosystem die-off. Field manipulations of parasite prevalence and salt stress in sediments in healthy marshes demonstrated that trematode parasites, by suppressing feeding activity of grazers that overgraze on drought-stressed plants, have the potential to slow the rate of ecosystem loss. Surveys along 1,000 km of coastline during an intense drought event revealed parasitism is common in grazers on die-off borders and that increasing infection prevalence along marsh die-off borders is negatively correlated with per capita grazing. Combined, results from this field experiment and survey suggested, but did not show, that parasites could affect rates of drought-driven salt marsh dieoff. To test whether parasites can indeed protect marshes under real drought conditions, we experimentally manipulated parasite prevalence in grazers over a month-long period on active die-off borders in three North Carolina marshes. Experimentally reducing parasite prevalence markedly increased the rate of plant ecosystem decline, an effect that scaled positively with prevalence. Thus parasites, by generating a trophic cascade, indirectly enhanced ecosystem resistance to overgrazing under intense drought in these North Carolina marshes. The generality of these results across the entire range of this keystone grazer in the southeastern United States needs to be tested, employing both experiments and extensive surveys that examine how the rate of ecosystem decline is mediated by parasitism. Given the ubiquity of parasites in ecosystems, our results suggest that more research effort should be invested in examining the possible roles for parasitism in regulating ecosystem function and stability.
%A Morton, Joe P.
%A Silliman, Brian R.
%K parasites

%0 Journal Article
%T Impact of tidal inundation on the net ecosystem exchange in daytime conditions in a salt marsh
%D 2020
%V 294
%P 108133
%B Agricultural and Forest Meteorology
%9 Article
%Z published
%M GCE.1183
%R 10.1016/j.agrformet.2020.108133
%X Salt marshes are highly productive ecosystems and yet we have only a preliminary understanding of how netecosystem exchange varies on daily and seasonal time scales. We used the eddy-covariance method to examinethe behaviour of the net ecosystem exchange as influenced by tidal flooding in daytime conditions in a coastalsalt marsh dominated by Spartina alterniflora in Georgia, USA. Two different analyses both found that the netecosystem exchange was ~ 60% greater during neap high tides than during spring high tides; the largest differencesoccurred early in the growing season. The effect of tidal flooding varied continuously with the degree towhich plants were inundated versus emergent. The total monthly reduction (less negative) in daytime netecosystem exchange due to flooding was 7-38% and 1-64% in 2014 and 2015 respectively. The highest CO2 fluxreductions were observed early and during the peak growing season (February, March, April and May) and thelowest during the summer season in both years. Our findings suggest that daytime CO2 flux was reduced (lessnegative) 20-60% during the peak growing season due to tidal flooding. A better understanding of the impact ofseasonal tidal flooding on net ecosystem exchange may allow more sophisticated predictions of how sea levelrise will affect marsh function and survival over the coming century.
%A Nahrawi, Hafsah Binti
%A Leclerc, Monique Y.
%A Pennings, Steven C.
%A Zhang, Gengsheng
%A Singh, N.
%A Pahari, R.
%K eddy-covariance, net ecosystem exchange, tidal inundation, Spartina alterniflora, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Microspatial differences in soil temperature cause phenology change on par with long-term climate warming in salt marshes
%D 2020
%V 23
%P 498–510
%B Ecosystems
%9 Article
%Z published
%M GCE.1131
%R 10.1007/s10021-019-00418-1
%X Phenology studies mostly focus on variation across time or landscapes. However, phenology can vary at fine spatial scales, and these differences may be as important as long-term change from climate warming. We used high-frequency ‘‘PhenoCam’’ data to examine phenology of Spartina alterniflora, afoundation species native to salt marshes on the US East and Gulf coasts, and a common colonizer elsewhere. We examined phenology across three microhabitats from 2013 to 2017 and used this information to create the first spring green-up model for S. alterniflora. We then compared modern spatial variation to that exhibited over a 60-year climate record. Marsh interior plants initiated spring growth 17 days earlier than channel edge plants and spent 35 days more in the green-up phenophase and 25 days less in the maturity phenophase. The start of green-up varied by 17 days among 3 years. The best spring green-up model was based on winter soil total growing degree days. Across microhabitats, spring green-up differences were caused by small elevation changes (15 cm) that drove soil temperature variation of 0.8C. Preliminary evidence indicated that high winter belowground biomass depletion triggered early green-up. Long-term change was similar: winter soil temperatures warmed 1.7 ± 0.3C since 1958, and green-up advanced 11 ± 6 days, whereas contemporary microhabitat differences were 17 ± 4 days. Incorporating local spatial variation into plant phenology models may provide an early warning of climate vulnerability and improve understanding of ecosystem-scale productivity. Microscale phenology variation likely exists in other systems and has been unappreciated.
%U https://link.springer.com/article/10.1007/s10021-019-00418-1
%A O'Connell, Jessica L
%A Alber, Merryl
%A Pennings, Steven C.
%K digital camera imagery, global climate change, coastal tidal marsh, Georgia Coastal Ecosystems LTER, microhabitat, PhenoCam, Spartina alterniflora, Sporobolus alterniflorus, soil temperature gradient, spring green-up, UGAMI Publication

%0 Conference Proceedings
%T Structural heterogeneity in above vs belowground biomass pools differ for Spartina alterniflora monocultures, with consequences for forecasting ecosystem resiliency
%D 2020
%B Ecological Society of America
%9 Meeting
%Z presented
%M GCE.1247
%A O'Connell, Jessica L.
%A Alber, Merryl
%A Mishra, Deepak
%A Byrd, Kristin
%K Spartina alterniflora, BERM, salt marsh, productivity

%0 Journal Article
%T Seamless retrievals of chlorophyll-a from Sentinel-2 (MSI) and Sentinel-3(OLCI) in inland and coastal waters: A machine-learning approach
%D 2020
%V 240
%P 111604
%B Remote Sensing of Environment
%9 Article
%Z published
%M GCE.1212
%R 10.1016/j.rse.2019.111604
%X Consistent, cross-mission retrievals of near-surface concentration of chlorophyll-a (Chla) in various aquatic ecosystems with broad ranges of trophic levels have long been a complex undertaking. Here, we introduce a machine-learning model, the Mixture Density Network (MDN), that largely outperforms existing algorithms when applied across different bio-optical regimes in inland and coastal waters. The model is trained and validated using a sizeable database of co-located Chla measurements (n=2943) and in situ hyperspectral radiometric data resampled to simulate the Multispectral Instrument (MSI) and the Ocean and Land Color Imager (OLCI) onboard Sentinel-2A/B and Sentinel-3A/B, respectively. Our performance evaluations of the model, via two-thirds of the in situ dataset with Chla ranging from 0.2 to 1209 mg/m3 and a mean Chla of 21.7 mg/m3, suggest significant improvements in Chla retrievals. For both MSI and OLCI, the mean absolute logarithmic error (MAE) and logarithmic bias (Bias) across the entire range reduced by 40–60%, whereas the root mean squared logarithmic error (RMSLE) and the median absolute percentage error (MAPE) improved two-to-three times overthose from the state-of-the-art algorithms. Using independent Chla matchups (n<800) for Sentinel-2A/B and 3A, we show that the MDN model provides most accurate products from recorded images processed via three different atmospheric correction processors, namely the SeaWiFS Data Analysis System (SeaDAS), POLYMER, and ACOLITE, though the model is found to be sensitive to uncertainties in remote-sensing reflectance products.This manuscript serves as a preliminary study on a machine-learning algorithm with potential utility in seamless construction of Chla data records in inland and coastal waters, i.e., harmonized, comparable products via a single algorithm for MSI and OLCI data processing. The model performance is anticipated to enhance by improving the global representativeness of the training data as well as simultaneous retrievals of multiple optically active components of the water column.
%U https://www.sciencedirect.com/science/article/pii/S0034425719306248
%A Pahlevan, Nima
%A Smith, Brandon 
%A Schalles, John F.
%A Binding, Caren
%A Cao, Zhigang
%A Ma, Ronghua
%A Alikas, Krista
%A Kangro, Kersti
%A Gurlin, Daniela
%A Ha, Nguyen
%A Matsushita, Bunkei
%A Moses, Wesley
%A Greb, Steven
%A Lehmann, Moritz K.
%A Ondrusek, Michael
%A Oppelt, Natascha
%A Stumpf, Richard
%K Keywords: Chlorophyll-a, Sentinel missions, Water quality Inland and coastal waters, Earth observation, Machine learning, Algorithm development, Cross-site Research

%0 Journal Article
%T Facilitating better outcomes: How positive species interactions can improve oyster reef restoration
%D 2020
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1224
%R 10.3389/fmars.2020.00656
%X Over 85% of the world’s oyster reefs have been lost in the past two centuries, triggeringa global effort to restore shellfish reef ecosystems and the ecosystem services theyprovide. While there has been considerable success in re-establishing oyster reefs,many challenges remain. These include: high incidence of failed restoration, high costof restoration per unit area, and increasing stress from climate change. In order toleverage our past successes and progress the field, we must increase restorationefficiencies that not only reduce cost per unit area, but also increase the resilience ofrestored ecosystems. To help address this need, we qualitatively review the literatureassociated with the structure and function of oyster reef ecosystems to identify keypositive species interactions (i.e., those species interactions where at least one partnerbenefits and no partners are harmed). We classified positive inter- and intraspecificinteractions between oysters and organisms associated with oyster ecosystems intothe following seven functional categories: (1) physical reef creation, (2) positive densitydependence, (3) refugia from physical stress, (4) refugia from biological stress, (5)biodiversity enhancement, (6) settlement improvement, and (7) long-distance facilitation.We discuss each category of positive interaction and how restoration practitioners canuse knowledge of such processes to enhance restoration success. We propose thatsystematic incorporation of positive species interactions into restoration practice will bothenhance ecological services provided by restored reefs and increase restoration success.
%A Reeves, Simon E.
%A Renzi, Julianna J.
%A Fobert, Emily K.
%A Silliman, Brian R.
%A Hancock, Boze
%A Gillies, Chris L.
%K mutualism, facilitation, restoration, oyster reef, ecosystem services, systematic review, positive interactions

%0 Journal Article
%T Predators enhance resilience of a saltmarsh foundation species to drought
%D 2020
%B Journal of Ecology
%9 Article
%Z published
%M GCE.1213
%R 10.1111/1365-2745.13525
%X Disturbances are increasing in size and frequency with climate change, facilitating species that opportunistically exploit areas where habitat&#8208;forming foundation species have been removed. Although it is well&#8208;recognized that consumers, disease and weedy space&#8208;holders can affect foundation species’ resistance to and recovery from disturbance, how predators influence their resilience is less clear.In salt marshareas de&#8208;vegetated by drought and intensive snail Littoraria irrorata grazing (hereafter, ‘die&#8208;offs’), we monitored bird use and experimentally manipulated bird and nekton access to the vegetated borders of die&#8208;off mudflats across periods of both vegetation die&#8208;off and regrowth to explore how these predators mediate the resilience of cordgrass Spartina alterniflora, the foundation species that structures US Atlantic coast salt marshes.Surveys revealed that birds, especially probers that agitate soils, forage year&#8208;round for invertebrates in die&#8208;off mudflats in our study area but not in adjacent vegetated areas.During periods of die&#8208;off, cordgrass borders accessible to bird and nekton predators retreated >3&#8208;times slower and snail densities were halved, relative to predator exclusion cages. In predator&#8208;accessible plots, slower border retreat corresponded to greater snail infection by a bird host&#8208;dependent trematode parasite. During recovery, cordgrass borders revegetated more quickly, and snail densities declined faster over time in unmanipulated controls relative to predator exclusions.Synthesis. These findings suggest that birds, through their transmission of parasites to snails, appear to act synergistically with snail&#8208;consuming nekton to slow cordgrass loss after drought&#8208;snail disturbances. Predator access also corresponds to faster cordgrass recovery as environmental conditions improve, although the mechanisms behind this need further investigation. Thus, predators that opportunistically forage within disturbances have the potential to suppress consumer impacts through multiple mechanisms, including consumption and disease transmission, thereby bolstering foundation species’ resilience and modulating whole ecosystem responses to climate change.
%A Sharp, Sean
%A Angelini, Christine
%K bird, climate change, food web, nekton, non-consumptive interactions, parasite, Spartina alterniflora, trophic cascade

%0 Journal Article
%T Declines in plant productivity drive loss of soil elevation in a tidal freshwater marsh exposed to saltwater intrusion
%D 2020
%V 101
%N 12
%P 13
%B Ecology
%9 Article
%Z published
%M GCE.1200
%R 10.1002/ecy.3148
%X We experimentally increased salinities in a tidal freshwater marsh on the Altamaha River (Georgia, USA) by exposing the organic rich soils to 3.5 yr of continuous (press) and episodic (pulse) treatments with dilute seawater to simulate the effects of climate change such as sea level rise (press) and drought (pulse). We quantified changes in root production and decomposition, soil elevation, and soil C stocks in replicated (n = 6) 2.5 × 2.5 m field plots. Elevated salinity had no effect on root decomposition, but it caused a significant reduction in root production and belowground biomass that is needed to build and maintain soil elevation capital. The lack of carbon inputs from root production resulted in reduced belowground biomass of 1631 ± 308 vs. 2964 ± 204 g/m2 in control plots and an overall 2.8 ± 0.9 cm decline in soil surface elevation in the press plots in the first 3.5 yr, whereas the control (no brackish water additions) and the fresh (river water only) treatments gained 1.2 ± 0.4 and 1.7 ± 0.3 cm, respectively, in a 3.5&#8208;yr period. There was no change in elevation of pulse plots after 3.5 yr. Based on measurements of bulk density and soil C, the decline of 2.8 cm of surface elevation resulted in a loss of 1.4 ± 0.08 kg C/m2 in press plots. In contrast, the control and the fresh treatment plots gained 0.7 ± 0.05 and 0.8 ± 0.05 kg C/m2, respectively, which represents a net change in C storage of more than 2 kg C/m2. We conclude that, when continuously exposed to saltwater intrusion, the tidal freshwater marsh’s net primary productivity, especially root production, and not decomposition, are the main drivers of soil organic matter (SOM) accumulation. Reduced productivity leads to loss of soil elevation and soil C, which has important implications for tidal freshwater marsh persistence in the face of rising sea level.
%U https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.3148
%A Solohin, Elena
%A Widney, Sarah
%A Craft, Christopher B.
%K decomposition, root production, saltwater intrusion, sea level rise, soil elevation, tidal wetlands, Signature Publication

%0 Journal Article
%T Mimicry of emergent traits amplifies coastal restoration success
%D 2020
%B Nature Communications
%9 Article
%Z published
%M GCE.1222
%R 10.1038/s41467-020-17438-4
%X Restoration is becoming a vital tool to counteract coastal ecosystem degradation. Modifying transplant designs of habitat-forming organisms from dispersed to clumped can amplify coastal restoration yields as it generates self-facilitation from emergent traits, i.e. traits not expressed by individuals or small clones, but that emerge in clumped individuals or large clones. Here, we advance restoration science by mimicking key emergent traits that locally suppress physical stress using biodegradable establishment structures. Experiments across (sub)tropical and temperate seagrass and salt marsh systems demonstrate greatly enhanced yields when individuals are transplanted within structures mimicking emergent traits that suppress waves or sediment mobility. Specifically, belowground mimics of dense root mats most facilitate seagrasses via sediment stabilization, while mimics of aboveground plant structures most facilitate marsh grasses by reducing stem movement. Mimicking key emergent traits may allow upscaling of restoration in many ecosystems that depend on self-facilitation for persistence, by constraining biological material requirements and implementation costs.
%A Temmink, Ralph J.
%A Christianen, M
%A Fivash, Gregory S.
%A Angelini, Christine
%A Bostrom, Christoffer
%A Didderen, Karin
%A Engel, Sabine M.
%A Esteban, Nicole
%A Gaeckle, Jeffrey L.
%A Gagnon, Karine
%A Govers, Laura L.
%A Infantes, Eduardo
%A van Katwijk, Marieke M.
%A Kipson, Silvija
%A Lamers, L.P.M.
%A Lengkeek, Wouter
%A Silliman, Brian R.
%A van Tussenbroek, Brigitta I.
%A Unsworth, Richard K. F.
%A Yaakub, Siti M.
%A Bouma, Tjeerd J.
%A van der Heide, Tjisse
%K mimicry, coastal restoration

%0 Journal Article
%T Ecosystem stability and Native American oyster harvesting along the Atlantic Coast of the United States
%D 2020
%V 6
%B Science Advances
%9 Article
%Z published
%M GCE.1181
%R 10.1126/sciadv.aba9652
%X The eastern oyster (Crassostrea virginica) is an important proxy for examining historical trajectories of coastal ecosystems. Measurement of ~40,000 oyster shells from archaeological sites along the Atlantic Coast of the United States provides a long-term record of oyster abundance and size. The data demonstrate increases in oyster size across time and a nonrandom pattern in their distributions across sites. We attribute this variation to processes related to Native American fishing rights and environmental variability. Mean oyster length is correlated with total oyster bed length within foraging radii (5 and 10 km) as mapped in 1889 and 1890. These data demonstrate the stability of oyster reefs despite different population densities and environmental shifts and have implications for oyster reef restoration in an age of global climate change.
%U https://advances.sciencemag.org/content/6/28/eaba9652/tab-pdf
%A Thompson, Victor D.
%A Rick, Torben
%A Garland, Carey J.
%A Thomas, David Hurst
%A Smith, Karen Y
%A Bergh, Sarah
%A Sanger, Matt
%A Tucker, Bryan
%A Lulewicz, Isabelle H.
%A Semon, Anna M
%A Schalles, John F.
%A Hladik, Christine M.
%A Alexander, Clark R., Jr.
%A Ritchison, Brandon Tyler
%K Ecosystem stability, Oysters, Signature Publication, UGAMI Publication

%0 Journal Article
%T Commodity Consistent Meta&#8209;Analysis of Wetland Values: An Illustration for Coastal Marsh Habitat
%D 2020
%V 75
%P 835–865
%B Environmental and Resource Economics
%9 Article
%Z published
%M GCE.1172
%R 10.1007/s10640-020-00409-0
%X Prior meta-regression models (MRMs) of wetland values pool value estimates associated with diverse commodity types—for example recreation, flood control, nutrient cycling, habitat provision, nonuse value, and carbon sequestration. Neither theory nor economic intuition justify the inclusion of such dissimilar commodities within a single meta-analytic value function, leading to validity concerns. This article seeks to advance methods for commodity and welfare consistent MRMs, applied to a particular category of wetland values. We develop a wetland value MRM restricted to a specific wetland type (coastal marshes), general location (US and Canada), commodity type (habitat provision and services), and valuation approach (stated preference methods). Results indicate that willingness to pay per household for marsh habitat changes is responsive to scope, spatial scale, market extent,the type of habitat change, household characteristics, and other factors suggested by theory and intuition. Results supersede those of prior wetland value MRMs in terms of statistical performance, estimation of anticipated value surface patterns, and capacity to support conceptually valid benefit transfers. Comparison with an otherwise identical but less commodity consistent MRM demonstrates that commodity consistency leads to improved statistical and benefit transfer performance.
%A Vedogbeton, H.
%A Johnston, R. J.
%K Benefit transfer, Meta-analysis, Salt marsh, Stated preference, Valuation, Wetland, Willingness to pay

%0 Journal Article
%T Salinity Affects Topsoil Organic Carbon Concentrations Through Regulating Vegetation Structure and Productivity
%D 2020
%V 125
%N 1
%P 14
%B Journal of Geophysical Research: Biogeosciences
%9 Article
%Z published
%M GCE.1154
%R 10.1029/2019JG005217
%X Estuarine salt marshes have been recognized as one of the most efficient carbon sinks in the biosphere, with considerable potential for climate change mitigation. However, there are still uncertainties about the response of soil carbon stocks to enhanced soil salinization caused by accelerated sea&#8208;level rises and aggravated saltwater intrusion. We therefore conducted both field investigations in the Chongming Dongtan salt marsh of the Yangtze River Estuary, China, and manipulative experiments on marsh soils occupied, respectively, by the invasive Spartina alterniflora, and the native Phragmites australis and Scirpus mariqueter, to identify the effects of elevated soil salinity on top soil organic carbon (SOC) concentration. Our field data showed that SOC concentrations were significantly positively associated with soil salinity concentrations, annual net primary productivity, and marsh surface elevation but showed a significant negative relationship with median grain size. Compared with the two native species, S. alterniflora preferred more saline conditions and had a higher SOC concentration. Although raised flooding salinities (0–35 ppt) did not strongly affect SOC concentrations, elevated soil salinities significantly corresponded with low SOC concentrations and plant biomass in manipulative experiments. These findings indicated that soil salinity, plant species, and soil texture were key factors controlling SOC concentrations in the studied salt marsh. Moreover, soil salinity could affect SOC concentrations through regulating vegetation spatial structure and plant biomass production. The further invasion of the S. alterniflora community will exert a positive influence on SOC concentrations in the Chongming Dongtan salt marsh.
%A Xue, Lian
%A Jiang, Junyan
%A Li, Xiuzhen
%A Yan, Zhongzheng
%A Zhang, Qian
%A Ge, Zhenming
%A Tian, Bo
%A Craft, Christopher B.
%K soil organic carbon, salinity, salt marsh, halophyte, net primary productivity, saltwater intrusion

%0 Journal Article
%T Distribution of organic carbon storage in different saltmarsh plant communities: A case study of the Yangtze Estuary
%D 2020
%V 243
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.1234
%R 10.1016/j.ecss.2020.106900
%X The high carbon (C) sequestration potentials of coastal wetlands play an important role in mitigating climate change associated with the greenhouse effect. In the present study, soil samples were collected from the 0–30-cm topsoil layers and from 0 to 100-cm cores for the analysis of the spatial dynamics and vertical distribution of organic carbon (OC) and biomass in different vegetation zones in a small tidal basin in Chongming Dongtan wetland. According to the results, sediments in the region were a mixture of terrestrial and marine sources and the proportions of terrestrial components decreased with an increase in depth. In addition, soil properties were quite similar in the top-soil layer. In the study area, the OC concentration was in the 0.7–10.93 g/kg range, which was positively correlated with halophyte biomass and negatively correlated with soil salinity and particle size. Furthermore, OC content decreased with an increase in depth. The OC content in different halophyte communities was in the order of Phragmites australis community >Mixed community >sedge community, and was consistent with the gross biomass. The total C sequestered of 100-cm depth in the area was 31,177 ton, with the P. australis community, mixed community, sedge community, and water sequestering 57.7, 49.2, 25.5 t/ha, and 8 t/tidal cycle, respectively. Tidal marshes in Chongming Dongtan exhibited a high C sequestration capacity, indicating that they play a major role in the C cycle in the Yangtze Estuary.
%A Yuan, Yiquan
%A Li, Xiuzhen
%A Jiang, Junyan
%A Xue, Liming
%A Craft, Christopher B.
%K Chongming Dongtan, Salt marsh vegetation, Organic carbon content, Organic carbon storage, Vegetation biomass

%0 Journal Article
%T Contrasting latitudinal clines of nematode diversity in Spartina alterniflora salt marshes between native and introduced ranges
%D 2020
%V 26
%P 623-631
%B Diversity and Distributions
%9 Article
%Z published
%M GCE.1176
%R 10.1111/ddi.13054
%X Aim: Introduced species may display or foster novel latitudinal clines because they are not well adapted to their new habitats. We tested the hypothesis that the latitudinal cline in nematode diversity in salt marshes would differ between the native (United States) and introduced (China) ranges of Spartina alterniflora.Location: East Coasts of the United States (30.32–43.33°N) and China (30.36–39.14°N).Methods: We extracted nematodes from soil samples collected at 32 sites along the United States East Coast and 41 sites along the Chinese coast. We compared latitudinal patterns in nematode diversity and composition between the native and introduced ranges.Results: In the native range of S. alterniflora, nematode richness at lower latitudes was almost twice as high as that at higher latitudes. In contrast, we found no latitudinal pattern in nematode richness or diversity in the introduced range of S. alterniflora. Nematode genus richness at all sites in China was about half that at lower latitudes in the United States. Beta diversity of nematodes increased with geographic distance in the United States, but not China.Main conclusions: Nematode diversity did not show latitudinal clines in salt marshes dominated by introduced S. alterniflora in China. A likely explanation is that the recently introduced populations are still relatively genetically homogenous, whereas in the native range, genetic variation in plant populations across latitude drives different nematode communities. We suggest that future studies of introduced species will gain additional insights by taking an explicitly geographic perspective.
%A Zhang, Youzheng
%A Li, Bo
%A Wu, Jihua
%A Pennings, Steven C.
%K latitudinal clines, native range, nematodes diversity, non-parallel pattern, plant invasion, salt marshes, Spartina alterniflora, UGAMI Publication

%0 Journal Article
%T Elevation drives gradients in surface soil temperature within salt marshes
%D 2019
%V 46
%P 5313-5322
%B Geophysical Research Letters
%9 Article
%Z published
%M GCE.1123
%R 10.1029/2019GL082374
%X Elevation differences in salt marshes result in numerous ecological consequences as a result of variation in tidal flooding. We demonstrate here that elevation differences are also negatively correlated with soil temperature on the marsh platform, irrespective of tidal flooding. Field observations of soil temperature at 10&#8208;cm depth in a Georgia marsh showed that elevation increases of 0.5 m corresponded to decreases in average soil temperature of 0.9–1.7°C during both winter and summer. Landsat 8 estimates of land surface temperatures across the marsh in dry (nonflooded) scenes also showed that temperature decreased with increasing elevation, which was consistent with soil observations. Similar satellite results were also found in a test marsh in Virginia. Biological reactions are temperature&#8208;dependent, and these findings indicate that metabolic processes will vary over short distances. This is important for accurately estimating marsh metabolism and predicting how changes in temperature will affect future productivity.
%U https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082374
%A Alber, Merryl
%A O'Connell, Jessica L.
%K salt marsh, LTER, Landsat, temperature, elevation, Spartina alterniflora, UGAMI Publication

%0 Journal Article
%T Drought alters the spatial distribution, grazing patterns, and radula morphology of a fungal-farming salt marsh snail
%D 2019
%V 620
%P 1-13
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.1159
%R 10.3354/meps12976
%X Climate change is altering consumer&#8722;plant interactions in ecosystems worldwide. How consumers alter their spatial distribution, grazing activities, and functional morphology in response to climate stress can determine whether their effects on plants intensify or relax. Few studies have considered multiple consumer response metrics to elucidate the mechanisms underpinning the resulting changes in consumer&#8722;plant interactions. Here, we tested how drought stress influences the interaction between the dominant consumer, the fungal-farming periwinkle snail Littoraria irrorata, and a foundational plant, cordgrass Spartina alterniflora, in a southeastern US salt marsh. In a 4 mo field experiment, we maintained moderate snail densities in mesh control chambers and clear plastic climate chambers that simulated drought by elevating temperatures and drying soils. Monitoring revealed that snails more often congregated on cordgrass stems than leaves in climate chambers than in controls. Image analyses indicated that this behavioral shift corresponded to snails inflicting shorter, but more numerous, fungal-infested scars on cordgrass leaves, and causing less plant damage in climate chambers than controls. Coincident with their net reduction in grazing, snails maintained longer radulae, whose central teeth were blunter and lateral teeth were sharper, in climate chambers compared to controls. These results suggest that under drought, snail radulae may experience less frictional wear and that, at inter mediate densities, snail&#8722; cordgrass interactions re lax. Together with prior research showing that at high densities, snails can denude cordgrass during drought, we conclude that consumer density, behavior, and morphological responses must be integrated in predictions of how climate change will affect the direction, strength, and stability of consumer&#8722; plant interactions.
%A Chalifour, B.
%A Hoogveld, J.R.H.
%A Derksen-Hooijberg, M.
%A Harris, K.L.
%A Uruena, J.M.
%A Sawyer, W.G.
%A van der Heide, Tjisse
%A Angelini, Christine
%K climate change, coastal wetland, herbivory, Littoraria irrorata, Spartina alterniflora, SINERR Publication, UGAMI Publication

%0 Thesis
%T Drivers and consequences of ribbed mussel spatial patterning in southeastern US salt marshes
%D 2019
%P 1-6
%I University of Florida
%9 Ph.D. Dissertation
%Z published
%M GCE.1173
%A Crotty, Sinead M.
%K ribbed mussel, salt marsh, Student Publication, UGAMI Publication

%0 Thesis
%T Trade-offs between multiple ecosystem services in UK and US salt marshes
%D 2019
%I Swansea University
%C Swansea, Wales, United Kingdom
%9 Ph.D. Dissertation
%Z published
%M GCE.1217
%X Salt marshes supply vital ecosystem services (ES), providing material goods and recreation space, regulating natural hazards, and supporting diverse wildlife. However, increases in the utilisation of one ES can lead to reductions or ‘trade-offs’ in others. Because salt marshes are commonly used for grazing livestock, it is important to understand how this grazing impacts the saltmarsh ecosystem, and the consequences for ES supply. This thesis (i) uses a global meta-analysis to investigate the effects of livestock grazing on saltmarsh properties, and finds multiple significant changes to soil, vegetation and fauna properties. The meta-analysis reveals that the response of soil carbon is context dependent – there is no effect in Europe but a reduction in the Americas. (ii) Extensive surveys of soil carbon in grazed and ungrazed US marshes, controlling for key covariates, confirm that grazing trades-off against carbon storage in US marshes. These observational surveys, together with 18-month experimental exclusion of horses from a salt marsh in Georgia, show that grazing also disrupts the plant community in US marshes, but has little effect on resident invertebrates. (iii) Focusing on bees in salt marshes, a three-year study in south Wales, UK shows that grazing trades-off against bee habitat by reducing the flower cover of two key food plants, and that increases in plant diversity with grazing do not compensate for this negative effect. (iv) Spatial analyses of seven saltmarsh ES supplied by an estuary complex in south Wales show that marshes are not achieving their potential as a bee habitat here, due to the predominance of grazing. These analyses also show that the provision of ES by salt marshes is spatially heterogeneous, dependent on management, size and location. As a whole, this thesis adds to the understanding of grazer impacts and ES trade-offs, and supplies crucial data to support evidence-based management of salt marshes.
%A Davidson, Kate
%K salt marsh, ecosystem, Student Publication

%0 Journal Article
%T Repetitive desiccation events weaken a salt marsh mutualism
%D 2019
%V 107
%N 5
%P 2415-2426
%B Journal of Ecology
%9 Article
%Z published
%M GCE.1160
%R 10.1111/1365-2745.13178
%X Salt marshes suffered large&#8208;scale degradation in recent decades. Extreme events such as hot and dry spells contributed significantly to this, and are predicted to increase not only in intensity, but also in frequency under future climate scenarios. Such repetitive extreme events may generate cumulative effects on ecosystem resilience. It is therefore important to elucidate how marsh vegetation responds to repetitive stress, and whether changes in key species interactions can modulate vegetation resilience.In this study, we investigated how moderate but repetitive desiccation events, caused by the combined effects of drought and high temperatures, affect cordgrass (Spartina alterniflora), the dominant habitat&#8208;forming grass in southeastern US salt marshes. In a 4&#8208;month field experiment, we simulated four consecutive desiccation events by periodically excluding tidal flooding and rainfall, while raising temperature. We crossed this desiccation treatment with the presence/absence of ribbed mussels (Geukensia demissa) – a mutualist of cordgrass known to enhance its desiccation resilience – and with grazing pressure by the marsh periwinkle (Littoraria irrorata) that is known to suppress cordgrass’ desiccation resilience.We found that each subsequent desiccation event deteriorated sediment porewater conditions, resulting in high salinity (53 ppt), low pH&#8208;levels (3.7) and increased porewater Al and Fe concentrations (&#8776;800 µmol/L and &#8776;1,500 µmol/L) upon rewetting. No effects on porewater chemistry were found as a result of snail grazing, while ribbed mussels strongly mitigated desiccation effects almost to control levels and increased cordgrass biomass by approximately 128%. Importantly, although cordgrass generally appeared healthy above&#8208;ground at the end of the experiment, we found clear negative responses of the repetitive desiccation treatment on cordgrass below&#8208;ground biomass, on proline (osmolyte) levels in shoots and on the number of tillers (&#8722;40%), regardless of mussel and/or snail presence.Synthesis. Even though the mutualism with mussels strongly mitigated chemical effects in the sediment porewater throughout the experiment, mussels could not buffer the adverse ecophysiological effects observed in cordgrass tissue. Our results therefore suggest that although mussels may alleviate desiccation stress, the predicted increased frequency and intensity of hot dry spells may eventually affect saltmarsh resilience by stressing the mutualism beyond its buffering capacity.
%A Derksen-Hooijberg, M.
%A Angelini, Christine
%A Hoogveld, J.R.H.
%A Lamers, L.P.M.
%A Borst, A.
%A Smolders, Alfons J. P.
%A Harpenslager, Sarah Fay
%A Govers, Laura L.
%A van der Heide, Tjisse
%K drought, Geukensis demissa, Littoraria irrorta, mussel, mutualism, salt stress, Spartina alterniflora, water stress, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Optimizing coastal restoration with the stress gradient hypothesis
%D 2019
%V 286
%N 1917
%P 10
%B Proceedings of the Royal Society B
%9 Article
%Z published
%M GCE.1156
%R 10.1098/rspb.2019.1978
%X Restoration efforts have been escalating worldwide in response to widespread habitat degradation. However, coastal restoration attempts notoriously vary in their ability to establish resilient, high-functioning ecosystems. Conventional restoration attempts disperse transplants in competition-minimizing arrays, yet recent studies suggest that clumping transplants to maximize facilitative interactions may improve restoration success. Here, we modify the stress gradient hypothesis to generate predictions about where each restoration design will perform best across environmental stress gradients. We then test this conceptual model with field experiments manipulating transplant density and configuration across dune elevations and latitudes. In hurricane-damaged Georgia (USA) dunes, grass transplanted in competition-minimizing (low-density, dispersed) arrays exhibited the highest growth, resilience to disturbance and dune formation in low-stress conditions. In contrast, transplants survived best in facilitation-maximizing (high-density, clumped) arrays in high-stress conditions, but these benefits did not translate to higher transplant growth or resilience. In a parallel experiment in Massachusetts where dune grasses experience frequent saltwater inundation, fewer transplants survived, suggesting that there are thresholds above which intraspecific facilitation cannot overcome local stressors. These results suggest that ecological theory can be used to guide restoration strategies based on local stress regimes, maximizing potential restoration success and return-on-investment of future efforts.
%A Fischman, Hallie
%A Crotty, Sinead M.
%A Angelini, Christine
%K coastal protection, facilitation, resilience, geomorphology, disturbance, competition

%0 Conference Proceedings
%T Salt marsh light use efficiency and gross primary production in response to environmental conditions
%D 2019
%I CERF
%C Mobile, Alabama
%B Coastal and Estuarine Research Federation (CERF)
%8 2019
%9 Poster
%Z presented
%M GCE.1168
%A Hawman, Peter
%A Mishra, Deepak
%A Cotten, David L.
%A O'Connell, Jessica
%A Mao, Lishen
%A Narron, Caroline
%K salt marsh, primary productivity

%0 Conference Proceedings
%T Salt marsh light use efficiency and gross primary productivity in response to environmental conditions
%D 2019
%C San Francisco, California
%B American Geophysical Union Fall Meeting 2019
%S Disturbance Impacts on Ecological and Biogeochemical Processes in Coastal Wetlands I
%8 December 12, 2019
%9 Presentation
%Z presented
%M GCE.1148
%X Light use efficiency (LUE) is an important predictor in estimating remote sensing-based gross primary productivity (GPP). Environmental factors influence a plant’s LUE - often in nonlinear relationships - and thus its GPP. Using generalized additive modeling (GAM), we explored the response of LUE and GPP in a Spartina alterniflora marsh on Sapelo Island, GA over a 17-month period. Eddy covariance (EC) vertical CO2 fluxes of net ecosystem exchange (NEE) were partitioned into GPP and ecosystem respiration (RE). LUE was derived using EC GPP, photosynthetically active radiation (PAR), and NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) MOD15 fraction of absorbed PAR (fAPAR) product. We produced two GAM models to characterize the effects of abiotic and biotic factors on LUE and GPP. Our models explained 76% and 87% of the deviance in LUE and GPP, respectively. Significant predictors of LUE were a cloudiness index, soil temperature, tidal creek salinity, a satellite-based phenology index, and modeled above-ground biomass. Significant GPP predictors included daily light integral, relative humidity, soil temperature, and the phenology index. Through cross-validation our two models had normalized root mean square errors (NRSME) of 21.8% and 19.6% for LUE and GPP, respectively. We compared our predicted LUE to LUE estimated by the method employed by the MODIS MOD17 product. MOD17 method uses only vapor pressure deficit (VPD) and air temperature to estimate LUE and when a GAM was fit, explained 45% of the deviance. To test which estimates of LUE were better predictors of GPP, we built GAMs where GPP was dependent on LUE, fAPAR, and incoming PAR. Explained deviance in GPP was higher when using our predictions of LUE (88%) compared to the simpler MOD17 LUE predictions (81%). Cross-validation results using mean absolute error indicated better goodness-of-fit using our predicted LUE (0.355 gCm-2d-1) compared to MOD17 LUE (0.445 gCm-2d-1). Our results indicate VPD and air temperature alone cannot fully explain the variation of LUE in marshes and inclusion of other factors such as diffuse radiation, soil temperature, salinity, and phenology should be considered for improved accuracy. This study provides insight on how satellite-based GPP can be improved for coastal wetlands by reparametrizing estimations of LUE.
%A Hawman, Peter
%A Mishra, Deepak
%A Cotten, David L.
%A O'Connell, Jessica
%A Narron, Caroline
%A Mao, Lishen
%K Flux, gross primary production, Eddy Covariance, Light Use Efficiency

%0 Conference Proceedings
%T Salt marsh light use efficiency and gross primary production in response to environmental conditions
%D 2019
%C Mobile, Alabama
%B CERF Biennial Conference 2019
%S Carbon fluxes in coastal systems
%8 November 5, 2019
%9 Presentation
%Z presented
%M GCE.1147
%X Light use efficiency (LUE) is the efficiency at which plants convert absorbed light into organic compounds through photosynthesis and is an important parameter in modeling gross primary production (GPP). LUE is controlled by environmental conditions that decrease plant photosynthetic efficiencies. To estimate LUE, we used eddy covariance vertical CO2 fluxes to derive GPP and ecosystem respiration (RE) from measured net ecosystem exchange (NEE) for a Spartina alterniflora marsh on Sapelo Island, GA over a 17-month period. Next, we explored the response of marsh LUE and GPP to measured environmental parameters including air and soil temperature, fraction of diffuse radiation through a cloudiness index (CI), vapor pressure deficit (VPD), and tidal flooding. LUE had the strongest association with CI (r = 0.58), followed by soil and air temperature (r = 0.59; r = 0.47), but  had only weak negative correlations with VPD (r = -0.30) for temperatures above 15°C. Marsh GPP showed similar associations with soil and air temperature (r = 0.82; r = 0.79) but opposing relationships for CI (r = -0.18) and VPD (r = 0.38) compared with LUE. The strong association between CI and LUE indicated that increased diffuse radiation directly facilitates plant LUE at the canopy scale. Further, this held true across all temperature ranges. However, because light reaching the canopy under diffuse conditions is reduced due to scattering, GPP remains higher under mixed sun-cloud conditions when light is not limited but diffuse enough to increase efficiency. Under tidal flooding, vertical CO2 fluxes over the marsh were lower compared to non-flooded periods. This could be due to reduced stomatal conductance or diffusion of CO2 into the water column. Further research is needed to detangle CO2 fluxes for partially or fully submerged plants. Overall, these results provide insight on marsh LUE and GPP responses to environmental conditions and will inform wetland-specific GPP modeling in the future.
%A Hawman, Peter
%A Mishra, Deepak
%A O'Connell, Jessica
%A Cotten, David L.
%A Narron, Caroline
%A Mao, Lishen
%K Flux, gross primary production, Eddy Covariance, Light Use Efficiency

%0 Journal Article
%T Climate Change, Human Impacts, and Coastal Ecosystems in the Anthropocene
%D 2019
%V 29
%N 19
%P 1021-1035
%B Current Biology
%9 Article
%Z published
%M GCE.1162
%R 10.1016/j.cub.2019.08.042
%X Coastal zones, the world’s most densely populated regions, are increasingly threatened by climate change stressors — rising and warming seas, intensifying storms and droughts, and acidifying oceans. Although coastal zones have been affected by local human activities for centuries, how local human impacts and climate change stressors may interact to jeopardize coastal ecosystems remains poorly understood. Here we provide a review on interactions between climate change and local human impacts (e.g., interactions between sea level rise and anthropogenic land subsidence, which are forcing Indonesia to relocate its capital city) in the coastal realm. We highlight how these interactions can impair and, at times, decimate a variety of coastal ecosystems, and examine how understanding and incorporating these interactions can reshape theory on climate change impacts and ecological resilience. We further discuss implications of interactions between climate change and local human impacts for coastal conservation and elucidate the context when and where local conservation is more likely to buffer the impacts of climate change, attempting to help reconcile the growing debate about whether to shift much of the investment in local conservation to global CO2 emission reductions. Our review underscores that an enhanced understanding of interactions between climate change and local human impacts is of profound importance to improving predictions of climate change impacts, devising climate-smart conservation actions, and helping enhance adaption of coastal societies to climate change in the Anthropocene.
%A He, Qiang
%A Silliman, Brian R.
%K climate change, coastal ecosystems, Anthropocene

%0 Journal Article
%T Does predator-driven, biotic resistance limit the northward spread of the non-native green porcelain crab, Petrolisthes armatus?
%D 2019
%V 21
%P 245-260
%B Biological Invasions
%9 Article
%Z published
%M GCE.1121
%R 10.1007/s10530-018-1821-1
%X Biotic resistance by native predators can limit the geographic range and abundance of nonnative species following introduction into an ecosystem. Here we tested the hypothesis that the strength ofpredation pressure varies with latitude and limits the abundance and northward expansion of the non-native green porcelain crab, Petrolisthes armatus, whose northern range is also hypothesized to be limited by physical tolerances to cold temperatures. We quantified the predation risk of P. armatus across 400 km of the crab’s invasive range along the coastline of the southeastern US. In addition, we measured the density of large P. armatus, habitat quality, and other environmental factors that may affect the crab’s predation risk. Finally, we conducted a size-selective predator exclusion experiment to determine the predator species and size classes that may be consuming P. armatus. Results indicated that neither the density of large P. armatus nor its predation risk varied systematically with latitude. Instead, variation in predation risk was best explained by local site-level differences in habitat quality, the density of large P. armatus, and the mean abundance of predators. The predator exclusion experiment indicated that both small and large size classes of predators are capable of equallystrong rates of predation on P. armatus. Together, our results suggest that although native predators readily consume P. armatus, they do not provide biotic resistance against its northward expansion. Instead, it seems likely that other latitudinally differential factors like low winter temperatures that decrease P. armatus survival are more influential in limiting the crab’s northern expansion.
%U http://jebyers.ecology.uga.edu/wp-content/uploads/2018/10/Kinney_etal_2018_BioInvasions_Petrolisthes.pdf
%A Kinney, Kaitlin A.
%A Pintor, Lauren M.
%A Byers, James
%K Density dependence, Enemy release hypothesis, Limiting factors, Range expansion, Top-down effects, Trophic interactions, SINERR Publication, Student Publication

%0 Journal Article
%T Dissolved organic matter composition in a marsh-dominated estuary: Response to seasonal forcing and to the passage of a hurricane
%D 2019
%V 124
%P 1545-1559
%B Journal of Geophysical Research: Biogeosciences
%9 Article
%Z Research Highlighted by Editor in Eos
%M GCE.1124
%R 10.1029/2018JG004982
%X Dissolved organic matter (DOM) is a large and complex mixture of compounds with source inputs that differ with location, season and environmental conditions. Here, we investigated drivers of DOM composition changes in a marsh-dominated estuary off the southeastern U.S. Monthly water samples were collected at a riverine and estuarine site from September 2015 to September 2016, and bulk, optical, and molecular analyses were conducted on samples before and after dark incubations. Results showed that river discharge was the primary driver changing the DOM composition at the mouth of the Altamaha River. For discharge higher than ~ 150 m3 s-1, DOC concentrations and the terrigenous character of the DOM increased approximately linearly with river flow. For low discharge conditions, a clear signature of salt marsh-derived compounds was observed in the river. At the head of Sapelo Sound, changes in DOM composition were primarily driven by river discharge and possibly by summer algae blooms. Microbial consumption of DOC was larger during periods of high discharge at both sites, potentially due to the higher mobilization and influx of fresh material to the system. The Georgia coast was hit by Hurricane Matthew in October 2016, which resulted in a large input of carbon to the estuary. The DOC concentration was ~ 2 times higher and DOM composition was more aromatic with a stronger terrigenous signature compared to the seasonal maximum observed earlier in the year during peak river discharge conditions. This suggests that extreme events notably impact DOM quantity and quality in estuarine regions.
%U https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG004982
%A Letourneau, Maria L.
%A Medeiros, Patricia M.
%K DOM, Hydrology, FT-ICR MS, Altamaha River and Estuary, Hurricane Matthew, Georgia, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Spatio-temporal changes in dissolved organic matter composition and biodegradation throughout the GCE-LTER domain
%D 2019
%I CERF
%C Mobile, AL
%B 25th Coastal and Estuarine Research Federation (CERF) Conference
%8 November 2019
%9 Poster
%Z presented
%M GCE.1141
%A Letourneau, Maria L.
%A Schaefer, Sylvia C.
%A Alber, Merryl
%A Medeiros, Patricia M.
%K DOM, Hydrology, Biodegradation, FT-ICR MS, GCE-LTER, Georgia

%0 Journal Article
%T Response and Recovery of Low-Salinity Marsh Plant Communities to Presses and Pulses of Elevated Salinity
%D 2019
%V 42
%P 708-718
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1140
%R 10.1007/s12237-018-00490-1
%X In estuaries, future variation in sea level and river discharge will lead to saline intrusion into low-salinity tidal marshes. Toinvestigate the processes that control the differential response and recovery of tidal freshwater marsh plant communities to salinepulses, a 3 × 5 factorial greenhouse experiment was conducted to examine the effects of a range of salinity levels (3, 5, and10 practical salinity units (PSU)) and pulse durations (5, 10, 15, 20, and 30 days per month) on community composition of tidalfreshwater marsh vegetation. Recovery of perturbed communities was also examined after 10 months. The results showed thatcommunity composition was increasingly affected by the more-saline and longer-duration treatments. The increasing suppressionof salt-sensitive species resulted in species reordering, decreased species richness, and decreased aboveground biomass. Most ofthe plant species were able to recover from low-salinity, short-duration saline pulses in less than 1 year. However, because not allspecies recovered in the heavily salinized treatments, species richness at the end of the recovery period remained low fortreatments that were heavily salinized during the treatment period. In contrast, plant aboveground biomass fully recovered inthe heavily salinized treatments. Although the magnitude and duration of pulsed environmental changes had strong effects oncommunity composition, shifts in community composition prevented long-term reductions in productivity. Thus, in this studysystem, environmental change affected species composition more strongly than it did ecosystem processes.
%A Li, Fan
%A Pennings, Steven C.
%K saline intrusion, global change, SINERR Publication, UGAMI Publication

%0 Journal Article
%T A comparison of coastal habitat restoration projects in China and the United States
%D 2019
%V 9
%N 14388
%B Scientific Reports
%9 Article
%Z published
%M GCE.1155
%R 10.1038/s41598-019-50930-6
%A Li, Shanze
%A Xie, Tian
%A Pennings, Steven C.
%A Wang, Yuchun
%A Craft, Christopher B.
%A Hu, Mingming
%K coastal habitat, restoration

%0 Journal Article
%T Self-thinning and size-dependent flowering of the grass Spartina alterniflora across space and time
%D 2019
%V 33
%P 1830-1841
%B Functional Ecology
%9 Article
%Z published
%M GCE.1138
%R 10.1111/1365-2435.13384
%X 1. Plants adjust their size and reproductive effort in response to numerous selectionpressures and constraints. The self&#8208;thinning law describes a well&#8208;known trade&#8208;offbetween size and density. Plants also trade&#8208;off investment into growth vs. sexualreproduction, as described by life&#8208;history theory.2. We build on past work on plant allometry and life history by examining both self&#8208;thinning and size&#8208;dependent reproduction in a single plant species, the saltmarshgrass Spartina alterniflora, across a wide range of settings: three landscape posi&#8208;tions, two habitats and eight sites, across sixteen years.3. Plants in different landscape positions and years varied tremendously in size andshoot density. However, all this variation could be explained by a single allometricrelationship consistent with the self&#8208;thinning law, but with a lower slope. Floweringwas size&#8208;dependent, and the size at which plants had a 50% probability of flower&#8208;ing varied among habitat, sites and years. Plants that were stressed reproducedat a smaller size than plants that were growing under good conditions, and thispattern was consistent among habitat, sites and years. Finally, reproductive bio&#8208;mass and the proportion of shoots flowering increased with increasing vegetativesize (plant height or shoot biomass). Combining these two patterns, S. alternifloraplants growing high density are small and reproduce at a smaller size than largeplants growing at low density.4. Although there is tremendous spatial and temporal variation in S. alternifloragrowth and reproductive patterns, all this variation can be understood as result&#8208;ing from two simple allometric trade&#8208;offs. Because saltmarsh plants often occur inmonospecific stands, they may serve as simple, model systems for studies of plantlife history.
%A Liu, Wenwen
%A Pennings, Steven C.
%K Spartina alterniflora, plant productivity, self-thinning, flowering, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Analyzing chlorophyll fluorescence in Juncus roemerianus by Pulse Amplitude Modulated (PAM) fluorometer at different plant heights
%D 2019
%C Yokohama, Japan
%B International Geoscience and Remote Sensing Society
%8 2019
%9 Poster
%Z presented
%M GCE.1171
%A Mao, Lishen
%A Mishra, Deepak
%A Cotten, David L.
%A O'Connell, Jessica
%A Narron, Caroline
%A Hawman, Peter
%K chlorophyll, plant heights, Juncus roemerianus

%0 Conference Proceedings
%T Effects of simulated seawater intrusion on soil biomarkers distribution in a tidal freshwater marsh wetland
%D 2019
%I CERF
%C Mobile, AL
%B 25th Coastal and Estuarine Research Federation (CERF) Conference
%8 November 2019
%9 Poster
%Z presented
%M GCE.1142
%A Martineac, Rachel P.
%A Craft, Christopher B.
%A Medeiros, Patricia M.
%K Biomarkers, Soil, SALTex, Georgia

%0 Conference Proceedings
%T What controls dissolved organic matter composition in marsh-dominated estuaries?
%D 2019
%I American Chemical Society
%C Savannah, GA
%B Southeastern Regional Meeting of the American Chemical Society (SERMACS)
%8 October 2019
%9 Presentation
%Z Invited speaker
%M GCE.1143
%A Medeiros, Patricia M.
%K DOM, Hydrology, Biodegradation, FT-ICR MS, GCE-LTER, Georgia

%0 Conference Proceedings
%T Seasonal changes in dissolved organic matter composition in the Altamaha River, Georgia, USA
%D 2019
%C San Juan, PR
%B ASLO 2019 Aquatic Sciences Meeting
%8 February 2019
%9 Poster
%Z presented
%M GCE.1125
%A Medeiros, Patricia M.
%A Letourneau, Maria L.
%K DOM, Hydrology, FT-ICR MS, Altamaha River and Estuary, Georgia, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T The breathing coastal zone: dynamics in Southeast US mars
%D 2019
%I ETH
%C Zuerich, Switzerland
%B Mini-Symposium
%8 22. November 2019
%9 Presentation
%Z presented
%M GCE.1146
%A Meile, Christof
%K marsh dynamics

%0 Conference Proceedings
%T Flow and short- and long-term carbon dynamics at tidally impacted coastal interfaces in the SE USA
%D 2019
%C Barcelona
%B Goldschmidt Conference
%8 August 18-23, 2019
%9 Keynote Address
%Z presented
%M GCE.1145
%A Meile, Christof
%A Schalles, John F.
%A Peterson, Richard N.
%A O'Donnell, John
%A Bice, Kadir
%A Medeiros, Patricia M.
%A Di Iorio, Daniela
%A Hopkinson, Charles S.
%A Joye, Samantha B.
%A Stegen, J.
%A Goldman, A.
%A Thomle, J.
%A Danczak, R.
%K marsh dynamics

%0 Conference Proceedings
%T Salt marsh light use efficiency and gross primary productivity in response to environmental conditions
%D 2019
%I AGU
%C San Francisco, CA
%B American Geophysical Union (AGU)
%8 2019
%9 Poster
%Z presented
%M GCE.1166
%A Mishra, Deepak
%A Cotten, David L.
%A O'Connell, Jessica
%A Mao, Lishen
%A Narron, Caroline
%A Hawman, Peter
%K salt marsh, primary production

%0 Journal Article
%T Radiocarbon Pretreatment Comparisons of Bald Cypress (Taxodium distichum) Wood Samples from a Massive Buried Deposit on the Georgia Coast, USA
%D 2019
%V 61
%P 1755-1763
%B Radiocarbon
%9 Article
%Z published
%M GCE.1139
%X We sampled individual growth rings from three ancient remnant bald cypress (Taxodium distichum) trees from a massive buried deposit at the mouth of the Altamaha River on the Georgia Coast to determine the best technique for radiocarbon (14C) dating pretreatment. The results of our comparison of traditional ABA pretreatment and holocellulose and &#945;-cellulose fractions show no significant differences among the pretreatments (<1 sigma) thereby suggesting that ABA pretreatment will prove sufficient for the development of a high-resolution 14C tree-ring chronology based on these ancient bald cypresses which will indicate whether the U.S. Southeast is subject to a regional radiocarbon offset.
%A Napora, Katharine
%A Cherkinsky, Alex
%A Speakman, Robert J.
%A Thompson, Victor D.
%A Horan, Robert
%A Jacobs, Craig
%K AMS dating, bald cypress, dendrochronology, pretreatments, radiocarbon offsets, Student Publication

%0 Conference Proceedings
%T Assessing tidal wetland above- and belowground net primary production using field and in situ measurements
%D 2019
%I Coastal and Estuarine Research Federation
%C Mobile, AL
%B 2019 CERF 25th Biennial Conference
%S Carbon fluxes in coastal systems
%8 11/05/2019
%9 Presentation
%Z presented
%M GCE.1218
%X Coastal salt and brackish marshes are highly productive systems that often function as reservoirs for atmospheric carbon, yet the flux of carbon into, out of, and within these systems is not fully understood. Examining above- and belowground tidal marsh vegetation dynamics can help provide insight into these complex carbon cycles as well as aid in the estimation of their carbon sequestration potential, which has broader implications for improving our understanding of the forthcoming effects of climate change. Belowground net primary production (BNPP) in particular can be an indicator of coastal marsh resiliency due to increased vertical accretion resulting from the accumulation of organic matter and root mass, preventing sea level rise induced marsh drowning. This study aimed to evaluate the empirical relationships between above- and belowground net primary production using field-based environmental and biophysical data as well as in situ micrometeorological measurements of CO2 flux via the Eddy Covariance (EC) method within two tidal wetlands. The EC flux towers used in this study were located in the Grand Bay National Estuarine Reserve in Mississippi and the Bayou Sauvage National Wildlife Refuge in Louisiana which are dominated by Juncus roemerianus and Spartina patens, respectfully. The relationship between aboveground net primary production (ANPP) and BNPP was analyzed to determine if both were mediated by the same environmental and biophysical variables over space and through time. Results from this study contribute essential information that enhances our knowledge of above- and belowground processes and their effects on carbon fluxes within tidal wetlands.
%A Narron, Caroline
%A Mishra, Deepak
%A O'Connell, Jessica L
%A Cotten, David L.
%A Hawman, Peter
%A Mao, Lishen
%K Belowground Net Primary Production, Blue Carbon, Carbon Fluxes, Coastal Wetland, Tidal Marshes

%0 Conference Proceedings
%T Patterns of Spartina alterniflora phenology and belowground biomass
%D 2019
%I Department of Marine Sciences, University of Georgia
%C Athens, GA
%B Departmental Seminar
%8 2019
%9 Presentation
%Z presented
%M GCE.1170
%A O'Connell, Jessica
%K Spartina alterniflora, biomass

%0 Conference Proceedings
%T Patterns of Spartina alterniflora phenology and belowground biomass
%D 2019
%I Department of Geosciences, University of Lafayette
%C Lafayette, LA
%B Departmental Seminar
%8 2019
%9 Presentation
%Z presented
%M GCE.1169
%A O'Connell, Jessica
%K Spartina alterniflora, biomass

%0 Conference Proceedings
%T Elevation drives gradients in surface soil temperature within salt marshes
%D 2019
%C Mobile, Alabama
%B Coastal and Estuarine Research Federation (CERF)
%8 2019
%9 Poster
%Z presented
%M GCE.1167
%A O'Connell, Jessica
%A Alber, Merryl
%K elevation, soil surface temperature, salt marshes

%0 Journal Article
%T Groundwater discharge dynamics into a salt marsh tidal river
%D 2019
%V 218
%P 324-333
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.1118
%R 10.1016/j.ecss.2019.01.007
%X Exchange of groundwater is an important transfer mechanism for nutrients and pollutants between coastal aquifers and surface waters.  Constraining such exchange in salt marshes - where biological productivity and biogeochemical cycling rates are among the highest of all coastal ecosystems – is vital for understanding ecosystem function and vulnerability.  Here, we quantify groundwater discharge into the tidal Duplin River from the adjoining salt marsh near Sapelo Island, Georgia using high spatial and temporal resolution field measurements of radon-222.  Field campaigns occurred for several weeks each summer during 2013, 2015, and 2016.  Spatial surveys reveal a general increase in radon activity upstream through the Duplin River, which may result from either higher groundwater discharge or lower mixing rates in the headwaters.  To distinguish between these possibilities, we use a radon mass balance model to determine groundwater input.  We find that groundwater discharge (normalized to inundated marsh surface area) to the headwaters average 5.1 – 5.8 cm3/cm2 marsh/day across all three field campaigns, which are comparable to those to the main channel (averaging 6.0 – 6.5 cm3/cm2 marsh/day across all three field campaigns).  Our work reveals a positive relationship between aerial extent of marsh inundation and groundwater discharge into the Duplin River.  Discharge is generally maximal during falling tide, reflecting a hydraulic gradient driver, but also is significant prior to high tide, indicative of sediment compression as a driver of groundwater inputs.  Constraining the relationship between marsh inundation and resulting groundwater dynamics is an integral aspect to assessing how salt marsh circulation processes may respond to intensifying inundation (from reduced sediment supply, subsidence, and/or rising sea levels).
%A Peterson, Richard N.
%A Meile, Christof
%A Peterson, Leigha
%A Carter, Matthew
%A Miklesh, David Michael
%K radon, groundwater discharge, radioisotopes, permeable sediments, Duplin River, Sapelo Island, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Harnessing positive species interactions to enhance coastal wetland restoration
%D 2019
%B Frontiers in Marine Science
%9 Article
%Z published
%M GCE.1225
%R 10.3389/fevo.2019.00131
%X Coastal wetlands are among the most productive ecosystems in the world. Theygenerate critical services for humans including shoreline protection, carbon storage,pollution mitigation, and fisheries production. Restoration of coastal wetlands hashistorically been viewed as a secondary conservation strategy, but recently—giventhe continued loss of wetlands worldwide—many non-governmental and governmentalorganizations have elevated habitat restoration to be a primary method for wetlandconservation. The long-held paradigm in coastal wetland restoration has been torestore target habitats by reducing physical stressors and avoiding competition amongoutplants, such as mangrove saplings or Spartina plugs. Recent ecological research,however, reveals that positive species interactions, such as facilitation, are critical towetland recovery after disturbance. Here, we review the scientific evidence for theimportance of positive species interactions in the recovery of salt-marsh and mangroveecosystems and assess the extent to which they have been integrated into restorationstudies. We found that only a small proportion of studies of marsh and mangroverestoration examined the effects of positive species interactions, despite the importantrole they play in the regrowth of coastal wetlands. We outline how positive speciesinteractions can be systematically incorporated into future restoration work and discusshow this incorporation can help the reestablishment of coastal wetland biota through: (1)trophic facilitation, (2) stress reduction, and (3) associational defenses. The absence ofpositive interactions in restoration designs may partially explain the significant disparitiesbetween the functioning of natural and restored coastal plant ecosystems.
%A Renzi, Julianna J.
%A He, Qiang
%A Silliman, Brian R.
%K salt marshes, mangroves, restoration, positive interactions, facilitation, coastal wetlands

%0 Journal Article
%T The role of landscape composition and disturbance type in mediating salt marsh resilience to feral hog invasion
%D 2019
%V 21
%N 9
%P 2857-2869
%B Biological Invasions
%9 Article
%Z published
%M GCE.1158
%R 10.1007/s10530-019-02018-5
%X Habitat patch composition and configuration mediate the fitness and distribution of many species. However, we know little about how this landscape complementation may influence the distribution of an invasive species’ ecological impacts and, in turn, how this affects ecosystem resilience to disturbance. We surveyed&#8201;>&#8201;820 km of coastline to evaluate how landscape complementation mediates patterns in invasive feral hog (Sus scrofa) rooting, trampling and wallowing disturbances in southeastern US salt marshes and assessed marsh resilience to these behaviors in an 8-site survey and 13-month field experiment. We discovered that hog rooting and trampling most often occur where hardwood forest comprises&#8201;>&#8201;30% and salt marsh&#8201;<&#8201;22% of habitat surrounding each surveyed site, respectively, while wallowing correlated most strongly with salt marsh invertebrate densities. At the 8 survey sites, vegetation cover, soil organic carbon, and surface elevation were consistently lower, and soil anoxia and porewater ammonium-nitrogen higher, in hog-disturbed relative to undisturbed areas. The experiment revealed that vegetation can recover when rooted or trampled, but remains depressed when wallowed or repeatedly disturbed. Together, these findings provide novel evidence that habitat patch composition at landscape scales can act together with local habitat attributes to dictate invasive species’ disturbance patterns and highlight areas most vulnerable to invaders. In salt marshes, insights gleaned from such consideration of landscape complementation can inform conservation and management strategies for curbing the impact of this prolific, global invader.
%A Sharp, Sean
%A Angelini, Christine
%K carbon sequestration, invasive species, landscape complementation, Spartina alterniflora, Sus scrofa, SINERR Publication, Student Publication, UGAMI Publication

%0 Report
%T An Examination of High Salinity Events in the Altamaha River Estuary.
%D 2019
%B Review prepared for GA DNR-CRD
%9 Article
%Z published
%M GCE.1237
%A Sheldon, Joan E.
%A Alber, Merryl
%K salinity

%0 Conference Proceedings
%T Using the GCE Data Toolbox to automate environmental data processing and produce EML-described data packages for the EDI repository
%D 2019
%I Environmental Data Initiative
%C Madison, Wisconsin
%B Environmental Data Initiative Webinar Series
%8 08-Jan-2019
%9 Presentation
%Z presented
%M GCE.1117
%U https://gce-lter.marsci.uga.edu/gce_toolbox/files/WSheldon_EDI_Webinar_Jan2019b.pdf
%A Sheldon, Wade M., Jr.
%K LTER-IMC, MATLAB, toolbox, GCE Data Toolbox, software, data management, sensor, quality control, UGAMI Publication

%0 Journal Article
%T Field Experiments and Meta-analysis Reveal Wetland Vegetation as a Crucial Element in the Coastal Protection Paradigm
%D 2019
%V 29
%N 11
%P 1800-1806
%B Current Biology
%9 Article
%Z published
%M GCE.1161
%R 10.1016/j.cub.2019.05.017
%X Increasing rates of sea-level rise and wave action threaten coastal populations. Defense of shorelines by protection and restoration of wetlands has been invoked as a win-win strategy for humans and nature, yet evidence from field experiments supporting the wetland protection function is uncommon, as is the understanding of its context dependency. Here we provide evidence from field manipulations showing that the loss of wetland vegetation, regardless of disturbance size, increases the rate of erosion on wave-stressed shorelines. Vegetation removal (simulated disturbance) along the edge of salt marshes reveals that loss of wetland plants elevates the rate of lateral erosion and that extensive root systems, rather than aboveground biomass, are primarily responsible for protection against edge erosion in marshes. Meta-analysis further shows that disturbances that generate plant die-off on salt marsh edges generally hasten edge erosion in coastal marshes and that the erosion protection function of wetlands relates more to lateral than vertical edge-erosional processes and is positively correlated with the amount of belowground plant biomass lost. Collectively, our findings substantiate a coastal protection paradigm that incorporates preservation of shoreline vegetation, illuminate key context dependencies in this theory, and highlight local disturbances (e.g., oil spills) that kill wetland plants as agents that can accelerate coastal erosion.
%A Silliman, Brian R.
%A He, Qiang
%A Angelini, Christine
%A Smith, Carter S.
%A Kirwan, Matthew Lynn
%A Daleo, P.
%A Renzi, Julianna J.
%A Butler, Jack
%A Osborne, Todd Z.
%A Nifong, James C.
%A van de Koppel, Johan
%K coastal protection, coastal wetlands, living shorelines, sea-level rise, coastal erosion, salt marshes, shoreline defense, disturbance

%0 Journal Article
%T Global-change controls on soil-carbon accumulation and loss in coastal vegetated ecosystems
%D 2019
%V 12
%P 685–692
%B Nature Geoscience
%9 Article
%Z published
%M GCE.1127
%R 10.1038/s41561-019-0435-2
%X Coastal seagrass, mangrove and salt-marsh ecosystems—also termed blue-carbon ecosystems—play an important role in theglobal carbon cycle. Much of the organic carbon they store rests in soils that have accumulated over thousands of years. Rapidly changing climate and environmental conditions, including sea-level rise, warming, eutrophication and landscape development, will impact decomposition and thus the global reservoir of blue soil organic carbon. Yet, it remains unclear how these disturbances will affect the key biogeochemical mechanisms controlling decomposition—mineral protection, redox zonation, water content and movement, and plant–microbe interactions. We assess the spatial and temporal scales over which decomposition mechanisms operate and how their effectiveness may change following disturbances. We suggest that better integration of decomposition mechanisms into blue-carbon models may improve predictions of soil organic carbon stores and facilitate incorporation of coastal vegetated ecosystems into global budgets and management tools.
%U https://www.nature.com/articles/s41561-019-0435-2
%A Spivak, Amanda C.
%A Sanderman, Jonathan
%A Bowen, Jennifer L.
%A Canuel, Elizabeth A.
%A Hopkinson, Charles S.
%K blue carbon, organic matter, seagrass, salt marsh, mangrove, climate change, soil, decomposition, preservation

%0 Book Section
%T Human-Environmental Dynamics of the Georgia Coast
%D 2019
%I University Press of Florida
%C Gainesville, GL
%B The Archaeology of Human-Environmental Dynamics on the North American Atlantic Coast
%9 Article
%Z published
%M GCE.1163
%A Turck, John A.
%A Thompson, Victor D.
%E Reeder-Myers, Leslie
%E Turck, John
%E Rick, Torben
%K Georgia coast

%0 Journal Article
%T Coastal dynamics and adaptation to uncertain sea level rise: Optimal portfolios for salt marsh migration
%D 2019
%V 98
%B Journal of Environmental Economics and Management
%9 Article
%Z published
%M GCE.1132
%R 10.1016/j.jeem.2019.102262
%X The sustainability of dynamic natural systems often depends on their capacity to adapt to uncertain climate-related changes, where different management options may be combined to facilitate this adaptation. Salt marshes exemplify such a system. Marsh sustainability under rapid sea level rise requires the preservation of transgression zones - undeveloped uplands onto which marshes migrate. Whether these uplands eventually become marsh depends on uncertain sea level rise and natural dynamics that determine migration onto different land types. Under conditions such as these, systematically diversified management actions generally outperform ad hoc or non-diversified alternatives. This paper develops the first adaptation portfolio model designed to optimize the benefits of a migrating coastal system. Results are illustrated using a case study of marsh conservation in Virginia, USA. Results suggest that models of this type can enhance adaptation benefits beyond those available through current approaches.
%U https://www.sciencedirect.com/science/article/pii/S0095069618304248
%A Vinent, O. D.
%A Johnston, R. J.
%A Kirwan, M.
%A Leroux, A.
%A Martin, V.
%K benefit, diversification, risk, spatial, climate change, wetland, optimal conservation, geomorphology

%0 Journal Article
%T Chronic but not acute saltwater intrusion leads to large release of inorganic N in a tidal freshwater marsh
%D 2019
%V 695
%B Science of the Total Environment
%9 Article
%Z published
%M GCE.1128
%R 10.1016/j.scitotenv.2019.133779
%X Sea level rise is expected to increase inundation and saltwater intrusion into many tidal freshwater marshes and forests. Saltwater intrusion may be long-term, as with rising seas, or episodic, as with low river flow or storm surge. We applied continuous (press) and episodic (pulse) treatments of dilute seawater to replicate 2.5&#8239;×&#8239;2.5&#8239;m field plots for three years and measured soil attributes, including soil porewater, oxidation-reduction potential, soil carbon (C), and nitrogen (N) to investigate the effects of continuous and episodic saltwater intrusion and increased inundation on tidal freshwater marsh elemental cycling and soil processes. Continuous additions of dilute seawater resulted in increased porewater chloride, sulfate, sulfide, ammonium, and nitrate concentrations. Plots that received press additions also had lower soil oxidation-reduction potentials beginning in the second year. Episodic additions of dilute seawater during typical low flow conditions (Sept.-Oct.) resulted in transient increases in porewater chloride and sulfate that returned to baseline conditions once dosing ceased. Freshwater additions did not affect porewater inorganic N or soil C or N. Persistent saltwater intrusion in freshwater marshes alters the N cycle by releasing ammonium-N from sorption sites, increasing nitrification and severely reducing N storage in macrophyte biomass. Chronic saltwater intrusion, as is expected with rising seas, is likely to shift tidal freshwater marshes from a sink to a source of N whereas intermittent intrusion from drought may have no long term effect on N cycling.
%U https://www.sciencedirect.com/science/article/pii/S0048969719337209?via%3Dihub
%A Widney, Sarah
%A Smith, Dontrece
%A Herbert, Ellen
%A Schubauer-Berigan, Joseph P.
%A Li, Fan
%A Pennings, Steven C.
%A Craft, Christopher B.
%K Ammonium, Nitrate, N cycle, Sulfate, Soil carbon, Sea level rise, UGAMI Publication

%0 Journal Article
%T Mapping salt marsh soil properties using imaging spectroscopy
%D 2019
%V 148
%P 221-234
%B ISPRS Journal of Photogrammetry and Remote Sensing
%9 Article
%Z published
%M GCE.1119
%R 10.1016/j.isprsjprs.2019.01.006
%X Tidal salt marshes sequester and store blue carbon at both short and long time scales. Marsh soils shape and maintain the ecosystem by supporting complex biogeochemical reactions, deposition of sediment, and accumulation of organic matter. In this study, we examined the potential of imaging spectroscopy techniques to indirectly quantify and map tidal marsh soil properties at a National Estuarine Research Reserve in Georgia, USA. A framework was developed to combine modern digital image processing techniques for marsh soil mapping, including object-based image analysis (OBIA), machine learning modeling, and ensemble analysis. We also evaluated the efficacy of airborne hyperspectral sensors in estimating marsh soil properties compared to spaceborne multispectral sensors, WorldView-2 and QuickBird. The pros and cons of object-based modeling and mapping were assessed and compared with traditional pixel-based mapping methods. The results showed that the designed framework was effective in quantifying and mapping three marsh soil properties using the composite reflectance from salt marsh environment: soil salinity, soil water content, and soil organic matter content. Multispectral sensors were successful in quantifying soil salinity and soil water content but failed to model soil organic matter. The study also demonstrated the value of minimum noise fraction transformation and ensemble analysis techniques for marsh soil mapping. The results suggest that imaging spectroscopy based modeling is a promising tool to quantify and map marsh soil properties at a local scale, and is a potential alternative to traditional soil data acquisition to support carbon cycle research and the conservation and restoration of tidal marshes.
%A Zhang, Caiyun
%A Mishra, Deepak
%A Pennings, Steven C.
%K salt marsh, soil properties, imaging spectroscopy, machine learning, object-based modeling, remote sensing, UGAMI Publication

%0 Journal Article
%T Biotic homogenization of wetland nematode communities by exotic Spartina alterniflora in China
%D 2019
%V 100
%B Ecology
%9 Article
%Z published
%M GCE.1235
%R 10.1002/ecy.2596
%X Introduced species may homogenize biotic communities. Whether this homogenization can erase latitudinal patterns of species diversity and composition has not been well studied. We examined this by comparing nematode and microbial communities in stands of native Phragmites australis and exotic Spartina alterniflora in coastal wetlands across 18° of latitude in China. We found clear latitudinal clines in nematode diversity and functional com-position, and in microbial composition, for soils collected from native P. australis. These latitudinal patterns were weak or absent for soils collected from nearby stands of the exotic S. alterniflora. Climatic and edaphic variables varied across latitude in similar ways in both community types. In P. australis there were strong correlations between community structure and environmental variables, whereas in S. alterniflora these correlations were weak. These results suggest that the invasion of S. alterniflora into the Chinese coastal wetlands has caused profound biotic homogenization of soil communities across latitude. We speculate that the variation in P. australis nematode and microbial communities across latitude is primarily driven by geographic variation in plant traits, but that such variation in plant traits is largely lacking for the recently introduced exotic S. alterniflora. These results indicate that widespread exotic species can homogenize nematode communities at large spatial scales.
%A Zhang, Y.
%A Pennings, Steven C.
%A Li, Bo
%A Wu, Jihua
%K biotic homogenization, exotic species, invasive ecology, latitudinal gradients, soil microbes, soil nematodes, Spartina alterniflora

%0 Conference Proceedings
%T Sustainability of salt marshes: still a realistic goal?
%D 2018
%C Alexandria, VA
%B NSF LTER Science Symposium
%9 Presentation
%Z presented
%M GCE.1134
%A Alber, Merryl
%K Salt marsh, sustainability

%0 Journal Article
%T The importance of an underestimated grazer under climate change: how crab density, consumer competition, and physical stress affect salt marsh resilience
%D 2018
%V 187
%N 1
%P 205-217
%B Oecologia
%9 Article
%Z published
%M GCE.1098
%R 10.1007/s00442-018-4112-8
%X Climate change and consumer outbreaks are driving ecosystem collapse worldwide. Although much research has demonstrated that these factors can interact, how heterogeneity in top–down control intensity and physical forcing modulates ecosystem resilience to climate stress remains poorly understood. Here, we explore whether the nocturnal herbivorous crab Sesarma reticulatum can control spatially dominant cordgrass (Spartina alterniflora) growth and how its top–down effects vary with crab density, drought stress, and large-scale disturbance in southeastern US salt marshes. In multiple field experiments and surveys, we show that Sesarma depresses cordgrass growth and that its effects increase in a saturating manner with increasing crab density, such that the highest naturally occurring densities of this consumer can trigger local cordgrass die-off. This top–down effect of Sesarma is similar in magnitude to what is thought to be the dominant grazer in the system, the marsh periwinkle snail Littoraria irrorata. In a drought stress by Sesarma density experiment, we further show that salinity stress and intensive crab herbivory additively suppress cordgrass drought resistance. After drought subsides, surveys and experiments reveal that Sesarma also stifles cordgrass re-growth into existing die-off areas. Together, these results show that multiple grazers powerfully regulate the productivity and drought resilience of these intertidal grasslands and that heterogeneity in physical stress and consumer density can dictate when and where top–down forcing is important. More generally, this work provides a rare, experimental demonstration of the critical role top–down control can play across the initiation and recovery stages of ecosystem die-off.
%U https://link.springer.com/article/10.1007/s00442-018-4112-8
%A Angelini, Christine
%A van Montfrans, Schuyler
%A Hensel, Marc Simon
%A He, Qiang
%A Silliman, Brian R.
%K Drought, Density dependence, Foundation species, Spartina alterniflora, Top, down control, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Using drones for high spatial and temporal resolution - Long term observations
%D 2018
%I National Science Foundation Long-Term Ecological Research
%C Asilomar Conference Center, Pacific Grove, CA
%B NSF LTER All Scientists Meeting
%8 Wednesday, October 3, 2018
%9 Presentation
%Z presented
%M GCE.1104
%X This workshop will introduce researchers to the use of drones for imaging study sites and best practices for creating actionable products and time series. We will start with the basics: FAA licensing, flight training, and designing a mission plan. We will discuss avoiding common hazards such as adverse weather conditions and low flying aircraft. The workshop will cover the use of color and multi / hyperspectral imaging, including the use of ground control points for georeferencing and reflectance panels for image calibration. We will demonstrate software for creating orthomosaics of drone imagery and performing common classification techniques. Finally, we will discuss the scaling of this high-resolution imagery to space-borne remote sensing technologies.
%U https://2018lterallscientistsmeeting.sched.com/event/FYqb/using-drones-for-high-spatial-and-temporal-resolution-long-term-observations
%A Bell, Tom
%A Castorani, Max
%A Schalles, John F.
%K drones, remote sensing, long term monitoring, SINERR Publication

%0 Journal Article
%T Foundation species enhance food web complexity through non-trophic facilitation
%D 2018
%V 13
%N 8
%B PloS ONE
%9 Article
%Z published
%M GCE.1088
%R 10.1371/journal.pone.0199152
%X Food webs are an integral part of every ecosystem on the planet, yet understanding the mechanisms shaping these complex networks remains a major challenge. Recently, several studies suggested that non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structure. However, it remains unclear whether these findings generalize across ecosystems, and whether non-trophic interactions affect food webs randomly, or affect specific trophic levels or functional groups. Here, we combine analyses of 58 food webs from seven terrestrial, freshwater and coastal systems to test (1) the general hypothesis that non-trophic facilitation by habitat-forming foundation species enhances food web complexity, and (2) whether these enhancements have either random or targeted effects on particular trophic levels, functional groups, and linkages throughout the food web. Our empirical results demonstrate that foundation species consistently enhance food web complexity in all seven ecosystems. Further analyses reveal that 15 out of 19 food web properties can be well-approximated by assuming that foundation species randomly facilitate species throughout the trophic network. However, basal species are less strongly, and carnivores are more strongly facilitated in foundation species' food webs than predicted based on random facilitation, resulting in a higher mean trophic level and a longer average chain length. Overall, we conclude that foundation species strongly enhance food web complexity through non-trophic facilitation of species across the entire trophic network. We therefore suggest that the structure and stability of food webs often depends critically on non-trophic facilitation by foundation species.
%U https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0199152
%A Borst, A.
%A van der Heide, Tjisse
%A Verbeek, Wouter
%A Schotanus, J
%A Christianen, M
%A Derksen-Hooijberg, M.
%A Angelini, Christine
%K positive interaction, facilitation, complex systems

%0 Thesis
%T Historical analysis of 70 years of salt marsh change at three coastal LTER sites.
%D 2018
%P 188
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.1144
%X Salt marshes are dynamic ecosystems that change in response to natural and human factors. This study used digitization of historical charts and imagery and the Analyzing Moving Boundaries Using R toolkit to measure approximately 70 years of change in lateral marsh extent and the distribution of interior features (ponds, upland, channels, and flats), in marshes of the Georgia Coastal Ecosystems (GCE), Virginia Coast Reserve (VCR), and Plum Island Ecosystems (PIE) LTER sites. Measuring the marsh edge exposed to high fetch and along channels was important for providing complete information on marsh change. Although GCE was dynamic, total marsh area was conserved. VCR experienced marsh loss to flat expansion, which was offset by marsh migration, and overall marsh area was conserved. PIE was erosional, losing marsh along the outer edge, channel widening, and ponding. GCE was considered the most resilient because of its tidal range, sediment supply, and elevation.
%A Burns, Christine
%K historical analysis, marsh change, AMBUR, LTER, marsh migration, ponding, shoreline change, channel migration, lateral change, cross site analysis, long term change, image interpretation, Cross-site Research, Student Publication

%0 Journal Article
%T Evaluating ultraviolet (UV) based photochemistry in optically complex coastal waters using the Hyperspectral Imager for the Coastal Ocean (HICO)
%D 2018
%V 215
%P 199-206
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z Online 10-23-2018
%M GCE.1100
%R 10.1016/j.ecss.2018.10.013
%X Knowledge of light partitioning into different optically active constituents, particularly chromophoric dissolved organic matter (CDOM) in the ultraviolet (UV) is indispensable for understanding UV dependent biogeochemical issues including photochemical processes in optically complex waters. Herein a new approach is presented to investigate photochemistry by blending two ocean color algorithms, namely the composite SeaUV (Cao et al., 2014) and the SeaCDOM (Cao and Miller, 2014) algorithms, and applying them to visible remote sensing reflectance (Rrs) measured using the Hyperspectral Imager for the Coastal Ocean (HICO). As illustrated using photochemical carbon monoxide (CO) production from CDOM, this model approach allows high resolution examination of UV optical details with estimates of both depth specific and depth-integrated photoproduction rates in a dynamic estuarine/coastal environment. Decoupled retrievals of inherent and apparent optical properties (i.e. diffuse attenuation coefficient (Kd) and CDOM absorption coefficient (ag)) using two distinct ocean color algorithms over the entire UV spectrum allow a synoptically dynamic view of CDOM’s contribution to light attenuation (ag/Kd). This provides new potential to probe UV processes in complex coastal waters on regional as well as global scales using remote sensing of ocean color.
%U https://www.sciencedirect.com/science/article/pii/S0272771417310569?dgcid=rss_sd_all
%A Cao, Fang
%A Mishra, Deepak
%A Schalles, John F.
%A Miller, William
%K CDOM, coastal waters, inshore waters, photochemistry, remote sensing, ocean color, HICO, Student Publication, UGAMI Publication

%0 Journal Article
%T Foundation species patch configurations mediates biodiversity, stability and multifunctionality
%D 2018
%V 21
%P 1681-1692
%B Ecology Letters
%9 Article
%Z published
%M GCE.1087
%R 10.1111/ele.13146
%X Foundation species enhance biodiversity and multifunctionality across many systems; however, whether foundation species patch configuration mediates their ecological effects is unknown. In a 6&#8208;month field experiment, we test which attributes of foundation species patch configuration – i.e. patch size, total patch area, perimeter, area&#8208;perimeter ratio, or connectivity – control biodiversity, stability and multifunctionality by adding a standardised density of mussel foundation species in patches of 1, 5, 10, 30, 60, 90 or 180 individuals to a southeastern US salt marsh. Over 67% of response variables increased with clustering of mussels, responses that were driven by increases in area–perimeter ratio (33%), decreases in perimeter (29%), or increases in patch size (5%), suggesting sensitivity to external stressors and/or dependence on foundation species&#8208;derived niche availability and segregation. Thus, mussel configuration – by controlling the relative distribution of multidimensional patch interior and edge niche space – critically modulates this foundation species’ effects on ecosystem structure, stability and function.
%U https://onlinelibrary.wiley.com/doi/epdf/10.1111/ele.13146
%A Crotty, Sinead M.
%A Sharp, Sean
%A Bersoza, Ada CH
%A Prince, Kimberley
%A Cronk, Katherine
%A Johnson, Emma
%A Angelini, Christine
%K positive interaction, facilitation, mussel, spartina, salt marsh, Student Publication

%0 Journal Article
%T Microbial oxidation of nitrogen supplied as selected organic nitrogen compounds in the South Atlantic Bight
%D 2018
%V 64
%P 982-995
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.1115
%R 10.1002/lno.11089
%X Dissolved organic nitrogen (DON) can account for a large fraction of the dissolved nitrogen (N) pool in the ocean, but the cycling of marine DON is poorly understood. Recent discoveries that urea- and cyanate-N can be oxidized by some strains of Thaumarchaeota suggest that these abundant microbes may be able to access and oxidize a fraction of the DON pool. However, measurements of the oxidation of N supplied as DON compounds are scarce. Here, we compare oxidation rates of N supplied as a variety of DON compounds in samples from Georgia coastal waters, where nitrifier communities are numerically dominated by Thaumarchaeota. Our data indicate that polyamine-N is particularly amenable to oxidation compared to the other DON compounds tested. Oxidation of N supplied as putrescine (1,4-diaminobutane) was generally higher than that of N supplied as glutamate, arginine, or urea, and was consistently 5–10% of the ammonia oxidation rate. Our data also suggest that the oxidation rate of polyamine-N may increase as the length of the carbon skeleton increases. Oxidation of N supplied as putrescine, urea, and glutamate were all highest near the coast and lower further offshore, consistent with patterns of ammonia oxidation in these waters. Though it is unclear whether oxidation of polyamine-N reflects direct oxidation by Thaumarchaeota or combines remineralization and subsequent ammonia oxidation, more rapid oxidation of N from putrescine compared to amino acids or urea suggests that polyamine-N may contribute significantly to nitrification in the ocean.
%A Damashek, Julian
%A Tolar, Bradley
%A Liu, Qian
%A Okotie-Oyekan, A.O.
%A Wallsgrove, Natalie J.
%A Popp, Brian N.
%A Hollibaugh, James T.
%K nitrification, polyamines, DON, organic nitrogen, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Generalizing Ecological Effects of Shoreline Armoring Across Soft Sediment Environments
%D 2018
%V 41
%N 1
%P 180-196
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1023
%R 10.1007/s12237-017-0254-x
%X Despite its widespread use, the ecological effects of shoreline armoring are poorly synthesized and difficult to generalize across soft sediment environments and structure types. We developed a conceptual model that scales predicted ecological effects of shore-parallel armoring based on two axes: engineering purpose of structure (reduce/slow velocities or prevent/stop flow of waves and currents) and hydrodynamic energy (e.g., tides, currents, waves) of soft sediment environments. We predicted greater ecological impacts for structures intended to stop as opposed to slow water flow and with increasing hydrodynamic energy of the environment. We evaluated our predictions with a literature review of effects of shoreline armoring for six possible ecological responses (habitat distribution, species assemblages, trophic structure, nutrient cycling, productivity, and connectivity). The majority of studies were in low-energy environments (51 of 88), and a preponderance addressed changes in two ecological responses associated with armoring: habitat distribution and species assemblages. Across the 207 armoring effects studied, 71% were significantly negative, 22% were significantly positive, and 7% reported no significant difference. Ecological responses varied with engineering purpose of structures, with a higher frequency of negative responses for structures designed to stop water flow within a given hydrodynamic energy level. Comparisons across the hydrodynamic energy axis were less clear-cut, but negative responses prevailed (>78%) in high-energy environments. These results suggest that generalizations of ecological responses to armoring across a range of environmental contexts are possible and that the proposed conceptual model is useful for generating predictions of the direction and relative ecological impacts of shoreline armoring in soft sediment ecosystems.
%U https://link.springer.com/content/pdf/10.1007%2Fs12237-017-0254-x.pdf
%A Dugan, J.E.
%A Emery, K.A.
%A Alber, Merryl
%A Alexander, Clark R., Jr.
%A Byers, James
%A Gehman, Alyssa
%A McLenaghan, Natalie Ann
%A Sojka, S.E.
%K Coastal armoring, Shore Protection, Cross-site Research, Student Publication

%0 Journal Article
%T Host and parasite thermal ecology jointly determine the effect of climate warming on epidemic dynamics
%D 2018
%V 115
%N 4
%P 744-749
%B Proceedings of the National Academy of Sciences
%9 Article
%Z published
%M GCE.1085
%R 10.1073/pnas.1705067115
%X Host–parasite systems have intricately coupled life cycles, but each interactor can respond differently to changes in environmental variables like temperature. Although vital to predicting how parasitism will respond to climate change, thermal responses of both host and parasite in key traits affecting infection dynamics have rarely been quantified. Through temperature-controlled experiments on an ectothermic host–parasite system, we demonstrate an offset in the thermal optima for survival of infected and uninfected hosts and parasite production. We combine experimentally derived thermal performance curves with field data on seasonal host abundance and parasite prevalence to parameterize an epidemiological model and forecast the dynamical responses to plausible future climate-warming scenarios. In warming scenarios within the coastal southeastern United States, the model predicts sharp declines in parasite prevalence, with local parasite extinction occurring with as little as 2 °C warming. The northern portion of the parasite’s current range could experience local increases in transmission, assuming no thermal adaptation of the parasite, but we find no evidence that the parasite will expand its range northward under warming. This work exemplifies that some host populations may experience reduced parasitism in a warming world and highlights the need to measure host and parasite thermal performance to predict infection responses to climate change.
%U https://www.ncbi.nlm.nih.gov/pubmed/29311324
%A Gehman, Alyssa
%A Hall, Richard
%A Byers, James
%K parasites, estuarine ecology, climate change, disease dynamics, Cross-site Research, Student Publication

%0 Journal Article
%T Effects of small-scale armoring and residential development on the salt marsh-upland ecotone
%D 2018
%V 41
%N 1
%P 54-67
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1024
%R 10.1007/s12237-017-0300-8
%X Small-scale armoring placed near the marsh-upland interface to protect single-family homes is widespread but understudied. Using a nested, spatially blocked sampling design on the coast of Georgia, USA, we compared the biota and environmental characteristics of 60 marshes adjacent to either a bulkhead, a residential backyard with no armoring, or an intact forest. We found that marshes adjacent to bulkheads were at lower tidal elevations and had features typical of lower elevation marsh habitats: high coverage of the marsh grass Spartina alterniflora, high density of crab burrows, and muddy sediments. Marshes adjacent to unarmored residential sites had higher soil water content and lower porewater salinities than the armored or forested sites, suggesting that there may be increased freshwater input to the marsh at these sites. Deposition of Spartina wrack on the marsh-upland ecotone was negatively related to elevation at armored sites and positively related at unarmored residential and forested sites. Armored and unarmored residential sites had reduced densities of the high marsh crab Armases cinereum, a species that moves readily across the ecotone at forested sites, using both upland and high marsh habitats. Distance from the upland to the nearest creek was longest at forested sites. The effects observed here were subtle, perhaps because of the small-scale, scattered nature of development. Continued installation of bulkheads in the southeast could lead to greater impacts such as those reported in more densely armored areas like the northeastern USA. Moreover, bulkheads provide a barrier to inland marsh migration in the face of sea level rise. Retaining some forest vegetation at the marsh-upland interface and discouraging armoring except in cases of demonstrated need could minimize these impacts.
%U https://link.springer.com/article/10.1007/s12237-017-0300-8
%A Gehman, Alyssa
%A McLenaghan, Natalie Ann
%A Byers, James
%A Alexander, Clark R., Jr.
%A Pennings, Steven C.
%A Alber, Merryl
%K bulkheads, residential development, shoreline armoring, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Facilitating and Improving Environmental Research Data Repository Interoperability
%D 2018
%V 17
%P 22
%B Data Science Journal
%9 Article
%Z published
%M GCE.1083
%R 10.5334/dsj-2018-022
%X Environmental research data repositories provide much needed services for data preservation and data dissemination to diverse communities with domain specific or programmatic data needs and standards. Due to independent development these repositories server their communities well, but were developed with different technologies, data models and using different ontologies. Hence, the effectiveness and efficiency of these services can be vastly improved if repositories work together adhering to a shared community platform that focuses on the implementation of agreed upon standards and best practices for curation and dissemination of data. Such a community platform drives forward the convergence of technologies and practices that will advance cross-domain interoperability. It will also facilitate contributions from investigators through standardized and streamlined workflows and provide increased visibility for the role of data managers and the curation services provided by data repositories, beyond preservation infrastructure. Ten specific suggestions for such standardizations are outlined without any suggestions for priority or technical implementation. Although the recommendations are for repositories to implement, they have been chosen specifically with the data provider/data curator and synthesis scientist in mind.
%U https://datascience.codata.org/articles/10.5334/dsj-2018-022/
%A Gries, Corinna
%A Budden, Amber
%A Laney, Christine
%A O'Brien, Margaret
%A Servilla, Mark
%A Sheldon, Wade M., Jr.
%A Vanderbilt, Kristin
%A Vieglais, David
%K data, repository, archiving, archival, data management, best practices, LTER-IMC, Cross-site Research

%0 Journal Article
%T Predator size-structure and species identity determine cascading effects in a coastal ecosystem
%D 2018
%V 8
%P 12435-12442
%B Ecology and Evolution
%9 Article
%Z published
%M GCE.1116
%R 10.1002/ece3.4571
%X Cascading consequences of predator extinctions are well documented, but impactsof perturbations to predator size&#8208;structure and how these vary across species remainunclear. Body size is hypothesized to be a key trait governing individual predators’impact on ecosystems. Therefore, shifts in predator size&#8208;structure should triggerecosystem ramifications which are consistent across functionally similar species.Using a US salt marsh as a model system, we tested this hypothesis by manipulatingsize class (small, medium, and large) and size diversity (combination of all three sizeclasses) within two closely related and functionally similar predatory crab speciesover 4 months. Across treatments, predators suppressed densities of a dominantgrazer and an ecosystem engineer, enhanced plant biomass, and altered sedimentproperties (redox potential and saturation). Over the metabolically equivalent experimentalpredator treatments, small size class predators had stronger average impactson response variables, and size class interacted with predator species identity todrive engineer suppression. Within both predator species, size diversity increasedcannibalism and slightly weakened the average impact. These results show that predatorimpacts in a salt marsh ecosystem are determined by both size class and sizediversity; they also highlight that size class can have species&#8208;dependent and response&#8208;dependent effects, underlining the challenge of generalizing trait effects.
%U http://gce-lter.marsci.uga.edu/public/uploads/Griffin_and__Silliman_2018-Ecology_and_Evolution_20181211T114329.pdf
%A Griffin, John
%A Silliman, Brian R.
%K biodiversity, ecosystem functioning, metabolic theory, multifunctionality, salt marsh, trophic cascade, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Differential effects of chronic and acute simulated seawater intrusion on tidal freshwater marsh carbon cycling
%D 2018
%V 138
%P 137–154
%B Biogeochemistry
%9 Article
%Z published
%M GCE.1072
%R 10.1007/s10533-018-0436-z
%X Tidal freshwater ecosystems experience acute seawater intrusion associated with periodic droughts, but are expected to become chronically salinized as sea level rises. Here we report the results from an experimental manipulation in a tidal freshwater Zizaniopsis miliacea marsh on the Altamaha River, GA where diluted seawater was added to replicate marsh plots on either a press (constant) or pulse (2 months per year) basis. We measured changes in porewater chemistry (SO4 2-, Cl-, organic C, inorganic nitrogen and phosphorus), ecosystem CO2 and CH4 exchange, and microbial extracellular enzyme activity. We found that press (chronic) seawater additions increased porewater chloride and sulfate almost immediately, and ammonium and phosphate after 2–4 months. Chronic increases in salinity also decreased net ecosystem exchange, resulting in reduced CO2 and CH4 emissions from press plots. Our pulse treatment, designed to mimic natural salinity incursion in the Altamaha River (September and October), temporarily increased porewater ammonium concentrations but had few lasting effects on porewater chemistry or ecosystem carbon balance. Our findings suggest that long-term, chronic saltwater intrusion will lead to reduced C fixation and the potential for increased nutrient (N, P) export while acute pulses of saltwater will have temporary effects.
%U https://doi.org/10.1007/s10533-018-0436-z
%A Herbert, Ellen
%A Schubauer-Berigan, Joseph P.
%A Craft, Christopher B.
%K freshwater, seawater intrusion, Altamaha River, Zizaniopsis miliacea, marsh, chemistry, sulfate, chloride, organic carbon, nitrogen, phosphorus, methane, carbon dioxide, porewater, salinity, Student Publication, UGAMI Publication

%0 Thesis
%T Modeling Growth and Production Dynamics of Spartina Alterniflora
%D 2018
%P 148
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z presented
%M GCE.1093
%X The goal of this work is to investigate the growth and production dynamics of the dominant salt marsh grass in the southeastern United States, Spartina alterniflora, including documenting non-structural carbohydrate pools and investigating seasonal changes in translocated biomass between above- and below-ground tissues.In Chapter 2, the dynamics of several non-structural carbohydrates (NSC) stored in S. alterniflora is investigated. Results show that sucrose is the dominant NSC in both above- and below-ground tissues and that the total NSC as a percentage of total biomass is highest in the summer through to early winter. The study suggests that sucrose is likely used for long-term storage whereas glucose is preferentially utilized for short-term storage.In Chapter 3, the growth and production dynamics of short, medium, and tall height forms of S. alterniflora are investigated using a phenology-based growth model (PG model), which includes the effects of light, temperature, and salinity on plant production. The model is used in combination with field observations of biomass to estimate values of physiological parameters such as mass-specific rates of carbon translocation. Once parameterized, the model is used in forward mode to predict whole-plant production, growth, respiration, mortality, and translocation. Model results indicate that the short height form of S. alterniflora translocates a higher proportion of photosynthates or remobilization of assimilates to below-ground tissues during periods of growth and senescence periods than medium or tall S. alterniflora, although the absolute amount of carbon translocation to below-ground tissues is greatest in the tall form of S. alterniflora because of its larger above-ground biomass.In Chapter 4, the model is used to compare the production and translocation dynamics of S. alterniflora along a latitudinal gradient using sites in Delaware, South Carolina, and Louisiana. Model results indicate that photosynthates make up the main source of carbon translocated to below-ground tissues at low latitudes, whereas at high latitudes, both photosynthates and remobilization of assimilates in senescing shoots are preferentially used. This shows the importance of taking into account the different translocation dynamics of the plants when comparing growth and production across sites at different latitudes.
%U https://getd.libs.uga.edu/pdfs/jung_yeajin_201805_phd.pdf
%A Jung, Yeajin
%K Spartina alterniflora, model, Student Publication, UGAMI Publication

%0 Book Section
%T Carbon and Nutrient (N, P) Cycling of Created and Restored Wetlands
%D 2018
%P 2009-2016
%B The Wetland Book
%9 Article
%Z published
%M GCE.813
%A Langman, Owen
%A Craft, Christopher B.
%E Finlayson, Max
%E Everard, Mark
%E Irvine, K.
%E McInnes, R.J.
%E Middleton, B.A.
%E van Dam, A.A.
%E Davidson, N.C.
%K Carbon, Nitrogen, Phosphorus, Recycling, History, Chemistry, Restoration, Student Publication

%0 Conference Proceedings
%T Temporal and spatial assessments of dissolved organic matter composition and biodegradation throughout the Georgia Coastal Ecosystem LTER domain
%D 2018
%C Holderness, NH
%B Gordon Research Conference - Organic Geochemistry
%8 August 2018
%9 Poster
%Z presented
%M GCE.1081
%A Letourneau, Maria L.
%A Schaefer, Sylvia C.
%A Medeiros, Patricia M.
%K DOM, Molecular composition, Biodegradation, GCE LTER domain, Student Publication

%0 Journal Article
%T Responses of tidal freshwater and brackish marsh macrophytes to pulses of saline water simulating sea level rise and reduced discharge
%D 2018
%V 38
%P 885-891
%B Wetlands
%9 Article
%Z published
%M GCE.1073
%R 10.1007/s13157-018-1037-2
%X Coastal low-salinity marshes are increasingly experiencing periodic to extended periods of elevated salinities due to the combined effects of sea level rise and altered hydrological and climatic conditions. However, we lack the ability to predict detailed vegetation responses, especially for saline pulses that are more realistic in nature than permanent saline presses. In this study, we exposed common freshwater and brackish plants to different durations (1–31 days per month for 3 months) of saline water (salinity of 5).We found that Zizaniopsis miliacea was more tolerant to salinity than the other two freshwater species, Polygonum hydropiperoides and Pontederia cordata. We also found that Zizaniopsis miliacea belowground and total biomass appeared to increase with salinity pulses up to 16 days in length, although this relationship was quite variable. Brackish plants, Spartina cynosuroides, Schoenoplectus americanus and Juncus roemerianus, were unaffected by the experimental treatments. Our experiment did not evaluate how competitive interactions would further affect responses to salinity but our results suggest thehypothesis that short pulses of saline water will increase the cover of Zizaniopsis miliacea and decrease the cover of Polygonum hydropiperoides and Pontederia cordata in tidal freshwater marshes, thereby reducing diversity without necessarily affecting total plant biomass.
%A Li, Fan
%A Pennings, Steven C.
%K salinity, Zizaniopsis, Polygonum, Pontederia, Spartina, Schoenoplectus, Juncus, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Climate drivers of Zizaniopsis miliacea biomass in a Georgia, U.S.A. tidal fresh marsh
%D 2018
%V 63
%P 2266-2276
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.1110
%R 10.1002/lno.10937
%X Tidal fresh marshes are at least as productive as nearby salt marshes, but much less is known about controlson primary production in tidal fresh vs. salt marshes. We studied a tidal fresh marsh in Georgia, U.S.A., dominatedby the C3 grass Zizaniopsis miliacea. We documented seasonal variation in Z. miliacea above-ground biomassand below-ground macro-organic matter over 1 yr, and annual variation in end-of-season abovegroundbiomass over 15 yr in creekbank and midmarsh zones. Aboveground biomass showed a distinct peak in Julyand October. Belowground macro-organic matter was much greater than aboveground biomass and peaked inOctober. Overall productivity was similar to that of salt marshes downstream. Z. miliacea end-of-season abovegroundbiomass showed a classic hump-shaped “subsidy-stress” relationship with plot elevation, but on averagethe creekbank supported about twofold more above-ground biomass than the midmarsh, and both zones variedin biomass about 1.7-fold among years. Annual variation in above-ground biomass was negatively correlatedwith maximum and mean temperature in both zones, and positively with river discharge in the creekbankzone. Sea level, precipitation and water column salinity showed biologically plausible trends with respect tobiomass. The responses of Z. miliacea to abiotic drivers were muted compared with the responses of nearby saltmarshes dominated by Spartina alterniflora. Temperature was more important for Z. miliacea, whereas drivers ofporewater salinity were more important in the salt marsh. Likely future changes in temperature, precipitation,and river discharge may pose a threat to the high productivity of tidal fresh marshes.
%A Li, Shanze
%A Hopkinson, Charles S.
%A Schubauer-Berigan, Joseph P.
%A Pennings, Steven C.
%K wild rice, Zizaniopsis, production, Student Publication, UGAMI Publication

%0 Journal Article
%T Coastal wetland loss, consequences, and challenges for restoration
%D 2018
%V 1
%N 1
%P 1-15
%B Anthropocene Coasts
%9 Article
%Z published
%M GCE.1112
%R 10.1139/anc-2017-0001
%X Coastal wetlands mainly include ecosystems of mangroves, coral reefs, salt marsh, and sea grass beds. As the buffer zone between land and sea, they are frequently threatened from both sides. The world coastal wetland lost more than 50% of its area in the 20th century, largely before their great value, such as wave attenuation, erosion control, biodiversity support, and carbon sequestration, was fully recognized. World wetland loss and degradation was accelerated in the last three decades, caused by both anthropogenic and natural factors, such as land reclamation, aquaculture, urbanization, harbor and navigation channel construction, decreased sediment input from the catchments, sea level rise, and erosion. Aquaculture is one of the key destinations of coastal wetland transformation. Profound consequences have been caused by coastal wetland loss, such as habitat loss for wild species, CO2 and N2O emission from land reclamation and aquaculture, and flooding. Great efforts have been made to restore coastal wetlands, but challenges remain due to lack of knowledge about interactions between vegetation and morphological dynamics. Compromise among the different functionalities remains a challenge during restoration of coastal wetlands, especially when faced with highly profitable coastal land use. To solve the problem, multi-disciplinary efforts are needed from physio-chemical–biological monitoring to modelling, designing, and restoring practices with site-specific knowledge.
%A Li, Xiuzhen
%A Bellerby, Richard
%A Craft, Christopher B.
%A Widney, Sarah
%K coastal wetlands, functionalities, loss, consequence, restoration

%0 Journal Article
%T Predator-prey interactions in a ladybeetle-aphid system depend on spatial scale
%D 2018
%V 8
%P 6537-6546
%B Ecology and Evolution
%9 Article
%Z published
%M GCE.1074
%R 10.1002/ece3.4117
%X The outcome of species interactions may manifest differently at different spatial scales; therefore, our interpretation of observed interactions will depend on the scale at which observations are made. For    example, in ladybeetle–aphid systems, the results from small-scale cage experiments usually cannot be extrapolated to landscape-scale field observations. To understand how ladybeetle–aphid interactions change across spatial scales, we evaluated predator–prey interactions in an experimental system. The experimental habitat consisted of 81 potted plants and was manipulated to facilitate analysis across four spatial scales. We also simulated a spatially explicit metacommunity model parallel to the experiment. In the experiment, we found that the negative effect of ladybeetles on   aphids decreased with increasing spatial scales. This pattern can be explained by ladybeetles strongly suppressing aphids at small scales, but not colonizing distant patches fast enough to suppress aphids at larger scales. In the experiment, the positive effects of aphids on ladybee-tles were strongest at   three-plant scale. In a model scenario where predators did not have demographic dynamics, we    found, consistent with the experiment, that both the effects of ladybeetles on aphids and the effects of   aphids on ladybeetles decreased with increasing spatial scales. These patterns suggest that dispersal was the primary cause of ladybeetle population dynamics in our experiment: aphids increased ladybeetle numbers at smaller scales because ladybeetles stayed in a patch longer and performed area-restricted searches after encountering aphids; these behaviors did not affect ladybeetle numbers at larger spatial scales. The parallel experimental and model results illustrate how predator–prey interactions can change across spatial scales, suggesting that our interpretation of observed predator–prey dynamics would differ if observations were made at different scales. This study demonstrates how studying ecological interactions at a range of scales can help link the results of   small-scale ecological experiments to landscape-scale ecological problems.
%A Lin, Wei-Ting
%A Pennings, Steven C.
%K ladybeetle, aphid, Iva, scale, predation, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Light and temperature control the seasonal distribution of Thaumarchaeota in the South Atlantic Bight
%D 2018
%V 12
%P 1473-1485
%B ISME Journal
%9 Article
%Z published
%M GCE.1022
%R 10.1038/s41396-018-0066-4
%X Previous work on the Georgia, USA coast revealed consistent mid-summer peaks in the abundance of Thaumarchaeota accompanied by spikes in nitrite concentration.  We collected data on the distribution of Thaumarchaeota, ammonia-oxidizing Betaproteobacteria (AOB), nitrite-oxidizing Nitrospina, environmental variables and rates of ammonia oxidation during 6 cruises in the South Atlantic Bight from April to November 2014 to evaluate the areal extent and timing of the bloom.  The abundance of Thaumarchaeota marker genes (16S rRNA and amoA) increased at inshore and nearshore stations starting in July and peaked in August at >107 copies L-1.  The bloom did not extend onto the mid-shelf, where Thaumarchaeota genes ranged from 103 to 105 copies L-1.  Clone libraries from samples collected at mid-shelf stations generated using Archaea 16S rRNA primers were dominated by sequences from Marine Group II and III Archaea, whereas libraries from inshore and nearshore stations were dominated by Thaumarchaeota.  Thaumarchaeota were also abundant in oxygen-depleted waters at depth at the shelf-break.  This population was phylogenetically-distinct from the inshore/nearshore population.  Ammonia oxidation rates (AO) were highest at inshore stations and were at the limit of detection at mid-shelf stations.  AO correlated significantly with ammonium concentration (r2=0.23) and Thaumarchaeota abundance (r2=0.14).  Nitrite concentration correlated with AO (r2=0.74).  Our analysis of environmental data suggests that Thaumarchaeota distributions in the SAB are controlled primarily by photoinhibition and secondarily by water temperature, while AO is controlled primarily by ammonium availability.
%A Liu, Qian
%A Tolar, Bradley
%A Ross, Meredith
%A Cheek, Jelani
%A Sweeney, Corinne
%A Wallsgrove, Natalie J.
%A Popp, Brian N.
%A Hollibaugh, James T.
%K Thaumarchaeota, ammonia-oxidation, nitrite oxidation, Nitrospina, nitrification, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Exploring Oyster (Crassostrea virginica) Habitat Collection via Oxygen Isotope Geochemistry and its Implications for Ritual and Mound Construction at Crystal River and Roberts Island, Florida
%D 2018
%V 13
%N 3
%P 388-404
%B The Journal of Island and Coastal Archaeology
%9 Article
%Z published
%M GCE.1097
%R 10.1080/15564894.2017.1363096
%X Research at Crystal River and Roberts Island Shell Mound Complex, on the western coast of Florida, USA, offers a quantitative assessment of the temporality of shell deposit construction, Native subsistence practices, and mobility patterns through stable oxygen isotope data from eastern oyster (C. virginica). The &#948;18Owater values of oysters vary synchronously with salinity, assuming relatively constant &#948;18Owater/salinity gradients since the time of occupation, allowing for an examination of shifts in oyster habitat exploitation over time. Our previous (Thompson et al. 2015) study indicated that midden accumulation occurred throughout the year, while oysters from mound deposits were collected in colder months. New data indicate that in addition to differential season of collection, habitat exploitation also varied. During early occupation at the site, oysters were collected primarily from lower saline habitats, while in later phases oysters were obtained from higher salinity waters; we relate this to a lower sea level and concomitant settlement shift seaward. Additionally, oyster from later mound contexts was collected from higher saline habitats relative to those in midden contexts; Native people may have targeted specific bioherms at certain times for the year for feasting-related mound construction.
%U https://www.tandfonline.com/doi/full/10.1080/15564894.2017.1363096
%A Lulewicz, Isabelle H.
%A Thompson, Victor D.
%A Pluckhahn, Thomas J.
%A Andrus,  C. F.T.
%A Das, Oindrila
%K coastal, economy and subsistence, mobility, paleoenvironment, Southeast

%0 Journal Article
%T Controls on porewater salinity in a Southeastern salt marsh
%D 2018
%V 6
%P e5911
%B PeerJ
%9 Article
%Z published
%M GCE.1026
%R 10.7717/peerj.5911
%X In coastal marsh ecosystems, porewater salinity strongly affects vegetation distribution and productivity. To simulate marsh porewater salinity, an integrated, spatially explicit model was developed, accounting for tidal inundation, evaporation, and precipitation, as well as lateral and vertical exchanges in both surface waters and the subsurface. It was applied to the Duplin River marsh, Sapelo Island, USA, over a 3-year period, which covered both drought and wet conditions. Simulated porewater salinity in the low and high marsh correlated with Duplin River salinity, withevapotranspiration and precipitation leading to substantial variations in porewater salinities across seasons, in particular in the high marsh. The model revealed substantial interannual variability in marsh soil conditions, and—due to its processbased approach linked to external forcings—can be used to explore effects of sea level rise and changes in hydrological forcings on marsh soil conditions.
%U https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6230441/
%A Miklesh, David Michael
%A Meile, Christof
%K porewater salinity marsh, Student Publication

%0 Conference Proceedings
%T Analysis of decadal-scale patterns of Spartina biomass in Georgia marshes using soil modeling and satellite imagery.
%D 2018
%I AGU, ASLO and TOS
%C Portland OR
%B Ocean Sciences Meeting
%8 Feb 11-16, 2018
%9 Poster
%Z presented
%M GCE.1090
%A Miklesh, David Michael
%A O'Donnell, J.P.
%A Schalles, John F.
%A Meile, Christof
%K soil salinity, biomass, Student Publication

%0 Conference Proceedings
%T Landsat models of Spartina alterniflora belowground biomass in coastal marshes
%D 2018
%C New Orleans, LA
%B Ecological Society of America
%9 Presentation
%Z presented
%M GCE.1133
%A O'Connell, Jessica
%A Alber, Merryl
%A Mishra, Deepak
%A Byrd, K. B.
%K Spartina alterniflora, coastal marshes, biomass, landsat

%0 Thesis
%T Assessing the export of terrigenous dissolved organic matter in the South Atlantic Bight using CDOM analysis: 2014 and 2016 cruises
%D 2018
%P 13
%I University of Georgia
%C Athens, GA
%9 B.S. Thesis
%Z A thesis submitted in partial fulfillment of the requirements for the Franklin College Interdisciplinary Studies degree in Marine Sciences 
%M GCE.1089
%A Pannill, V.R.
%K CDOM, optical, terrigenous, SAB, Student Publication

%0 Journal Article
%T Using a marsh organ to predict future plant communities in a Chinese estuary invaded by an exotic grass and mangrove
%D 2018
%V 63
%P 2595-2605
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.1109
%R 10.1002/lno.10962
%X Exotic species vary in how harmful they are. The earlier we can predict the outcome of an invasion, the moretime is available for management. We conducted a “marsh organ” experiment with six elevation treatments toevaluate how the exotic grass Spartina alterniflora, which has invaded almost the entire coastline of China,affects a native (Kandelia obovata) and an exotic (Sonneratia apetala) mangrove in Zhangjiang Estuary, southernChina. Survival of transplants in monoculture over two growing seasons in the marsh organ was high except atextreme high and low elevations. All three plants displayed hump-shaped patterns of biomass across elevationin monoculture, but K. obovata performed best at slightly higher and S. alterniflora at slightly lower elevations,whereas S. apetala performed well across all four intermediate elevations and grew larger than the other twoplants. In mixtures, S. alterniflora suppressed growth of mangrove seedlings of both species by up to 90%. Thecompetitive effect of S. alterniflora was greatest at intermediate elevations where its biomass was greatest. Whentransplanted into adjacent stands of S. alterniflora, K. obovata remained stunted, but S. apetala grew quickly andbegan to emerge from the canopy of S. alterniflora by the end of the second growing season. At this site, pastand ongoing disturbances to mature stands of K. obovata are likely to allow both exotics to increase inabundance. Aggressive management intervention will be needed to prevent estuaries in southern China fromtransitioning to near complete dominance by the exotic mangrove S. apetala.
%A Peng, Dan
%A Chen, Luzhen
%A Pennings, Steven C.
%A Zhang, Y.
%K exotic species, Spartina, mangrove, China, marsh organ, Student Publication

%0 Thesis
%T A spatial and temporal investigation of estuarine and shelf flows on the Georgia Coast
%D 2018
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z presented
%M GCE.1106
%A Richards, Trevor
%K Georgia coast, estuarine, shelf flows, Student Publication

%0 Journal Article
%T Hydrological controls on the seasonal variability of dissolved and particulate black carbon in the Altamaha River, GA.
%D 2018
%V 123
%P 3055-3071
%B Journal of Geophysical Research - Biogeosciences
%9 Article
%Z published
%M GCE.1079
%R 10.1029/2018JG004406
%X Rivers play an important role in the transport of organic carbon from terrestrial to marine environments. A significant portion of this material is black carbon (BC), a residue of incomplete biomass and fossil fuel combustion. BC is mobilized in fluvial systems as both particulate BC (PBC) and dissolved BC (DBC) and the export of BC to coastal environments may have significant implications for carbon cycling in marine environments. However, while little is known regarding the potential connectivity between riverine export of PBC and DBC or the potential importance of such a relationship in constraining future BC budgets, current knowledge suggests that fluvial export of PBC and DBC are decoupled in small fire&#8208;impacted watersheds. This study aims to further address this subject on a larger watershed scale. For this study, thirteen monthly samples were collected (Sept. 2015 &#8208; Sept. 2016) near the mouth of the Altamaha River, Georgia. PBC and DBC were characterized using the benzenzepolycarboxylic acid method. Seasonal hydrology and regional shifts in storm events play an important role for both PBC and DBC export during high flow months. The DBC concentrations were comparable among wet and dry seasons, whereas evidence of seasonal salt&#8208;water intrusions suggests an additional estuarine contribution of PBC at the sampling location. The DBC and PBC fluxes were generally coupled, although this pattern was disrupted during initial storm pulses. While this is the first report of potential coupling between DBC and PBC export, environmental drivers controlling this behavior between DBC and PBC remain to be constrained.
%A Roebuck, J.A.
%A Medeiros, Patricia M.
%A Letourneau, Maria L.
%A Jaffe, R.
%K Black carbon (BC), Dissolved, Particulate, Hydrology, Altamaha River, Cross-site Research, Student Publication

%0 Conference Proceedings
%T Hydrological controls on the seasonal variability of dissolved and particulate black carbon in the Altamaha River, GA
%D 2018
%I AGU
%C Portland, OR
%B Ocean Sciences Meeting
%8 February 2018
%9 Poster
%Z presented
%M GCE.1082
%A Roebuck, J.A.
%A Medeiros, Patricia M.
%A Letourneau, Maria L.
%A Jaffe, R.
%K Black carbon (BC), Dissolved, Particulate, Hydrology, Altamaha River, Student Publication

%0 Conference Proceedings
%T Spatial and temporal perpectives on multiple stressor impacts spanning inland to coastal ecosystems
%D 2018
%I GLOBOLakes and GEO Aquawatch
%C University of Stirling, Stirling, Scotland, UK
%B GLOBOLakes and GEO Aquawatch Joint Workshop
%S Agency & International Program Lightning Talks
%8 August 30, 2018
%9 Presentation
%Z presented
%M GCE.1102
%X This talk will provide perspectives on aquatic ecosystem stress responses acquired from 40+ years of field experiences in inland, estuarine, and coastal waters. Increasing, our study units are expressing multiple stressors and accelerated rates of ecosystem response. I'll use several examples from larger scale, synoptic studies using remote sensing to examine salt marshes, algal blooms, and fates of suspended sediments. Finally, I'll emphasize the value of place-based, local knowledge and talking with the stake-holders experiencing changes in aquatic systems.
%U https://www.geoaquawatch.org/final-programme-announced-joint-geo-aquawatch-and-globolakes-workshop/
%A Schalles, John F.
%K Stressors, climate change, coastal ecosystems, spatial-temporal patterns, SINERR Publication

%0 Conference Proceedings
%T The dynamic littoral fringe –  Spatial and temporal patterns in community structureand productivity in North American coastal ecosystems
%D 2018
%I GLOBOLakes and GEO Aquawatch
%C University of Stirling, Stirling, Scotland, UK
%B GLOBOLakes and GEO Aquawatch Joint Workshop
%S Poster Session - Tuesday,
%8 Wednesday, August 29, 2018
%9 Poster
%Z presented
%M GCE.1103
%X This presentation will illustrate case studies of changes in littoral ecosystems on the Northern Gulf of Mexico and Southeastern Atlantic coasts, as captured with satellite and airborne imagery analysis. On the Georgia coast, 35 years of Landsat imagery revealed large scale (3 fold) inter-annual variation and a cumulative net loss of 16.5% in the aboveground biomass of the keystone salt marsh species, Spartina alterniflora. Spatial differences and temporal changes in 620 km2 (about 680,000 pixels of Spartina habitat) were linked to climate variables, river hydrology, and sea level dynamics. In the same area, riparian brackish and freshwater wetlands are sensitive indicators of changes in salinity patterns. On the Texas coast, Black Mangrove vegetation is replacing salt marsh communities, as shown in analysis of high resolution WorldView satellite imagery. This “tropicalization” is well underway, but also reveals instabilities due to occasional winter incursions of arctic air. Finally, at multiple sites, we’ve used airborne hyperspectral and HICO Space Station imagery to document patterns of phytoplankton chlorophyll (including HABs) and CDOM in estuarine, inshore, and shelf waters.
%U https://www.geoaquawatch.org/final-programme-announced-joint-geo-aquawatch-and-globolakes-workshop/
%A Schalles, John F.
%A O'Donnell, J.P.
%A Hladik, Christine M.
%A Ponzi, Sonya
%A Cao, Fang
%A Miller, William
%K remote sensing, wetlands, community structure, coastal waters, algal chlorophyll, CDOM, Student Publication

%0 Conference Proceedings
%T Multidecadal biomass declines and controlling variables for the keystone salt marsh species, Spartina alterniflora, in coastal Georgia 
%D 2018
%I Association for the Sciences of Liminology and Oceanography
%C Victoria, British Columbia, BC
%B ASLO 2018 Summer Meeting
%S SS86: Connecting the Dots – Signals of Global Change Effects in Freshwater and Marine Ecosystems
%8 June 15, 2018
%9 Presentation
%Z presented
%M GCE.1101
%X We studied aboveground biomass dynamics and spatial patterns of Marsh Cordgrass, Spartina alterniflora, on the Central Georgia Coast. This keystone species accounts for 98% of the aerial extent of salt marshes in Georgia and comprise about 33% of all salt marsh on the U.S. Western Atlantic Coast. Geospatial techniques were used to scale up in situ biomass measurements within the NSF Georgia Coastal Ecosystems research domain on the Central Georgia Coast to landscape scale estimates using 290 Landsat 5 TM scenes from 1984 to 2011. Climate and hydrological variables were then used to explain variations in aboveground production for each of the three height classes of S. alterniflora. River discharge, total precipitation, minimum temperature, and mean sea level had positive relationships with and best explained biomass variation for all dates. Over the 28-year study period we documented biomass declines of 31.6 %, 33.4 %, and 38.7% for tall, medium, and short S. alterniflora height classes. These biomass declines were linked to increased drought severity and frequency over the last half of our study period. We then applied a larger, synoptic scale approach to riverine and tidal watersheds containing 620 square kilometers of S. alterniflora marshlands on the Georgia Coast (Savannah River to St Simon’s Sound) and found similar inter and intra-annual biomass patterns. Importantly, S. alterniflora biomass production was greatest in areas closest to larger inputs of freshwater and high precipitation. We infer that these areas of high production, especially in the Lower Altamaha River Watershed, were better buffered against drought stress, including soil salinization, and also experienced greater nitrogen loading rates. Overall, this much larger study area experienced a 20.6% average decline, representing a reduction of about 108,000 MT in aboveground live carbon biomass. This loss in marsh production presumably affects valuable ecosystem services, including wetland soil carbon sequestration and organic matter export (both particulate and dissolved). Thus, declines in marsh production could significantly reduce nutritional support to food webs and carbon biogeochemical cycling, as well as commercial fish and shellfish production, in Georgia’s estuaries and coastal ocean ecosystems. Finally, we are carrying our analyses forward using newer Landsat 8 OLI imagery. In addition, Landsat 7 ETM imagery is serving as a “bridge” to cross-calibrate between the Landsat 5 and Landsat 8 sensors and provide “gap coverage” between 2011 and 2014.
%U https://aslo.org/victoria2018/special-sessions
%A Schalles, John F.
%A O'Donnell, John
%A Nealy, Nicholas
%A Mizoguchi, Trek
%A Hladik, Christine M.
%K Spartina alterniflora, plant biomass, remote sensing, climate drivers, river hydrology, SINERR Publication, Student Publication

%0 Thesis
%T Disturbance and Recovery of Southeastern Salt Marshes: Drivers of Change and Ecosystem Service Dynamics
%D 2018
%P 121
%I University of Florida
%C Gainesville, FL
%9 Ph.D. Dissertation
%Z published
%M GCE.1129
%A Sharp, Sean
%K salt marsh

%0 Journal Article
%T Physical Stress, Consumer Control, and New Theory in Ecology
%D 2018
%V 33
%N 7
%P 492 - 503
%B Trends in Ecology and Evolution
%9 Article
%Z published
%M GCE.1061
%R 10.1016/j.tree.2018.04.015
%X Consumer–prey interactions form the foundation of food webs and are affected by the physical environment. Multiple foundational theories in ecology [e.g., the environmental stress model (ESM), the stress–gradient hypothesis (SGH), and ecosystem resilience theory] assume increased physical stress dampens top-down control of prey. In the large majority of empirical studies, however, physical stress either does not affect or amplifies consumer control. Additive and synergistic impacts of physical stress on consumer control appear more common, for example, for herbivory versus predation, and for warm- versus cold-blooded consumers. Predictability in how physical stress affects consumer control, however, remains largely unknown. We expand classical theories in ecology so that their assumption about physical stress–consumer control relationships can be inclusive of what primarily occurs in nature.
%A Silliman, Brian R.
%A He, Qiang
%K ecological theory, predator–prey interactions, environmental change, positive species interactions, ecosystem resilience

%0 Journal Article
%T Are the ghosts of nature’s past haunting ecology today?
%D 2018
%V 28
%P R527–R548
%B Current Biology
%9 Article
%Z published
%M GCE.1060
%R 10.1016/j.cub.2018.04.002
%X Humans have decimated populations of large-bodied consumers and their functions in most of the world’s ecosystems. It is less clear how human activities have affected the diversity of habitats these consumers occupy. Rebounding populations of some predators after conservation provides an opportunity to begin to investigate this question. Recent research shows that following longterm protection, sea otters along the northeast Pacific coast have expanded into estuarine marshes and seagrasses, and alligators on the southeast US coast have expanded into saltwater ecosystems, habitats presently thought beyond their niche space. There is also evidence that seals have expanded into subtropical climates, mountain lions into grasslands, orangutans into disturbed forests and wolves into coastal marine ecosystems. Historical records, surveys of protected areas and patterns of animals moving into habitats that were former hunting hotspots indicate that — rather than occupying them for the first time — many of these animals are in fact recolonizing ecosystems. Recognizing that many large consumers naturally live and thrive across a greater diversity of ecosystems has implications for setting historical baselines for predator diversity within specific habitats, enhancing the resilience of newly colonized ecosystems and for plans to recover endangered species, as a greater range of habitats is available for large consumers as refugia from climate-induced threats.
%U https://www.sciencedirect.com/science/article/pii/S0960982218304305?via%3Dihub
%A Silliman, Brian R.
%A Hughes, Brent B.
%A Gaskins, Leo
%A He, Qiang
%A Tinker, T.
%A Read, A.
%A Nifong, James C.
%A Stepp, Rick
%K predator, diversity, Student Publication

%0 Journal Article
%T Tidal freshwater forests: Sentinels for climate change
%D 2018
%V 116
%P 104-109
%B Ecological Engineering
%9 Article
%Z published
%M GCE.1071
%R 10.1016/j.ecoleng.2018.03.002
%X We measured plant community composition and productivity, soil accretion, and C, N, and P burial in a tidal freshwater forest of the Altamaha River, Georgia to gain a better understanding of the ecosystem services they deliver and their ability to keep pace with current and future rates of sea level rise. Ten species were identified in two 0.1 ha plots. Nyssa aquatica (Tupelo Gum) made up 50% of the density and 57% of the total basal area. Nyssa biflora, Liquidambar styraciflua, and Fraxinus pennsylvanica were the next dominant species, collectively accounting for 37% of the density and 26% of the total basal area. Taxodium distichum only accounted for 3% of the density, but 12% of the total basal area. Aboveground productivity, measured as litterfall and stem wood growth, averaged 927 and 1030 g/m2 in 2015 and 2016, respectively, with litterfall accounting for 60% of the total. Tidal forest soils in the streamside and the interior (0–60 cm) contained 3–6% organic C, 0.20–0.40% N, and 270–540 µg/g P. Soil accretion based on 137Cs was 4.0 mm/year on the streamside and 0.2 mm/year in the forest interior. The rate of accretion in the interior is considerably less than the current rate of sea level rise (3.1 mm/year) along the Georgia coast. Because the accretion rate was much higher on the streamside, rates of C sequestration, N and P accumulation, and mineral sediment deposition also were much greater. Low accretion rates in the interior of the forest that accounts for most of the acreage suggests that accelerated sea level rise is likely to lead to foreseeable death of tidal forests from saltwater intrusion and submergence.
%U https://www.sciencedirect.com/science/article/pii/S0925857418300715
%A Stahl, McKenna
%A Widney, Sarah
%A Craft, Christopher B.
%K Tidal forest, climate change, sea level rise, nutrient cycling, Student Publication, UGAMI Publication

%0 Journal Article
%T A Comparison between the MODIS Product (MOD17A2) and a Tide-Robust Empirical GPP Model Evaluated in a Georgia Wetland
%D 2018
%V 10
%P 1831
%B Remote Sensing
%9 Article
%Z published
%M GCE.1114
%R 10.3390/rs10111831
%X Despite the importance of tidal ecosystems in the global carbon budget, the relationshipsbetween environmental drivers and carbon dynamics in these wetlands remain poorly understood.This limited understanding results from the challenges associated with in situ flux studies andtheir correlation with satellite imagery which can be affected by periodic tidal flooding. Carbondioxide eddy covariance (EC) towers are installed in only a few wetlands worldwide, and thelongest eddy-covariance record from Georgia (GA) wetlands contains only two continuous yearsof observations. The goals of the present study were to evaluate the performance of existingMODIS Gross Primary Production (GPP) products (MOD17A2) against EC derived GPP anddevelop a tide-robust Normalized Difference Moisture Index (NDMI) based model to predict GPPwithin a Spartina alterniflora salt marsh on Sapelo Island, GA. These EC tower-based observationsrepresent a basis to associate CO2 fluxes with canopy reflectance and thus provide the means touse satellite-based reflectance data for broader scale investigations. We demonstrate that Light UseEfficiency (LUE)-based MOD17A2 does not accurately reflect tidal wetland GPP compared to a simpleempirical vegetation index-based model where tidal influence was accounted for. The NDMI-basedGPP model was capable of predicting changes in wetland CO2 fluxes and explained 46% of thevariation in flux-estimated GPP within the training data, and a root mean square error of 6.96 g C m&#1048576;2in the validation data. Our investigation is the first to create a MODIS-based wetland GPP estimationprocedure that demonstrates the importance of filtering tidal observations from satellite surfacereflectance data.
%U https://www.mdpi.com/2072-4292/10/11/1831
%A Tao, J.
%A Mishra, Deepak
%A Cotten, David L.
%A O'Connell, Jessica
%A Leclerc, Monique Y.
%A Nahrawi, Hafsah Binti
%A Zhang, Gengsheng
%A Pahari, R.
%K MODIS GPP Calibration, MOD17A2, Normalized Distribution Moisture Index, Tide Adjusted Wetland Index, flux GPP, salt marsh, tidal wetlands, Student Publication, UGAMI Publication

%0 Book Section
%T Collective Action and Village Life during the Late Archaic on the Georgia Coast
%D 2018
%P 20-35
%I University Press of Florida
%C Gainesville
%B The Archaeology of Villages in Eastern North America
%9 Article
%Z published
%M GCE.1092
%A Thompson, Victor D.
%E Thompson, Victor D.
%K Southeastern Archaeology, shell rings, oyster

%0 Journal Article
%T Secondary foundation species enhance biodiversity.
%D 2018
%V 2
%P 634-639
%B Nature Ecology and Evolution
%9 Article
%Z published
%M GCE.1058
%R 10.1038/s41559-018-0487-5
%X It has long been recognized that primary foundation species (FS), such as trees and seagrasses, enhance biodiversity. Among the species facilitated are secondary FS, including mistletoes and epiphytes. Case studies have demonstrated that secondary FS can further modify habitat-associated organisms (‘inhabitants’), but their net effects remain unknown. Here we assess how inhabitants, globally, are affected by secondary FS. We extracted and calculated 2,187 abundance and 397 richness Hedges’ g effect sizes from 91 and 50 publications, respectively. A weighted meta-analysis revealed that secondary FS significantly enhanced the abundance and richness of inhabitants compared to the primary FS alone. This indirect facilitation arising through sequential habitat formation was consistent across environmental and experimental conditions. Complementary unweighted analyses on log response ratios revealed that the magnitude of these effects was similar to the global average strength of direct facilitation from primary foundation species and greater than the average strength of trophic cascades, a widely recognized type of indirect facilitation arising through sequential consumption. The finding that secondary FS enhance the abundance and richness of inhabitants has important implications for understanding the mechanisms that regulate biodiversity. Integrating secondary FS into conservation practice will improve our ability to protect biodiversity and ecosystem function.
%A Thomsen, M. S
%A Alteiri, A.
%A Angelini, Christine
%A Bishop, M.
%A Gribben, G.
%A Lear, G.
%A Schiel, D.R.
%A Silliman, Brian R.
%A South, P.
%A Watson, D.
%A Wernberg, T.
%A Zotz, G.
%K biodiversity, foundation species, Student Publication

%0 Journal Article
%T Identifying labile DOM components in a coastal ocean through depleted bacterial transcripts and chemical signals
%D 2018
%V 20
%P 3012-3030
%B Environmental Microbiology
%9 Article
%Z published
%M GCE.1080
%R 10.1111/1462-2920.14344
%X Understanding which compounds comprising the complex and dynamic marine dissolved organic matter (DOM) pool are important in supporting heterotrophic bacterial production remains a major challenge. We eliminated sources of labile phytoplankton products, advected terrestrial material and photodegradation products to coastal microbial communities by enclosing water samples in situ for 24 h in the dark. Bacterial genes for which expression decreased between the beginning and end of the incubation and chemical formulae that were depleted over this same time frame were used as indicators of bioavailable compounds, an approach that avoids augmenting or modifying the natural DOM pool. Transport&#8208; and metabolism&#8208;related genes whose relative expression decreased implicated osmolytes, carboxylic acids, fatty acids, sugars and organic sulfur compounds as candidate bioreactive molecules. FT&#8208;ICR MS analysis of depleted molecular formulae implicated functional groups ~ 30–40 Da in size cleaved from semi&#8208;polar components of DOM as bioreactive components. Both gene expression and FT&#8208;ICR MS analyses indicated higher lability of compounds with sulfur and nitrogen heteroatoms. Untargeted methodologies able to integrate biological and chemical perspectives can be effective strategies for characterizing the labile microbial metabolites participating in carbon flux.
%A Vorobev, A.
%A Sharma, S.
%A Yu, M.
%A Lee, J.
%A Washington, B.J.
%A Whitman, W.B.
%A Ballantyne, F.
%A Medeiros, Patricia M.
%A Moran, Mary Ann
%K Bacterioplankton, DOM, Gene expression, Metatranscriptomics, FT-ICR MS, UGAMI Publication

%0 Journal Article
%T Predators mediate above- vs belowground herbivory in a salt marsh crab
%D 2018
%V 9
%N 2
%P e02107
%B Ecosphere
%9 Article
%Z published
%M GCE.1091
%R 10.1002/ecs2.2107
%X Predators can significantly affect prey by removing prey individuals and by changing preybehavior. The tradeoff between foraging behavior and predation risk may result in a trophic cascade that can have important effects on ecosystem processes. For herbivores that can feed both above- and belowground, it is likely that predation risk affects the location of feeding. We tested whether two species of predatory marsh crabs affected feeding behavior of the herbivorous crab, Sesarma reticulatum. We found that predatory crabs could kill or injure Sesarma and that Sesarma did less damage to its food plant Spartina alterniflora in the presence of the more dangerous predator. Sesarma prefers to feed on and grows better on belowground rhizomes than aboveground leaves; however, the costs of digging burrows to access rhizomes lead to higher mortality if it is the only diet option. The location of feeding did not affect total biomass of S. alterniflora. For Sesarma, a choice in feeding location allows the crabs the behavioral flexibility to balance the risks of predation, the nutritional benefit of feeding belowground, and the survival costs of belowground feeding. Similar tradeoffs are likely to increase the success of other herbivores that can feed both above- and belowground.
%A Vu, Huy
%A Pennings, Steven C.
%K Sesarma, Panopeus, Eurytium, Spartina, predation, herbivory, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Inorganic carbon and oxygen dynamics in a marsh-dominated estuary
%D 2018
%V 63
%N 1
%P 47-71
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.1050
%R 10.1002/lno.10614
%X We conducted a free-water mass balance-based study to address the rate of metabolism and net carbon exchange for the tidal wetland and estuarine portion of the coastal ocean and the uncertainties associated with this approach were assessed. We measured open water diurnal O2 and dissolved inorganic carbon (DIC) dynamics seasonally in a salt marsh-estuary in Georgia, U.S.A. with a focus on the marsh-estuary linkage associated with tidal flooding. We observed that the overall estuarine system was a net source of CO2 to the atmosphere and coastal ocean and a net sink for oceanic and atmospheric O2. Rates of metabolism were extremely high, with respiration (43 mol m&#8722;2 yr&#8722;1) greatly exceeding gross primary production (28 mol m&#8722;2 yr&#8722;1), such that the overall system was net heterotrophic. Metabolism measured with DIC were higher than with O2, which we attribute to high rates of anaerobic respiration and reduced sulfur storage in salt marsh sediments, and we assume substantial levels of anoxygenic photosynthesis. We found gas exchange from a flooded marsh is substantial, accounting for about 28% of total O2 and CO2 air–water exchange. A significant percentage of the overall estuarine aquatic metabolism is attributable to metabolism of marsh organisms during inundation. Our study suggests not rely on oceanographic stoichiometry to convert from O2 to C based measurements when constructing C balances for the coastal ocean. We also suggest eddy covariance measurements of salt marsh net ecosystem exchange underestimate net ecosystem production as they do not account for lateral DIC exchange associated with marsh tidal inundation.
%U http://onlinelibrary.wiley.com/doi/10.1002/lno.10614/full
%A Wang, Shiyu
%A Di Iorio, Daniela
%A Cai, Wei-Jun
%A Hopkinson, Charles S.
%K Inorganic carbon, oxygen dynamics, marsh-dominated estuary, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Integrating new and existing sand resources data for Georgia coastal recovery and resiliency
%D 2017
%C Richmond, VA.
%B Southeastern Section of the Geological Society of America Annual Meeting
%8 30-31 March 2017
%9 Presentation
%Z presented
%M GCE.1033
%A Alexander, Clark R., Jr.
%K sediments

%0 Journal Article
%T Sedimentary processes and products in a mesotidal salt marsh environment: insights from Groves Creek, Georgia
%D 2017
%V 37
%P 345-359
%B Geo-Marine Letters
%9 Article
%Z published
%M GCE.965
%R 10.1007/s00367-017-0499-1
%X Southeastern salt marshes are important repositories of sediment and carbon, and their formation is heavily dependent on deposition and accumulation of inorganic sediment. This study examined Groves Creek marsh near Savannah, GA, a typical Spartina alterniflora salt marsh of the southeastern US. Analyses were focused on the character, deposition and accumulation of material within the marsh on daily, monthly, decadal and centennial timescales, to determine the dominant factors in material supply and redistribution, and on its stratigraphy to determine the 1,000-year history of Groves Creek salt marsh development. Modern processes create gradients in grain size, which shows little variation from the tidal channel flanks up to mean sea level, and which coarsens with distance into the marsh from mean sea level to mean high water. This unexpected result suggests that,although floc transport is an important mechanism of sediment supply near the channel margins, energetic events must supply coarser materials to the marsh platform, where they are notreadily removed by typical energy regimes. Daily deposition can approach ~3 g/cm2 year; however, centennial accumulation rates are orders of magnitude lower (0.11±0.05 g/cm2 year) and are similar to those present over the past 300 years (0.05–0.2 g/cm2 year), indicating that much of the daily deposition is remobilized. Stable isotopic &#948;13C (average –18.7‰) and &#948;15N (average 5.7‰) values most likely indicate a large contribution from S. alterniflora as a carbon source throughout the marsh, although heavier &#948;15N on the channel flanks suggest that benthic algae may be locally important. Geologic, geochemical and microfossil evidence suggests that depositional conditions in the Groves Creek marsh have changed significantly over the past ~1,000 years, creating a distinct fining-upward sequence. This sequence preserves the signature (from bottom to top) of subtidal flats grading to intertidal sandflats, an erosional lag created by a migrating tidal channel, point bar deposits, channel fill deposits, and a capping salt marsh. A significant change in environmental conditions occurred between 360–500 cal years BP, which changed the character of geological, geochemical and microfossil components in the marsh, and, because this observation is robust throughout the southeastern US, hints at a major change in estuarine and coastal systems at this time.
%A Alexander, Clark R., Jr.
%A Hodgson, J.Y.S.
%A Brandes, J.A.
%K marsh stratigraphy

%0 Conference Proceedings
%T Historical analysis of marsh extent at three LTER site along the US Atlantic coast.
%D 2017
%C Providence, RI.
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 5-9 Nov., 2017
%9 Presentation
%Z accepted
%M GCE.1035
%A Burns, Christine
%A Alber, Merryl
%A Alexander, Clark R., Jr.
%K marsh, GIS, mapping, Student Publication

%0 Conference Proceedings
%T Tidal freshwater forests: sentinels for climate change
%D 2017
%C Trebon, Czech Republic
%B 10th International Workshop on Nutrient Cycling and Retention in Natural and Constructed Wetlands
%8 September 21-24
%9 Presentation
%Z presented
%M GCE.1038
%A Craft, Christopher B.
%A Stahl, McKenna
%A Widney, Sarah
%K accretion rate, sea level rise, Student Publication

%0 Journal Article
%T Mutualistic interactions amplify saltmarsh restoration success
%D 2017
%V 2017
%P 1-10
%B Journal of Applied Ecology
%9 Article
%Z published
%M GCE.1062
%R 10.1111/1365-2664.12960
%X 1.	 Mounting evidence shows that the functioning and stability of coastal ecosystemsoften depends critically on habitat-forming foundation species such as seagrasses, mangroves and saltmarsh grasses that engage in facultative mutualistic interactions. However, although restoration science is now gradually expanding its longstanding paradigm of minimizing competition to including intraspecific, or within species, facilitation in its designs, the potential of harnessing mutualistic interactions between species for restoration purposes remains uninvestigated.2.	 Here, we experimentally tested whether a previously documented mutualism between marsh-forming Spartina alterniflora (cordgrass) and Geukensia demissa (mussels) can increase restoration success in degraded US saltmarshes.3.	 We found that co-transplanted mussels locally increased nutrients and reduced sulphide stress, thereby increasing cordgrass growth and clonal expansion by 50%. We then removed above-ground vegetation and mussels to simulate a disturbance event and discovered that cordgrass co-transplanted with mussels experienced three times greater survival than control transplants.4.	 Synthesis and applications. Our findings indicate that mussels amplify cordgrass recolonization and resilience over spatial and temporal scales that exceed those of their actual mutualistic interaction. By experimentally demonstrating that mutualistic partners can enable foundation species to overcome stress barriers to establish and persist, we highlight that coastal restoration needs to evolve beyond the sole inclusion of intraspecific-positive interactions. In particular, we suggest that integrating mutualisms in restoration designs may powerfully enhance long-term restoration success and ecosystem resilience in the many coastal ecosystems where mutualisms involving foundation species are important ecosystem-structuring interactions.
%U http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12960/full
%A Derksen-Hooijberg, M.
%A Angelini, Christine
%A Lamers, L.P.M.
%A Borst, A.
%A Smolders, Alfons J. P.
%A Hoogveld, J.R.H.
%A de Paoli, H.
%A Silliman, Brian R.
%A van der Heide, Tjisse
%K coastal ecosystems, cordgrass, facilitation, foundation species, Geukensia demissa, mussels, positive interactions, resilience, saltmarsh, Spartina alterniflor, SINERR Publication, Student Publication

%0 Journal Article
%T Submarine groundwater discharge and solute transport under a transgressive barrier island
%D 2017
%V 547
%P 97-110
%B Journal of Hydrology
%9 Article
%Z published
%M GCE.1094
%R 10.1016/j.jhydrol.2017.01.028
%X Many recent investigations of groundwater dynamics in beaches employed groundwater models that assumed isotropic, numerically-convenient hydrogeological conditions. Real beaches exhibit local variability with respect to stratigraphy, sediment grain size and associated topographic profile, so that groundwater flow may diverge significantly from idealized models. We used a combination of hydrogeologic field methods and a variable-density, saturated-unsaturated, transient groundwater flow model to investigate SGD and solute transport under Cabretta Beach, a small transgressive barrier island seaward of Sapelo Island, Georgia. We found that the inclusion of real beach heterogeneity drove important deviations from predictions based on theoretical beaches. Cabretta Beach sustained a stronger upper saline plume than predicted due to the presence of a buried silty mud layer beneath the surface. Infiltration of seawater was greater for neap tides than for spring tides due to variations in beach slope. The strength of the upper saline plume was greatest during spring tides, contrary to recent model predictions. The position and width of the upper saline plume was highly dynamic through the lunar cycle. Our results suggest that field measurements of salinity gradients may be useful for estimating rates of tidally and density driven recirculation through the beach. Finally, our results indicate that several important biogeochemical cycles recently studied at Cabretta Beach were heavily influenced by groundwater flow and associated solute transport.
%U https://www.sciencedirect.com/science/article/pii/S002216941730029X
%A Evans, Tyler
%A Wilson, Alicia M.
%K Beach, Groundwater, Freshwater-saltwater interface, Upper saline plume, Numerical modeling, Variable-density, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Racial coastal formation: The environmental injustice of colorblind adaptation planning for sea-level rise
%D 2017
%V 87
%N December 2017
%P 62-72
%B Geoforum
%9 Article
%Z published
%M GCE.1095
%R 10.1016/j.geoforum.2017.10.005
%X The United States’ deeply racialized history currently operates below the surface of contemporary apolitical narratives on vulnerability mitigation and adaptation to sea-level rise. As communities, regulatory agencies, and policy-makers plan for rising seas, it is important to recognize the landscapes of race and deep histories of racism that have shaped the socio-ecological formations of coastal regions. If this history goes unrecognized, what we label colorblind adaptation planning is likely to perpetuate what Rob Nixon calls the “slow violence” of environmental racism, characterized by policies that benefit some populations while abandoning others. By colorblind adaptation planning, we refer to vulnerability mitigation and adaptation planning projects that altogether overlook racial inequality—or worse dismiss its systemic causes and explain away racial inequality by attributing racial disparities to non-racial causes. We contend that responses to sea-level rise must be attuned to racial difference and structures of racial inequality. In this article, we combine the theory of racial formation with the geographical study of environmental justice and point to the ways racial formations are also environmental. We examine vulnerability to sea-level rise through the process of racial coastal formation on Sapelo Island, Georgia, specifically analyzing its deep history, the uneven racial development of land ownership and employment, and barriers to African American participation and inclusion in adaptation planning. Racial coastal formation’s potential makes way for radical transformation in climate change science not only in coastal areas, but other spaces as situated territorial racial formations.
%U https://www.sciencedirect.com/science/article/pii/S0016718517302944
%A Hardy, Dean
%A Milligan, Richard A.
%A Heynen, Nik
%K Race, Vulnerability, Sea-level rise, Political ecology, Gullah Geechee, Georgia, SINERR Publication, Student Publication

%0 Conference Proceedings
%T LIGHT AND TEMPERATURE CONTROL THE SEASONAL DISTRIBUTION OF  THAUMARCHAEOTA IN THE SOUTH ATLANTIC BIGHT
%D 2017
%C Vienna, Austria
%B Fifth International Conference on Nitrification and Related Processes (ICoN5)23-27 July, 2017
%8 23-27 July, 2017
%9 Poster
%Z Full (to be published in Conference Volume?) abstract submitted as a "reprint"
%M GCE.1021
%X Previous work on the Georgia, USA coast revealed consistent mid-summer peaks in the abundance of Thaumarchaeota accompanied by spikes in nitrite concentration.  We collected data on the distribution of Thaumarchaeota, ammonia-oxidizing Betaproteobacteria (AOB), nitrite-oxidizing Nitrospina, environmental variables and rates of ammonia oxidation during 6 cruises in the South Atlantic Bight from April to November 2014 to evaluate the areal extent and timing of the bloom.  The abundance of Thaumarchaeota marker genes (16S rRNA and amoA) increased at inshore and nearshore stations starting in July and peaked in August at >107 copies L-1, a period when free Cu2+ concentrations (sub-fM) were well below those believed to limit Thaumarchaeota growth.  The bloom did not extend onto the mid-shelf, where Thaumarchaeota genes ranged from 103 to 105 copies L-1.  Clone libraries from samples collected at mid-shelf stations generated using Archaea 16S rRNA primers were dominated by sequences from Marine Group II and III Archaea, whereas libraries from inshore and nearshore stations were dominated by Thaumarchaeota.  Thaumarchaeota were also abundant in oxygen-depleted waters at depth at the shelf-break.  This population was phylogenetically-distinct from the inshore/nearshore population.  Ammonia oxidation rates (AO) were highest at inshore stations and were at the limit of detection at mid-shelf stations.  AO correlated significantly with ammonium concentration (r2=0.23) and Thaumarchaeota abundance (r2=0.14).  Nitrite concentration correlated with AO (r2=0.74).  Our analysis of environmental data suggests that Thaumarchaeota distributions in the SAB are controlled primarily by photoinhibition and secondarily by water temperature, while AO is controlled primarily by ammonium availability.
%U http://gce-lter.marsci.uga.edu/public/uploads/ICoN-5_Abstract_20170719T185828.docx
%A Hollibaugh, James T.
%A Bratcher, Annie
%A Cheek, Jelani
%A Liu, Qian
%A Malagon, Erica
%A Popp, Brian N.
%A Ross, Meredith
%A Schaefer, Sylvia C.
%A Sweeney, Corinne
%A Tolar, Bradley
%A van den Berg, Constant M.G.
%A Wallsgrove, Natalie J.
%A Whitby, Hannah
%K Ammonia oxidation, Thaumarchaea, nitrification, Nitrospina, nitrite-oxidation, SINERR Publication, Student Publication

%0 Journal Article
%T Seasonal changes in above- and below-ground non-structural carbohydrates (NSC) in Spartina alterniflora in a marsh in Georgia, USA
%D 2017
%V 140
%P 13-22
%B Aquatic Botany
%9 Article
%Z published
%M GCE.1018
%R 10.1016/j.aquabot.2017.04.003
%X Spartina alterniflora is the dominant grass appearing in salt marshes along the east coast of the USA. The development of predictive, mechanistic models of Spartina has been hindered by the lack of information on below-ground biomass and its dynamics, and in particular the storage of resources that can be used for spring re-growth. We studied the dynamics of non-structural carbohydrates (glucose, fructose, sucrose, and starch) and biomass in 8 different above- and below-ground tissues in S. alterniflora over the course of a year in a salt marsh on Sapelo Island, Georgia, USA. We found greater seasonal variability in non-structural carbohydrates in S. alterniflora than had been previously reported, with concentrations varying between 3.3% through 17.3% of the total biomass and between 0% and 19.5% of dry weight depending on the type of tissue, with statistical differences between the different tissues. We found that sucrose was the dominant non-structural carbohydrate in above- and below-ground tissue, and that this sugar was likely used for long-term storage during winter months and as a resource for early spring growth. Glucose, fructose, and starch showed less variability, with glucose following changes in above-ground biomass more closely indicating their use as short-term storage. We were unable to develop a coherent carbon budget for the plants largely because of uncertainties in modeled net primary production and heterogeneity in below-ground biomass.
%U https://doi.org/10.1016/j.aquabot.2017.04.003
%A Jung, Yeajin
%A Burd, Adrian B.
%K Non-structural carbohydrate, Carbon allocation, Salt marsh grass, Net primary production, Spartina alterniflora, Spartina biomass, Model, Sapelo Island, Student Publication

%0 Conference Proceedings
%T The influence of hydrology on dissolved organic matter composition and degradation in the Altamaha River and Estuary
%D 2017
%C Honolulu, Hawaii
%B ASLO 2017 Aquatic Science Meeting
%8 March 2017
%9 Poster
%Z presented
%M GCE.1016
%A Letourneau, Maria L.
%A Medeiros, Patricia M.
%K DOM composition, Hydrology, biodegradation, Altamaha River and Estuary, Student Publication

%0 Conference Proceedings
%T Temporal changes in dissolved organic matter composition in a marsh-dominated estuary: insights from optical and FT-ICR MS analyses.
%D 2017
%C Athens, GA
%B 4th Annual Southeastern Biogeochemistry Symposium
%8 April 2017
%9 Poster
%Z presented
%M GCE.1043
%A Letourneau, Maria L.
%A Pannill, V.R.
%A Medeiros, Patricia M.
%K DOM, optical, FTICRMS, estuary, Student Publication

%0 Thesis
%T Response and recovery of low-salinity marsh plant communities to constant and pulsed saline intrusion
%D 2017
%I University of Houston
%C Houston, TX, USA
%9 Ph.D. Dissertation
%Z published
%M GCE.1120
%X The effects of climate change on environmental conditions will be manifest as both chronic changes and pulse changes of varying durations. In estuaries, future variation in sea level, freshwater withdrawal and drought will lead to saline intrusion into low-salinity tidal marshes. I sought to understand the responses to various salinization scenarios on individual, community and ecosystem levels. First, I used a mesocosm experiment to assess the responses of individual low-salinity marsh macrophytes to different durations of saline water exposure, without interspecific interactions. Second, I used another mesocosm experiment to assess the response of plant communities to saline water pulses of three salinities for five durations, and then assessed subsequent community recovery when the saline pulses were withdrawn. Third, I used a field experiment to explore the impacts on a freshwater marsh plant community of short- and long-term changes in salinity.I found that freshwater marsh plants varied in their tolerance to saline water addition. I ranked the species as follows, in order from least to most salt tolerant: L. peploides, P. hydropiperoides, P. cordata and Z. miliacea, followed by S. lancifolia and E. palustris in a tie. I found that community composition was increasingly affected by the more-saline and longer-duration treatments. In the second mesocosm experiment, most but not all of the plant species were able to recover from low-salinity, short-duration saline pulses in less than one year. Because not all the species recovered, post-disturbance community structure diverged among salinization treatments. In the field experiment, both presses and pulses of saline water addition caused the loss of L. repens, resulting in community composition diverging away from the controls. In the pressvtreatment, plant biomass and diversity was strongly suppressed. In the pulse treatment, community composition did not recover to the baseline conditions in between pulses of saline water, as L. repens failed to fully recover from pulses of salinity. In the second mesocosm experiment, shifts in community composition prevented long-term reductions in productivity. In the field experiment, however, salt-tolerant plants could not immigrate, and salinity presses caused significant decrease in aboveground biomass. In contrast, salinity pulses had no effect on plant production. These results show that species composition is more sensitive to environmental changes than overall ecosystem processes. However, changes in ecosystem structure due to pulse changes may not preclude recovery in ecosystem function.
%A Li, Fan
%K salinity, Zizaniopsis, Polygonum, Pontederia, Spartina, Schoenoplectus, Juncus, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Timing of disturbance affects biomass and flowering of a saltmarsh plant and attack by stem-boring herbivores
%D 2017
%V 8
%N 2
%P 9
%B Ecosphere
%9 Article
%Z published
%M GCE.1047
%R 10.1002/ecs2.1675
%X In salt marshes, disturbance by wrack (floating mats of dead vegetation) is common andaffects plant productivity and species composition, but little is known about how the timing of disturbance mediates these effects, nor how it interacts with herbivory. Using a field experiment on the Georgia coast, we simulated the effects of wrack disturbance at different times of the year on the marsh grass Spartina alterniflora and its stem-boring herbivorous insects. The timing of disturbance throughout the growing season strongly affected fall biomass, stem height, the proportion of stems flowering, and the proportion of stems colonized by stem-boring herbivorous insects. End-of-season biomass in plots disturbed in March did not differ from undisturbed controls, but biomass was reduced by 50% in plots disturbed in May, and by over 90% in plots disturbed in September. Disturbance in March and May stimulated flowering, but disturbance later in the growing season suppressed it. Plots disturbed late in the growing season had a low frequency of stem-boring herbivores. Stems containing stem borers rarely flowered. These results indicate that the timing of disturbance matters in coastal salt marshes. Late-season disturbances had the strongest effects on S. alterniflora and its herbivores. Disturbances early in the growing season did not affect endof-season biomass, and stimulated flowering, suggesting parallels between fire disturbance in grasslands and wrack disturbance in salt marshes. Late-season disturbance did reduce herbivory by stem-boring insects, but not enough to compensate for the direct effects of disturbance on the plants. Future studies of disturbance in salt marshes should consider how the timing of experimental disturbance treatments relates to the timing of natural disturbances.
%U https://www.researchgate.net/publication/313582558_Timing_of_disturbance_affects_biomass_and_flowering_of_a_saltmarsh_plant_and_attack_by_stem-boring_herbivores
%A Li, Shanze
%A Pennings, Steven C.
%K disturbance, owering, phenology, plant population and community dynamics, plant–herbivoreinteractions, primary production, stem borer, wrack, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Provenance-by-environment interaction of reproductive traits in the invasion of Spartina alterniflora in China.
%D 2017
%V 98
%N 6
%P 1591-1599
%B Ecology
%9 Article
%Z published
%M GCE.1065
%R 10.1002/ecy.1815
%X Ecological invasions are facilitated by pre-adaptation and phenotypic plasticity, upon which evolution can act. The rapid invasion of the intertidal grass Spartina alterniflora in China during the last 36 yr is a test case for the roles of these mechanisms. A previous study of S. alterniflora in China found strong latitudinal clines in vegetative and sexual traits and concluded that most of this variation was due to phenotypic plasticity. Recent observations suggested provenance-by-environment interactions, and we employed common gardens at multiple latitudes as a test of this idea. Phenotypically, field plant height, which correlates strongly with biomass and other indices of vegetative performance in this species, showed a hump-shaped relationship across 10 sites, covering 19° of latitude; field seed set increased linearly with latitude. To assess the role of plasticity vs. genetic differentiation in these patterns, we grew plants from the ten field sites in three common gardens at low (20.9° N), mid (28.3° N), and high (38.0° N) latitudes to maturity, at 18 months. Plant height varied among common gardens, with the tallest plants at mid latitude, mirroring the field pattern, consistent with the previous study. Within the gardens, latitude of origin also affected plant height. Seed set varied among the gardens, with the greatest values at high latitudes, again mirroring the field pattern and indicating substantial plasticity. Evidence of evolution was found as increasing seed set with latitude among provenances within common gardens. However, the effect differed among common gardens, with the greatest slope in the high-latitude garden, lower slope in the mid-latitude garden, and no relationship in the low-latitude garden, indicating a provenance-by-environment interaction. The number of surviving plants also suggested a provenance-by-environment interaction; no relationship with latitude among provenances in the two southern gardens and increasing survival with latitude in the northern garden. Field seedling density was ~200-fold greater at high than at low latitude sites. The profuse seed germination and recruitment in the north could have created high selection intensity resulting in evolution of reproductive traits at high latitudes with the result that the mechanisms of the invasion differ with latitude.
%A Liu, Wenwen
%A Strong, Donald R.
%A Pennings, Steven C.
%A Zhang, Yihui
%K biological invasion, genetic differentiation, latitudinal cline, pre-adaptation, provenance-by-environment interaction, recruitment, sexual reproduction, Spartina alterniflora., Student Publication

%0 Journal Article
%T Oyster paleoecology and Native American subsistence practices on Ossabaw Island, Georgia, USA
%D 2017
%V 15
%P 282 - 289
%B Journal of Archaeological Science: Reports
%9 Article
%Z published
%M GCE.1046
%R 10.1016/j.jasrep.2017.07.028
%X We examined the shell size of 3262 eastern oysters (Crassostrea virginica) to assess diachronic patterns in shellfish exploitation on Ossabaw Island, Georgia. These measurements taken on shell size and morphology were compared between a Late Archaic shell ring, a Late Woodland shell-filled pit, and a Late Mississippian midden-mound to evaluate changes in oyster population ecology, as it related to large scale changing environmental conditions and Native America subsistence practices over time. Our results indicate stability in oyster populations during the Late Archaic with a following decrease in oyster size through the Late Woodland into the Late Mississippian. We attribute this decrease to combination to human predation and large-scale climate fluctuations, with the latter being the primary driver of this shift in size.
%U http://www.sciencedirect.com/science/article/pii/S2352409X17302754?via%3Dihub
%A Lulewicz, Isabelle H.
%A Thompson, Victor D.
%A Cramb, Justin
%A Tucker, Bryan
%K Subsistence economy, Shellfish, Georgia coast, Environmental change, Oyster, Southeast

%0 Journal Article
%T Export of terrigenous dissolved organic matter in a broad continental shelf
%D 2017
%V 62
%P 1718-1731
%B Limnology & Oceanography
%9 Article
%Z published
%M GCE.1025
%R 10.1002/lno.10528
%X Export of terrigenous dissolved organic matter (DOM) from rivers to the ocean plays an important role in the carbon cycle. Observations from six research cruises in 2014 were used to characterize the seasonal evolution of terrigenous DOM in the shallow and broad South Atlantic Bight (SAB) shelf. While DOM with a strong terrigenous molecular, optical and isotopic signature was restricted to a coastal band early in the year, a plume with terrigenous DOM extended further to the shelf break in late spring. The offshore transport of this terrigenous DOM was consistent with wind-driven advection in a surface Ekman layer. On time scales spanning about 1 month, the traceable riverine DOM compounds were mostly resistant to bio- and photo-degradation, and the decrease in their relative abundance over the shelf following peak river discharge during spring was consistent with dilution of the river plume due to entrainment of oceanic water associated with wind-driven mixing. Comparisons between optical absorbance measurements and ultrahigh resolution mass spectrometry data revealed that the fraction of the DOM pool with a riverine signature in the SAB can be estimated using the spectral slope coefficient of chromophoric DOM in the 275–295 nm range. This finding opens up the possibility of observing the distribution of riverine DOM on the SAB shelf in high spatial resolution and by using remote sensing methods, a crucial step for quantifying shelf-slope exchange and the fate of terrigenous DOM in shelf seas.
%A Medeiros, Patricia M.
%A Babcock-Adams, Lydia
%A Seidel, Michael
%A Castelao, Renato
%A Di Iorio, Daniela
%A Hollibaugh, James T.
%A Dittmar, Thorsten
%K Dissolved organic matter, DOM, terrigenous, South Atlantic Bight, SAB, Student Publication, UGAMI Publication

%0 Journal Article
%T Microbially-mediated transformations of estuarine dissolved organic matter
%D 2017
%V 4
%N 69
%B Frontiers in Marine Science
%S Integrative Research on Organic Matter Cycling Across Aquatic Gradients
%9 Article
%Z published
%M GCE.1015
%R 10.3389/fmars.2017.00069
%X Microbially-mediated transformations of dissolved organic matter (DOM) in a marsh-dominated estuarine system were investigated at the molecular level using ultrahigh resolution mass spectrometry. In addition to observing spatial and temporal variability in DOM sources in the estuary, multiple incubations with endogenous microorganisms identified the influence of DOM composition on biodegradation. A clear microbial preference for degradation of compounds associated with marine DOM relative to those of terrestrial origin was observed, resulting in an overall shift of the remaining DOM toward a stronger terrigenous signature. During short, 1-day long incubations of samples rich in marine DOM, the molecular formulae that were enriched had slightly smaller mass (20–30 Da) and number of carbon atoms compared to the molecular formulae that were depleted. Over longer time scales (70 days), the mean differences in molecular mass between formulae that were depleted and enriched were substantially larger (~270 Da). The differences in elemental composition over daily time scales were consistent with transformations in functional groups; over longer time scales, the differences in elemental composition may be related to progressive transformations of functional groups of intermediate products and/or other reactions. Our results infused new data toward the understanding of DOM processing by bacterioplankton in estuarine systems.
%A Medeiros, Patricia M.
%A Seidel, Michael
%A Gifford, Scott
%A Ballantyne, Ford
%A Dittmar, Thorsten
%A Whitman, William B.
%A Moran, Mary Ann
%K Dissolved organic matter, biodegradation, estuarine processes, DOM composition, FT-ICR MS, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Hydrologic processes determining porewater salinity in a southeastern salt marsh.
%D 2017
%C Athens GA
%B Georgia Water Resources Conference
%8 April 19-20, 2017
%9 Poster
%Z presented
%M GCE.1030
%A Miklesh, David Michael
%A Meile, Christof
%K porewater salinity marsh, Student Publication

%0 Conference Proceedings
%T Hydrologic processes determining porewater salinity in a southeastern salt marsh
%D 2017
%C Athen GA
%B SBS Symposium
%8 April 1-2, 2017
%9 Poster
%Z presented
%M GCE.1031
%A Miklesh, David Michael
%A Meile, Christof
%K porewater salinity marsh, Student Publication

%0 Journal Article
%T Abiotic factors influence the dynamics of marine habitat use by a highly mobile “freshwater” top predator
%D 2017
%V 802
%N 1
%P 155-174
%B Hydrobiologia
%9 Article
%Z published
%M GCE.1045
%R 10.1007/s10750-017-3255-7
%X Cross-ecosystem movements of mobile consumers are a primary mechanism by which energy and nutrients are exchanged between disparate ecosystems. While factors influencing variation in bottom–up subsidies between ecosystems have been well studied, much less is known regarding how biotic and abiotic factors influence the dynamics of mobile consumer-driven connectivity. In a literature survey, we found only 14% of studies examined factors contributing to variation in cross-ecosystem marine foraging by freshwater-adapted consumers. Here, we examine the relationships between abiotic factors and cross-ecosystem movements of a highly mobile freshwater-adapted top predator, Alligator mississippiensis (American alligator). As alligators lack physiological adaptations to survive in marine environments, we predict this linkage would be affected by factors that modify the ability to cope with high salinities. Our results reveal that multiple abiotic factors (e.g., relative humidity, temperature, total precipitation) are key explanatory variables of the duration of cross-ecosystem foraging trips by alligators, and that the absence of salt glands does not preclude them from performing long forays into marine environments. More broadly, our results expand our understanding of mobile consumer-driven ecosystem connectivity at the land–sea interface by demonstrating connectivity is highest when physical stressors are relaxed, and access to and availability of resources are maximized.
%U https://link.springer.com/article/10.1007%2Fs10750-017-3255-7
%A Nifong, James C.
%A Silliman, Brian R.
%K Alligator mississippiensis, Crocodilian, Cross-ecosystem movement, Ecosystem connectivity, GPS–VHF telemetry, Mobile consumer, Trophic coupling, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Estimating patterns in Spartina alterniflora belowground biomass within salt marshes
%D 2017
%C New Orleans, LA
%B American Geophysical Union
%9 Presentation
%Z presented
%M GCE.1135
%A O'Connell, Jessica
%A Mishra, Deepak
%A Alber, Merryl
%A Byrd, K. B.
%K Spartina, Spartina alterniflora, biomass, salt marsh

%0 Journal Article
%T 'The Tidal Marsh Inundation Index (TMII): An inundation filter to flag flooded pixels and improve MODIS tidal marsh vegetation time-series analysis '
%D 2017
%V 201
%N November 2017
%P 34-46
%B Remote Sensing of the Environment
%9 Article
%Z published
%M GCE.1007
%R 10.1016/j.rse.2017.08.008
%X Remote sensing in tidal marshes can provide regional assessments of wetland extent, phenology, primary production, and carbon sequestration. However, periodic tidal flooding reduces spectral reflectance, especially in the near and short-wave infrared wavelengths. Consequently, marsh vegetation time-series products that lack tidal filtering, such as those provided by MODIS (Moderate Resolution Imaging Spectroradiometer), may not reflect true vegetation trends. We created a new Tidal Marsh Inundation Index (TMII) for processing daily 500-m MODIS surface reflectance data and calibrated it with a Spartina alterniflora salt marsh pixel on Sapelo Island, GA. Ground-truth data for TMII was extracted from a PhenoCam, which collected high frequency digital photography of the TMII calibration pixel. To identify the best wavelengths to include in the TMII, we compared goodness of fit metrics from generalized linear models (GLMs). Predictors for these GLMs included suites of normalized difference indices from the literature as well as other band combinations. We also explored including a phenology parameter that could scale TMII relative to vegetation development. Ultimately, TMII was based on the normalized difference of green and shortwave infrared reflectance in combination with a phenology parameter composed of the moving average of the normalized difference of near infrared and shortwave infrared reflectance. This final index allowed a single optimized decision boundary to identify flooding across the annual growth cycle. When compared to ground-truth data from the PhenoCam, the TMII classified flooded conditions with 67–82% and dry conditions with 75–81% accuracy, respectively, across training, testing and validation datasets. We applied TMII to new S. alterniflora marsh MODIS pixels on Sapelo Island, GA as well as on Plum Island, MA. For these new pixels, TMII classified marsh flooding with 77–80% overall accuracy. We also demonstrated how users can apply TMII filtering in a MODIS workflow to create vegetation time-series composites within S. alterniflora, Spartina patens and Juncus roemerianus marshes. We showed how a new user can validate and optimize TMII in their application, either by comparing it to inundation data or by validating the filtered vegetation time series against field data. We also compared TMII-filtered composites to the existing MODIS MOD13 16-d Normalized Difference Vegetation Index (NDVI) product. TMII-filtered composites generated less noisy time-series that fit field data better than MOD13. TMII filtering was most important on Sapelo Island, where the tide range was high and vegetation was sparse. Results were less dramatic when TMII was applied to different marsh species within the Gulf Coast sites with lower tidal ranges, but TMII-filtering still improved vegetation time series. Thus, preprocessing MODIS imagery with the TMII effectively identified most inundated pixels. The TMII represents a step forward for wetland remote sensing that will be useful for improved estimation of phenology, biomass and carbon storage in coastal marshes.
%U https://www.sciencedirect.com/science/article/pii/S0034425717303619
%A O'Connell, Jessica
%A Mishra, Deepak
%A Cotten, David L.
%A Wang, Li
%A Alber, Merryl
%K remote sensing, MODIS, Spartina alterniflora, PhenoCam, SINERR Publication, UGAMI Publication

%0 Conference Proceedings
%T Serious declines in Georgia salt marsh plant biomass are linked to climate variables
%D 2017
%I Loyola University Chicago’s 4th Annual Climate Change Conference
%C Chicago, IL
%B Climate Justice: The Struggle for Our Common Home. Loyola University 4th Annual Climate Change Conference
%S Poster Session
%8 March 17, 2017
%9 Poster
%Z presented
%M GCE.1053
%X We studied aboveground biomass dynamics and spatial patterns of Spartina alterniflora, the keystone species of Central Georgia’s salt marshes. Geospatial techniques were used to scale up in situ biomass measurements to landscape scale and applied to 290 Landsat 5 TM scenes from 1984 to 2011. We documented biomass declines of 31.6 %, 33.4 %, and 38.7% for tall, medium, and short Spartina classes. The declines strongly correlated with increased drought frequency and severity and coincided with marsh die-back events and increased snail grazing. To explain temporal patterns, we compared biomass estimates with a suite of abiotic drivers. River discharge, total precipitation, minimum temperature, and mean sea level best explained biomass variations. We extended our analysis to a much larger area (St. Simons Sound to the Savannah River) and found the same inter and intra-annual biomass patterns. Moreover, higher biomass was associated with proximity to larger rivers (Altamaha, Ogeechee, and Savannah) and greater precipitation. We’re using Landsat 8 OLI imagery to update our analysis. Collectively, these approaches address a key question: Are the serious declines we documented in Spartina alterniflora biomass and marsh health cyclical, or are they longer-term, directional trends related to climate change?
%A O'Donnell, John
%A Schalles, John F.
%K Coastal wetlands, remote sensing, vegetation stress, climate change, Landsat imagery, SINERR Publication, Student Publication

%0 Conference Proceedings
%T Serious declines in a large area of Georgia Salt marsh plant biomass are linked to climate variables
%D 2017
%I Coastal and Estuarine Research Federation
%C Providence, Rhode Island
%B Coastal and Estuarine Research Federation Biennial Meeting
%S Collaborating across geographic scales: integrating estuarine and coastal ocean information
%8 November 9, 2017
%9 Presentation
%Z presented
%M GCE.1099
%X In initial work, we studied aboveground biomass dynamics and spatial patterns of Spartina alterniflora, the keystone species of Central Georgia’s salt marshes. Geospatial techniques were used to scale up in situ biomass measurements to landscape scale and applied to 290 Landsat 5 TM scenes from 1984 to 2011. We documented biomass declines of 31.6 %, 33.4 %, and 38.7% for tall, medium, and short Spartina classes. The declines strongly correlated with increased drought frequency and severity and coincided with marsh die-back events and increased snail grazing. To explain temporal patterns, we compared biomass estimates with a suite of abiotic drivers. River discharge, total precipitation, Palmer Drought Severity Index, and mean sea level best explained biomass variations. We then extended our analysis to a much larger area (620 km2; St. Simons Sound to the Savannah River) and found the same inter and intra-annual biomass patterns. Moreover, higher biomass was associated with proximity to larger rivers (Altamaha, Ogeechee, and Savannah) and greater precipitation. In 2001, after an extended and severe drought, there was little net growth between late winter and fall and many marsh areas had net biomass loss. We’re now using Landsat 7 and 8 imagery to update our analysis to the present time. Collectively, these approaches address a key question: Are the serious declines we documented in Spartina alterniflora biomass and marsh health cyclical, or are they longer-term, directional trends related to climate change?
%U https://cerf.confex.com/cerf/2017/meetingapp.cgi/Session/1329
%A O'Donnell, J.P.
%A Schalles, John F.
%A Hladik, Christine M.
%K Spartina alterniflora, plant biomass, remote sensing, climate drivers, Student Publication

%0 Conference Proceedings
%T Assessing the export of terrigenous dissolved organic matter in the South Atlantic Bight using CDOM analysis: 2014 and 2016 cruises.
%D 2017
%C Athens, GA
%B 4th Annual Southeastern Biogeochemistry Symposium
%8 April 2017
%9 Poster
%Z presented
%M GCE.1042
%A Pannill, V.R.
%A Letourneau, Maria L.
%A Medeiros, Patricia M.
%K DOM, Terrigenous, CDOM, South Atlantic Bight, Student Publication

%0 Conference Proceedings
%T Groundwater inputs to a back-barrier salt marsh tidal river
%D 2017
%C Holderness, NH
%B 2017 Chemical Oceanography Gordon Research Conference
%8 July 2017
%9 Poster
%Z presented
%M GCE.1056
%A Peterson, Richard N.
%A Meile, Christof
%A Carter, Matthew
%A Peterson, Leigha
%A Waldorf, Austin
%A Miklesh, David Michael
%K Radon, Duplin, Sapelo, Time-Series, Survey, Student Publication

%0 Conference Proceedings
%T Groundwater inputs to a back-barrier salt marsh tidal river.
%D 2017
%C New London NH
%B Chemical Oceanography Gordon Conference
%8 July 23-28, 2017
%9 Poster
%Z presented
%M GCE.1029
%A Peterson, Richard N.
%A Meile, Christof
%A Carter, Matthew
%A Viso, Richard F.
%A Waldorf, Austin
%A Miklesh, David Michael
%K groundwater flux radon, Student Publication

%0 Journal Article
%T Methods to summarize change among land categories across time intervals
%D 2017
%V 12
%N 4
%P 218-230
%B Journal of Land Use Science
%9 Article
%Z published
%M GCE.1096
%R 10.1080/1747423X.2017.1338768
%X Time-series maps have become more detailed in terms of numbers of categories and time points. Our paper proposes methods for raster datasets where detailed analysis of all categorical transitions would be initially overwhelming. We create two measurements: Incidents and States. The former is the number of times a pixel’s category changes across time intervals; the latter is the number of categories that a pixel represents across time points. The combinations of Incidents and States summarize change trajectories. We also describe categorical transitions in terms of annual flow matrices, which quantify the additional information generated by intermediate time points within the temporal extent. Our approach summarizes change at the pixel and landscape levels in ways that communicate where and how categories transition over time. These methods are useful to detect hotspots of change and to consider whether the apparent changes are real or due to map error.
%U https://www.tandfonline.com/doi/full/10.1080/1747423X.2017.1338768
%A Pontius, Robert G.
%A Krithivasan, roopa
%A Sauls, Laura
%A Yan, Yan
%A Zhang, Yujia
%K Category, GIS, land change, flow matrix, time, transition, Cross-site Research, Student Publication

%0 Journal Article
%T Time series pCO2 at a coastal mooring: Internal consistency, seasonal cycles, and interannual variability
%D 2017
%V 145
%P 95-108
%B Continental Shelf Research
%9 Article
%Z published
%M GCE.1066
%R 10.1016/j.csr.2017.06.022
%X Marine carbonate system monitoring programs often consist of multiple observational methods that include underway cruise data, moored autonomous time series, and discrete water bottle samples. Monitored parameters include all, or some of the following: partial pressure of CO2 of the water (pCO2w) and air, dissolved inorganic carbon (DIC), total alkalinity (TA), and pH. Any combination of at least two of the aforementioned parameters can be used to calculate the others. In this study at the Gray's Reef (GR) mooring in the South Atlantic Bight (SAB) we: examine the internal consistency of pCO2w from underway cruise, moored autonomous time series, and calculated from bottle samples (DIC-TA pairing); describe the seasonal to interannual pCO2w time series variability and air-sea flux (FCO2), as well as describe the potential sources of pCO2w variability; and determine the source/sink for atmospheric pCO2. Over the ~8.5 years of GR mooring time series, mooring-underway and mooring-bottle calculated-pCO2w strongly correlate with r-values > 0.90. pCO2w and FCO2 time series follow seasonal thermal patterns; however, seasonal non-thermal processes, such as terrestrial export, net biological production, and air-sea exchange also influence variability. The linear slope of time series pCO2w increases by 5.2 ± 1.4 µatm y&#8722;1 with FCO2 increasing 51–70 mmol m&#8722;2 y&#8722;1. The net FCO2 sign can switch interannually with the magnitude varying greatly. Non-thermal pCO2w is also increasing over the time series, likely indicating that terrestrial export and net biological processes drive the long term pCO2w increase.
%A Reimer, Janet J.
%A Cai, Wei-Jun
%A Xue, Liang
%A Vargas, Rodrigo
%A Noakes, Scott
%A Hu, Xinping
%A Signorini, Sergio R.
%A Mathis, Jeremy T.
%A Feely, Richard A.
%A Sutton, Adrienne J.
%A Sabine, Christopher
%A Musielewicz, Sylvia
%A Chen, Baoshan
%A Wanninkhof, R.
%K Ocean margin CO2, East coast, Inorganic carbon system internal consistency

%0 Journal Article
%T Temperature Decouples Ammonium and Nitrite Oxidation in Coastal Waters
%D 2017
%V 51
%N 6
%P 3157-3164
%B Environmental Science and Technology
%9 Article
%Z published
%M GCE.1107
%R 10.1021/acs.est.6b03483
%X Nitrification is a two-step process linking the reduced and oxidized sides of the nitrogen cycle. These steps are typically tightly coupled with the primary intermediate, nitrite, rarely accumulating in coastal environments. Nitrite concentrations can exceed 10 µM during summer in estuarine waters adjacent to Sapelo Island, Georgia, U.S.A. Similar peaks at other locations have been attributed to decoupling of the two steps of nitrification by hypoxia; however, the waters around Sapelo Island are aerobic and well-mixed. Experiments examining the response to temperature shifts of a nitrifying assemblage composed of the same organisms found in the field indicate that ammonia- and nitrite-oxidation become uncoupled between 20 and 30 °C, leading to nitrite accumulation. This suggests that nitrite peaks in coastal waters might be explained by differences in the responses of ammonia- and nitrite-oxidizers to increased summer temperatures. Analysis of field data from 270 stations in 29 temperate and subtropical estuaries and lagoons show transient accumulation of nitrite driven primarily by water temperatures, rather than by hypoxia. Increased climate variability and warming coastal waters may therefore increase the frequency of these nitrite peaks, with potential ecosystem consequences that include increased N2O production, NO2– toxicity, and shifts in phytoplankton community composition.
%A Schaefer, Sylvia C.
%A Hollibaugh, James T.
%K Nitrification, coastal waters, ammonium, nitrite, Cross-site Research

%0 Conference Proceedings
%T Chlorophyll retrieval Algorithms and effects of highly variable TSS and CDOM using a large spectral library of inland and coastal observations.
%D 2017
%I Association for the Sciences of Limnology and Oceanography
%C Honolulu, HI
%B Association for the Sciences of Limnology and Oceanography Annual Meeting
%S #031 Global Remote Sensing of Inland Waters
%8 February 28, 2017
%9 Presentation
%Z presented
%M GCE.1052
%X Since 1996, we’ve used consistent procedures to measure water reflectance (n > 980) and optically active and other constituents at stations in highly variable conditions of lakes and reservoirs, freshwater rivers and their estuaries, and coastal and deep oceans. Prior to 2002, we used an Ocean Optics ST1000 spectrophotometer for water reflectance, normalized with a spectralon panel. All measures since (~80% of our measurements) used a cross-calibrated pair of Ocean Optics USB 2000 spectrometers for solar downwelling and water signals. Major optical constituents varied by 4 to 5 orders of magnitude (chlorophyll a ranged from 0.04 – 490 mg/m3, total suspended sediments from 0.2 – 726 mg/L, and CDOM (abs 440 nm, 0.01 – 21.1 per m) and had low intracorrelations. These conditions provided a robust test bed for comparing chlorophyll retrieval algorithms and assessing impacts of non-algal constituents. Algorithms using higher visible and near-infrared bands, developed for turbid Case 2 waters, performed very well (r2 values > 0.85) across the range of measurements. These algorithms use band combinations that effectively normalize for TSS and CDOM, although residual analysis reveals the variable influences of higher amounts of these two variables. In general, the salinity of a station had minimal influence on our results, indicating ability to use these approaches in a wide array of surface waters. A critique of the applicability of retrieval procedures and case examples of their applications with aerial and space-borne hyperspectral instruments will be presented.
%A Schalles, John F.
%A Hladik, Christine M.
%A Yacobi, Y.Z.
%A Olley, J.T.
%A O'Donnell, J.P.
%K chlorophyll, inland waters, coastal waters, retrieval algorithm, CDOM, suspended matter, SINERR Publication, Student Publication

%0 Journal Article
%T Deep oxygen penetration drives nitrification in intertidal beach sands
%D 2017
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.1069
%R 10.1002/lno.10731
%X We discovered a hotspot of elevated nitrate concentration (median&#8201;=&#8201;431 µM) in shallow beach pore water that extended across the entire length of two barrier islands in the southeastern United States of America. We investigated this feature by surveying groundwater geochemistry, measuring fluctuations in in situ dissolved oxygen (DO) concentrations, modeling groundwater flow, and quantifying nitrification rates. Nitrification of groundwater ammonium was the only possible nitrate source, with a measured potential rate of 0.84 µmol m&#8722;2 h&#8722;1. However, the observed nitrate concentrations were far in excess of the predicted maximum achievable by aerobic nitrification assuming a 2 : 1 ratio of O : N and around 200 µM DO in air-saturated seawater. Groundwater DO concentrations within the hotspot (65 cm depth) were consistently 20–50 µM. The nitrate hotspot was located at the top of the water table beneath dry, undersaturated sand that allowed the penetration of air and the dissolution of excess oxygen into the pore fluids. The total dissolved nitrogen concentration of the hotspot was higher than anywhere else on the island, indicating nitrogen accumulation within the hotspot, most likely via ammonium adsorption. Vertical dispersion was the dominant pathway for nitrate loss from the hotspot. This nitrate was consumed in underlying anoxic sand, coupling microbial pathways of nitrogen oxidation and reduction and removing bioavailable nitrogen from the beach ecosystem.
%A Schutte, Charles
%A Wilson, Alicia M.
%A Evans, Tyler
%A Moore, Willard S.
%A Joye, Samantha B.
%K nitrification, beach, sand, oxygen, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T EML Packages from the GCE Data Toolbox
%D 2017
%I Long Term Ecological Research Network
%C Bloomington, Indiana
%B 2017 LTER Information Managers Meeting
%8 July 24, 2017
%9 Presentation
%Z presented
%M GCE.1036
%U http://gce-lter.marsci.uga.edu/public/uploads/EML_GCE_Toolbox_20171016T92518.pdf
%A Sheldon, Wade M., Jr.
%K LTER-IMC, MATLAB, metadata, database, XML, EML

%0 Conference Proceedings
%T Tools for Sensor Data Quality Control
%D 2017
%I Earth Science Information Partners
%C Bloomington, Indiana
%B ESIP Summer Meeting 2017
%S Envirosensing
%8 July 25-28, 2017
%9 Presentation
%Z presented
%M GCE.1034
%X Regardless of Q/A procedures, data quality issues are guaranteed with environmental sensor data. Without good Q/C data users can draw invalid conclusions (untrustworthy data). Therefore Q/C analysis is a critical part of any monitoring program.
%U http://gce-lter.marsci.uga.edu/public/uploads/WSheldon_SensorQC_ESIP_EnviroSensing_2017_20171016T91742.pdf
%A Sheldon, Wade M., Jr.
%K LTER-IMC, sensor, MATLAB, quality control, data, streaming, qa/qc

%0 Journal Article
%T Optical types of inland and coastal waters
%D 2017
%P 1-25
%B Limnology and Oceanography
%9 Article
%Z Open Access paper. In situ water reflectance spectral data from Schalles lab (measured with dual spectroradiometer Ocean Optics system) and bulk optical properties of Georgia coastal rivers, estuaries, and nearshore were contributed to the LIMNADES s
%M GCE.1051
%R 10.1002/lno.10674
%X Inland and coastal water bodies are critical components of the global biosphere. Timely monitoring is necessary to enhance our understanding of their functions, the drivers impacting on these functions and to deliver more effective management. The ability to observe water bodies from space has led to Earth observation (EO) becoming established as an important source of information on water quality and ecosystem condition. However, progress toward a globally valid EO approach is still largely hampered by inconsistences over temporally and spatially variable in-water optical conditions. In this study, a comprehensive dataset from more than 250 aquatic systems, representing a wide range of conditions, was analyzed in order to develop a typology of optical water types (OWTs) for inland and coastal waters. We introduce a novel approach for clustering in situ hyperspectral water reflectance measurements (n54045) from multiple sources based on a functional data analysis. The resulting classification algorithm identified 13 spectrally distinct clusters of measurements in inland waters, and a further nine clusters from the marine environment. The distinction and characterization of OWTs was supported by the availability of a wide range of coincident data on biogeochemical and inherent optical properties from inland waters. Phylogenetic trees based on the shapes of cluster means were constructed to identify similarities among the derived clusters with respect to spectral diversity. This typification provides a valuable framework for a globally applicable EO scheme and the design of future EO missions.
%U http://doi.org/10.1002/lno.10674
%A Spyrakos, E. 
%A O'Donnell, R.
%A Hunter, P.D.
%A Miller, C.
%A Scott, M.
%A Simis, S.G.
%A Neil, C.
%A Barbarosa, C.C.F.
%A Binding, C.E.
%A Bradt, S.
%A Bresciani, M.
%A Dall'Olmo, G.
%A Giardino, C.
%A Gitelson, A.A.
%A Kutser, T.
%A Li, L.
%A Matsusguta, B.
%A Martinez-Vicente, V.
%A Matthews, M.W.
%A Ogashawara, I.
%A Ruiz-Verdu, A.
%A Schalles, John F.
%A Tebbs, E.
%A Zhang, Y.
%A Tyler, A.N.
%K Water quality, water optics, inland waters, coastal waters, classification algorithm, cluster analysis, Cross-site Research

%0 Conference Proceedings
%T Tidal freshwater forests: a sentinel for climate change.
%D 2017
%C Bloomington, IN
%B SPEA Ph.D. Students' 17th Annual Conference
%8 February 24, 2017
%9 Presentation
%Z presented
%M GCE.1037
%A Stahl, McKenna
%A Widney, Sarah
%A Craft, Christopher B.
%K accretion rate, sea level rise, Student Publication

%0 Journal Article
%T Agents of change and temporal nutrient dynamics in the Altamaha River Watershed
%D 2017
%V 8
%N 1
%P 33
%B Ecosphere
%9 Article
%Z published
%M GCE.1044
%R 10.1002/ecs2.1519
%X Nutrient and carbon dynamics in river ecosystems are shifting, and climate change is likely a driving factor; however, some previous studies indicate anthropogenic modification of natural resources may supersede the effects of climate. To understand temporal changes in river ecosystems, consideration of how these agents act independently and collectively to affect watershed biogeochemistry is necessary. Through the Georgia Coastal Ecosystems Long-Term Ecological Research Project, we assessed nutrient (phosphorus, nitrogen, silicate) and carbon dynamics, with specific regard to import and export, in the Altamaha River Basin from 2000 to 2012. This is the first study in the region to document the biogeochemical patterns in the Altamaha's four main tributaries, the Little Ocmulgee, Ocmulgee, Oconee, and Ohoopee rivers, and the relationships between biogeochemistry and historical precipitation and discharge patterns as well as agricultural and population census data. As discharge patterns are a primary driver of nutrient loads, we determined that water use was a dominant factor in the shifting ecosystem dynamics. Dissolved inorganic nitrogen loads were primarily driven by population density and dissolved inorganic phosphorus loads were strongly influenced by livestock biomass. Taken together, we conclude that both the transportation and biogeochemical cycling of nutrients within the Altamaha River Watershed were highly impacted by anthropogenic influences, which were then further exacerbated by continued climate change. Furthermore, the N- and P-loads in the Altamaha River and tributaries were dominated by dissolved organic nitrogen and dissolved organic phosphorus, emphasizing a need to further study the bioavailability of these species and the mechanisms driving their potential ecological impacts.
%U http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1519/full
%A Takagi, Kimberly
%A Hunter, Kimberley S.
%A Cai, Wei-Jun
%A Joye, Samantha B.
%K biogeochemical, carbon, climate change, nutrients, water quality, watersheds

%0 Journal Article
%T Ecosystem engineers drive creek formation in salt marshes
%D 2017
%V 98
%N 1
%P 162-174
%B Ecology
%9 Article
%Z published
%M GCE.984
%X Ecosystem engineers affect different organisms and processes in multiple ways atdifferent spatial scales. Moreover, similar species may differ in their engineering effects forreasons that are not always clear. We examined the role of four species of burrowing crabs(Sesarma reticulatum, Eurytium limosum, Panopeus herbstii, Uca pugnax) in engineering tidalcreek networks in salt marshes experiencing sea level rise. In the field, crab burrows were associatedwith heads of eroding creeks and the loss of plant (Spartina alterniflora) stems. S. reticulatumwas closely associated with creek heads, but densities of the other crab species did notvary across marsh zones. In mesocosm experiments, S. reticulatum excavated the most soil andstrongly reduced S. alterniflora biomass. The other three species excavated less and did notaffect S. alterniflora. Creek heads with vegetation removed to simulate crab herbivory grewsignificantly faster than controls. Percolation rates of water into marsh sediments were 10 timesfaster at creek heads than on the marsh platform. Biomass decomposed two times faster atcreek heads than on the marsh platform. Our results indicate that S. reticulatum increases creekgrowth by excavating sediments and by consuming plants, thereby increasing water flow anderosion at creek heads. Moreover, it is possible that S. reticulatum burrows also increase creekgrowth by increasing surface and subsurface erosion, and by increasing decomposition of organicmatter at creek heads. Our results show that the interaction between crab and plantecosystem engineers can have both positive and negative effects. At a small scale, in contrast toother marsh crabs, S. reticulatum harms rather than benefits plants, and increases erosion ratherthan marsh growth. At a large scale, however, S. reticulatum facilitates the drainage efficiencyof the marsh through the expansion of tidal creek networks, and promotes marsh health.
%A Vu, Huy
%A Wieski, Kazimierz
%A Pennings, Steven C.
%K crabs, Spartina, salt marsh, creeks, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Salinity Variability and Water Exchange in Interconnected Estuaries
%D 2017
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.1010
%R 10.1007/s12237-016-0195-9
%X A high-resolution coastal ocean model is used to investigate salinity variability and water exchange in a complex coastal system off the southern U.S. characterized by three adjacent sounds that are interconnected by a network of channels, creeks, and intertidal areas. Model results are generally highly correlated with observations from the Georgia Coastal Ecosystem Long Term Ecological Research(GCE-LTER) program, revealing a high degree of salinity variability at the Altamaha River and Doboy Sound, decreasing sharply to ward Sapelo Sound. A Lagrangian particle tracking method is used to investigate local residence time and connectivity in the system. Local residence time is highly variable, increasing with distance from the Altamaha River and decreasing with river flow, revealing that discharge plays a dominant role on transport processes and estuary-shelf ex-change. The Altamaha River and Doboy Sound are connected to each other in all seasons, with exchange occurring both via coastal and estuarine pathways. While particles released at the Altamaha and Doboy rarely reach Sapelo Sound, particles released at Sapelo Sound and the creeks surrounding its main channel can reach the entire estuarine system.
%U https://link.springer.com/article/10.1007/s12237-016-0195-9
%A Wang, Yuntao
%A Castelao, Renato
%A Di Iorio, Daniela
%K Residence time, Connectivity, FVCOM, Exchange, SINERR Publication, Student Publication

%0 Journal Article
%T Chemical speciation of copper in a salt marsh estuary and bioavailability to Thaumarchaeota
%D 2017
%V 4
%B Frontiers in Marine Sciences
%S Organic ligands - A key control on trace metal biogeochemistry in the ocean
%9 Article
%Z International collaboration - University of Liverpool
%M GCE.1013
%R 10.3389/fmars.2017.00178
%X The concentrations of dissolved copper (Cud), copper-binding ligands, thiourea-type thiols, and humic substances (HSCu) were measured in estuarine waters adjacent to Sapelo Island, Georgia, USA, on a monthly basis from April to December 2014. Here we present the seasonal cycle of copper speciation within the estuary and compare it to the development of an annually occurring bloom of Ammonia Oxidizing Archaea (AOA), which require copper for many enzymes. Two types of complexing ligands (L1 and L2) were found to dominate with mean complex stabilities (log K&#8242;CuL) of 14.5 and 12.8. Strong complexation resulted in lowering the concentration of free cupric ion (Cu2+) to femtomolar (fM) levels throughout the study and to sub-fM levels during the summer months. A Thaumarchaeota bloom during this period suggests that this organism manages to grow at very low Cu2+ concentrations. Correlation of the concentration of the L1 ligand class with a thiourea-type thiol and the L2 ligand class with HSCu provide an interesting dimension to the identity of the ligand classes. Due to the stronger complex stability, 82–99% of the copper was bound to L1. Thiourea-type thiols typically form Cu(I) species, which would suggest that up to ~90% copper could be present as Cu(I) in this region. In view of the very low concentration of free copper (pCu > 15 at the onset and during the bloom) and a reputedly high requirement for copper, it is likely that the Thaumarchaeota are able to access thiol-bound copper directly.
%U http://journal.frontiersin.org/article/10.3389/fmars.2017.00178/full
%A Whitby, Hannah
%A Hollibaugh, James T.
%A van den Berg, Constant M.G.
%K copper, salt marsh, estuary, Archaea, Thaumarchaeota, chemistry, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Changes in sediment porewater chemistry in response to simulated seawater intrusion in tidal freshwater marshes, Altamaha River, GA
%D 2017
%C San Juan, Puerto Rico
%B Society of Wetland Scientists Annual Meeting
%8 June 5-8
%9 Poster
%Z presented
%M GCE.1040
%X Tidal freshwater ecosystems currently experience seawater intrusion associated with periodic droughts but are expected to become chronically salinized with sea level rise, impacting both marsh stability and associated ecological services. We experimentally increased salinities in a tidal freshwater marsh on the Altamaha River (GA) by adding diluted seawater to replicated marsh plots on either a press (chronic) or pulse (2 months/ year) basis. Seawater additions immediately increased porewater SO42- and Cl-, followed by increases in porewater nitrogen and phosphorus 2-4 months after initial seawater application. We observed evidence of increased SO42- reduction in saltwater addition plots.  After two years, chronic seawater addition increased the efflux of N and P into porewater, while the 2-month seawater pulse, designed to mimic natural saltwater intrusion, caused only transient effects on porewater chemistry that dissipated rapidly after the reintroduction of freshwater. Understanding the response of marshes to salinization will inform adaptive management.
%A Widney, Sarah
%A Smith, Dontrece
%A Schubauer-Berigan, Joseph P.
%A Herbert, Ellen
%A Desha, Jennifer
%A Craft, Christopher B.
%K nutrients, sulfur, nitrogen, phosphorus, climate change, Student Publication

%0 Conference Proceedings
%T Tidal forests: sentinels for climate change
%D 2017
%C San Juan, Puerto Rico
%B Society of Wetland Scientists Annual Meeting
%8 June 8, 2017
%9 Presentation
%Z presented
%M GCE.1039
%X Tidal freshwater forests are sentinels of climate change due to their sensitivity to saltwater intrusion in coastal regions. They also provide important ecosystem services to coastal areas, such as buffering against the effects of storms. However, little is known about their ability to keep pace with projected sea level rise.Plant community composition & productivity and soil accretion rates were measured in a tidal forest of the Altamaha River, Georgia to gain a better understanding of how these ecosystems respond to climate change. Annual litterfall in 2015 averaged nearly 500 g/m2. Taxodium distichum, Nyssa aquatica, and Nyssa biflora, the three dominant species, accounted for 45% of the total litterfall. Woody biomass, based on dendrometer bands, added 1.5 m2/hectare of basal area over the course of 2015.  Soil accretion, determined by radiometric dating of Cs-137 and Pb-210, averaged 1.9 mm/year, which is lower than the current rate of sea level rise in this area (3.1 mm/year). As sea level continues to rise in response to climate change, tidal forests are especially sensitive to increased frequencies in inundation and saltwater intrusion, which may result in loss of important ecosystem functions.
%A Widney, Sarah
%A Stahl, McKenna
%A Craft, Christopher B.
%K accretion rate, sea level rise, litterfall, productivity, nutrient retention, Student Publication

%0 Journal Article
%T Variability in along-shelf and cross-shelf circulation in the South Atlantic Bight
%D 2017
%V 134
%P 52-62
%B Continental Shelf Research
%9 Article
%Z published
%M GCE.1122
%R 10.1016/j.csr.2017.01.006
%X Variability in along-shelf and cross-shelf circulation in the South Atlantic Bight (SAB) is investigated using altimetry observations. Satellite-derived along-shelf velocity anomalies are in good agreement with independent near-surface current measurements from moored acoustic Doppler current profilers and surface velocities from high frequency radar at adjacent locations. This is especially true if wind-driven Ekman velocities are added to the geostrophic velocities, suggesting that the influence of Ekman dynamics to surface along-shelf flow in the SAB is unusually large. The decade-long time series reveals substantial seasonal variability in surface velocities, with peak poleward anomalies during late spring and summer and strong equatorward flow during autumn. Convergences and divergences in the along-shelf transport between two cross-sections are compared with three-dimensional numerical model results and used to estimate cross-shelf transport across the 50 m isobath in the SAB. The calculation suggests a pattern of weak offshore flow during spring followed by prolonged and relatively stronger offshore flow during summer and early autumn, while cross-shelf velocity anomalies during winter are weak and slightly onshore. Prolonged offshore flow following the peak in river discharge that generally occurs in spring indicates the potential for the establishment of a conduit for offshore export of riverine material. The long-term time series also reveals several large events of interannual variability, including the 2003 cold event observed in the SAB.
%U https://www.sciencedirect.com/science/article/pii/S0278434316302709
%A Yuan, Yeping
%A Castelao, Renato
%A He, Ruoying
%K South Atlantic Bight, Coastal currents, Satellite altimeter, Geostrophic velocity, Ekman velocity, Cross-shelf transport

%0 Journal Article
%T Five years of Deepwater Horizon oil spill effects on marsh periwinkles Littoraria irrorata
%D 2017
%V 576
%P 135-144
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.1063
%R 10.3354/meps11827
%X The Deepwater Horizon spill (2010) was the largest marine oil spill in US waters to date and one of the largest worldwide. To examine effects of the oil spill on an important salt marsh species over time, we conducted a meta-analysis on marsh periwinkles Littoraria irrorata using published and unpublished sources spanning more than 5 yr (2010&#8722;2015), including newly available Natural Resources Damage Assessment (NRDA) and Gulf of Mexico Research Initiative (GoMRI) data sets. We tested the hypotheses that the spill decreased mean periwinkle density, reduced mean snail shell length, and changed periwinkle size distribution. Averaged across multiplestudies, sites, marsh zones (edge versus interior), and years, our synthesis revealed a negative effect of heavy oiling on periwinkles. Snail densities were reduced by 73% in heavily oiled sites across all study-zone-by-year combinations, including adverse effects for both the oiled marsh edge and oiled marsh interior, with impacts observed over more than 5 yr. Mean periwinkle shell length was somewhat reduced at the oiled marsh edge in a few cases; however, periwinkle size distributions displayed greater relative proportions of smaller adults and sub-adults, and fewer large adults, across all years. Given the spatial and temporal extent of data analyzed, this synthesis provides evidence that the Deepwater Horizon spill suppressed populations of marsh periwinkles in heavily oiled marshes for over 5 yr, and that impacts were ongoing and recovery was incomplete, likely affecting other ecosystem components, including marsh productivity, organic matter and nutrient cycling, marsh&#8722;estuarine food webs, and associated predators.
%A Zengel, S.
%A Weaver, J.
%A Pennings, Steven C.
%A Silliman, Brian R.
%A Deis, D.R.
%A Montague, Clay L.
%A Zimmerman, A.
%A Rutherford, N.
%A Nixon, Z.
%K Deepwater Horizon, Oil spill, Salt marsh, Marsh periwinkle, Littoraria irrorata, Ecological impacts, Ecological recovery, Gulf of Mexico, Student Publication

%0 Journal Article
%T The presence of nocturnal LLJ-associated shear-sheltering and its impact on atmospheric turbulence
%D 2017
%B Journal of Geophysical Research - Atmospheres
%9 Article
%Z in review
%M GCE.1048
%X This paper confirms the existence of atmospheric shear sheltering whose validation has confounded researchers in otherwise well designed experimental studies. Low-level jets present in the stable boundary layer are theorized by Hunt and Durbin (1999) to prevent large eddies present above the jet from penetrating downward through the jet layer thus modulating both surface turbulence and transport/turbulence properties. Previous studies in the literature present contrasting results when this theory is applied to the atmosphere. The present paper suggests that a key difference between both studies could well lie in the fact that the Smedman et al. (2004) study took place over the ocean while the Duarte et al. (2012) study was carried out at a homogeneous site on land. Spectral analysis of turbulence over a salt marsh on the Georgia coastin the presence of low-level jets shows a suppression of spectral energy at low frequencies in both velocity components and temperature signals. This suppression mechanism maybe partly attributed to the presence of large upward shear above jet cores at this coastal site, effectively impeding larger eddies aloft to penetrate through the jet cores to move downward to the surface. This recent evidence, when coupled with the recent study by both Duarte et al. (2012) and Smedman et al. (2004), thus suggest that shear-sheltering theory appears to hold true for regions of very large horizontally uniform homogeneity such as seas and oceans rather than over land.
%A Zhang, Gengsheng
%A Leclerc, Monique Y.
%A Nahrawi, Hafsah Binti
%A Pahari, R.
%K shear-sheltering theory, low-level jets, nocturnal stable boundary layer, atmospheric turbulence, marine boundary layer, Student Publication

%0 Conference Proceedings
%T Status of Sand Resource Assessments for Georgia Coastal Resiliency and Recovery
%D 2016
%C Columbia, SC
%B Southeastern Section of the Geological Society of America Annual Meeting
%8 31 March - 1 April 2016
%9 Presentation
%Z presented
%M GCE.978
%A Alexander, C.R.
%K sand grain size barrier islands

%0 Conference Proceedings
%T Stratigraphic Development of Georgia Estuarine Sequences on Holocene and Modern Timescales
%D 2016
%C Columbia, SC
%B Southeastern Section of the Geological Society of America Annual Meeting
%8 31 March - 1 April 2016
%9 Presentation
%Z presented
%M GCE.979
%A Alexander, C.R.
%A Hodgson, J.Y.S.
%A Brandes, J.A.
%K salt marsh stratigraphy development

%0 Conference Proceedings
%T Application of a New Coastal Hazard Vulnerability Assessment Tool to the Southeastern United States: AMBUR-HVA
%D 2016
%C Columbia SC
%B Southeastern Section of the Geological Society of America Annual Meeting
%8 31 March-1 April 2016
%9 Presentation
%Z presented
%M GCE.968
%A Alexander, C.R.
%A Jackson, C.
%A Howard, S.
%A Jaeger, J.M.
%A Corbett, D.R.
%A Walsh, J.P.
%K hazards AMBUR

%0 Journal Article
%T A keystone mutualism underpins resilience of a coastal ecosystem to drought
%D 2016
%V 7
%P 12473
%B Nature Communications
%9 Article
%Z published
%M GCE.967
%R 10.1038/ncomms12473
%X Droughts are increasing in severity and frequency, yet the mechanisms that strengthen ecosystem resilience to this stress remain poorly understood. Here, we test whether positive interactions in the form of a mutualism between mussels and dominant cordgrass in salt marshes enhance ecosystem resistance to and recovery from drought. Surveys spanning 250&#8201;km of southeastern US coastline reveal spatially dispersed mussel mounds increased cordgrass survival during severe drought by 5- to 25-times. Surveys and mussel addition experiments indicate this positive effect of mussels on cordgrass was due to mounds enhancing water storage and reducing soil salinity stress. Observations and models then demonstrate that surviving cordgrass patches associated with mussels function as nuclei for vegetative re-growth and, despite covering only 0.1–12% of die-offs, markedly shorten marsh recovery periods. These results indicate that mutualisms, in supporting stress-resistant patches, can play a disproportionately large, keystone role in enhancing ecosystem resilience to climatic extremes.
%U http://www.nature.com/articles/ncomms12473
%A Angelini, Christine
%A Griffin, John
%A van de Koppel, Johan
%A Derksen-Hooijberg, M.
%A Lamers, L.P.M.
%A Smolders, Alfons J. P.
%A van der Heide, Tjisse
%A Silliman, Brian R.
%K climate change, salt marsh, mussel, spartina, biodiversity, SINERR Publication, UGAMI Publication

%0 Thesis
%T Elucidating natural and anthropogenic marine processes using molecular biomarkers.
%D 2016
%P 111
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.1005
%A Babcock-Adams, Lydia
%K Molecular biomarkers, Coastal environments, Anthropogenic input, Student Publication

%0 Journal Article
%T Living oysters and their shells as sites of nitrification and denitrification
%D 2016
%B Marine Pollution Bulletin
%9 Article
%Z published
%M GCE.972
%R 10.1016/j.marpolbul.2016.08.038.
%X Oysters provide a critical habitat, are a food resource for higher trophic levels and support important commercial fisheries throughout the world. Oyster reefs can improve water quality by removing phytoplankton.While sediment denitrification may be enhanced adjacent to oyster reefs, little is known about nitrification and denitrification associated with living oysters and their shells. Wemeasured nitrification and denitrification in living oysters (Crassostrea virginica and Crassostrea gigas) and empty oyster shells. Nitrification was similar between live oysters and empty oyster shells, however, denitrification was enhanced significantly on living oysters compared to shells. This is the first demonstration of nitrification and denitrification associated with living oysters and their shells. Our data suggest that loss of historic oyster reefs has likely affected the resilience of estuaries to eutrophication. The additional benefit of oystermediated denitrification should be considered in restoration of oyster reefs as a tool for managing eutrophication.
%U http://gce-lter.marsci.uga.edu/public/uploads/Caffrey_et_al_2016_20160906T154700.pdf
%A Caffrey, Jane M.
%A Hollibaugh, James T.
%A Mortazavi, Behzad
%K nutrients, bivalves, nitrification, denitrification, oysters

%0 Conference Proceedings
%T Sediment Size and the Limits of Recent Sediment in the Georgia Bight
%D 2016
%C Columbia SC
%B Southeastern Section of the Geological Society of America Annual Meeting
%8 31 March-1 April 2016
%9 Meeting
%Z presented
%M GCE.966
%R 10.1130/abs/2016SE-273699
%A Colley, J.
%A Alexander, C.R.
%K grain size, zone of influence

%0 Book
%T Creating and Restoring Wetlands: From Theory to Practice.
%D 2016
%I Elsevier
%C Amsterdam, The Netherlands
%9 Editorial Material
%Z published
%M GCE.938
%A Craft, Christopher B.
%K wetland restoration, created wetlands

%0 Journal Article
%T Climate change and the fate of coastal wetlands
%D 2016
%V 33
%N 3
%P 70-73
%B Wetland Science and Practice
%9 Article
%Z published
%M GCE.980
%X Coastal wetlands, including tidal marshes and forests, provide a number of key ecosystem services, including habitat for recreationally and commercially important finfish and shellfish, protection from wind, waves, storms and floods, and removal of excess nutrients, namely nitrogen (N) and phosphorus (P), from agricultural and urban runoff (e.g., Tiner 2013). Along the coast, climate change will be manifested as rising sea level with attendant coastal flooding and saltwater intrusion. A more immediate impact which has already been experienced is drought, particularly in late summer and fall. These processes will lead to migration of tidal wetlands inland, where possible, and changes in habitat as freshwater wetlands convert to brackish marsh or open water. As part of the National Science Foundation’s Georgia Coastal Ecosystems Long Term Ecological Research (GCE LTER) project, scientists from seven institutions of higher learning, including the University of Georgia, Indiana University, Virginia Institute of Marine Sciences, University of Houston, University of Florida, Georgia Southern University, College of Coastal Georgia, and the U.S. Environmental Protection Agency, initiated a field experiment - Seawater Addition Long Term Experiment or SALTEx - to investigate how saltwater intrusion and increased flooding will alter the direction and pace of change of microbial, plant, and animal communities and key biogeochemical processes in a tidal freshwater marsh. SALTEx consists of an array of field plots that are used to answer three main questions regarding sea level rise and saltwater intrusion: 1. How does long-term, chronic (“press”) addition of diluted seawater affect tidal freshwater marsh structure and function? 2. What are the effects of periodic pulsing of diluted seawater to simulate low river flow or drought conditions? 3. What are the effects of freshwater additions?
%U https://www.researchgate.net/publication/311263349_Climate_Change_and_the_Fate_of_Coastal_Wetlands_Wetland_Science_and_Practice_33370-77
%A Craft, Christopher B.
%A Herbert, Ellen
%A Li, Fan
%A Smith, Dontrece
%A Schubauer-Berigan, Joseph P.
%A Widney, Sarah
%A Angelini, Christine
%A Pennings, Steven C.
%A Medeiros, Patricia M.
%A Byers, James
%A Alber, Merryl
%K sea level rise, tidal freshwater marsh, salinization, climate change

%0 Journal Article
%T Marginalization of the Margins: The Importance of Smaller Islands in Human Prehistory
%D 2016
%V 11
%N 2
%P 155-170
%B The Journal of Island and Coastal Archaeology
%S Small Islands in Prehistory
%9 Article
%Z published
%M GCE.1105
%R 10.1080/15564894.2016.1192568
%X Across the world's seas and oceans, archaeological research focused on islands has generally privileged those that are larger in size. Explanations for this phenomenon range from the (mis)perception by scholars that prehistoric peoples were more attracted to the presumed greater number and diversity of resources typically available on larger islands, to the ephemeral aspect of archaeological evidence on smaller land areas. These are coupled with logistical and infrastructure issues that often limit access to labor, equipment, and transportation to conduct field activities (e.g., remote atolls in the Pacific). A growing body of research demonstrates, however, that ancient peoples regularly and readily occupied and/or accessed many smaller islands for both terrestrial and marine resources. In some cases, within an archipelago, evidence shows an earlier occupation on smaller islands versus larger ones, or an attraction to the former given unique or seasonal resource availability and/or defensive capabilities. We describe cases from several areas of the world that highlight the importance of relatively small islands (&#8764;1–500 km2) for understanding human adaptations in what many have considered to be among the most marginal of environments.
%U https://www.tandfonline.com/doi/full/10.1080/15564894.2016.1192568
%A Fitzpatrick, Scott M.
%A Thompson, Victor D.
%A Poteate, Aaron S.
%A Napolitano, Matthew
%A Erlandson, Jon M.
%K marginality, island archaeology, insularity, Caribbean, Southeast USA, California Channel Islands, Pacific, Student Publication

%0 Journal Article
%T Genetic and epigenetic differences associated with environmental gradients in replicate populations of two salt marsh perennials
%D 2016
%V 25
%P 1639-1652
%B Molecular Ecology
%S Epigenetic Studies in Ecology and Evolution
%9 Article
%Z published
%M GCE.960
%R 10.1111/mec.13522
%X While traits and trait plasticity are partly genetically based, investigating epigenetic mechanisms may provide more nuanced understanding of the mechanisms underlying response to environment. Using AFLP and methylation-sensitive AFLP, we tested the hypothesis that differentiation to habitats along natural salt marsh environmental gradients occurs at epigenetic, but not genetic loci in two salt marsh perennials. We detected significant genetic and epigenetic structure among populations and among subpopulations, but we found multilocus patterns of differentiation to habitat type only in epigenetic variation for both species. In addition, more epigenetic than genetic loci were correlated with habitat in both species. When we analysed genetic and epigenetic variation simultaneously with partial Mantel, we found no correlation between genetic variation and habitat and a significant correlation between epigenetic variation and habitat in Spartina alterniflora. In Borrichia frutescens, we found significant correlations between epigenetic and/or genetic variation and habitat in four of five populations when populations were analysed individually, but there was no significant correlation between genetic or epigenetic variation and habitat when analysed jointly across the five populations. These analyses suggest that epigenetic mechanisms are involved in the response to salt marsh habitats, but also that the relationships among genetic and epigenetic variation and habitat vary by species. Site-specific conditions may also cloud our ability to detect response in replicate populations with similar environmental gradients. Future studies analysing sequence data and the correlation between genetic variation and DNA methylation will be powerful to identify the contributions of genetic and epigenetic response to environmental gradients.
%U http://onlinelibrary.wiley.com/doi/10.1111/mec.13522/full
%A Foust, Christy M.
%A Preite, Veronica
%A Schrey, Aaron W.
%A Alvarez, Mariano
%A Robertson, M. H.
%A Verhoeven, Koen J.F.
%A Richards, Christina L.
%K DNA methylation, environmental gradient, MS-AFLP, partial Mantel, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Consumer control of the establishment of marsh foundation plants in intertidal mudflats
%D 2016
%V 547
%P 79-89
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.988
%R 10.3354/meps11624
%X The establishment of foundation plants in bare mudflats is a critical process. While consumers are increasingly recognized to exert strong top-down control of plant performance in salt marshes, studies to date have focused on the effects of consumers on mature stands rather than on plants that are recolonizing after disturbance or where restoration has occurred. Furthermore, whether consumer-facilitated fungal infection differentially affects newly establishing plants in mudflats compared to mature stands remains poorly understood. In a salt marsh in southern Brazil, we examined the effects of herbivory by the crab Neohelice granulata and fungal infection on the survival and growth of Spartina alterniflora transplanted into mudflats. We additionally tested the effects of herbivory and fungi on newly established versus well-established stands of S. alterniflora. Highly intensive natural crab herbivory significantly reduced the development of S. alterniflora and increased its fungal infection by 50%. Light herbivory, removing only small areas of plant leaves, reduced the height growth and leaf production of directly affected tillers by about 14 to 18%, and both newly and well-established, clonally integrated stands of S. alterniflora allocated energy towards the formation of new tillers. While herbivory facilitated fungal infection and subsequent fungal damage in leaves, no significant effects of fungicide treatment or its interactions with crab grazing on S. alterniflora growth were detected, suggesting a saprophytic rather than a pathogenic role of fungi in this 3-species interaction. Here, we found that marsh grasses transplanted for restoration or those colonizing disturbance-generated mudflats may be facilitated by protection against consumers.
%A Freita, R.
%A Schrack, Elizabeth
%A He, Qiang
%A Silliman, Brian R.
%A Furlong, Eliana B.
%A Telles, Annie C.
%A Costa, Cesar S.B.
%K Top-down control, Herbivory, Spartina alterniflora, Fungal infection, Student Publication

%0 Journal Article
%T Relative Sea-Level Change in Northeastern Florida (USA) During the Last ~8.0 KA
%D 2016
%B Quaternary Science Reviews
%9 Article
%Z published
%M GCE.964
%R 10.1016/j.quascirev.2016.04.016
%X An existing database of relative sea-level (RSL) reconstructions from the U.S. Atlantic coast lacked valid sea-level index points from Georgia and Florida. This region lies on the edge of the collapsing forebulge of the former Laurentide Ice Sheet making it an important location for understanding glacio-isostatic adjustment and the history of ice-sheet melt. To address the paucity of data, we reconstruct RSL in northeastern Florida (St. Marys) over the last &#8764;8.0 ka from samples of basal salt-marsh sediment that minimize the influence of compaction. The analogy between modern salt-marsh foraminifera and their fossil counterparts preserved in the sedimentary record was used to estimate paleomarsh surface elevation. Sample ages were determined by radiocarbon dating of identifiable and in-situ plant macrofossils. This approach yielded 25 new sea-level index points that constrain a &#8764;5.7 m rise in RSL during the last &#8764;8.0 ka. The record shows that no highstand in sea level occurred in this region over the period of the reconstruction. We compared the new reconstruction to Earth-ice models ICE 6G-C VM5a and ICE 6G-C VM6. There is good fit in the later part of the Holocene with VM5a and for a brief time in the earlier Holocene with VM6. However, there are discrepancies in model-reconstruction fit in the early to mid Holocene in northeastern Florida and elsewhere along the Atlantic coast at locations with early Holocene RSL reconstructions. The most pronounced feature of the new reconstruction is a slow down in the rate of RSL rise from approximately 5.0 to 3.0 ka. This trend may reflect a significant contribution from local-scale processes such as tidal-range change and/or change in base flow of the St. Marys River in response to paleoclimate changes. However, the spatial expression (local vs. regional) of this slow down is undetermined and corroborative records are needed to establish its geographical extent.
%U http://www.sciencedirect.com/science/article/pii/S0277379116301275
%A Hawkes, A.D.
%A Kemp, A.C.
%A Donnelly, J.P.
%A Horton, B.P.
%A Peltier, W.R.
%A Cahill, N.
%A Hill, D.F.
%A Ashe, E.
%A Alexander, C.R.
%K sea-level

%0 Journal Article
%T Consumer control as a common driver of coastal vegetation worldwide
%D 2016
%V 86
%N 3
%P 278-294
%B Ecological Monographs
%9 Article
%Z published
%M GCE.987
%R 10.1002/ecm.1221
%X Rapid, global, anthropogenic alteration of food webs in ecosystems necessitates a better understanding of how consumers regulate natural communities. We provide a global synthesis of consumer control of vegetation in coastal wetlands, where the domineering role of physical factors such as nutrient and salinity, rather than consumers, has been emphasized for decades. Using a data set of 1748 measures of consumer effects reported in 443 experiments/observations on all continents except Antarctica, we examine the generality of consumer control in salt marshes and mangroves globally. Our analyses show that salt marsh herbivores, including insects, snails, crabs, waterfowl, small mammals, and livestock, generally and often strongly suppress plant survival, aboveground biomass, and height, while their effects on plant density, belowground biomass, reproduction, and cover are more variable. These effects occur in forbs, grasses, and shrubs, and in both seedlings and adult plants. Herbivores additionally affect plant nutrient stoichiometry, and mediate plant interactions, though their effects on plant diversity are less consistent. Higher trophic levels also affect plants, as predators facilitate plant growth through trophic cascades that suppress grazer abundance and grazing rate. In mangroves, there are also signs of consumer control, though the relatively few studies available have often focused on mangrove propagules and seedlings rather than adults. Our analyses further reveal that the strength of consumer control is regulated by many physical factors. Nutrient, disturbance, and flooding, for example, amplify the negative effects of herbivores. Along latitudinal gradients, increased temperature enhances the negative effects of ectothermic herbivores, but has no effect on those of endothermic herbivores. Consumer control of coastal plants is also apparent across study methodologies: in field and laboratory settings, in observational studies, in consumer exclusion and addition experiments, in natural and transplanted plants, and in experiments of various durations. The role of consumer control in coastal vegetation worldwide highlights the need to better recognize and theoretically conceptualize both top-down and bottom-up forcing and their interactions in coastal wetlands. Improved understanding and conservation of coastal wetlands will only occur if we incorporate what the science has revealed: trophic feedbacks are an important and pervasive determinant of coastal plant communities.
%A He, Qiang
%A Silliman, Brian R.
%K coastal vegetation, consumer controls

%0 Journal Article
%T Accumulation of soil carbon drives denitrification potential and labincubatedgas production along a chronosequence of salt marshdevelopment
%D 2016
%V 172
%N 5
%P 72-80
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.994
%R 10.1016/j.ecss.2016.02.002
%X We measured sediment organic carbon and nitrogen accumulation and rates of denitrification enzyme activity and greenhouse gas (CO2, CH4, N2O) production from slurries of sediments of a mudflat that formed in 2002, a young (8-year-old) natural Spartina alterniflora salt marsh that developed on part of the mudflat, and four mature (>200 years old) salt marshes in southeastern Georgia to examine microbial processes related to carbon (C) and nitrogen (N) cycling during succession from mudflat to mature marsh. Soil organic C and N and C: N ratio (0–30 cm) increased across the chronosequence from mudflat (791 ± 35 g C/m2, 125 ± 17 g N/m2) to young marsh (2520 ± 131 g C/m2, 190 ± 10 g N/m2) to mature marshes (5827 ± 250 g C/m2, 372 ± 20 g N/m2). After 8 years of colonization by S. alterniflora, sediment organic carbon increased 3.2 times, and nitrogen increased 1.5 times relative to the mudflat. The high rate of organic C and N accumulation based on time series measurements (188 g C/m2/yr, 7.8 g N/m2/yr) and feldspar marker layers (359 g C/m2/yr, 26.2 g N/m2/yr) was attributed to high accretion (3 cm/yr) in this low elevation (0.18 m NAVD88) emerging marsh. Carbon dioxide production increased with increasing sediment organic C from mudflat to mature marshes. Un-amended denitrification enzyme activity, measured in slurry incubations, ranged from an average of 0.020 ± 0.005 µg g&#8722;1 hr&#8722;1 in the mature marshes to 0.094 ± 0.03 µg g&#8722;1 hr&#8722;1 in the young marsh. We also measured denitrification potential in slurry incubations amended with C (glucose), N (nitrate), and C + N to assess the potential for substrate limitations. Denitrification potential in the mudflat did not show strong nutrient limitation. In the young marsh, denitrification potential was C-limited, and in the mature marsh, it was co-limited by C and N. In July samples, CO2 production showed a statistically significant increase with age from the mudflat to the mature marshes. However, in both months, CO2 production efficiency (expressed on a per g C basis) was significantly higher in the mudflat sediment slurries than in the young marsh and mature marsh samples. Spartina colonization of mudflats and the subsequent accumulation of organic matter are key to enriching sediment organic C and N pools that control microbial heterotrophy, particularly denitrification and CO2 production, which play important roles in marsh C and N cycling.
%A He, Yahlong
%A Widney, Sarah
%A Ruan, Michelle
%A Herbert, Ellen
%A Li, Xiuzhen
%A Craft, Christopher B.
%K Denitrification potential, Greenhouse gas production, Soil carbon, Organic matter accumulation, Salt marsh, Ecosystem development, USA, Georgia, Sapelo Island, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Seasonal Dynamics of Ammonia- and Nitrite-Oxidizing Organisms in the Sediment and Water Column of a Tidal Creek in a Salt Marsh Estuary.
%D 2016
%I ASLO
%C New Orleans LA
%B ASLO Ocean Sciences Meeting
%8 21-26 February 2016
%9 Poster
%Z presented
%M GCE.974
%X We have monitored the population dynamics of nitrifying organisms in the water column at Marsh Landing on the Georgia, USA, coast for several years.  We have documented a midsummer peak in the abundance of ammonia oxidizing Archaea (AOA) at the site.  Marsh Landing is at the mouth of the Duplin River, a dead-end tidal channel that drains an extensive area of salt marsh.  While the lower Duplin River exchanges tidally with Doboy Sound and thus South Atlantic Bight (SAB) coastal waters, water in its upper reaches has a residence time of weeks.  The work reported here had two goals:  1) test the hypothesis that the surrounding salt marsh is the source of nitrifiers seen in water samples taken at Marsh Landing; and 2) compare the seasonal dynamics of nitrifiers in surficial sediments with those in the water column.  We sampled 6 stations along the ~20 km length of the Duplin River.  We collected surface water samples (0.20 m) at mid-tide, monthly from April-December 2014.  Sediment samples (top 1 cm) were collected at the same time from unvegetated creek bank at 2 locations on the Duplin River and from 4 locations spanning the creek bank-to-upland gradient of the saltmarsh.  Abundance of AOA, ammonia oxidizing beta-Proteobacteria (AOB) and Nitrospina, a nitrite oxidizing bacterium, were determined by qPCR of DNA extracted from the samples.  The seasonal dynamics seen at Marsh Landing were reflected in Duplin River water; however, the data suggest that the AOA bloom begins in the adjacent tidally mixed, deep water of Doboy Sound then propagates into the Duplin River, not vice versa.  Variability in abundance between sediment sampling sites exceeded the seasonal variation in abundance of AOA (0-65*106 gws-1), AOB (0-8.6*106 gws-1) and Nitrospina (0.1-9.1*106 gws-1). The ratio of AOA:AOB appears to be consistently lower in sediment samples than in the water column (0.35 vs 80.2).  We are in the process of comparing the phylogenetic composition of AOA in these populations.
%A Hollibaugh, James T.
%A Liu, Qian
%A Ross, Meredith
%A Cheek, Jelani
%A Sweeney, Corinne
%K nitrification, nitrous oxide, greenhouse gas, Thaumarchaeota, Student Publication

%0 Conference Proceedings
%T Coupling between Sediment and Water Column Populations of Ammonia Oxidizing Thaumarchaeota in a Salt Marsh Estuary
%D 2016
%9 Poster
%Z presented
%M GCE.1017
%X Populations of nitrifying organisms in the water column at Marsh Landing display a midsummer peak in the abundance of ammonia oxidizing Archaea (AOA) at the site, coinciding with a peak in nitrite concentration.  Marsh Landing is at the mouth of the Duplin River, a dead-end tidal channel that drains an extensive area of salt marsh.  While the lower Duplin River at Marsh Landing exchanges tidally with Doboy Sound and thus South Atlantic Bight (SAB) coastal waters, water in its upper reaches has a residence time of weeks.  The work reported here had two goals:  1) test the hypothesis that the surrounding salt marsh is the source of nitrifiers seen in water samples taken at Marsh Landing; and 2) compare the seasonal dynamics of nitrifiers in surficial sediments with those in the water column.  We sampled 6 stations along the ~20 km length of the Duplin River.  We collected surface water samples (~0.20 m) at low- to mid-tide, monthly from April-December 2014.  Sediment samples (top 1 cm) were collected at the same time from unvegetated creek bank at 2 locations on the Duplin River and from 4 locations spanning the creek bank-to-upland gradient of the saltmarsh accessible from the Teal Boardwalk.  The abundance of ammonia oxidizing Archaea, Marine Group 1 Archaea (Thaumarchaeota), ammonia oxidizing Betaproteobacteria (AOB), Bacteria and Nitrospina, a nitrite oxidizing bacterium, were determined by qPCR of DNA extracted from the samples.
%A Hollibaugh, James T.
%A Liu, Qian
%A Ross, Meredith
%A Cheek, Jelani
%A Sweeney, Corinne
%A Tolar, Bradley
%A Hagan, Patrick
%A Whitby, Hannah
%A Bratcher, Annie
%A Malagon, Erica
%A Lynn-Bell, Nicole
%A Shalack, Jacob
%A Reddy, Caroline M.
%A Walker, John T.
%K nitrogen, salt marsh, estuary, Archaea, Thaumarchaeota, chemistry, qPCR, sediment, water, ammonia, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Rates of Estuarine Shoreline Change in Eastern Florida During a Period of Rapid Anthropogenic Change, 1940s to 2009
%D 2016
%C Columbia SC
%B Southeastern Section of the Geological Society of America Annual Meeting
%8 31 March-1 April 2016
%9 Presentation
%Z presented
%M GCE.977
%A Jaeger, J.M.
%A Alexander, C.R.
%A Jackson, C.
%K shoreline change AMBUR

%0 Conference Proceedings
%T Dissolved organic matter composition and processing in the Altamaha River and Estuary: The influence of hydrology.
%D 2016
%C Yokohama, Japan
%B Goldschmidt Conference
%8 June 2016
%9 Presentation
%Z presented
%M GCE.995
%A Letourneau, Maria L.
%A Pannill, Virginia
%A Babcock-Adams, Lydia
%A Medeiros, Patricia M.
%K Dissolved organic matter, Altamaha River, estuary, hydrology, Student Publication

%0 Journal Article
%T Disturbance in Georgia salt marshes: variation across space and time
%D 2016
%V 7
%N 10
%P e01487
%B Ecosphere
%9 Article
%Z published
%M GCE.985
%R 10.1002/ecs2.1487
%X We documented the frequency and effect on live biomass of five different types of disturbance over 14 years in creekbank and mid-marsh zones of eight salt marshes dominated by Spartina alterniflora in Georgia, USA. Wrack (floating debris) and creekbank slumping were the most common disturbances at the creekbank, and snails were the most common disturbance agent in the mid-marsh. Disturbance frequency varied among sites due to differences in plot elevation and landscape position. Wrack disturbance at the creekbank was positively correlated with plot elevation, and both initial slumping and terminal slumping of creekbank plots were negatively correlated with plot elevation. Wrack disturbance at the creekbank and snail disturbance in the mid-marsh were also most common at barrier island vs. interior marshes. Disturbance varied up to 14-fold among years. Wrack disturbance at the creekbank was negatively correlated with river discharge and sea level, and initial slumping of creekbank plots was also negatively correlated with sea level. The different disturbance types varied in their effects on end-of-year standing plant biomass. At the creekbank, wrack disturbance reduced biomass in affected plots by ~46%, but slumping did not affect biomass until the plot was totally lost. In the mid-marsh, slumping and wrack were not important disturbances, but snail disturbance reduced biomass in affected plots by ~70%. In addition, abiotic conditions (river discharge, maximum monthly temperature, sea level, and precipitation) strongly affected year-to-year variation in biomass. Across the entire landscape, fewer than a quarter of the plots on average were disturbed, and disturbance reduced overall standing biomass by ~18% in the creekbank zone and ~3% in the mid-marsh zone. Our results indicate that wrack has fairly strong effects on end-of-year biomass at the creekbank. Overall, however, variation in abiotic conditions among years had stronger effects on end-of-year standing biomass in both marsh zones than did disturbance.
%U http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1487/abstract
%A Li, Shanze
%A Pennings, Steven C.
%K disturbance, Spartina, wrack, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Biogeochemical cycling of polyamines in a coastal marine environment
%D 2016
%P 197
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.998
%X Polyamines are a group of short-chain aliphatic compounds containing multiple primary or secondary amine groups. They are ubiquitous in aquatic environments with concentrations in the sub-nanomolar range, while their concentrations in cells are at millimolar levels. They are commonly regarded as important osmolytes, synthesized or assimilated by osmotrophs, like bacterioplankton. They play a key role in cellular growth and synthesis of nucleic acids and proteins, maintaining physiological functions. However, few studies have examined the role of polyamines in oceanic N cycling. In this study, I hypothesized that polyamines could contribute a significant amount of nitrogen to bacterial N production because of greater N: C ratio in polyamines than other labile organic nitrogen compounds. I determined the turnover rates of three polyamines (putrescine, spermidine and spermine) in water samples using 3 H-labeled compounds and measured their concentrations by HPLC in the South Atlantic Bight (SAB) from the inner continental shelf to the shelf-break at the edge of the Gulf Stream and in salt marsh estuaries. I sampled during different times of the years to assess temporal variability of polyamine dynamics. The data showed that polyamines were rapidly assimilated by bacterioplankton, especially in samples from salt marshes and the inner-shelf of the SAB. However, the low ambient concentrations of polyamines limited their contribution to bacterioplankton C (<5%) and N (10%) demand compared to dissolved free amino acids (L-arginine and L-glutamate) that were used as controls. My study of polyamine metabolism in phytoplankton suggested that bacterial uptake of polyamines was limited by the sources of polyamines. I found low concentrations (nmol-1 ) of dissolved polyamine pools in media of phytoplankton cultures, similar to concentrations measured in the field. My data suggested that the composition and concentration of dissolved polyamines is a result of low diffusion from intracellular pools, selective release and uptake by healthy phytoplankton cells, as well as modifications due to bacterioplankton uptake. Thaumarchaeota have been shown to oxidize polyamine nitrogen. This dissertation investigated the spatial and seasonal variability of the abundances and activity of Thaumarchaeota in the SAB by quantitative PCR of Thaumarchaeota 16S rRNA and Archaea ammonia monooxygenase subunit A (amoA) genes and simulated in situ incubations with 15NH4Cl. I found a peak in Thaumarchaeota abundance (>1000-fold increase) in mid-summer at inshore and nearshore stations, but rapid ammonia oxidation was constrained to the inner-shelf at the mouth of the estuaries, probably driven by the substrate availability.
%A Liu, Qian
%K Polyamines, putrescine, spermidine, spermine, Turnover rates, Uptake rates, HPLC, Bacterial Production, Phytoplankton, Diatom, Environmental variables, Thaumarchaeota, Ammonia-oxidizing Archaea, Nitrification, South Atlantic Bight, Student Publication

%0 Journal Article
%T Geographical variation in vegetative growth and sexual reproduction of the invasive Spartina alterniflora in China
%D 2016
%V 104
%P 173-181
%B Journal of Ecology
%9 Article
%Z published
%M GCE.942
%R 10.1111/1365-2745.12487
%X 1. Phenotypic variation plays an important role in successful plant invasions. The spread of invasive species over large geographic ranges may be facilitated if plants can match their phenotype to local abiotic conditions. Spartina alterniflora, native to the United States, was introduced into China in 1979 and has spread over 19&#7506; of latitude along the eastern coast of China.2. We studied patterns in vegetative growth and sexual reproduction of S. alterniflora at 22 sites at 11 geographic locations over a latitudinal gradient of ~2000 km from Tanggu (39.05 °N, high latitude) to Leizhou (20.90 °N, low latitude) in China. We further evaluated the basis of phenotypic differences by growing plants from across the range in a common garden for 2 growing seasons.3. We found distinct latitudinal clines in plant height, shoot density, and sexual reproduction across latitude. Some traits exhibited linear relationships with latitude; others exhibited hump-shaped relationships. We identified correlations between plant traits and abiotic conditions such as mean annual temperature, growing degree days, tidal range, and soil nitrogen content. However, geographic variation in all but one trait disappeared in the common garden, indicating that variation largely due to phenotypic plasticity. Only a slight tendency for latitudinal variation in seed set persisted for two years in the common garden, suggesting that plants may be evolving genetic clines for this trait.4. Synthesis. The rapid spread of Spartina alterniflora (S. alterniflora) in China has probably been facilitated by phenotypic plasticity in growth and reproductive traits. We found little evidence for the evolution of genetic clines in China, even though these exist for some traits in the native range. The considerable variation among clones, within provenances, that persisted in the common garden suggests a potential for the evolution of geographic clines in the future. Low fecundity of low latitude S. alterniflora populations in China might result in a slower spread atlow latitudes, but S. alterniflora is likely to continue to spread rapidly at high latitudes in China and into the Korean peninsula.
%A Liu, Wenwen
%A Maung-Douglass, Keith
%A Strong, Donald R.
%A Pennings, Steven C.
%A Zhang, Yihui
%K introduced species, sexual reproduction, Spartina, salt marsh, Student Publication

%0 Thesis
%T A modelling study of horizontal transport and residence time in the Duplin River estuary, Sapelo Island GA.
%D 2016
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.962
%X A high-resolution, three-dimensional, hydrodynamic model of the Duplin River estuary on Sapelo Island Georgia has been developed using Finite Volume Community Ocean Model. Using a model to describe transport and retention is a good way to estimate the efficiency of an estuary at remediating contaminants. The model shows good agreement with time series of sea surface height and salinity from monitoring stations within the domain. The model does well at predicting tidal oscillations and subtidal SSH and salinity variations. However, there is room for improvement with regard to salinity variability in the upper model domain. A Lagrangian particle tracking analysis was carried out to study the effects of semi-diurnal tides, spring/neap tidal cycles, and seasonal forcings on residence times. Residence time is most sensitive to the stage of the tide (slack high or slack low) when starting the particle tracking and had maximum values on slack low water. Neap tides had characteristically longer residence times than spring tides. Residence time was also dependent on seasonal changes and was higher during periods of low river discharge which correspond to higher sea surface inundation than periods of high river discharge. An Eulerian salt flux analysis was carried out to study the relative roles of advective and dispersive flux on transport processes. The residual or advective flux, dominates the transport within the system and marsh circulation in the upper reaches shows net inward movement along the channel and net outward movement over the marsh. Tidal flux dominates the dispersive flux over estuarine exchange flux and thus controls the horizontal dispersion. The horizontal dispersion coefficient was dependent on seasonal river discharge as the horizontal salinity gradient switches from a positive to a negative estuary causing very large and highly variable values during periods of high river discharge. Alternatively, the horizontal dispersion coefficient was more periodic and controlled by the spring/neap cycle, showing maxima on spring tides during the season of low river discharge and high sea surface inundation.
%A McKnight, Charles Jared
%K Duplin, river, estuary, physics, physical oceanography, residence time, circulation, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T A high-resolution hydrodynamic model of the Duplin River Estuary, Sapelo Island GA with groundwater as the major buoyancy forcing
%D 2016
%C New Orleans, LA
%B 2016 Ocean Sciences Meeting
%S EC11B-03
%8 Feb 21-26, 2016
%9 Presentation
%Z presented
%M GCE.990
%A McKnight, Charles Jared
%A Di Iorio, Daniela
%K hydrodynamic model, Duplin River, FVCOM, Student Publication

%0 Journal Article
%T A novel molecular approach for tracing terrigenous dissolved organic matter into the deep ocean
%D 2016
%V 30
%N 5
%P 689–699
%B Global Biogeochemical Cycles
%9 Article
%Z published
%M GCE.1068
%R 10.1002/2015GB005320
%X Marine dissolved organic matter (DOM) contains one of the largest exchangeable organic carbon pools on Earth. Riverine input represents an important source of DOM to the oceans, yet much remains to be learned about the fate of the DOM linking terrestrial to oceanic carbon cycles through rivers at the global scale. Here we use ultrahigh-resolution mass spectrometry to identify 184 molecular formulae that are indicators of riverine inputs (referred to as t-Peaks) and to track their distribution in the deep North Atlantic and North Pacific Oceans. The t-Peaks were found to be enriched in the Amazon River, to be highly correlated with known tracers of terrigenous input, and to be observed in all samples from four different rivers characterized by vastly different landscapes and vegetation coverage spanning equatorial (Amazon and Congo), subtropical (Altamaha), and Arctic (Kolyma) regions. Their distribution reveals that terrigenous organic matter is injected into the deep ocean by the global meridional overturning circulation, indicating that a fraction of the terrigenous DOM introduced by rivers contributes to the DOM pool observed in the deep ocean and to the storage of terrigenous organic carbon. This novel molecular approach can be used to further constrain the transfer of DOM from land to sea, especially considering that Fourier transform ion cyclotron resonance mass spectrometer analysis is becoming increasingly frequent in studies characterizing the molecular composition of DOM in lakes, rivers, and the ocean.
%U http://onlinelibrary.wiley.com/doi/10.1002/2015GB005320/abstract
%A Medeiros, Patricia M.
%A Seidel, Michael
%A Niggemann, Jutta
%A Spencer, Robert G.
%A Hernes, Peter J.
%A Yager, Patricia
%A Miller, William
%A Dittmar, Thorsten
%A Hansell, Dennis A.
%K organic matter, DOM, organic carbon, riverine, terrigenous, ocean, chemistry, biogeochemistry

%0 Conference Proceedings
%T Hydrologic controls on porewater salinity in a Southeastern salt marsh
%D 2016
%I GA Department of Natural Resources
%C Jekyll Island GA
%B Prepare, Respond, and Adapt: Is Georgia Climate-ready?
%8 November 2-3, 2016
%9 Poster
%Z presented
%M GCE.1032
%A Miklesh, David Michael
%A McKnight, Charles Jared
%A Di Iorio, Daniela
%A Meile, Christof
%K porewater salinity marsh, Student Publication

%0 Conference Proceedings
%T Physical, Hydrological, and Biological Processes Controlling Porewater Salinity Distributions in a Southeastern Salt Marsh
%D 2016
%I IECA
%C San Antonio TX
%B International Erosion Control Association (IECA) Conference
%8 Feb 16-19, 2016
%9 Poster
%Z presented
%M GCE.969
%A Miklesh, David Michael
%A McKnight, Charles Jared
%A Di Iorio, Daniela
%A Meile, Christof
%K marsh, soil salinity, Student Publication

%0 Conference Proceedings
%T Processes controlling porewater salinity distributions in a Southeastern salt marsh
%D 2016
%I Geological Society of America
%C Columbia
%B Geological Society of America Southeastern Section 65th Annual Meeting
%8 March 31- April 1, 2016
%9 Poster
%Z presented
%M GCE.970
%A Miklesh, David Michael
%A McKnight, Charles Jared
%A Di Iorio, Daniela
%A Meile, Christof
%K marsh, soil salinity, Student Publication

%0 Journal Article
%T A smart classifier for extracting environmental data from digital image time-series: Applications for PhenoCam data in a tidal salt marsh
%D 2016
%V 84
%P 134-139
%B Environmental Modelling & Software
%9 Article
%Z published
%M GCE.986
%R 10.1016/j.envsoft.2016.06.025
%X PhenoCams are part of a national network of automated digital cameras used to assess vegetation phenology transitions. Effectively analyzing PhenoCam time-series involves eliminating scenes with poor solar illumination or high cover of non-target objects such as water. We created a smart classifier to process images from the “GCESapelo” PhenoCam, which photographs a regularly-flooded salt marsh. The smart classifier, written in R, assigns pixels to target (vegetation) and non-target (water, shadows, fog and clouds) classes, allowing automated identification of optimal scenes for evaluating phenology. When compared to hand-classified validation images, the smart classifier identified scenes with optimal vegetation cover with 96% accuracy and other object classes with accuracies ranging from 86 to 100%. Accuracy for estimating object percent cover ranged from 74 to 100%. Pixel-classification with the smart classifier outperformed previous approaches (i.e. indices based on average color content within ROIs) and reduced variance in phenology index time-series. It can be readily adapted for other applications.
%U http://www.sciencedirect.com/science/article/pii/S1364815216302729
%A O'Connell, Jessica
%A Alber, Merryl
%K Flooding, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Examination of Abiotic Drivers and Their Influence on Spartina alterniflora Biomass over a Twenty-Eight Year Period Using Landsat 5 TM Satellite Imagery of the Central Georgia Coast
%D 2016
%V 8
%N 6
%P 22
%B Remote Sensing
%S Remote Sensing in Coastal Environments
%9 Article
%Z published
%M GCE.961
%R 10.3390/rs8060477
%X We examined the influence of abiotic drivers on inter-annual and phenological patterns of aboveground biomass for Marsh Cordgrass, Spartina alterniflora, on the Central Georgia Coast. The linkages between drivers and plant response via soil edaphic factors are captured in our graphical conceptual model. We used geospatial techniques to scale up in situ measurements of aboveground S. alterniflora biomass to landscape level estimates using 294 Landsat 5 TM scenes acquired between 1984 and 2011. For each scene we extracted data from the same 63 sampling polygons, containing 1222 pixels covering about 1.1 million m2. Using univariate and multiple regression tests, we compared Landsat derived biomass estimates for three S. alterniflora size classes against a suite of abiotic drivers. River discharge, total precipitation, minimum temperature, and mean sea level had positive relationships with and best explained biomass for all dates. Additional results, using seasonally binned data, indicated biomass was responsive to changing combinations of variables across the seasons. Our 28-year analysis revealed aboveground biomass declines of 33%, 35%, and 39% for S. alterniflora tall, medium, and short size classes, respectively. This decline correlated with drought frequency and severity trends and coincided with marsh die-backs events and increased snail herbivory in the second half of the study period.
%U http://www.mdpi.com/2072-4292/8/6/477
%A O'Donnell, John
%A Schalles, John F.
%K 	coastal remote sensing, salt marsh ecology, vegetation stress, ecosystem health, Spartina alterniflora, Landsat 5 TM, long-term data, climate forcing, river discharge, sea level, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Recent declines in Georgia salt marsh plant  biomass and health are linked to climate and hydrologic variables
%D 2016
%I Georgia Department of Natural Resources Coastal Resources Division
%C Jekyll Island, GA
%B Georgia Department of Natural Resources Coastal Climate Change Conference: Prepare, Respond, and Adapt
%S Poster Session
%8 November 2, 2016
%9 Poster
%Z presented
%M GCE.1055
%X We studied aboveground biomass dynamics and spatial patterns of Spartina alterniflora in Georgia salt marshes. Geospatial techniques were used to scale up in situ measurements to landscape level estimates using 290 Landsat 5 TM scenes acquired between 1984 and 2011. Our 28-year analysis revealed biomass declines of 31.6 %, 33.4 %, and 38.7% for tall, medium, and short size classes of S. alterniflora. The declines correlated with increased drought frequency and severity and coincided with marsh die-back events and heightened snail herbivory – especially since 2000. To explain S. alterniflora biomass dynamics, we compared our estimates for each size class against a suite of abiotic drivers. Altamaha River discharge, total precipitation, minimum temperature, and mean sea level had positive relationships with and best explained biomass variations. Biomass was responsive to changing combinations of variables across all seasons. We recently extended our analysis to a much larger area (St. Simons Sound to the Savannah River) and found that these inter and intra-annual biomass patterns occur within this larger domain. Moreover, Spartina biomass was positively and strongly associated with proximity to larger river systems (Altamaha, Ogeechee, and Savannah) and periods of higher precipitation. We are currently extending our analysis to the period of Landsat 8 OLI sensor coverage, beginning in 2013. Collectively, these approaches should help to answer the question: Are the serious declines we documented in S. alterniflora biomass and Georgia salt marsh health cyclical in nature, or are they longer-term, directional changes related to global warming impacts?
%A O'Donnell, John
%A Schalles, John F.
%A Hladik, Christine M.
%K Georiga, salt marshes, Spartina, climate change, vegetation stress, above-ground biomass, SINERR Publication, Student Publication

%0 Journal Article
%T Methanotrophy controls groundwater methane export from a barrier island.
%D 2016
%V 179
%P 242-256
%B Geochimica et Cosmochimica Acta
%9 Article
%Z published
%M GCE.1070
%R 10.1016/j.gca.2016.01.022
%X Methane concentrations can be high in coastal groundwater, resulting in methane export driven by submarine groundwater discharge. However, the magnitude of this methane flux depends significantly on the rate of methanotrophy, the often overlooked process of microbial methane consumption that occurs within coastal aquifer sediments. Here we describe a zone of methanogenesis within the freshwater lens of a barrier island aquifer and investigate the methane source/sink behavior of the barrier island system as a whole. The median concentration of methane dissolved in fresh groundwater beneath the center of the island was 0.6 mM, supported by high rates of potential methanogenesis (22 mmol m&#8722;2 day&#8722;1). However, rates of microbial methane consumption were also elevated in surrounding sediments (18 mmol m&#8722;2 day&#8722;1). Groundwater flowing from the zone of methanogenesis to the point of discharge into the ocean had a long residence time within methanotrophic sediments (&#8764;195 days) such that the majority of the methane produced within the barrier island aquifer was likely consumed there.
%A Schutte, Charles
%A Wilson, Alicia M.
%A Evans, Tyler
%A Moore, Willard S.
%A Joye, Samantha B.
%K groundwater, methane, barrier island, Student Publication, UGAMI Publication

%0 Journal Article
%T Whether disturbances alter salt marsh soil structure dramaticallyaffects Spartina alterniflora recolonization rate
%D 2016
%V 7
%N 11
%P 16
%B Ecosphere
%9 Article
%Z published
%M GCE.1012
%R 10.1002/ecs2.1540
%X Disturbance regimes are shifting in response to climate change, land-use change, species’ invasions, and other stressors, challenging ecologists to improve understanding of the mechanisms controlling plant recovery under different  conditions. In this study, we investigate mechanisms that underpin plant recolonization of two types of disturbance: disturbances that remove standing plant biomass, but leave the underlying soil structure largely intact, and those that remove standing biomass and physically disrupt soil structure. In the southeastern United States, salt marshes, drought and invasive feral hogs (Sus scrofa) are associated with disturbances of these respective types and both leave behind mudflats dotted with patches of cordgrass (Spartina alterniflora), the system’s dominant foundation species. To test how disturbance type and remnant patch size may interact to affect cordgrass recolonization, we transplanted replicate cordgrass patches of three sizes into one mudflat that experienced vegetation-only disturbance (VD) during a recent drought, and a second mudflat where hog activities had disrupted the soil structure creating a soil + vegetation disturbance (soil + VD). Over one year, we monitored plant performance and properties of soil. Compared with the drought-associatedVD where patches, regardless of their size, expanded vigorously, large and medium patches grew little and smaller patches even less in the hog-associated soil + VD mudflat. Moreover while biogeochemical properties varied little in the VD compared with adjacent vegetated marsh areas, the mudflats with soil + VD had less soil-binding organic matter and, hence, were too soft to support crab burrows, leading to a reduction in oxygen availability and cordgrass expansion. These results indicate that cordgrass recovery is far faster from disturbances that do not degrade soil structure than those that do and therefore advocate for disturbance-specific management strategies. Specifically, while transplanting patches is effective in restoring marshes disturbed by drought, wrack, or other factors that leave soil structure intact, preventative measures, like hog population culling, are essential to mitigating the ecological impacts of soil structure-altering disturbances.
%A Sharp, Sean
%A Angelini, Christine
%K biogeochemistry, drought, ecosystem engineers, foundation species, invasive species, resilience, restoration, Sus scrofa, wetland, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Thresholds in marsh resilience to the Deepwater Horizon oil spill
%D 2016
%V 6
%N 32520
%B Scientific Reports
%9 Article
%Z published
%M GCE.991
%R 10.1038/srep32520
%X Ecosystem boundary retreat due to human-induced pressure is a generally observed phenomenon. However, studies that document thresholds beyond which internal resistance mechanisms are overwhelmed are uncommon. Following the Deepwater Horizon (DWH) oil spill, field studies from a few sites suggested that oiling of salt marshes could lead to a biogeomorphic feedback where plant death resulted in increased marsh erosion. We tested for spatial generality of and thresholds in this effect across 103 salt marsh sites spanning ~430&#8201;kilometers of shoreline in coastal Louisiana, Alabama, and Mississippi, using data collected as part of the natural resource damage assessment (NRDA). Our analyses revealed a threshold for oil impacts on marsh edge erosion, with higher erosion rates occurring for ~1–2 years after the spill at sites with the highest amounts of plant stem oiling (90–100%). These results provide compelling evidence showing large-scale ecosystem loss following the Deepwater Horizon oil spill. More broadly, these findings provide rare empirical evidence identifying a geomorphologic threshold in the resistance of an ecosystem to increasing intensity of human-induced disturbance.
%A Silliman, Brian R.
%A Dixon, Philip M.
%A Wobus, Cameron
%A He, Qiang
%A Daleo, P.
%A Hughes, Brent B.
%A Rissing, Matthew
%A Willis, Jonathan M.
%A Hester, Mark
%K marsh resilience, salt marsh

%0 Conference Proceedings
%T Seawater Addition Long Term Experiment (SALTEx)
%D 2016
%C Jekyll Island, GA
%B Georgia Department of Natural Resources Coastal Resources Division 2016 Climate Conference
%8 November 2-3, 2016
%9 Poster
%Z presented
%M GCE.1041
%X Sea level rise and changes in river flows are expected to alter estuarine salinity gradients, resulting in saltwater intrusion into historically freshwater environments. Seawater Addition Long Term Experiment (SALTEx) is a field experiment designed to simulate saltwater intrusion in a tidal freshwater wetland to predict how chronic (Press) and acute (Pulse) salinization will affect this and other tidal freshwater ecosystems. Porewater chloride and sulfate concentrations increased in the Press plots within 2-3 months after treatments were initiated in April 2014. Increased sulfate reduction in response to seawater sulfate additions led to elevated porewater sulfide concentrations in the Press plots. Pulse additions of seawater in September-October of 2014 and 2015 led to transient increases in porewater chloride concentrations. In the first year of treatments, Ludwigia was eliminated from the Press plots and percent cover of Polygonum, Pontederia, and Zizaniopsis decreased.  Ludwigia also disappeared from the Pulse plots in the first treatment year, and did not recover when pulse treatments ceased. Net ecosystem productivity and methane emissions decreased in the Press plots in 2014 and remained low in 2015, but were unaffected by the Pulse treatments in both years. Our findings indicate that chronic (Press) additions of brackish water have an immediate effect on porewater chemistry, followed by the loss of soft-stem/emergent vegetation, and result in a negative effect on ecosystem processes.
%A Smith, Dontrece
%A Herbert, Ellen
%A Li, Fan
%A Widney, Sarah
%A Desha, Jennifer
%A Schubauer-Berigan, Joseph P.
%A Pennings, Steven C.
%A Angelini, Christine
%A Medeiros, Patricia M.
%A Byers, James
%A Alber, Merryl
%A Craft, Christopher B.
%K climate change, sulfur, vegetation, greenhouse gases, Student Publication

%0 Conference Proceedings
%T Seawater Addition Long Term Experiment (SALTEx)
%D 2016
%I Southeastern Estuarine Research Society
%C Bluffton, South Carolina
%B SEERS 2016 Spring Meeting
%8 March 10-12, 2016
%9 Poster
%Z presented
%M GCE.959
%X SALTEx is a field experiment designed to simulate the effects of saltwater intrusion in a tidal freshwater marsh to help GCE scientists understand and predict changes resulting from chronic and acute salinization driven by sea level rise and climate variability.
%U http://gce-lter.marsci.uga.edu/public/uploads/SALTEx_SEERS2016_Poster_20160318T134204.pdf
%A Smith, Dontrece
%A Herbert, Ellen
%A Li, Fan
%A Widney, Sarah
%A Desha, Jennifer
%A Schubauer-Berigan, Joseph P.
%A Pennings, Steven C.
%A Angelini, Christine
%A Medeiros, Patricia M.
%A Byers, James
%A Alber, Merryl
%A Craft, Christopher B.
%K seawater, salt, experiment, marsh, inundation, disturbance, manipulation, Student Publication

%0 Journal Article
%T Ammonia oxidation is inhibited by hydrogen peroxide at environmentally-relevant concentrations.
%D 2016
%B Frontiers in Microbiology
%9 Article
%Z published
%M GCE.973
%X Marine Thaumarchaeota were discovered over 20 years ago and although a few isolates from this group are now available for study, we do not yet understand the environmental controls on their growth and distribution. Thaumarchaeotes oxidize ammonia to nitrite, mediating a key step in the global nitrogen cycle, and it is estimated that about 20% of all prokaryotic cells in the ocean belong to this phylum. Despite their almost ubiquitous distribution, marine Thaumarchaeota are rarely abundant in open-ocean surface (<100 m) waters. We tested the hypothesis that this vertical distribution is driven by reactive oxygen species (ROS), specifically H2O2, generated by photochemical and biological processes – ‘indirect photoinhibition’ rather than light inhibition as previously postulated for ammonia-oxidizing Archaea. Here we show that H2O2 can be surprisingly toxic to Thaumarchaeota from the Southern Ocean, with ammonia oxidation inhibited by additions of as little as 10 nM H2O2, while temperate Thaumarchaeota ecotypes were more tolerant. This sensitivity could explain the seasonal disappearance of Thaumarchaeota from polar surface waters and the increase in ammonia oxidation rates with depth commonly observed in marine environments. Our results highlight the need for further physiological studies of Thaumarchaeota, and indicate that ROS sensitivity could be used as a characteristic for dividing the group into meaningful ecotypes.
%A Tolar, Bradley
%A Powers, Leanne C
%A Miller, William
%A Wallsgrove, Natalie J.
%A Popp, Brian N.
%A Hollibaugh, James T.
%K Thaumarchaeota, ammonia oxidation, nitrification, nitrogen, ammonia, reactive oxygen species, hydrogen peroxide., Cross-site Research, Student Publication, UGAMI Publication

%0 Journal Article
%T Contribution of ammonia oxidation to chemoautotrophy in Antarctic coastal waters
%D 2016
%P 1-15
%B The ISME Journal
%9 Article
%Z published
%M GCE.963
%R 10.1038/ismej.2016.61
%X There are few measurements of nitrification in polar regions, yet geochemical evidence suggests that it is significant, and chemoautotrophy supported by nitrification has been suggested as an important contribution to prokaryotic production during the polar winter. This study reports seasonal ammonia oxidation (AO) rates, gene and transcript abundance in continental shelf waters west of the Antarctic Peninsula, where Thaumarchaeota strongly dominate populations of ammonia-oxidizing organisms. Higher AO rates were observed in the late winter surface mixed layer compared with the same water mass sampled during summer (mean±s.e.: 62±16 versus 13±2.8&#8201;nm per day, t-test P<0.0005). AO rates in the circumpolar deep water did not differ between seasons (21±5.7 versus 24±6.6&#8201;nm per day; P=0.83), despite 5- to 20-fold greater Thaumarchaeota abundance during summer. AO rates correlated with concentrations of Archaea ammonia monooxygenase (amoA) genes during summer, but not with concentrations of Archaea amoA transcripts, or with ratios of Archaea amoA transcripts per gene, or with concentrations of Betaproteobacterial amoA genes or transcripts. The AO rates we report (<0.1–220&#8201;nm per day) are ~10-fold greater than reported previously for Antarctic waters and suggest that inclusion of Antarctic coastal waters in global estimates of oceanic nitrification could increase global rate estimates by ~9%. Chemoautotrophic carbon fixation supported by AO was 3–6% of annualized phytoplankton primary production and production of Thaumarchaeota biomass supported by AO could account for ~9% of the bacterioplankton production measured in winter. Growth rates of thaumarchaeote populations inferred from AO rates averaged 0.3 per day and ranged from 0.01 to 2.1 per day.
%U http://www.nature.com/ismej/journal/vaop/ncurrent/abs/ismej201661a.html
%A Tolar, Bradley
%A Ross, Meredith
%A Wallsgrove, Natalie J.
%A Liu, Qian
%A Aluwihare, Lihini I.
%A Popp, Brian N.
%A Hollibaugh, James T.
%K ammonia oxidation, chemoautotrophy, coastal waters, Antarctic, Cross-site Research, Student Publication

%0 Journal Article
%T Oxidation of urea nitrogen in marine nitrifying communities dominated by Thaumarchaeota
%D 2016
%B Environmental Microbiology
%9 Article
%Z published
%M GCE.971
%R 10.1111/1462-2920.13457
%X Urea nitrogen has been proposed to contribute significantly to nitrification by marine thaumarchaeotes.  These inferences are based on distributions of thaumarchaeote urease genes rather than activity measurements. We found that ammonia oxidation rates were always higher than oxidation rates of urea-derived N in samples from coastal Georgia, USA (means±SEM: 382±35 versus 73±24 nmol L-1 d-1, Mann-Whitney U-test p<0.0001), and the South Atlantic Bight (20±8.8 versus 2.2±1.7 nmol L-1 d-1, p=0.026) but not the Gulf of Alaska (8.8±4.0 versus 1.5±0.6, p>0.05).  Urea-derived N was relatively more important in samples from Antarctic continental shelf waters, though the difference was not statistically significant (19.4±4.8 versus 12.0±2.7 nmol L-1 d-1, p>0.05).  We found only weak correlations between oxidation rates of urea-derived N and the abundance or transcription of putative Thaumarchaeota ureC genes.  Dependence on urea-derived N does not appear to be directly related to pH or ammonium concentrations.  Competition experiments and release of 15NH3 suggest that urea is hydrolyzed to ammonia intracellularly, then a portion is lost to the dissolved pool.  The contribution of urea-derived N to nitrification appears to be minor in temperate coastal waters, but may represent a significant portion of the nitrification flux in Antarctic coastal waters.
%U http://gce-lter.marsci.uga.edu/public/uploads/Tolar_et_al_2016_Environ_Microbiol_20160906T155450.pdf
%A Tolar, Bradley
%A Wallsgrove, Natalie J.
%A Popp, Brian N.
%A Hollibaugh, James T.
%K Nitrification, urea, Thaumarchaeota, ammonia oxidation, Duplin River, PAL-LTER, GCE-LTER, South Atlantic Bight, Southern Ocean, Antarctica, Cross-site Research, Student Publication

%0 Journal Article
%T Revisiting the resilience of Late Archaic hunter-gatherers along the Georgia coast
%D 2016
%V 43
%P 39-55
%B Journal of Anthropological Archaeology
%9 Article
%Z published
%M GCE.1000
%R 10.1016/j.jaa.2016.05.006
%X This paper addresses fisher-hunter-gatherer settlement and subsistence variability of the Georgia Coast during the Archaic-Woodland transition, framed within ideas derived from Resilience Theory, and focusing on systemic shifts, or “collapse.” A critical examination of these shifts is needed to understand how communities experience change differentially, which in turn can lead to differential community resilience. Analysis of site file and radiocarbon date databases, as well as Bayesian modeling on a subset of dates, was performed at multiple scales and within distinct micro-environmental habitats. Results indicate that as sea levels dropped, there was continuity in Late Archaic occupation within deltaic areas of the coast, with intensive shellfishing occurring earlier (&#8764;5000 cal. BP) and lasting longer (&#8764;3500 cal. BP). In certain habitats, occupation may have continued into the following Early Woodland period. In non-deltaic areas, shellfishing occurs between 4500 and 3800 cal. BP, followed by subsistence changes and population movement. However, some of the post-3800 cal. BP occupations were fairly substantial. This differential experience of change between deltaic and non-deltaic areas was not accompanied by collapse: both areas had resilient communities. We conclude that inter-village relationships developed during the early Late Archaic period continued into the terminal portion, leading to resilience in the face of change.
%A Turck, John A.
%A Thompson, Victor D.
%K Resilience theory, Spatial analysis, Radiocarbon, Island and coastal, American Southeast, Archaic, Student Publication

%0 Journal Article
%T How habitat-modifying organisms structure the food web of two coastal ecosystems
%D 2016
%V 283
%N 1826
%P 9
%B Proc. R. Soc. B
%9 Article
%Z published
%M GCE.992
%R 10.1098/rspb.2015.2326
%X The diversity and structure of ecosystems has been found to depend both on trophic interactions in food webs and on other species interactions such as habitat modification and mutualism that form non-trophic interaction networks. However, quantification of the dependencies between these two main interaction networks has remained elusive. In this study, we assessed how habitat-modifying organisms affect basic food web properties by conducting in-depth empirical investigations of two ecosystems: North American temperate fringing marshes and West African tropical seagrass meadows. Results reveal that habitat-modifying species, through non-trophic facilitation rather than their trophic role, enhance species richness across multiple trophic levels, increase the number of interactions per species (link density), but decrease the realized fraction of all possible links within the food web (connectance). Compared to the trophic role of the most highly connected species, we found this non-trophic effects to be more important for species richness and of more or similar importance for link density and connectance. Our findings demonstrate that food webs can be fundamentally shaped by interactions outside the trophic network, yet intrinsic to the species participating in it. Better integration of non-trophic interactions in food web analyses may therefore strongly contribute to their explanatory and predictive capacity.
%A van der Zee, Els M.
%A Angelini, Christine
%A Govers, Laura L.
%A Christianen, Marjolijn J.A.
%A Alteiri, A.
%A van der Reijden, Karin J.
%A Silliman, Brian R.
%A van de Koppel, Johan
%A van der Geest, Matthiis
%A van Gils, Jan A.
%A van der Veer, Henk W.
%A Piersma, Theunis
%A de Ruiter, Peter C.
%A Olff, Han
%A van der Heide, Tjisse
%K consumer–resource interactions, non-trophic interactions, facilitation, ecological networks, ecosystem engineering, foundation species

%0 Book
%T Wetland Soils: Genesis, Hydrology, Landscapes, and Classification
%D 2016
%I CRC Press
%C Boca Raton, FL
%7 2nd
%9 Book
%Z published
%M GCE.940
%A Vepraskas, M.J.
%A Craft, Christopher B.
%E Vepraskas, M.J.
%E Craft, C.B.
%K wetland soils, hydric soils, hydrology

%0 Thesis
%T Biophysical Feedbacks Mediate Tidal Creek Formation in Salt Marshes
%D 2016
%P 93
%I University of Houston
%C Houston, Texas
%9 Ph.D. Dissertation
%Z published
%M GCE.1006
%X How organisms and ecological systems respond to global change is of great interest to ecologists. These responses may or may not be beneficial because there might be positive or negative feedbacks that would make the impacts larger or smaller than expected. I conducted laboratory and field experiments to explore the mechanisms driving tidal creek formation in southeastern US salt marshes, focusing on three topics. 1) The effect of crabs on creek growth via four potential mechanisms: sediment excavation, plant removal, subterranean erosion, and decomposition. I found that Sesarma reticulatum (henceforth Sesarma) is the primary crab species mediating creek growth.Sesarma is concentrated at creek heads where plants are dying and creeks eroding.Sesarma excavated larger amounts of sediment through burrowing than other crabs, and is unique in creating burrow networks that likely increase belowground erosion and decomposition. Sesarma also is the only crab species that directly kills vegetation. Thus, Sesarma negatively impacts the marsh plant Spartina alterniflora and alters marsh geomorphology by engineering creek growth. 2) The factors mediating crab feeding preferences. I discovered that Sesarma did less damage to its food plant S. alterniflora in the presence of predators. Sesarma prefers and grows better consuming rhizomes than leaves; however, the cost of accessing rhizomes leads to higher mortality if rhizomes are the only diet option. A choice in feeding location allows Sesarma flexibility to balance the risks of predation, the nutritional benefit of feeding below-ground, and the survival costs of below-ground feeding. 3) The factors driving the aggregation and movement of Sesarma at creek heads. Creek heads are cooler, have higher dissolved oxygen levels, and lower hydrogen sulfide concentrations than elsewhere on the marsh. These superior conditions drive Sesarma aggregation. Additionally, I found that hydrology drives Sesarma aggregations when creek conditions were mimicked on the marsh platform. Theresults of this dissertation suggest that there is a biophysical feedback loop in marsh creek formation: creek growth is driven by a positive feedback between Sesarma crabs, which accelerate erosion, and creeks, which create abiotic conditions favorable for Sesarma crabs.
%A Vu, Huy
%K Tidal Creek, Biophysical feedbacks, salt marshes, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Inorganic carbon and oxygen dynamics in a marsh-dominated estuary
%D 2016
%P 81
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.1009
%X We conducted a study to address uncertainties associated with the metabolism and netcarbon fluxes for the tidal wetland and estuarine portion of the coastal ocean because of thesezones disproportionately large role in ocean carbon dynamics. We measured open water diurnalO2 and CO2 dynamics seasonally in the Duplin River salt marsh-estuary in Georgia, USA with aparticular focus on the marsh-estuary linkage associated with tidal flooding. We observed that theoverall system was a net source of CO2 to the atmosphere and adjacent coastal ocean and a netsink for oceanic and atmospheric O2. Rates of metabolism were extremely high, with respiration(R: 43 mol/m2/yr) exceeding gross primary production (GPP: 28 mol/m2/yr). Rates of metabolismmeasured with CO2 were substantially higher than with O2. The net heterotrophy of the aquaticsalt marsh-estuary system is supported primarily by the net production of the salt marsh proper.
%A Wang, Shiyu
%K salt marsh, estuary, metabolism, CO2 exchange, O2 exchange, inundation, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Fronts and variability in the coastal ocean
%D 2016
%P 231
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.997
%X The coastal ocean is characterized by strong gradients in water properties, which influences circulation and ocean-atmosphere interactions. Fronts and variability in the coastal ocean are studied using a combination of satellite observations and numerical model simulations. Satellite sea surface temperature (SST) and wind observations are used to describe the seasonal evolution of temperature fronts and their relation to wind forcing in Eastern Boundary Current Systems (EBCS). Front activity is closely related to seasonal variability in wind forcing and to the presence of topographic perturbations such as capes. Investigation of the coupling between SST gradients and wind variables in the global coastal ocean reveals that regions with strong front activity are generally also characterized by strong ocean-atmosphere interaction. Mid-latitude regions, especially in EBCS, are characterized by enhanced ocean-atmosphere coupling during local summer. In several low-latitude regions, however, the coupling is stronger during winter. Although the coupling between SST gradients and wind stress divergence is stronger at seasonal scales, intraseasonal variability associated with mesoscale eddies is stronger for the coupling between SST gradients and wind stress curl. Coastal regions can also present strong salinity gradients, especially near river mouths. The circulation at a complex estuarine system off Georgia is investigated using a numerical model. The estuary includes three major sounds that are connected by a network of channels, creeks and intertidal areas. Spatial and temporal variability in residence time and connectivity between the sounds are influenced primarily by the Altamaha River discharge, by seasonally-varying winds, and by tidal forcing.
%A Wang, Yuntao
%K Coastal ocean, Front, Ocean-atmosphere interaction, Residence time, Connectivity, Estuary of Georgia, Student Publication, UGAMI Publication

%0 Thesis
%T Identifying the factors affecting copper speciation in estuarine, coastal and open ocean waters
%D 2016
%P 181
%I University of Liverpool, School of Environmental Sciences, Department of Earth, Ocean and Ecological Sciences
%C Liverpool, England
%9 Ph.D. Dissertation
%Z published
%M GCE.1014
%X Copper (Cu) is an important micronutrient, predominantly occurring as organic complexes in marine waters. The composition of the ligands forming these metal complexes has implications for the bioavailability of the trace metals to marine microorganisms, both as nutrients and toxicants. A variety of samples from estuarine, coastal and open ocean waters were studied in an effort to further our understanding of the ligands responsible for controlling the bioavailability of copper. Presented here are findings on the nature and likely identity of such ligands, including humic substances and various thiols. A novel method was developed to measure copper-binding humic substances, which werediscovered to be synonymous with iron-binding humic substances. Using the new method on samples from the Mersey Estuary, humics were found to account for around 70% of the total ligand available for copper complexation in the estuarine and coastal samples. Samples from a very different estuarine environment, Sapelo Nature Reserve, Georgia, were then analysed in order to study potential copper limitation in blooms of Thaumarchaeota, prolific to the region and with a high copper requirement. Again, it was discovered that around 70% of the total available ligand for copper were humic substances, but that over 90% of the copper was complexed to thiourea-type thiols, also present in excess of the copper concentration. Comparing competitive ligand exchange (CLE) titrations to independent measurements of thiols and humic substances, the L1 and L2 ligand classes obtained viatitrations were found to correlate very well with thiols and humics respectively, providing an indication of the nature of the ligands responsible for copper complexation. Furthermore, these findings suggested that copper was predominantly complexed (90%) as Cu(I), contrary to our current understanding of copper speciation. A study across the seasonal cycle at these stations provided further insight into the complexities of copper speciation. Cu2+ was found to be exceptionally low throughout the study, at sub-femtomolar concentrations, and lowest during the Thaumarchaeota bloom itself. Although previously considered to be limited by Cu2+ concentrations lower than 2 x10-13 M (when induced by the presence of artificial ligands), here it was demonstrated that Thaumarchaeota must be able to access the naturally complexed copper in order to bloom at these levels, posing questions for our understanding of copper bioavailability to these organisms. Finally, the copper speciation of two profiles from Line P of the Northeast Pacific, coastal station P4 and open ocean station P26, were assessed in an attempt to characterise the ligands in ocean samples. Thiols and humic substances were detected at both stations but at concentrations lower than the ligand concentrations measured from titrations, suggesting additional ligands play a part in copper complexation in the open ocean.
%A Whitby, Hannah
%K copper, metal, coastal, ocean, chemistry, estuary, Student Publication

%0 Journal Article
%T Sea surface aragonite saturation state variations and control mechanisms at the Gray's Reef time-series site off Georgia, USA (2006–2007)
%D 2016
%V 195
%P 27-40
%B Marine Chemistry
%9 Article
%Z published
%M GCE.1057
%R 10.1016/j.marchem.2017.05.009
%X We report an annual cycle of surface seawater aragonite mineral saturation state (&#937;arag) during 2006–2007 at the Gray's Reef time-series site off Georgia, USA, calculated based on three-hourly observations of carbon dioxide partial pressure (pCO2) and salinity-derived total alkalinity. &#937;arag varied between 2.30 and 4.39 with low values (< 3.00) mainly during February–April 2007 and high values (> 3.50) during July–October 2006 and July–September 2007 as well as during two biological production spikes (April–June 2007). We first present a qualitative analysis of the drivers of &#937;arag variability based on property regressions with surface temperature, salinity and apparent oxygen utilization, and then quantify the contributions of temperature, air-sea exchange, mixing, and biological processes to monthly &#937;arag net changes using a simple 1-D mass budget model. Our analyses suggest that river inputs played the most important role in the seasonal variation of surface &#937;arag, in contrast to temperature control on pCO2. Nevertheless, the primary processes controlling monthly &#937;arag net change varied with time of year. Furthermore, river inputs lowered &#937;arag by 0.28 and 0.48 in July–August and September–October 2007 relative to the equivalent periods of 2006. This implies that interannual &#937;arag variability at this location may be greater than that due to the influence of increased atmospheric CO2 over the past few decades, making efforts to discern decadal coastal ocean acidification trends particularly challenging. In addition, although sea surface salinity varies substantially in coastal waters, our analysis suggests that similar to the open ocean &#937;arag is essentially determined by carbonate ion concentration ([CO32 &#8722;]), not calcium ion concentration ([Ca2 +]) or the stoichiometric solubility product (K&#8242;sp), both varying substantially with salinity. Finally, we show that the difference between total alkalinity (TA) and dissolved inorganic carbon (DIC) is a better proxy for [CO32 &#8722;] and &#937;arag compared with the ratio (TA/DIC) and helps to better elucidate processes affecting &#937;arag in coastal oceans.
%U https://www.researchgate.net/publication/317300430_Sea_surface_aragonite_saturation_state_variations_and_control_mechanisms_at_the_Gray's_Reef_time-series_site_off_Georgia_USA_2006-2007
%A Xue, Liang
%A Cai, Wei-Jun
%A Sutton, Adrienne J.
%A Sabine, Christopher
%K Aragonite, saturation state, Time-series, Coastal waters, South Atlantic Bight

%0 Conference Proceedings
%T AMBUR-HVA: A New Hazard Vulnerability Assessment Tool for Regional Coastal Resiliency Planning.
%D 2015
%C Fort Lauderdale, FL
%B SURA Coastal Resilience Workshop
%8 October 26-28, 2015
%9 Poster
%Z presented
%M GCE.929
%A Alexander, Clark R., Jr.
%A Jackson, C.
%A Jaeger, J.M.
%A Corbett, D.R.
%A Howard, S.
%A Walsh, J.P.
%K Coastal Resiliency, Vulnerability Assessment

%0 Journal Article
%T Spillover of Secondary Foundation Species Transforms Community Structure and Accelerates Decomposition in Oak Savannas
%D 2015
%V 18
%P 780-791
%B Ecosystems
%9 Article
%Z published
%M GCE.1001
%R 10.1007/s10021-015-9862-0
%X Secondary foundation species facilitate biodiversity by providing complex habitat within the protective structures of many primary foundation species; whether they retain this role when they are dispersed in novel environments is unclear. Here, we explore how secondary foundation species’ density within hosts controls the rate at which individuals accrue and test if dislodged secondary foundation species then bolster the abundance and diversity of associated species and decomposition in a widespread system: southern live oaks, Quercus virginiana, hosting festoons of the bromeliad, Tillandsia usneoides, in southeastern US savannas. One year of monitoring showed that as Tillandsia density within oaks increases, Tillandsia deposition beneath oaks increases linearly in kind. Once on the ground, two manipulative experiments revealed that: on small scales, individual festoons retain moisture, reduce temperature, and facilitate invertebrates and fungi which combine to accelerate litter decomposition and, on larger scales, continual deposition of festoons dramatically reduces grass cover and increases litter layer depth, invertebrate and fungi richness and density, and decomposition. Surveys further suggest that Tillandsia populations within oaks, in moderating festoon accumulation, are shaping understory communities throughout this geographic region. Thus, disturbance-induced spillover enables secondary foundation species to define biodiversity and ecosystem functioning beyond the boundaries of their hosts.
%A Angelini, Christine
%A Briggs, Kristen
%K biodiversity, decomposition, ecosystem function, facilitation, fungi, invertebrate, litter layer, Tillandsia usneoides, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Foundation species' overlap enhances biodiversity and ecosystem multifunctionality from the patch to landscape scale.
%D 2015
%B Proceedings of the Royal Society B
%9 Article
%Z published
%M GCE.934
%R 10.1098/rspb.2015.0421
%X Although there is mounting evidence that biodiversity is an important and widespread driver of ecosystem multifunctionality, much of this research has focused on small-scale biodiversity manipulations. Hence, which mechanisms maintain patches of enhanced biodiversity in natural systems and if these patches elevate ecosystem multifunctionality at both local and landscape scales remain outstanding questions. In a 17 month experiment conducted within southeastern United States salt marshes, we found that patches of enhanced biodiversity and multifunctionality arise only where habitat-forming foundation species overlap--i.e. where aggregations of ribbed mussels (Geukensia demissa) form around cordgrass (Spartina alterniflora) stems. By empirically scaling up our experimental results to the marsh platform at 12 sites, we further show that mussels--despite covering only approximately 1% of the marsh surface--strongly enhance five distinct ecosystem functions, including decomposition, primary production and water infiltration rate, at the landscape scale. Thus, mussels create conditions that support the co-occurrence of high densities of functionally distinct organisms within cordgrass and, in doing so, elevate salt marsh multifunctionality from the patch to landscape scale. Collectively, these findings suggest that patterns in foundation species' overlap drive variation in biodiversity and ecosystem functioning within and across natural ecosystems.We therefore argue that foundation species should be integrated in our conceptual understanding of forces that moderate biodiversity--ecosystem functioning relationships, approaches for conserving species diversity and strategies to improve the multifunctionality of degraded ecosystems.
%A Angelini, Christine
%A van der Heide, J.
%A Griffin, John
%A Derksen-Hooijberg, M.
%A Lamers, L.P.M.
%A Smolders, Alfons J. P.
%A Silliman, Brian R.
%K decomposition, ecosystem function, facilitation, primary production, salt marsh, Spartina alterniflora, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Consumer- plant interaction strength: importance of body size, density and metabolic biomass.
%D 2015
%B OIKOS
%9 Article
%Z published
%M GCE.935
%R 10.1111/oik.01966
%X Explaining variability in the strength and sign of trophic interactions between primary consumers and plants is a long-standing research challenge. Consumer density and body size vary widely in space and time and are predicted to have interactive effects on consumer–plant interactions. In a southern US salt marsh, we used replicate field enclosures to orthogonally manipulate the body size (mass) and density of a dominant consumer (a snail). We investigated impacts (leaf damage and biomass) on monocultures of cordgrass, the foundation species, over three months. Increasing consumer density and body size increased leaf damage additively and, as predicted, multiplicatively reduced plant biomass. Notably, size and density determined the sign of consumer impact on plants: low to medium densities of small consumers enhanced, while high densities of large consumers strongly suppressed plant biomass. Finally, total consumer metabolic biomass (mass0.75) within an enclosure parsimoniously explained plant biomass response, supporting theoretical predictions and suggesting that multiplicative effects of density and body size resulted from their effects on total metabolic biomass. The consequences of changes in consumer density and body size resulting from anthropogenic perturbations may therefore be predicted based on metabolic biomass.
%A Atkins, Rebecca
%A Griffin, John N.
%A Angelini, Christine
%A O'Connor, M.I.
%A Silliman, Brian R.
%K consumer-plant interactions, snail, salt marsh, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Armored Estuarine Shorelines of Coastal Georgia - Patterns, Trends and Projections.
%D 2015
%C Portland, OR
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 November 8-12, 2015
%9 Poster
%Z presented
%M GCE.926
%A Bulski, K.
%A Alexander, Clark R., Jr.
%A Venherm, Claudia
%A Robinson, Michael
%A DeLeo, LeeAnn
%K Armored shorelines, Coastal Georgia

%0 Journal Article
%T Non-consumptive predator effects intensify grazer-plant interactions by driving vertical habitat shifts.
%D 2015
%V 537
%P 49-58
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.936
%R 10.3354/meps11419
%X Predators non-consumptively induce prey habitat shifts, driving trait-mediated indirect interactions (TMIIs) with basal resources. Whether prey seek refuge within or avoid predator-containing patches determines the spatial re-distribution of prey and influences the nature of resulting TMIIs. In a southeastern US salt marsh we tested how two species of sit-and-wait benthic predatory crab non-consumptively affect the habitat choices of grazing snails and how the resultant behavior affects cordgrass health. We first observed that snails climb higher on cordgrass around naturally-occurring crab burrows and that this habitat shift corresponds with increased cordgrass leaf damage, suggesting a localized TMII. Then, by adding caged crabs to artificial burrows in the field, we found causative evidence that either crab species could drive snails upwards to the cordgrass canopy, thereby increasing leaf damage within a ~12 cm radius, but found no evidence that experimentally added crabs induce horizontal dispersal of snails. Next, in a marsh undergoing die-off, we added caged crabs to remnant cordgrass patches being rapidly colonized by snails. Crabs did not affect the rate of snail colonization of remnant patches, but did drive snails upwards once they had colonized a patch, suggesting snails do not preferentially avoid - but alter how they locally utilize - patches of cordgrass in marsh die-off contexts. Our documentation of the spatial-scale and dimensionality of TMIIs in the field paves the way for spatially- explicit models of this interaction. More generally, our results suggest that TMIIs may be consistent, predictable and tractable, lending themselves to incorporation into food-web models.
%U https://www.int-res.com/articles/meps2015/537/m537p049.pdf
%A Davidson, Andrew
%A Griffin, John
%A Atkins, Rebecca
%A Angelini, Christine
%A Coleman, F.
%A Silliman, Brian R.
%K predator-prey interactions, habitat shifts, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Geospatial analysis of the distribution and variability of Spartina wrack in Georgia marshes.
%D 2015
%C Portland, OR
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 November 8-12, 2015
%9 Poster
%Z presented
%M GCE.925
%A DeLeo, LeeAnn
%A Alexander, Clark R., Jr.
%A Robinson, Michael
%A Bulski, K.
%A Venherm, Claudia
%K Spartina, Georgia marshes, geospatial analysis

%0 Journal Article
%T Carbon sequestration in tidal salt marshes of the Northeast United States
%D 2015
%V 56
%N 4
%P 998-1008
%B Environmental Management
%9 Article
%Z published
%M GCE.939
%R 10.1007/s00267-015-0568-z
%X Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m(2) compared to 16.2 kg C/m(2) in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on Cs-137 and Pb-210 dating of soil cores, ranged from 41 to 152 g/m(2)/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands.
%U http://dx.doi.org/10.1007/s00267-015-0568-z
%A Drake, Katherine
%A Halifax, H
%A Adamowicz, Susan C.
%A Craft, Christopher B.
%K Salt marsh, Radiometric dating, Carbon sequestration, Management, US National Wildlife Refuge, Carbon trading

%0 Conference Proceedings
%T A conceptual model for predicting the ecological effects of coastal armoring in soft-sediment environments.
%D 2015
%C Estes Park, CO
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 August 30 - September 2, 2015
%9 Poster
%Z presented
%M GCE.931
%A Dugan, J.
%A Alber, Merryl
%A Alexander, Clark R., Jr.
%A Byers, James
%A Emery, K.
%A Gehman, Alyssa
%A Lawson, S.
%A McLenaghan, Natalie Ann
%K coastal armoring, modeling, soft sediments, Student Publication

%0 Conference Proceedings
%T A conceptual model for predicting the ecological effects of coastal armoring in soft-sediment environments.
%D 2015
%C Portland, OR
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 November 8-12, 2015
%9 Poster
%Z presented
%M GCE.924
%A Dugan, J.
%A Alber, Merryl
%A Alexander, Clark R., Jr.
%A Byers, James
%A Emery, K.
%A Gehman, Alyssa
%A Lawson, S.
%A McLenaghan, Natalie Ann
%K coastal armoring, modeling, soft sediments, Student Publication

%0 Conference Proceedings
%T Effects of development and shoreline armoring on the high marsh ecosystem.
%D 2015
%C Quebec City, CN
%B Benthic Society Ecology Meeting 2015
%8 March 4-7, 2015
%9 Poster
%Z presented
%M GCE.930
%A Gehman, Alyssa
%A McLenaghan, Natalie Ann
%A Byers, James
%A Alexander, Clark R., Jr.
%A Pennings, Steven C.
%A Alber, Merryl
%K Shoreline armoring, high marsh, Student Publication

%0 Journal Article
%T Comparison of the Gut Microbiomes of 12 Bony Fish and 3 Shark Species
%D 2015
%V 518
%P 209-223
%B Marine Ecology Progress Series
%9 Article
%Z Primary grant was NOAA Oceans and Human Health, but Givens and Hollibaugh were partially supported by GCE when writing the MS and GCE covered some of the materials and supplies used in the study
%M GCE.816
%R 10.3354/meps11034
%X We used massively parallel sequencing (pyrosequencing) of 16S rRNA genes to compare the composition of microbial communities in the guts of 12 bony fish and 3 shark species. The species analyzed encompass herbivores and carnivores with varied digestive physiologies, are classified as pelagic and demersal species, and reside in estuarine to marine environments. We also compared the gut microbial assemblages of wild and cultured Fundulus heteroclitus and of juvenile and adult Lagodon rhomboides. A total of 1 214 355 sequences were filtered, denoised, trimmed, and then sorted into operational taxonomic units (OTUs) based on 97% sequence similarity. Bacteria representing 17 phyla were found among the sampled fish, with most fish hosting between 7 and 15 phyla. Proteobacteria OTUs were present in all fish and often dominated the libraries (3.0 to 98%; average: 61%). Firmicutes were also prevalent, but at a lower relative abundance, ranging between 1.3 and 45% (average: 17%). In most cases, the gut microflora of individual fish of a given species contained many of the same OTUs; however, some species (e.g. great barracuda) shared few OTUs among the individuals sampled. Although no single OTU was shared among all fish species, many of the OTUs present in one species’ core group were also found in the core groups of other species. Several OTUs were consistently found in the guts of multiple species, suggesting that these OTUs may be important contributors to fish gut functions such as digestion, nutrient absorption, and immune response.
%U http://www.int-res.com/abstracts/meps/v518/
%A Givens, Carrie
%A Ransom, Briana
%A Bano, Nasreen
%A Hollibaugh, James T.
%K Fish gut, gut microbiome, 16S rRNA, gut microflora, 454-pyrosequencing, shark gut, core gut microbiome, Student Publication

%0 Journal Article
%T Does relative abundance modify multiple predator effects?
%D 2015
%V 7
%P 641-651.
%B Basic and Applied Ecology
%9 Article
%Z published
%M GCE.900
%R 10.1016/j.baae.2015.05.003
%X Ecologists have long known that multiple predator species can interact with each other and thereby either strengthen or weaken overall prey regulation. With few exceptions, our understanding of such ‘multiple predator effects’ (MPEs) is based on exper-imental combinations of predators at a single relative density (usually 1:1). Because MPEs depend on interspecific interactions between predators, we hypothesized they would vary, potentially non-linearly, with predator species relative abundance. We tested this hypothesis in a southeastern US salt marsh by manipulating two species of predatory crab to generate a continuous relative abundance gradient. After four months, we evaluated the density of two shared prey species (snails and fiddler crabs) across this gradient, before explicitly testing for: (1) the presence of overall MPEs on the densities of these prey; (2) whether (and how) potential MPEs varied as a function of relative abundance; and (3) how indicators of predator–predator interactions (survivorship and limbs lost in contests) were affected by relative abundance. The final density of both prey species varied with relative abundance, but the sign of these effects switched depending on prey identity. The results failed to support an overall MPE on snail density, but final fiddler crab density was higher than expected (i.e., risk reduction, or an overall negative MPE on fiddler crab suppression). Counter to our prediction, this MPE did not vary as a function of relative abundance. Predator survivorship and limb loss indicated asymmetrical negative interactions that strongly impacted the predator species most effective at sup-pressing fiddler crabs, suggesting an explanation for the negative MPE observed for this prey species. Our findings suggest that MPEs are not always sensitive to species relative abundance, but given that shifts in predator relative abundance are frequently observed in nature, future studies should incorporate this aspect of biodiversity change into their designs wherever possible.
%U https://www.researchgate.net/publication/277337467_Does_relative_abundance_modify_multiple_predator_effects
%A Griffin, John N.
%A Toscano, B.D.
%A Griffen, B.D.
%A Silliman, Brian R.
%K predator, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Geographic Variation in Plant Community Structure of Salt Marshes: Species, Functional and Phylogenetic Perspectives
%D 2015
%V 10
%N 5
%B PLOS ONE
%9 Article
%Z published
%M GCE.917
%R 10.1371/journal.pone.0127781
%X In general, community similarity is thought to decay with distance; however, this view maybe complicated by the relative roles of different ecological processes at different geographicalscales, and by the compositional perspective (e.g. species, functional group and phylogeneticlineage) used. Coastal salt marshes are widely distributed worldwide, but nostudies have explicitly examined variation in salt marsh plant community compositionacross geographical scales, and from species, functional and phylogenetic perspectives.Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, communityturnover would be more rapid at local versus larger geographical scales; and thatcommunity turnover patterns would diverge among compositional perspectives, with agreater distance decay at the species level than at the functional or phylogenetic levels. Wetested these hypotheses in salt marshes of two regions: The southern Atlantic and GulfCoasts of the United States. We examined the characteristics of plant community compositionat each salt marsh site, how community similarity decayed with distance within individualsalt marshes versus among sites in each region, and how community similarity differedamong regions, using species, functional and phylogenetic perspectives. We found that resultsfrom the three compositional perspectives generally showed similar patterns: therewas strong variation in community composition within individual salt marsh sites across elevation;in contrast, community similarity decayed with distance four to five orders of magnitudemore slowly across sites within each region. Overall, community dissimilarity of saltmarshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relativelymore important than regional processes in structuring coastal salt marsh communities. Ourresults also suggested that in ecosystems with low species diversity, functional and phylogeneticapproaches may not provide additional insight over a species-based approach.
%U http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0127781
%A Guo, Hongyu
%A Chamberlain, Scott A
%A Elhaik, Eran
%A Jalli, Inder
%A Lynes, Alana R.
%A Marczak, Laurie
%A Sabath, Niv
%A Vargas, Amy
%A Wieski, Kazimierz
%A Zelig, Emily
%A Pennings, Steven C.
%K trait-based, phylogeny, plants, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Sea-Level Rise and Sub-County Population Projections in Coastal Georgia.
%D 2015
%V 37
%P 44-62
%B Population and the Environment.
%9 Article
%Z published
%M GCE.920
%R 10.1007/s11111-015-0233-8
%X It is increasingly apparent that stressors associated with anthropocentric climate change are likely to have dramatic effects on future human settlement patterns. Although sea-level rise is one of the best understood implications of climate change, geographically precise estimation of potential population displacement due to tidewater inundation has proven remarkably problematic. At least within the USA, these problems partially stem from methodological limitations of population projection methodology at sub-county scales. Using a case study of coastal Georgia, USA, this paper develops and demonstrates a new housing unitbased population projection method that is applied at the sub-county scale of Census Block Groups. These projections are then overlaid with spatiotemporally explicit assessments of future sea-level rise inundation provided through the Sea Level Affecting Marsh Model (SLAMM). We find that between 62,000 and 159,000 people are at risk of between 1 and 2 m of sea-level rise by 2100 in coastal Georgia.
%A Hauer, M.
%A Evans, J
%A Alexander, Clark R., Jr.
%K Sea-level rise, Sub-county, Population projections, Hammer method, Housing unit method, Climate change

%0 Journal Article
%T Biogeographic consequences of nutrient enrichment for plant-herbivore interactions in coastal wetlands.
%D 2015
%V 18
%P 462–471
%B Ecology Letters
%9 Article
%Z published
%M GCE.899
%R 10.1111/ele.12429
%X A major challenge in ecology is to understand broadscale trends in the impact of environmental change. We provide the first integrative analysis of the effects of eutrophication on plants, herbivores, and their interactions in coastal wetlands across latitudes. We show that fertilisation strongly increases herbivory in salt marshes, but not in mangroves, and that this effect increases with increasing latitude in salt marshes. We further show that stronger nutrient effects on plant nitrogen concentration at higher latitudes is the mechanism likely underlying this pattern. This biogeographic variation in nutrient effects on plant–herbivore interactions has consequences for vegetation, with those at higher latitudes being more vulnerable to consumer pressure fuelled by eutrophication. Our work provides a novel, mechanistic understanding of how eutrophication affects plant–herbivore systems predictably across broad latitudinal gradients, and highlights the power of incorporating biogeography into understanding large-scale variability in the impacts of environmental change.
%U http://onlinelibrary.wiley.com/doi/10.1111/ele.12429/abstract
%A He, Qiang
%A Silliman, Brian R.
%K nutrients, wetlands, Cross-site Research

%0 Thesis
%T The effects of global change on the fate of soil organic matter in tidal freshwater wetlands
%D 2015
%I Indiana University
%C Bloomington, IN
%9 Ph.D. Dissertation
%Z published
%M GCE.941
%X Tidal wetlands are sentinel ecosystems for environmental change and human-induced degradation of natural systems. They have existed in a state of equilibrium with sea level rise (SLR) over the past 4,000 years by accumulating soil organic matter (SOM) produced by plants and trapping mineral sediment. Accumulation of SOM is controlled by the balance between plant productivity and decomposition. Both processes are susceptible to anthropogenic disturbance, including salinization caused by declining freshwater flows, eutrophication from fertilizer runoff, or accelerated SLR. I utilized field measurements and a stable-isotope tracer approach to examine how anthropogenic disturbances alter SOM through the direct effects of changes on microbial metabolism and the indirect effects mediated through changes in plant communities. Increased salinity and eutrophication accelerate microbial mineralization of organic matter by providing more energetically efficient metabolic pathways, sulfate reduction (salinity) and nitrate reduction (eutrophication). However, the microbial response is dwarfed by changes in plant productivity and biomass allocation. Salinity and eutrophication reduce total root biomass and allocation of carbon to the rooting zone. Incorporating the observed biogeochemical changes into models of marsh geomorphology reveals that increased salinity reduces the contribution of SOM to vertical accretion and reduces marsh resiliency to accelerated SLR. These results highlight the importance of the complex interactions between plant  productivity, microbial activity, and geomorphic processes in tidal wetland landscapes. Because tidal wetlands integrate impacts to both freshwater and marine systems, their survival depends on maintaining the integrity in the continuum of landscapes from the headwaters of rivers to theocean.
%A Herbert, Ellen
%K climate change, sea level rise, tidal freshwater wetlands, nutrient cycling, biogeochemistry, Student Publication

%0 Journal Article
%T A global perspective on wetland salinization: Ecological consequences of a growing threat to freshwater wetlands
%D 2015
%V 6(10)
%N 206
%P 1-43
%B Ecosphere
%9 Article
%Z published
%M GCE.902
%R 10.1890/ES14-00534.1
%X Salinization, a widespread threat to the structure and ecological functioning of inland and coastal wetlands, is currently occurring at an unprecedented rate and geographic scale. The causes of salinization are diverse and include alterations of freshwater flows, land-clearance, irrigation, sea level rise, wastewater effluent, applications of de-icing salts, and storm surges. Climate change and anthropogenic modifications to the hydrologic cycle are expected to further increase the extent and severity of wetland salinization. Salinization alters the fundamental physicochemical nature of the soil-water environment, increasing ionic concentrations and altering chemical equilibria and mineral solubility. Increased concentrations of solutes, especially sulfate, alter the biogeochemical cycling of major elements including carbon, nitrogen, phosphorus, sulfur, iron, and silica. The effects of salinization on wetland biogeochemistry typically include decreased inorganic nitrogen removal (with implications for water quality and climate regulation), decreased carbon storage (with implications for climate regulation and wetland accretion), and increased generation of toxic sulfides (with implications for nutrient cycling and the health/functioning of wetland biota). Indeed, increased salt and sulfide levels induce physiological stress in wetland biota and ultimately can result in large shifts in wetland communities and their associated ecosystem functions. The productivity and composition of freshwater species assemblages will be highly altered, and there is a high potential for the disruption of existing interspecific interactions. Although there is a wealth of information on how salinization impacts individual ecosystem components, relatively few studies have addressed the complex and often non-linear feedbacks that determine ecosystem-scale responses or how wetland salinization will affect landscape-level processes. While the salinization of wetlands may be unavoidable in many cases, these systems may also prove to be a fertile testing ground for broader ecological theories including (but not limited to): alternative stable states and tipping points, trophic cascades, disturbance-recovery, and the role of historical events and landscape context in driving community response to disturbance.
%U https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/ES14-00534.1
%A Herbert, Ellen
%A Boon, Paul
%A Burgin, Amy J.
%A Neubauer, S. C.
%A Franklin, Rima B
%A Ardon, Marcelo
%A Hopfensperger, Kristine N.
%A Lamers, L.P.M.
%A Gell, Peter
%K wetland, salinization, salinification, saltwater intrusion, global change, biodiversity, ecosystem services, biogeochemistry, hydrology, non-linear feedbacks, Student Publication, UGAMI Publication

%0 Journal Article
%T Net ecosystem production and organic carbon balance of U.S. East Coast estuaries: A synthesis approach
%D 2015
%V 29
%N 1
%P 96-111
%B Global Biogeochemical Cycles
%9 Article
%Z published
%M GCE.1002
%R 10.1002/2013GB004736
%X Net ecosystem production (NEP) and the overall organic carbon budget for the estuaries along the East Coast of the United States are estimated. We focus on the open estuarine waters, excluding the fringing wetlands. We developed empirical models relating NEP to loading ratios of dissolved inorganic nitrogen to total organic carbon, and carbon burial in the sediment to estuarine water residence time and total nitrogen input across the landward boundary. Output from a data-constrained water quality model was used to estimate inputs of total nitrogen and organic carbon to the estuaries across the landward boundary, including fluvial and tidal-wetland sources. Organic carbon export from the estuaries to the continental shelf was computed by difference, assuming steady state. Uncertainties in the budget were estimated by allowing uncertainties in the supporting model relations. Collectively, U.S. East Coast estuaries are net heterotrophic, with the area-integrated NEP of &#8722;1.5 (&#8722;2.8, &#8722;1.0)&#8201;Tg&#8201;C&#8201;yr&#8722;1 (best estimate and 95% confidence interval) and area-normalized NEP of &#8722;3.2 (&#8722;6.1, &#8722;2.3)&#8201;mol&#8201;C&#8201;m&#8722;2&#8201;yr&#8722;1. East Coast estuaries serve as a source of organic carbon to the shelf, exporting 3.4 (2.0, 4.3)&#8201;Tg&#8201;C&#8201;yr&#8722;1 or 7.6 (4.4, 9.5)&#8201;mol&#8201;C&#8201;m&#8722;2&#8201;yr&#8722;1. Organic carbon inputs from fluvial and tidal-wetland sources for the region are estimated at 5.4 (4.6, 6.5)&#8201;Tg&#8201;C&#8201;yr&#8722;1 or 12 (10, 14)&#8201;mol&#8201;C&#8201;m&#8722;2&#8201;yr&#8722;1 and carbon burial in the open estuarine waters at 0.50 (0.33, 0.78)&#8201;Tg&#8201;C&#8201;yr&#8722;1 or 1.1 (0.73, 1.7)&#8201;mol&#8201;C&#8201;m&#8722;2&#8201;yr&#8722;1. Our results highlight the importance of estuarine systems in the overall coastal budget of organic carbon, suggesting that in the aggregate, U.S. East Coast estuaries assimilate (via respiration and burial) ~40% of organic carbon inputs from fluvial and tidal-wetland sources and allow ~60% to be exported to the shelf.
%A Herrmann, Maria
%A Najjar, Raymond G.
%A Kemp, Michael
%A Alexander, Richard B.
%A Boyer, Elizabeth W.
%A Cai, Wei-Jun
%A Griffith, Peter C.
%A Kroeger, Kevin D
%A McCallister, S. Leigh
%A Smith, Richard A.
%K organic carbon budget, U.S. East Coast estuaries

%0 Journal Article
%T Sex- and habitat-specific movement of an omnivorous semi-terrestrial crab controls habitat connectivity and subsidies: A multi-parameter approach
%D 2015
%V 3/2015
%P 17
%B Oecologia
%9 Article
%Z published
%M GCE.898
%R 10.1007/s00442-015-3271-0
%X Distinct habitats are often linked through fluxes of matter and migration of organisms. In particular, intertidal ecotones are prone to being influenced from both the marine and the terrestrial realms, but whether or not small-scale migration for feeding, sheltering or reproducing is detectable may depend on the parameter studied. Within the ecotone of an upper saltmarsh in the United States, we investigated the sex-specific movement of the semi-terrestrial crab Armases cinereum using an approach of determining multiple measures of across-ecotone migration. To this end, we determined food preference, digestive abilities (enzyme activities), bacterial hindgut communities (genetic fingerprint), and the trophic position of Armases and potential food sources (stable isotopes) of males versus females of different sub-habitats, namely high saltmarsh and coastal forest. Daily observations showed that Armases moved frequently between high-intertidal (saltmarsh) and terrestrial (forest) habitats. Males were encountered more often in the forest habitat, whilst gravid females tended to be more abundant in the marsh habitat but moved more frequently. Food preference was driven by both sex and habitat. The needlerush Juncus was preferred over three other high-marsh detrital food sources, and the periwinkle Littoraria was the preferred prey of male (but not female) crabs from the forest habitats; both male and female crabs from marsh habitat preferred the fiddler crab Uca over three other prey items. In the field, the major food sources were clearly vegetal, but males have a higher trophic position than females. In contrast to food preference, isotope data excluded Uca and Littoraria as major food sources, except for males from the forest, and suggested that Armases consumes a mix of C4 and C3 plants along with animal prey. Digestive enzyme activities differed significantly between sexes and habitats and were higher in females and in marsh crabs. The bacterial hindgut community differed significantly between sexes, but habitat effects were greater than sex effects. By combining multiple measures of feeding ecology, we demonstrate that Armases exhibits sex-specific habitat choice and food preference. By using both coastal forest and saltmarsh habitats, but feeding predominantly in the latter, they possibly act as a key biotic vector of spatial subsidies across habitat borders. The degree of contributing to fluxes of matter, nutrients and energy, however, depends on their sex, indicating that changes in population structure would likely have profound effects on ecosystem connectivity and functioning.
%U http://link.springer.com/article/10.1007%2Fs00442-015-3271-0
%A Hübner, L.
%A Pennings, Steven C.
%A Zimmer, Martin
%K omnivorous, crab, sex, habitat, connectivity, ecology, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Coastal vertebrate exposure to predicted habitat changes due to sea level rise.
%D 2015
%P 1-10
%B Environmental Management
%9 Article
%Z published
%M GCE.921
%R 10.1007/s00267-015-0580-3
%X Sea level rise (SLR) may degrade habitat for coastal vertebrates in the Southeastern United States, but it is unclear which groups or species will be most exposed to habitat changes. We assessed 28 coastal Georgia vertebrate species for their exposure to potential habitat changes due to SLR using output from the Sea Level Affecting Marshes Model and information on the species’ fundamental niches. We assessed forecasted habitat change up to the year 2100 using three structural habitat metrics: total area, patch size, and habitat permanence. Almost all of the species (n = 24) experienced negative habitat changes due to SLR as measured by at least one of the metrics. Salt marsh and ocean beach habitats experienced the most change (out of 16 categorical land cover types) across the three metrics and species that used salt marsh extensively (rails and marsh sparrows) were ranked highest for exposure to habitat changes. Species that nested on ocean beaches (Diamondback Terrapins, shorebirds, and terns) were also ranked highly, but their use of other foraging habitatsreduced their overall exposure. Future studies on potential effects of SLR on vertebrates in southeastern coastal ecosystems should focus on the relative importance of different habitat types to these species’ foraging and nesting requirements. Our straightforward prioritization approach is applicable to other coastal systems and can provide insight to managers on which species to focusresources, what components of their habitats need to be protected, and which locations in the study area will provide habitat refuges in the face of SLR.
%A Hunter, E.A.
%A Nibbelink, N.P.
%A Alexander, Clark R., Jr.
%A Barrett, K.
%A Mengak, L.F.
%A Guy, R.K.
%A Moore, C.T.
%A Cooper, R.J.
%K Coastal ecosystems, Endangered species, Habitat loss, Salt marsh, Sea level rise, Vulnerability, Student Publication

%0 Thesis
%T Drivers of groundwater flow at a back barrier island - marsh transect in coastal Georgia
%D 2015
%P 104
%I The University of Georgia
%C Athens
%9 M.S. Thesis
%Z published
%M GCE.923
%X The tidal marsh connects terrestrial landscapes with the coastal ocean. Groundwater within this environment has the ability to move nutrients and influence plant distribution. Land-use change and Sea Level Rise (SLR) threaten to change these groundwater patterns. Monitoring wells recording conductivity, temperature, and water level across a back barrier island-marsh transect at Sapelo Island, GA, identified drivers of groundwater flow. Pressure propagation from tidal variations in creek water level was negligible at the study site. Density-driven flow had little impact on groundwatermovement. The saturated nature of the marsh allowed for the well nearest the tidal creek to be used as an inundation meter, and the effect of tidal flooding was identified using three different techniques. Filtering the tidal signal record demonstrated that precipitation, was a main factor for water level changes in the well nearest the upland.
%A Ledoux, Jonathan G.
%K Groundwater, Sapelo Island, Slug Test, Density Driven Flow, Precipitation, Cross Correlation, CTD Sonde, Darcy Velocities, Student Publication

%0 Conference Proceedings
%T Groundwater flow at the Georgia coast: Magnitude and drivers across a back barrier island – marsh transect
%D 2015
%C Estes Park, CO
%B LTER All Scientists Meeting
%8 Aug 30-Sept 2
%9 Poster
%Z presented
%M GCE.916
%A Ledoux, Jonathan G.
%A Alexander, Clark R., Jr.
%A Meile, Christof
%K groundwater hammock, Student Publication

%0 Journal Article
%T Concentrations, turnover rates and fluxes of polyamines in coastal waters of the South Atlantic Bight.
%D 2015
%V Online Early
%B Biogeochemistry
%9 Article
%Z NSF supported, GCE acknowledged for support with field logistics
%M GCE.817
%R 10.1007/s10533-014-0056-1
%X Polyamines are short-chain aliphatic compounds containing multiple amine groups.  They are important components of the cytosol of eukaryotes and are present at mmol L-1 concentrations inside phytoplankton cells, while complex polyamines play a role in biosilica deposition.  Concentrations of polyamines measured in seawater are typically in the sub-nmol L-1 range, implying rapid and efficient uptake by osmotrophs, likely bacterioplankton.  We measured turnover rates of 3 polyamines (putrescine, spermidine and spermine) using 3H-labeled compounds and determined their concentrations by HPLC to estimate polyamine contributions to dissolved organic matter and bacterioplankton carbon and nitrogen demand.  These measurements were made on transects from the inner shelf to the Gulf Stream across the South Atlantic Bight (SAB) during April and October of 2011 and in salt marsh estuaries on the Georgia coast during August of 2011 and April of 2012.  We found that turnover rates of polyamines were similar to those of amino acids (arginine and glutamic acid) measured in the same samples; however, fluxes of polyamines into bacterioplankton were much lower than amino acid fluxes as a result of low ambient concentrations. Turnover rates and fluxes of polyamines decreased from near-shore waters to the shelf-break, following the pattern of chlorophyll a concentration. Polyamine uptake accounted for less than 10% of bacterial N demand and 5% of bacterial C demand on average, with a large variation among water masses.
%U http://link.springer.com/article/10.1007%2Fs10533-014-0056-1
%A Liu, Qian
%A Lu, Xinxin
%A Tolar, Bradley
%A Mou, Xiaozhen
%A Hollibaugh, James T.
%K Polyamines, amino acids, turnover rate, bacterial production, DON, Student Publication

%0 Journal Article
%T Identification of polyamine-responsive bacterioplankton taxa in South Atlantic Bight
%D 2015
%V 7
%N 6
%P 831-838
%B Environmental Microbiology Reports
%9 Article
%Z published
%M GCE.1003
%R 10.1111/1758-2229.12311
%X Putrescine and spermidine are short-chained aliphatic polyamines (PAs) that are ubiquitously distributed in seawater. These compounds may be important sources of dissolved organic carbon and nitrogen for marine bacterioplankton. Here, we used pyrotag sequencing to quantify the response of bacterioplankton to putrescine and spermidine amendments in microcosms established using surface waters collected at various stations in the South Atlantic Bight in October 2011. Our analysis showed that PA-responsive bacterioplankton consisted of bacterial taxa that are typically dominant in marine systems. Rhodobacteraceae (Alphaproteobacteria) was the taxon most responsive to PA additions at the nearshore site. Gammaproteobacteria of the families Piscirickettsiaceae; Vibrionaceae; and Vibrionaceae and Pseudoalteromonadaceae, were the dominant PA-responsive taxa in samples from the river-influenced coastal station, offshore station and open ocean station, respectively. The spatial variability of PA-responsive taxa may be attributed to differences in composition of the initial bacterial community and variations of in situ physiochemical conditions among sites. Our results also provided the first empirical evidence that Gammaproteobacteria might play an important role in PA transformation in marine systems.
%A Lu, Xinxin
%A Sun, S.
%A Hollibaugh, James T.
%A Mou, Xiaozhen
%K bacterioplankton, Student Publication

%0 Journal Article
%T Context-dependent effects of the loss of Spartina alterniflora on salt marsh invertebrate communities
%D 2015
%V 163
%P 218-230
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.864
%R 10.1016/j.ecss.2015.05.045
%X Sudden dieback of the salt marsh grass Spartina alterniflora during 2000-2002 transformed once-vegetated areas to bare sediment in coastal Georgia and Louisiana. We investigated the effects of losing this foundation species on habitat provisioning for benthic epifauna, macroinfauna, and meiofauna in these distinct geographical regions. In GA, significant shifts in invertebrate community assemblages were observed between bare and reference (vegetated) plots, with abundances of all invertebrate groups and the diversity of macroinfauna lower in bare plots. In LA, community assemblages overlapped considerably in dieback and reference plots. Although epifaunal snails were significantly decreased in dieback plots, meiofauna were unexpectedly increased. Other invertebrates did not differ between plots. Supplemental transplanted plots allowed for direct evaluation of stem density effects on invertebrates. Stem density predicted abundances of all invertebrate groups in GA, and was positively correlated with increased soil moisture. In LA, elevation and soil moisture were good predictors of infauna but were not related to stem density. Differences between the states suggest that S. alterniflora may not provide equivalent ecosystem services in all salt marshes. Additional disturbances (drought, GA; hurricanes, LA) decreased infaunal density and taxon richness in 2008. However, in both states the reduction of macroinfauna was larger in bare than reference areas, suggesting that vegetation protected against further disturbance. Our results suggest that the role of S. alterniflora is context-dependent both in terms of geographic setting and the specific ecosystem service under consideration.
%U https://www.researchgate.net/publication/277818162_Context-dependent_effects_of_the_loss_of_Spartina_altemiflora_on_salt_marsh_invertebrate_communities
%A McFarlin, Caroline R.
%A Bishop, Thomas Dale
%A Hester, Mark
%A Alber, Merryl
%K Spartina alterniflora, epifauna, macroinfauna, meiofauna, sudden marsh dieback, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T A High Resolution Hydrodynamics Model of the Duplin River Estuary, Sapelo Island GA
%D 2015
%C Dartmouth, NS Canada
%B 2015 FVCOM User's Workshop
%8 Oct 20-22, 2015
%9 Presentation
%Z presented
%M GCE.989
%A McKnight, Charles Jared
%A Di Iorio, Daniela
%K hydrodynamic model, Duplin River, FVCOM, Student Publication

%0 Journal Article
%T Drought-induced variability in dissolved organic matter composition in a marsh-dominated estuary
%D 2015
%V 42
%P 6446-6453
%B Geophysical Research Letters
%9 Article
%Z published
%M GCE.937
%R 10.1002/2015GL064653
%X The composition of dissolved organic matter (DOM) in an estuary characterized by extensive salt marsh vegetation was investigated at the molecular level using ultrahigh-resolution mass spectrometry and stable carbon isotope analyses. Samples from multiple seasons covered different hydrological regimes, including anomalously low-discharge conditions. The untargeted approach used allowed for identifying the DOM molecular signatures associated with different DOM sources in the estuary. DOM composition was strongly modulated by river discharge at monthly scales, with high river flow leading to significant increases in the terrigenous signature of the DOM throughout the estuary. During a severe/exceptional drought, estuarine DOM was imprinted with a distinct signature of marsh-derived compounds. The frequency of occurrence of anomalously low-discharge conditions seems to have increased over the last decades. If predictions of anthropogenically driven changes in hydroclimate are confirmed, they will likely be accompanied by changes in DOM composition in estuaries at multidecadal time scales.
%U https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL064653
%A Medeiros, Patricia M.
%A Seidel, Michael
%A Dittmar, Thorsten
%A Whitman, William B.
%A Moran, Mary Ann
%K DOM composition, Drought, FT-ICRMS, Altamaha-Doboy-Sapelo system, UGAMI Publication

%0 Conference Proceedings
%T Controls on porewater salinity distributions in a southeastern salt marsh
%D 2015
%C Estes Park, CO
%B LTER All Scientists Meeting
%8 Aug 30-Sept 2
%9 Poster
%Z presented
%M GCE.915
%A Miklesh, David Michael
%A McKnight, Charles Jared
%A Di Iorio, Daniela
%A Meile, Christof
%K groundwater porewater salinity, Student Publication

%0 Conference Proceedings
%T Influence of Daytime Tide Events on CO2 Exchange between Salt Marshes and the Atmosphere.
%D 2015
%C Estes Park, CO
%B Long-term Ecological Research All Scientist Meeting (LTER ASM)
%8 Aug 29 - Sept 3 2015
%9 Poster
%Z presented
%M GCE.943
%A Nahrawi, Hafsah Binti
%A Leclerc, Monique Y.
%A Zhang, Gengsheng
%A Pahari, R.
%A Di Iorio, Daniela
%A Alber, Merryl
%A Sheldon, Wade M., Jr.
%A Shalack, Jacob
%K CO2 exchange, Salt marshes, Student Publication

%0 Journal Article
%T Size, sex, and individual-level behavior drive intra-population variation in cross-ecosystem foraging of a top-predator.
%D 2015
%B Journal of Animal Ecology
%9 Article
%Z published
%M GCE.903
%R 10.1111/1365-2656.12306
%X Large-bodied top-predators exert pervasive top-down effects within food webs, thereby affecting ecosystem structure and function. Effects of these consumers are propagated by a range of mechanisms including consumptive and non-consumptive interactions with prey, and the translocation of nutrients, among others (Terborgh et al. 2010; Rosenblatt et al. 2013a). Large-bodied predators are often highly mobile and can link spatially distinct habitats while acquiring prey, increasing connectivity between ecosystems. Predator-driven linkages have important ecological implications; for instance, these linkages are hypothesized to stabilize food webs by dampening population oscillation cycles (e.g. McCauley, Wilson & de Roos 1996; Loreau & Holt 2004; McCann, Rasmussen & Umbanhowar 2005). An understanding of factors regulating the occurrence and strength of predator-driven connectivity can inform predictions of when and where these species may influence structure and function of interconnected communities and ecosystems (e.g. Huxel & McCann 1998; Leroux & Loreau 2008; Rooney, McCann & Moore 2008).
%U http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12306/abstract
%A Nifong, James C.
%A Layman, C.
%A Silliman, Brian R.
%K ecosystem, predator, populations, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T 28 Years of Landsat5 TM and external forcing data for analysis of Spartina biomass on the Central Georgia coast.
%D 2015
%C Portland, OR.
%B Coastal and Estuarine Research Federation Biennial Meeting.
%8 November 2015
%9 Poster
%Z presented
%M GCE.948
%A O'Donnell, John
%A Schalles, John F.
%K Spartina, biomass, Landsat, Georgia Coast, Student Publication

%0 Conference Proceedings
%T Regional Abandonment and Community Organization: Regional and Community Perspectives on the North Georgia Coast
%D 2015
%C Valdosta, GA
%B Society for Georgia Archaeology meeting
%8 2015
%9 Poster
%Z presented
%M GCE.946
%A Ritchison, Brandon Tyler
%K GA coast, Community Organization, Student Publication

%0 Conference Proceedings
%T Integrated survey methods document estuarine bathymetry and benthic habitats for research and management: Coastal Georgia.
%D 2015
%C Portland, OR
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 November 8-12, 2015
%9 Poster
%Z presented
%M GCE.928
%A Robinson, Michael
%A Alexander, Clark R., Jr.
%A Venherm, Claudia
%A DeLeo, LeeAnn
%K bathymetry, benthic habitats, Coastal Georgia

%0 Journal Article
%T Factors affecting individual foraging specialization and temporal diet stability across the range of a large “generalist” apex predator
%D 2015
%V 178
%P 5-16
%B Oecologia
%S INDIVIDUAL-LEVEL NICHE SPECIALIZATION
%9 Article
%Z published
%M GCE.872
%R 10.1007/s00442-014-3201-6
%X Individual niche specialization (INS) is increasingly recognized as an important component of ecological and evolutionary dynamics. However, most studies that have investigated INS have focused on the effects of niche width and inter- and intraspecific competition on INS in small-bodied species for short time periods, with less attention paid to INS in large-bodied reptilian predators and the effects of available prey types on INS. We investigated the prevalence, causes, and consequences of INS in foraging behaviors across different populations of American alligators (Alligator mississippiensis), the dominant aquatic apex predator across the southeast US, using stomach contents and stable isotopes. Gut contents revealed that, over the short term, although alligator populations occupied wide ranges of the INS spectrum, general patterns were apparent. Alligator populations inhabiting lakes exhibited lower INS than coastal populations, likely driven by variation in habitat type and available prey types. Stable isotopes revealed that over longer time spans alligators exhibited remarkably consistent use of variable mixtures of carbon pools (e.g., marine and freshwater food webs). We conclude that INS in large-bodied reptilian predator populations is likely affected by variation in available prey types and habitat heterogeneity, and that INS should be incorporated into management strategies to efficiently meet intended goals. Also, ecological models, which typically do not consider behavioral variability, should include INS to increase model realismand applicability.
%U http://link.springer.com/article/10.1007%2Fs00442-014-3201-6
%A Rosenblatt, A. E.
%A Nifong, James C.
%A Heithaus, M.R.
%A Mazzotti, Frank J.
%A Cherkiss, M.S.
%A Jeffery, B.M.
%A Elsey, Ruth M.
%A Decker, R.A.
%A Silliman, Brian R.
%A Guillette, L.J.
%A Lowers, R.H.
%A Larson, J.C.
%K American alligator · Alligator mississippiensis ·, Student Publication

%0 Conference Proceedings
%T Coastal systems in a time of climate change: The mangroves are coming.
%D 2015
%C Loyola University – Chicago, IL.
%B Climate Change Actions – Sustainable Solutions for a Living Earth.
%8 March, 2015
%9 Poster
%Z presented
%M GCE.950
%A Schalles, John F.
%A Hart, Alissa C.
%A Altrichter, Adam E.
%A Carpenter, Eryn J.
%A Vichienwanitchkul, Prem
%K Mangroves, climate change, coastal systems

%0 Conference Proceedings
%T Replacement of marsh with mangrove communities in Coastal Texas and potential impact to Whooping Cranes.
%D 2015
%C Portland, OR
%B Coastal & Estuarine Research Federation Meetings
%8 November, 2015
%9 Poster
%Z presented
%M GCE.949
%A Schalles, John F.
%A Smith, Elizabeth
%A Chaves-Rameriz, Felipe
%A Davis, Nicole
%A Altrichter, Adam E.
%A Hart, Alissa C.
%A Carpenter, Eryn J.
%A Seminara, D.N.
%A Vichienwanitchkul, Prem
%K Whooping Cranes, mangroves, Coastal Texas, marsh

%0 Journal Article
%T Intense nitrogen cycling in permeable intertidal sediment revealed by a nitrous oxide hotspot
%D 2015
%V 29
%N 10
%P 1584–1598
%B Global Biogeochemical Cycles
%9 Article
%Z published
%M GCE.955
%R 10.1002/2014GB005052
%X Approximately 40% of the total global rate of nitrogen fixation is the result of human activities, and most of this anthropogenic nitrogen is used to fertilize agricultural fields. Approximately 23% of the applied agricultural nitrogen is delivered to the coastal zone, often reducing water quality and driving eutrophication. Nitrogen cycling in coastal sediments can mitigate eutrophication by removing bioavailable nitrogen. However, some of these processes generate nitrous oxide, a potent greenhouse gas, as a by-product. Here we report the discovery of a nitrous oxide production hot spot in shallow barrier island sands. Nitrous oxide concentrations, production and consumption rates, vertical diffusion fluxes, and flux to the atmosphere were measured across triplicate depth profiles. Using a mass balance approach, rates of net nitrous oxide production were estimated to be 40&#8201;µmol&#8201;m&#8722;2&#8201;d&#8722;1. This production was driven by a hot spot of nitrate consumption that removed bioavailable nitrogen from the coastal environment at a rate of 10&#8201;mmol&#8201;m&#8722;2&#8201;d&#8722;1, a rate that is comparable with the highest rates of denitrification reported for coastal sediments.
%U http://onlinelibrary.wiley.com/doi/10.1002/2014GB005052/abstract
%A Schutte, Charles
%A Joye, Samantha B.
%A Wilson, Alicia M.
%A Evans, Tyler
%A Moore, Willard S.
%A Casciotti, Karen
%K sediment, nitrogen cycling, Student Publication, UGAMI Publication

%0 Journal Article
%T Facilitation shifts paradigms and can amplify coastal restoration efforts
%D 2015
%V 112
%N 46
%P 14295 - 14300
%B PNAS
%9 Article
%Z published
%M GCE.958
%R 10.1073/pnas.1515297112
%X Restoration has been elevated as an important strategy to reverse the decline of coastal wetlands worldwide. Current practice in restoration science emphasizes minimizing competition between out-planted propagules to maximize planting success. This paradigm persists despite the fact that foundational theory in ecology demonstrates that positive species interactions are key to organism success under high physical stress, such as recolonization of bare substrate. As evidence of how entrenched this restoration paradigm is, our survey of 25 restoration organizations in 14 states in the United States revealed that >95% of these agencies assume minimizing negative interactions (i.e., competition) between outplants will maximize propagule growth. Restoration experiments in both Western and Eastern Atlantic salt marshes demonstrate, however, that a simple change in planting configuration (placing propagules next to, rather than at a distance from, each other) results in harnessing facilitation and increased yields by 107% on average. Thus, small adjustments in restoration design may catalyze untapped positive species interactions, resulting in significantly higher restoration success with no added cost. As positive interactions between organisms commonly occur in coastal ecosystems (especially in more physically stressful areas like uncolonized substrate) and conservation resources are limited, transformation of the coastal restoration paradigm to incorporate facilitation theory may enhance conservation efforts, shoreline defense, and provisioning of ecosystem services such as fisheries production.
%U http://www.pnas.org/content/112/46/14295
%A Silliman, Brian R.
%A Schrack, Elizabeth
%A He, Qiang
%A Cope, Rebecca
%A Santoni, A.
%A van der Heide, Tjisse
%A Jacobi, R.
%A van de Koppel, Johan
%K shoreline defense, facilitation, coastal wetlands, wetland restoration, Cross-site Research, Student Publication

%0 Journal Article
%T Complexity in Salt Marsh Circulation for a Semi-enclosed Basin
%D 2015
%B Journal of Geophysical Research - Earth Surface
%9 Article
%Z published
%M GCE.922
%R 10.1002/2014JF003365
%X The fine details of overmarsh circulation remain largely unexplored and yet they aretypically assumed to control many attributes of salt marsh material cycling, transport and accretion. We characterized the spatial and temporal variability in overmarsh circulation at a 2 km2 Georgia, USA salt marsh using field observations, dye tracer and numerical simulations. The marsh bathymetry was created with a high precision Global Positioning System survey that details the geomorphic structure of intertidal creeks and salt marsh platform features greater than about one meter in width. We assessed flow path dynamics at four spatial scales ranging from 1 m to 1,000 m. Results show the development and decay of simultaneous flow divergence and convergence, concentrated flow and large-scale rotational flow, as well as strong differences between flood and ebb pathways. This current complexity is set by submergence and emergence of subtle salt marsh platform geomorphic structure andit highlights the role of topography in system-wide flow processes.
%U http://onlinelibrary.wiley.com/doi/10.1002/2014JF003365/abstract
%A Sullivan, Jessica C.
%A Torres, R.
%A Garrett, A.
%A Blanton, Jackson O.
%A Alexander, Clark R., Jr.
%A Robinson, Michael
%A Moore, Trent C.
%A Amft, Julie
%A Hayes, D.
%K Overmarsh circulation, salt marsh topography, numerical modeling, dye transport

%0 Book Section
%T The sociality of surplus among Late Archaic hunter-gatherers of coastal Georgia
%D 2015
%P 304
%I University Press of Colorado
%B Surplus: The Politics of Production and the Strategies of Everyday Life
%7 1
%9 Article
%Z published
%M GCE.1004
%A Thompson, Victor D.
%A Moore, Christopher R.
%E Morehart, Christopher T. 
%E De Lucia, Kristin
%K coastal Georgia, sociality, Late Archaic, hunter-gathers

%0 Conference Proceedings
%T Evidence for the direct oxidation of polyamine nitrogen by Thaumarchaeota-dominated marine nitrifying communities.
%D 2015
%I ASLO
%C Granada Spain
%B ASLO Ocean Sciences Meeting
%8 22-27 February 2015
%9 Presentation
%Z presented
%M GCE.975
%X Chemoautotrophy supported by ammonia oxidation is important to the metabolism of Thaumarchaeota.  While several reports suggest the potential for mixotrophy in this group, the potential to oxidize reduced nitrogen species other than ammonia has not been reported.  We found that coastal bacterioplankton and an ammonium-grown enrichment culture of a marine thaumarchaeote are capable of oxidizing polyamine-N directly to NOx, without first degrading the molecule to regenerate ammonia.  Although we first discovered this process using putrescine, other polyamines are also oxidized and activity increases with length of the C skeleton.  Neither amino acid- nor urea-N is oxidized in this manner.  The process does not appear to be due simply to low fidelity of ammonia-monooxygenase, as a competition experiment revealed little effect of ammonium concentration on putrescine oxidation, though high putrescine concentrations appear to decrease ammonia oxidation rates.  Although polyamines are present in organisms at concentrations (mM) comparable to dissolved free amino acids (DFAA), the concentrations of individual polyamines in seawater (nM) are typically an order of magnitude lower than DFAA.  Direct oxidation of polyamine-N provides a mechanism to explain this discrepancy.
%A Tolar, Bradley
%A Popp, Brian N.
%A Wallsgrove, Natalie J.
%A Liu, Qian
%K polyamines, Thaumarchaeota, nitrification, Student Publication

%0 Conference Proceedings
%T Oxidation of ammonia versus urea by marine nitrifying organisms
%D 2015
%I ASLO
%C Granada Spain
%B ASLO Ocean Sciences Meeting,
%8 23 February 2015
%9 Presentation
%Z presented
%M GCE.976
%A Tolar, Bradley
%A Wallsgrove, Natalie J.
%A Popp, Brian N.
%A Hollibaugh, James T.
%K Urea, nitrification, Thaumarchaeota, Student Publication

%0 Conference Proceedings
%T Shoreline Characterization in Coastal Georgia Using a Geospatial Video Mapping System.
%D 2015
%C Portland, OR
%B Coastal and Estuarine Research Federation Biennial Meeting
%8 November 8-12, 2015
%9 Poster
%Z presented
%M GCE.927
%A Venherm, Claudia
%A Alexander, Clark R., Jr.
%A DeLeo, LeeAnn
%A Robinson, Michael
%K Shoreline characterization, Coastal Georgia, Video mapping

%0 Journal Article
%T Long-distance interactions regulate the structure and resilience of coastal ecosystems.
%D 2015
%V 7
%P 139–158
%B Annual Review of Marine Science
%9 Article
%Z published
%M GCE.876
%R 10.1146/annurev-marine-010814-015805
%X Mounting evidence indicates that spatial interactions are important in structuring coastal ecosystems. Until recently, however, most of this work has been focused on seemingly exceptional systems that are characterized by regular, self-organized patterns. In this review, we document that interactions that operate at long distances, beyond the direct neighborhood of individual organisms, are more common and have much more far-reaching implications for coastal ecosystems than was previously realized. We review studies from a variety of ecosystem types—including cobble beaches, mussel beds, coral reefs, seagrass meadows, and mangrove forests—that reveal a startling interplay of positive and negative interactions between habitats across distances of up to a kilometer. In addition to classical feeding relations, alterations of physical conditions constitute an important part of these long-distance interactions. This entanglement of habitats has crucial implications for how humans manage coastal ecosystems, and evaluations of anthropogenic impact should explicitly address long-distance and system-wide effects before we deem these human activities to be causing little harm.
%U http://www.annualreviews.org/doi/10.1146/annurev-marine-010814-015805
%A von de Koppel, J.
%A van der Heide, J.
%A Alteiri, A.
%A Eriksson, B.
%A Bouma, H.
%A Olff, Han
%A Silliman, Brian R.
%K coastal ecosystems

%0 Journal Article
%T What time scales are important for monitoring tidally influenced submarine groundwater discharge? Insights from a salt marsh
%D 2015
%V 51
%N 6
%B Water Resources Research
%9 Article
%Z published
%M GCE.954
%R 10.1002/2014WR015984
%X Submarine groundwater discharge (SGD) varies significantly across time scales ranging from hours to years, but studies that allow quantitative comparisons between different time scales are few. Most of these studies have focused on beach settings, where the combined variations in fresh and saline SGD can be difficult to interpret. We calculated variations in saline SGD based on a 1 year record of hydraulic head in a salt marsh, where we could isolate variations in saline, tidally driven SGD. Observed SGD varied by an order of magnitude over the course of the year. Groundwater discharge was proportional to tidal amplitude and varied by at least a factor of 2 between spring and neap tides. Monthly average SGD was inversely proportional to average sea level; it increased by nearly a factor of 2 as sea level declined by &#8764;50 cm from late summer to late winter. This variation was far larger than that predicted by analytic models, owing to the flat topography and inundation of the marsh platform. The effect of short-term (days) variations in sea level associated with wind events and storms was small in comparison. SGD is probably proportional to tidal amplitude in nearly all coastal settings, including beaches. Seasonal variations in sea level may not affect the volume of SGD as significantly in coastal settings where the slope of the intertidal zone is relatively constant, but such variations have the potential to strongly affect the composition of SGD.
%U http://onlinelibrary.wiley.com/doi/10.1002/2014WR015984/abstract
%A Wilson, Alicia M.
%A Evans, Tyler
%A Moore, Willard S.
%A Schutte, Charles
%A Joye, Samantha B.
%K groundwater, Student Publication, UGAMI Publication

%0 Journal Article
%T Groundwater controls ecological zonation of salt marsh macrophytes
%D 2015
%V 96
%N 3
%P 840-849
%B Ecology
%9 Article
%Z published
%M GCE.953
%R 10.1890/13-2183.1
%X Ecological zonation of salt marsh macrophytes is strongly influenced by hydrologic factors, but these factors are poorly understood. We examined groundwater flow patterns through surficial sediments in two salt marshes in the southeastern United States to quantify hydrologic differences between distinct ecological zones. Both sites included tall- or medium-form Spartina alterniflora near the creek bank; short-form Spartina alterniflora in the mid-marsh; salt flats and Salicornia virginica in the high marsh; and Juncus roemarianus in brackish-to-fresh areas adjacent to uplands. Both sites had relatively small, sandy uplands and similar stratigraphy consisting of marsh muds overlying a deeper sand layer. We found significant hydrologic differences between the four ecological zones. In the zones colonized by S. alterniflora, the vertical flow direction oscillated with semi-diurnal tides. Net flow (14-day average) through the tall S. alterniflora zones was downward, whereas the short S. alterniflora zones included significant periods of net upward groundwater flow. An examination of tidal efficiency at these sites suggested that the net flow patterns rather than tidal damping controlled the width of the tall S. alterniflora zone. In contrast to the S. alterniflora zones, hypersaline zones populated by S. virginica were characterized by sustained periods (days) of continuous upward flow of saline water during neap tides. The fresher zone populated by J. roemarianus showed physical flow patterns that were similar to the hypersaline zones, but the upwelling porewaters were fresh rather than saline. These flow patterns were influenced by the hydrogeologic framework of the marshes, particularly differences in hydraulic head between the upland water table and the tidal creeks. We observed increases in hydraulic head of ~40 cm from the creek to the upland in the sand layers below both marshes, which is consistent with previous observations that sandy aquifers below fine-grained marsh soils act as conduits for flow from uplands to tidal creeks. This hydrologic framework supports relatively good drainage near the creek, increased waterlogging in the mid-marsh, and the development of hypersalinity adjacent to the freshwater upland. These hydrologic differences in turn support distinct ecological zones.
%U http://onlinelibrary.wiley.com/doi/10.1890/13-2183.1/abstract
%A Wilson, Alicia M.
%A Evans, Tyler
%A Moore, Willard S.
%A Schutte, Charles
%A Joye, Samantha B.
%A Hughes, Andrea H.
%A Anderson, J.
%K groundwater, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Listening to and learning from local ecological knowledge: A social science pilot study in McIntosh County, GA
%D 2014
%I NOAA Office for Coastal Management
%C Charleston, South Carolina
%B Social Coast Forum 2014
%S Exploring the Values of the Coast
%8 February 18-20, 2014
%9 Presentation
%Z presented
%M GCE.893
%X In this presentation I will share findings from a series of 19 interviews with long -term residents of McIntosh County Georgia. The interviews were designed to gather basic information about local perceptions of land -use and environmental change in this coastal county over the last 50 years. They were also conducted in order to gather information about resident’s primary environmental concerns and explore local ecological knowledge held by long-term residents. I will share the way participants voiced concerns about the loss of wetlands, changes in freshwater flow and salinity, and changes in populations of marine organ isms. Some commonly shared ideas raise additional questions about perceptions of environmental health. For example, the idea that trawling in areas like Sapelo Sound may have been beneficial and that the absence of this activity may have lead to a decline in water quality and the health of shellfish and finfish populations.
%U http://csc.noaa.gov/socialcoastforum/2014AbstractsandPPTs/Addes_ppt_pdf.pdf
%A Addes, Danyel
%K social science, pilot, listening, citizens, McIntosh, anthropology

%0 Conference Proceedings
%T Using Geospatial Tools to Quantify the Threat To Archaeological, Historic and Cultural Resources From Shoreline Change: The Georgia Coast Example.
%D 2014
%I Geological Society of America Annual Meeting
%C Vancouver, B.C.
%B Geological Society of America Annual Meeting
%8 19-22 October 2014
%9 Abstract
%Z published
%M GCE.829
%A Alexander, Clark R., Jr.
%A Mccabe, C.
%A Venherm, Claudia
%A Robinson, Michael
%K Geospatial, Archaeology, Historic and Cultural resources, shoreline change, Georgia Coast

%0 Book Section
%T Developments in Salt Marsh Topography Analysis Using Airborne Infrared Photography
%D 2014
%V 9
%P 317-331
%I Springer International Publishing
%B Remote Sensing and Modeling
%9 Article
%Z Volume 9 in Coastal Research Library series.  Book subtitle: "Advances in Coastal and Marine Resources"
%M GCE.914
%R 10.1007/978-3-319-06326-3_13
%X Salt marshes occur throughout the extra-tropical regions of the world, along low energy shores, where a surplus of fine sediment is available, and they have been estimated as some of the most valuable ecosystems on Earth. They exhibit complex topographies primarily modelled by hydrodynamics which, in turn, determine geobiophysical processes and the pattern of occurring communities. This makes accurate salt marsh topography a prerequisite for the understanding of their function and structure. Only recently, have remote-sensing techniques become widely available to obtain high-resolution topographic data in an environment otherwise extremely arduous to access. Still, extraction of bare-earth surface remains difficult and especially problematic in areas of dense vegetation. LiDAR data, although widely in use still isn’t readily available worldwide and requires intensive post-processing and validation.A detailed digital elevation model (DEM) of the Duplin River (Georgia, SoutheasternUSA) was constructed with a 1 m2 resolution. The model was created by the classification and analysis of a time-series of 7 IR (infrared) aerial photographic mosaics taken at 1 h intervals from low- to high-water during a rising tide. The technique is based on the premise that flooded areas can be objectively recognized through image analysis and that the water surface is horizontal throughout the system, thereby defining a reference level at any given time. We focus on the description of the method, and results from its use in a large intertidal area. We also discuss the advantages of the method and its shortcomings when applied to vegetated intertidal areas, and propose further developments and applications.
%A Andrade, Francisco
%A Blanton, Jackson O.
%A Ferreira, M. Adelaide
%A Amft, Julie
%E Finkl, Charles W.
%E Makowski, Christopher
%K Salt marsh, topography, infrared photography, DEM, SINERR Publication, UGAMI Publication

%0 Thesis
%T Foundation species as drivers of ecosystem structure, multifunctionality, and resilience.
%D 2014
%P 164
%I University of Florida
%C Gainesville, FL
%9 Ph.D. Dissertation
%Z published
%M GCE.952
%X Foundation species are dominant, structure-forming organisms that modify physical and biotic conditions to facilitate associated communities { TC ABSTRACT }. Although foundation species nearly always co-occur, our understanding of how they interact with each other and collectively influence how ecosystems are structured, function, and respond to disturbance remains limited. Here, I synthesize research on foundation species interactions and quantify the effect that facilitation cascades, interaction chains in which primary foundation species facilitate secondary foundation species, have on ecosystem structure, functioning, and resilience. Many studies have either examined how competition and facilitative interactions drive spatial segregation and overlap, respectively, of foundation species, or what effects a single foundation species or functional group have on associated community characteristics. Integrating these complementary fields of research, I propose that the nature of interactions among foundation species controls landscape patterns in community structure. I then present results from experiments and surveys that assess mechanisms of facilitation that structure a tree (Quercus virginiana)- epiphyte (Tillandsia usneoides) cascade and 13 examine its effect on invertebrate species, functional group, and life stage diversity. I discovered that Tillandsia relies on physical stress reduction provided by Quercus, and secondarily reduces multiple stressors to enhance all aspects of arboreal invertebrate diversity. To assess whether the presence of multiple foundation species may also regulate ecosystem functioning, I tested how the density of ribbed mussels (Geukensia demissa) that occur in aggregations within salt marsh habitat formed by cordgrass (Spartina alterniflora) influences salt marsh invertebrate diversity, 7 ecosystem functions, and multifunctionality, the simultaneous performance of these functions. Using surveys of mussel distribution, I then extrapolated my experimental results to estimate the net effect of mussels, and the diverse invertebrate communities they facilitate, on multifunctionality at the landscape scale. In my final study, I used monitoring, model simulations, and experiments to demonstrate that the resilience of southeastern US salt marshes to drought hinges on the presence and spatial distribution of remnant cordgrass patches and that mussels, in facilitating cordgrass survival during drought, are likely playing a keystone role in regulating the resilience of this ecosystem. Combined, my research advances our understanding of how the interactions among foundation species regulates biodiversity, multifunctionality, and resilience within natural ecosystems.
%A Angelini, Christine
%K foundation species, ecosystem structure, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Secondary foundation species as drivers of trophic and functional diversity: evidence from a tree-epiphyte system
%D 2014
%V 95
%N 1
%P 185-196
%B Ecology
%9 Article
%Z published
%M GCE.811
%X Facilitation cascades arise where primary foundation species facilitate secondary (dependent) foundation species, and collectively, they increase habitat complexity and quality to enhance biodiversity. Whether such phenomena occur in nonmarine systemsand if secondary foundation species enhance food web structure (e.g., support novel feeding guilds) and ecosystem function (e.g., provide nursery for juveniles) remain unclear. Here we report on field experiments designed to test whether trees improve epiphyte survival and epiphytes secondarily increase the number and diversity of adult and juvenile invertebrates in a potential live oak–Tillandsia usneoides (Spanish moss) facilitation cascade. Our results reveal that trees reduce physical stress to facilitate Tillandsia, which, in turn, reduces desiccation and predation stress to facilitate invertebrates. In experimental removals, invertebrate total density, juvenile density, species richness and H0 diversity were 16, 60, 1.7, and 1.5 times higher, and feeding guild richness and H0 were 5 and 11 times greater in Tillandsia-colonized relative to Tillandsia-removal limb plots. Tillandsia enhanced communities similarly in a survey across the southeastern United States. These findings reveal that a facilitation cascade organizes this widespread terrestrial assemblage and expand the role of secondary foundation species as drivers of trophic structure and ecosystem function. We conceptualize the relationship between foundation species’ structural attributes and associated species abundance and composition in a Foundation Species–Biodiversity (FSB) model. Importantly, the FSB predicts that, where secondary foundation species form expansive and functionally distinct structures that increase habitat availability and complexity within primary foundation species, they generate and maintain hot spots of biodiversity and trophic interactions.
%A Angelini, Christine
%A Silliman, Brian R.
%K Biodiversity, community structure, facilitation cascade, food web, invertebrate, nursery habitat, positive interaction, predator prey interaction, Tillandsia unseoides, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Benthic primary production and nitrogen cycling in Spartina alterniflora marshes: effect of restoration after acute dieback
%D 2014
%V 117
%N 2-3
%P 511-524
%B Biogeochemistry
%9 Article
%Z published
%M GCE.885
%R 10.1007/s10533-013-9897-2
%X The sudden and massive Spartina alterniflora dieback at the turn of the millennium generated numerous unanswered questions regarding its mechanistic causes and consequences. This study, conducted during 2007–2008, aimed to elucidate mechanisms of recovery and determine whether recovery was accelerated by replanting efforts. The onset of a severe drought during the summer of 2007, however, provided a potential glimpse into the mechanisms driving dieback events. Study sites were established in two of the hardest hit states, Georgia and Louisiana. Each site had a replicated block design consisting of the following four treatments: reference, dieback, dieback with low density replanting (90 cm spacing), and dieback with high density replanting (30 cm spacing). To assess biogeochemical cycling and ecosystem functioning, we quantified rates of nitrogen fixation, potential nitrification, potential denitrification, and benthic production biannually. All measured process rates decreased following the drought year of 2007. Nitrogen fixation was positively correlated with benthic production rates in Louisiana, while denitrification was positively correlated with benthic production rates in Georgia and Louisiana. The lack of decreased benthic production during the 2007 drought could indicate that benthic microphytes cope with better with drought than plants, but may be outcompeted during non-drought years. Replanting efforts significantly increased ecosystem recovery in Louisiana and to a lesser extent in Georgia.
%A Baas, Peter
%A Hester, Mark
%A Joye, Samantha B.
%K Microphytobenthos Spartina marsh Acute dieback Pho, SINERR Publication, Student Publication, UGAMI Publication

%0 Book Section
%T Spatial variability in sedimentation, carbon sequestration, and nutrient accumulation in an alluvial floodplain forest
%D 2014
%I Springer
%C New York
%B The Role of Natural and Constructed Wetlands in Nutrient Cycling and Retention on the Landscape
%9 Article
%Z published
%M GCE.723
%A Bannister, J.M.
%A Herbert, Ellen
%A Craft, Christopher B.
%E Vymazal, jan
%K spatial variability, alluvial floodplain forest, Student Publication, UGAMI Publication

%0 Thesis
%T Characterization of Groundwater Discharge in a Back Barrier Tidal Creek
%D 2014
%P 66
%I Coastal Carolina University
%C Conway, SC
%9 M.S. Thesis
%Z published
%M GCE.831
%X Groundwater discharge in the coastal environment is known to be a complex process. The driving mechanisms of groundwater discharge vary on spatial and temporal scales that can significantly impact coastal water chemistry and play a role in ecological zonation. Evolving combinations of observational and modeling approaches provide a basis to quantify groundwater discharge in a spatial and temporal sense. Here we employ a combination of geochemical (naturally occurring radon isotope) and geophysical (electrical resistivity) techniques to measure groundwater-surface water interactions along a back-barrier tidal creek. In addition to field measurements, a unique non-steadystate radon mass balance equation was developed to better constrain groundwater estimates. The radon mass balance shows spatial and temporal variance in groundwater composition along the tidal creek. Our estimates suggest that groundwater discharge is grater in the Upper Duplin compared to the Lower Duplin section. Spring tide conditions yielded greater groundwater discharge at all sites, but the Lower Duplin section had significantly greater discharge when compared to neap tide discharge. Electrical resistivity serves as a qualitative assessment to support the radon mass balance findingsof marsh zone water circulation on both daily and spring/neap cycles. Our observations proved baseline groundwater contributions to the Duplin River system. This can be used to constrain aquifer characteristic used in numerical simulations of chemical and nutrient transport the systems.
%A Carter, Matthew
%K radon, Duplin River, Sapelo Island, groundwater, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Grazing scar characteristics impact degree of fungal facilitation in /Spartina alterniflora/ leaves in a South American Salt Marsh.
%D 2014
%V 58
%N 1
%P 103-108
%B Brazilian Archives of Biology and Technology
%9 Article
%Z ISSN 1516-8913
%M GCE.874
%R 10.1590/S1516-8913201400030
%X Grazing scars of burrowing crabs and Hemiptera insects were simulated on leaves of the salt marsh grass Spartinaalterniflora. Simulations of crab feeding generated two-fold higher fungal (ergosterol) content in leaves incomparison to that generated by insect scar simulations (1.26 ± 0.55 and 0.57 ± 0.25 µg per cm˛, respe ctively). Thisstudy provided evidence that herbivory could facilitate microbial infection by fungi in dominant South American saltmarsh plants and indicated that specific feeding mechanisms used by different herbivores might differentially impactthe strength of this interaction
%U http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132015000100103&lng=en&nrm=iso&tlng=en
%A Freita, R.
%A Schrack, L.
%A Sieg, R. D. 
%A Silliman, Brian R.
%A Costa, C.
%K fungi infestation, phytopathology, biotic interactions, aphids, Neohelice granulata, Student Publication

%0 Conference Proceedings
%T Utilizing Complementary Techniques to Understand Formation Processes at the Ossabaw Island Shell Ring (9CH203)
%D 2014
%C Greenville, SC
%B Southeastern Archaeological Conference
%8 2014
%9 Poster
%Z presented
%M GCE.945
%A Golsch, Matthew
%A Ritchison, Brandon Tyler
%A Colvin, Matthew H.
%A Tucker, Bryan
%A Thompson, Victor D.
%K Formation Processes, Ossabaw Island, Shell ring, Student Publication

%0 Newspaper Article
%T Sensor and sensor data management best practices released
%D 2014
%I LTER Network
%C Albuquerque, NM
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Spring 2014
%9 Article
%Z published
%M GCE.890
%X Rapid advances and decreasing costs in sensor technology, wireless communication, data processing speed, and data storage capacity have enabled widespread deployment of automated environmental sensing systems. Basic environmental processes can be monitored continuously in habitats ranging from very remote to urban providing information in unprecedented temporal and spatial resolution. Although research questions that may be answered based on these data are very diverse (Porter et al. 2009), the design process, establishment and maintenance of most environmental sensor systems, and resulting data handling have many commonalities.
%U https://lternet.edu/wp-content/uploads/2017/12/2014-spring-lter-databits.pdf
%A Gries, Corinna
%A Henshaw, Donald L.
%A Brown, Renee F.
%A Cary, Richard
%A Downing, Jason
%A Jones, Christopher
%A Kennedy, Adam
%A Laney, Christine
%A Martin, Mary
%A Morse, Jennifer
%A Porter, John
%A Read, Jordan
%A Rettig, Andrew
%A Sheldon, Wade M., Jr.
%A Strachan, Scotty
%A Zdravkovic, Branko
%K LTER-IMC, sensor, data, management, best practices, networking, IT

%0 Journal Article
%T Relative influence of deterministic processes on structuring marsh plant communities varies across an abiotic gradient
%D 2014
%V 123
%N 2
%P 173-178
%B Oikos
%9 Article
%Z published
%M GCE.783
%R 10.1111/j.1600-0706.2013.00425.x
%X Understanding the processes determining community structure is one of the major goals of ecological research. Both deterministic and stochastic processes may shape community structure. The challenge is to understand the relative influence of each type of process across different environmental conditions. We investigated the influence of deterministic and stochastic processes on plant community assembly in tidal marshes across a strong abiotic (salinity) gradient in three estuaries in Georgia, USA using probabilistic Raup–Crick community dissimilarity. Our results indicated thatdeterministic processes had an increasingly important influence on structuring plant communities in salt and brackish marshes, probably due to high heterogeneity of microhabitats produced by the interplay between abiotic stress and biotic interactions. In contrast, the influence of deterministic processes on plant community assembly decreased in tidal freshwater marshes, suggesting an increasingly important role of stochastic processes in plant community assembly in tidal freshwater marshes, probably due to the higher species richness, higher recruitment from seed, and lower levels of abiotic stress in these habitats. At the estuarine scale (across tidal freshwater, brackish and salt marshes in each estuary), our results suggested that deterministic processes also had a relatively important influence on shaping plant communitystructure. Our results illustrated that plant community structure in tidal marshes is influenced by both deterministic and stochastic processes, but that the relative influence of these two types of processes varies across estuarine landscapes.
%A Guo, Hongyu
%A Wieski, Kazimierz
%A Lan, Zhenjiang
%A Pennings, Steven C.
%K salinity, diversity, estuary, plant, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Economic development and coastal ecosystem change in China
%D 2014
%V 4
%N 5995
%P 9
%B Scientific Reports
%9 Article
%Z published
%M GCE.808
%R 10.1038/srep05995
%X Despite their value, coastal ecosystems are globally threatened by anthropogenic impacts, yet how these impacts are driven by economic development is not well understood. We compiled a multifaceted dataset to quantify coastal trends and examine the role of economic growth in China's coastal degradation since the 1950s. Although China's coastal population growth did not change following the 1978 economic reforms, its coastal economy increased by orders of magnitude. All 15 coastal human impacts examined increased over time, especially after the reforms. Econometric analysis revealed positive relationships between most impacts and GDP across temporal and spatial scales, often lacking dropping thresholds. These relationships generally held when influences of population growth were addressed by analyzing per capita impacts, and when population density was included as explanatory variables. Historical trends in physical and biotic indicators showed that China's coastal ecosystems changed little or slowly between the 1950s and 1978, but have degraded at accelerated rates since 1978. Thus economic growth has been the cause of accelerating human damage to China's coastal ecosystems. China's GDP per capita remains very low. Without strict conservation efforts, continuing economic growth will further degrade China's coastal ecosystems.
%U http://www.nature.com/articles/srep05995
%A He, Qiang
%A Bertness, Mark D.
%A Bruno, John F.
%A Li, Bo
%A Chen, Guoqian
%A Coverdale, Tyler C.
%A Alteiri, A.
%A Bai, Junhong
%A Sun, Tao
%A Pennings, Steven C.
%A Liu, Jianguo
%A Ehrlich, Paul R.
%A Cui, Baoshan
%K China, environmental impact, mangrove, salt marsh

%0 Journal Article
%T Classification of salt marsh vegetation using edaphic and remote sensing-derived variables
%D 2014
%V 141
%P 47 - 57
%B Estuarine, Coastal and Shelf Sciences
%9 Article
%Z published
%M GCE.780
%R 10.1016/j.ecss.2014.01.011
%X Salt marsh plant communities are known for their striking patterns of vertical zonation. Two of the most important edaphic parameters that affect species distribution patterns are soil salinity and waterlogging, both of which are related to topographical variations and distance to the water. The primary objective of this study was to evaluate whether information on elevation and distance derived through remote sensing could be used to predict plant distributions in a southeastern salt marsh. We classified four marsh vegetation classes (tall Spartina alterniflora, medium S. alterniflora/short S. alterniflora, marsh meadow, and Borrichia frutescens/Juncus roemerianus) based on landscape metrics obtained from a light detection and ranging (LIDAR)-derived digital elevation model (DEM) and compared results to a classification based on field-collected edaphic variables. Our secondary objective was to compare the performance of linear discriminant analysis (LDA) with non-parametric classification and regression trees (CART) for these classifications. Models based on the edaphic variables soil water content, salinity, and redox attained accuracies of 0.62 and 0.71 with LDA and CART, respectively. When the remote sensing-derived variables DEM elevation, slope, distance to the mean high water line, and distance to upland area were used, classification accuracies improved to 0.78 for LDA and 0.79 for CART. Our results suggest that remote sensing-derived metrics can capture edaphic gradients effectively, which makes them especially suited to landscape level analyses of salt marsh plant habitats, with potential application for predicting the effects of sea level rise on salt marsh plant distribution.
%A Hladik, Christine M.
%A Alber, Merryl
%K salt marsh, habitat mapping, remote sensing, digital elevation model (DEM), linear discriminant analysis (LDA), classification and regression trees (CART), SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Seasonal variation in the metratranscriptomes of a Thaumarchaeota population from SE USA coastal waters
%D 2014
%V 8
%P 685 - 698
%B ISME Journal
%9 Article
%Z published
%M GCE.850
%R 10.1038/ismej.2013.171
%X We used a combination of metatranscriptomic analyses and quantitative PCR (qPCR) to study seasonal changes in Thaumarchaeota populations from a salt marsh-dominated estuary. Surface waters (0.5&#8201;m depth) were sampled quarterly at Marsh Landing, Sapelo Island, GA, USA over a 3-year period. We found a mid-summer peak in Thaumarchaeota abundance measured by qPCR of either 16S rRNA or amoA genes in each of the 3 years. Thaumarchaeota were 100–1000-fold more abundant during the peak than at other times of the year, whereas the abundance of ammonia- and nitrite-oxidizing Bacteria varied <10-fold over the same period. Analysis of the microdiversity of several highly transcribed genes in 20 metatranscriptomes from a 1-year subset of these samples showed that the transcriptionally active population consisted of 2 or 3 dominant phylotypes that differed between successive summers. This shift appeared to have begun during the preceding winter and spring. Transcripts from the same genes dominated the Thaumarchaeota mRNA pool throughout the year, with genes encoding proteins believed to be involved in nitrogen uptake and oxidation, and two hypothetical proteins being the most abundant transcripts in all libraries. Analysis of individual genes over the seasonal cycle suggested that transcription was tied more closely to variation in growth rates than to seasonal changes in environmental conditions. Day–night differences in the relative abundance of transcripts for ribosomal proteins suggested diurnal variation in Thaumarchaeota growth.
%U http://gce-lter.marsci.uga.edu/public/uploads/Hollibaugh_et_al_2014_20160906T155818.pdf
%A Hollibaugh, James T.
%A Gifford, Scott
%A Moran, Mary Ann
%A Ross, Meredith
%A Sharma, S.
%A Tolar, Bradley
%K ammonia oxidation, nitrification, estuary, Thaumarchaeota, nitrite, diurnal, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Delineating groundwater flow along a marsh transect at a back barrier island on the coast of Georgia
%D 2014
%C Carolina Beach, NC
%B Southeastern Estuarine Research Society Fall meeting
%8 November 6-8
%9 Poster
%Z presented
%M GCE.896
%A Ledoux, Jonathan G.
%A Alexander, Clark R., Jr.
%A Meile, Christof
%K groundwater marsh, Student Publication

%0 Journal Article
%T Isotopes and elemental ratios in multi-parameter mixing models
%D 2014
%V 12
%P 694-702
%B Limnology and Oceanography: Methods
%9 Article
%Z published
%M GCE.815
%R 10.4319/lom.2014.12.694
%X Concentration measurements, stable isotope signatures, and elemental ratios are extensively used as parameters in mixing models to identify the source material contributing to mixtures. Determining these contributions in complex mixtures necessitates the use of multiple tracers. Here, we show that this requires careful selection of the parameters used, and that the common direct use of isotopic signatures or elemental ratios in mixing models when combined with other tracers can lead to erroneous results. We further demonstrate that when the number of available tracers exceeds the number of source materials, finding the fractional contributions that best fit the data may benefit from normalization, and we present a simple measure indicating when the outcome of mixing model calculations is poorly constrained. Finally, as a practical example, we investigated the impact of parameter choices through a reanalysis of literature data on organic matter cycling along the Altamaha River Estuary.
%U http://www.aslo.org/lomethods/free/2014/0694.pdf
%A Loftis, Kathy
%A Meile, Christof
%K multi-parameter mixing models

%0 Conference Proceedings
%T Modeling the Effects of Changes to Physical, Hydrological, and Biological Processes on Porewater Salinity Distributions in a Southeastern Salt Marsh
%D 2014
%C San Francisco
%B 2014 AGU Fall Meeting
%8 15-19 December 2014
%9 Poster
%Z presented
%M GCE.895
%A Miklesh, David Michael
%A McKnight, Charles Jared
%A McLenaghan, Natalie Ann
%A Di Iorio, Daniela
%A Meile, Christof
%K porewater, salinity, soil, model, Student Publication

%0 Conference Proceedings
%T Attack of the clones: multiscale modeling of clonal plant dynamic
%D 2014
%I The Interagency Modeling and Analysis Group
%C NIH campus, Bethesda Maryland
%B 2014 Multi-Scale Modeling Consortium
%8 September 3-4, 2014
%9 Poster
%Z presented
%M GCE.810
%A Mony, Cendrine
%A Pennings, Steven C.
%A Bittebiere, Anne-Kristel
%A Garbey, Marc
%K model, clonal plants, competition

%0 Thesis
%T Use of marine habitat and food resources by coastal inhabiting Alligator Mississipiensis (American Alligator): implications for food webs and community dynamics
%D 2014
%P 201
%I University of Florida
%C Gainesville, FL
%9 Ph.D. Dissertation
%Z published
%M GCE.912
%X The American alligator (Alligator mississippiensis) is a widespread aquatic predator throughout the southeastern United States. Historically, the ecological interactions of A. mississippiensis have been studied in the context of freshwater ecosystems such as inland lakes. Lacking salt secreting glands maintained in closely related crocodiles (Crocodylidae), the occurrence of A. mississippiensis in higher salinity marine and estuarine ecosystems has often been considered aberrant and of no particular importance to ecological processes in these coastal systems. However, it is well known that top-predators have the potential to exhibit strong effects within foodwebs through their interactions with prey and movement between disparate ecosystems. Within this dissertation, I set out to demonstrate that the use of marine  and estuarine ecosystems by A. mississippiensis is common and that these behaviors have the potential to affect isolated freshwater ponds and wetlands by transferring marinederived nutrients and salt marshes through their interactions with an importantmesopredator (Callinectes sapidus, Blue crab). First, I employed field studies using nightlight surveys, stomach content analysis, and stable isotope analysis to assess intra-population variation in the use of marine habitat and food resources by A. mississippiensis inhabiting an Atlantic barrier island.Second, I used GPS/VHF telemetry to assess the effect of abiotic factors on crossecosystem movement patterns of adult individuals. Third, I attached and deployed animal-borne imaging systems (Crittercam) to quantify prey attack and capture success rates as well as diel activity patterns and investigated variation in these parameters. Lastly, I experimentally tested the potential of A. mississippiensis to elicit a trophic cascade within a simplified salt marsh food web through consumptive and nonconsumptive interactions with the mesopredator C. sapidus.Results from this body of work will advance our understanding of the role A. mississippiensis serves in coastal ecosystems and provide essential data to predict consequences of changing environment conditions.
%A Nifong, James C.
%K American Alligator, coastal habitat, food resources, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Animal-borne imaging reveals novel insights into the foraging behaviors and diel activity of a large-bodied apex predator, the American alligator (Alligator mississippiensis).
%D 2014
%V 9
%N 1
%B PLOS One
%9 Article
%Z published
%M GCE.879
%R 10.1371/journal.pone.0083953
%X Large-bodied, top- and apex predators (e.g., crocodilians, sharks, wolves, killer whales) can exert strong top-down effects within ecological communities through their interactions with prey. Due to inherent difficulties while studying the behavior of these often dangerous predatory species, relatively little is known regarding their feeding behaviors and activity patterns, information that is essential to understanding their role in regulating food web dynamics and ecological processes. Here we use animal-borne imaging systems (Crittercam) to study the foraging behavior and activity patterns of a cryptic, large-bodied predator, the American alligator (Alligator mississippiensis) in two estuaries of coastal Florida, USA. Using retrieved video data we examine the variation in foraging behaviors and activity patterns due to abiotic factors. We found the frequency of prey-attacks (mean = 0.49 prey attacks/hour) as well as the probability of prey-capture success (mean = 0.52 per attack) were significantly affected by time of day. Alligators attempted to capture prey most frequently during the night. Probability of prey-capture success per attack was highest during morning hours and sequentially lower during day, night, and sunset, respectively. Position in the water column also significantly affected prey-capture success, as individuals’ experienced two-fold greater success when attacking prey while submerged. These estimates are the first for wild adult American alligators and one of the few examples for any crocodilian species worldwide. More broadly, these results reveal that our understandings of crocodilian foraging behaviors are biased due to previous studies containing limited observations of cryptic and nocturnal foraging interactions. Our results can be used to inform greater understanding regarding the top-down effects of American alligators in estuarine food webs. Additionally, our results highlight the importance and power of using animal-borne imaging when studying the behavior of elusive large-bodied, apex predators, as it provides critical insights into their trophic and behavioral interactions.
%U https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0083953
%A Nifong, James C.
%A Nifong, R.
%A Silliman, Brian R.
%A Lowers, R.H.
%A Guillette, L.J.
%A Ferguson, M.
%A Welsh, M.
%A Abernathy, K.
%A Marshall, G.
%K apex predator, American alligator, Student Publication

%0 Journal Article
%T Effects of oil spills on terrestrial arthropods in coastal wetlands
%D 2014
%V 64
%P 789-795
%B Bioscience
%9 Article
%Z published
%M GCE.807
%R 10.1093/biosci/biu118
%X Coastal wetlands are important to human well-being and vulnerable to oil spills. Research on biotic effects of oil has been focused on microbes,plants, and benthic invertebrates, neglecting terrestrial arthropods. We review how oil affects terrestrial arthropods in coastal marshes andsuggest future research topics. Terrestrial arthropods play important ecological roles in coastal marshes, affecting primary production anddecomposition and providing food to terrestrial and marine vertebrates. Some species are pests and disease vectors for humans and livestock.Terrestrial arthropods are sensitive to oil exposure and are suppressed even in lightly oiled sites where plants are not affected. Some arthropodslater reinhabit oiled marshes, which demonstrates that portions of the arthropod community may be resilient to oil exposure. However, oil thatremains in sediments may affect terrestrial populations for years after the spill. The sensitivity of arthropods to oil exposure makes them usefulindicators of marsh health following environmental impacts.
%U https://academic.oup.com/bioscience/article/64/9/789/269346
%A Pennings, Steven C.
%A McCall, Brittany DeLoach
%A Hooper-Bui, Linda
%K Deepwater Horizon, insects, Macondo, oil spill, salt marsh, Student Publication

%0 Journal Article
%T Application of hyperspectral remote sensing reflectance data to photochemical rate calculations in the Duplin River, a tidal river on the coast of Georgia, USA
%D 2014
%V 51
%N 2
%P 199-211
%B GIScience & Remote Sensing
%9 Article
%Z published
%M GCE.865
%R 10.1080/15481603.2014.895583
%X Estuaries are photochemically dynamic environments with high carbon loads andrelatively small areas. The small area poses problems for large-scale satellite-basedremote sensing calculations, where the resolution is too coarse to distinguish land fromwater. Airborne remote sensing instruments have the potential to reveal the dynamicsof these areas with fine-scale resolution. In June 2006, hyperspectral remote sensingimagery, using an AISA Eagle instrument, was collected over the tidal Duplin River,Georgia, USA. A dark-water updated version of the SeaUV algorithm was applied tothe AISA remote sensing image to determine diffuse attenuation constants in theultraviolet and calculate surface photochemical production rates of two inorganicproducts – carbon monoxide (CO) and carbon dioxide (CO2). For an average day inJune at the study site, the modeled photoproduction rates for CO2 and CO averaged~7 × 10&#8722;1 nmol C/day/cm3 and ~3.5 × 10&#8722;2 nmol C/day/cm3, respectively.
%A Reader, Heather E.
%A Miller, William
%K photochemistry, ocean color, remote sensing, carbon cycles, CO2, CO, coastal ocean, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Changing Communities: Mississippi Period Transitions on the Georgia Coast.
%D 2014
%C Greenville, SC
%B Southeastern Archaeological Conference
%8 2014
%9 Poster
%Z presented
%M GCE.944
%A Ritchison, Brandon Tyler
%K Communities, GA coast, Student Publication

%0 Conference Proceedings
%T Articulating Management and Research on Ossabaw Island, Georgia
%D 2014
%C Greenville, SC
%B Southeastern Archaeological Conference
%8 2014
%9 Poster
%Z presented
%M GCE.947
%A Roberts Thompson, Amanda D.
%A Tucker, Bryan
%A Bedell, Jennifer
%A Tucker, Megan T.
%A Golsch, Matthew
%A Ritchison, Brandon Tyler
%A Colvin, Matthew H.
%A Napora, Katherine
%A Black, Rachel
%A Bouzigard, Aimee
%A Thompson, Victor D.
%K management and research, Student Publication

%0 Thesis
%T Controls on nitrogen inputs, loads, and in-stream concentrations in the Altamaha River, Georgia, and beyond.
%D 2014
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.863
%X Human activity has increased the availability of reactive nitrogen (N), an element of critical importance to life. The broad goal of this dissertation was to understand which sources of N to a watershed reach rivers.      Nitrogen input budgets were calculated for 18 watersheds on the United States west coast. Fertilizer was the most important source of new N, with atmospheric deposition second. N export was best correlated with streamflow variations, which explained 66% of the variance. Including inputs explained an additional 16% of the variance. Riverine N export averaged 12% of inputs. Percentage export was also best related to streamflow. These results were likely due to the large range of streamflows across the study region, which may have overwhelmed other factors contributing to N export.      An in-depth examination of the Altamaha River watershed (Georgia, USA) found that riverine N concentrations and cumulative loads were best related to population density, rather than input factors. Concentrations were highest in the upper watershed and lowest in blackwater streams and a sampling station downstream of a dam. Isotopic analysis of nitrate suggested that most in-stream nitrate is derived from sewage or manure. Where the concentration was particularly low, an atmospheric signal was observed, suggesting that background nitrate is of atmospheric origin. N in this system appeared to be lost primarily on the watershed surface, as only a small proportion of inputs reached the stream, N was transported downstream conservatively, and an isotopic mixing model fit the data well.      The Altamaha is comparable to other watersheds worldwide in its nitrate concentrations and population density. A metadata analysis of medium-sized (2,000-50,000 km2) watersheds, which are under-studied relative to large watersheds, revealed that nitrate concentrations are generally low (<25 µM). We found a relationship between population density and riverine NO3- concentration, which varied among continents and latitudinal zones. A combination of population density, population density without access to improved sanitation, temperature, precipitation, slope, and fertilizer use, explained 45% of the variation in nitrate concentrations. The relationship had less explanatory power than in large watersheds, potentially due to increased variation in NO3- concentrations with decreased watershed size.
%A Schaefer, Sylvia C.
%K nitrogen, Altamaha River, Student Publication

%0 Conference Proceedings
%T Remote sensing and geospatial analysis of material gradients and fronts within the Inner Shelf of the Central South Atlantic Bight
%D 2014
%I ASLO / TOS / AGU
%C Honolulu, Hawaii
%B Ocean Sciences Meeting
%S 42. Optical Remote Sensing of Freshwater, Estuarine, and Coastal Environments: Water Quality and Other Applications
%8 February, 2014
%9 Poster
%Z presented
%M GCE.833
%X This paper examines patterns of optically active constituents (chlorophyll, total suspended matter, and CDOM) of estuaries and inner shelf waters ofthe South Atlantic Bight in Georgia, USA. These inner shelf waters have notable turbidity and reduced salinity. Tidal channels and alongshore currents circulate materials across estuaries. Complex fronts are commonly observed in the inner shelf "confrontation zone". We used boat transects,hyperspectral HICO and airborne imagery, and high spatial resolution satellite imagery (Worldview2, Geoeye, Quickbird2) to examine the complexpatterns associated with river discharges and high amplitude (~1.5 - 3 m) tidal exchanges with the extensive inshore habitats. Coincident with thecomplex hydrology, Chl, TSS, and CDOM (abs 440 nm) had strong spatial and temporal variability: with ranges of about 1 - 30 ug/L, 1 - 70 mg/L, and0.04 - 0.9 m-1, respectively. Inshore to offshore gradients were obvious, but water masses were commonly divided by density-driven fronts, withdiscernable color differences relatable to differing mixtures of our measured constituents. Quantification of gradients and areal coverages / mappingof these water parcels will be presented.
%A Schalles, John F.
%A O'Donnell, J.P.
%A Olley, J.T.
%K Chlorophyll, CDOM. satellite imagery, HICO, fronts, South Atlantic Bight, Student Publication

%0 Journal Article
%T Integrating ecosystem services and local government finances intoland use planning: A case study from coastal Georgia
%D 2014
%V 122
%P 56 - 67
%B Landscape and Urban Planning
%9 Article
%Z published
%M GCE.861
%R 10.1016/j.landurbplan.2013.11.008
%X This work presents a novel approach to assessing the impact of future growth in rural regions faced with rapid growth. We investigate one of the most rural counties on the eastern coast of the U.S. (McIntosh County, Georgia) from the dual perspective of (1) ecosystem services and (2) costs assumed by local government. As land cover in our focal locality is overwhelmingly forest or wetland, we compiled estimates from multiple sources to map the value per ha/year of (1) timber sales and recreational leases to private landowners and (2) a suite of non-market public amenities: rare species habitat, carbon sequestration, flood control, pollution treatment, water supply, and storm protection. We then quantified, based on county budgets, expenditures and revenues deriving from major land use categories (residential, commercial/industrial, agricultural/open-space). Results indicate that (1) forested wetlands generate relatively little revenue to either private landowners or in taxes to the county from extractive uses, but have very high value relative other land cover types in the provision of ecosystem services, (2) forest lands contribute much more in revenue than they receive in services, whereas residential properties cost more in services, than they generate in revenue, and (3) significant gains in both ecosystem service preservation, hazard reduction, and in lower costs to the county in municipal services could be achieved by restricting new development from within the Federal Insurance Rate Map (FIRM)-determined 500 year floodplain.
%A Schmidt, John Paul
%A Moore, Rebecca
%A Alber, Merryl
%K Ecosystem service valuation Cost of community serv

%0 Thesis
%T Nitrogen cycling and trace gas dynamics in shallow coastal aquifers.
%D 2014
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.889
%X Since the industrial revolution, human activity has doubled the amount of carbon in Earth’s atmosphere and increased the rate of nitrogen supply to its biosphere by 40%. As a result, the climate is warming, sea level is rising, and fresh and saltwater resources are being threatened by eutrophication. Coastal areas are among the most vulnerable to these environmental challenges, and are economically critical zones that support tourism, fisheries, and half of the world’s population. Primary production in coastal waters tends to be nitrogen limited, so anthropogenic nitrogen inputs results in eutrophication and degraded coastal water quality. Groundwater discharge is the dominant source of nitrogen to the South Atlantic Bight and rivals riverine nitrogen loading in many coastalecosystems globally. However, groundwater must transit coastal aquifers prior to discharge where microbial communities have the potential to remove bioavailable nitrogen via coupled nitrification and denitrification or anammox. This microbial activity also generates methane and nitrous oxide, which are potent greenhouse gases. Thus, coastal groundwater influences both water quality and atmospheric chemistry.      The goal of this work was to quantify patterns and rates of microbial processes in shallow coastal aquifers that contribute to the production and consumption of bioavailable nitrogen and the greenhouse gases nitrous oxide and methane. High nitrification rates (0.78 ± 0.26 mmol m-2 day-1) were found in shallow beach sand on a barrier island in coastal Georgia, USA. High nitrous oxide concentrations were also observed at this location (median = 282 nM, n = 32). Nitrous oxide production was supported by a nitrate loss rate of 11 mmol m-2 day-1, which in turn, was too high to be supported by the observed nitrification rate alone, suggesting that nitrogen fixation was also important at this site. A hotspot of methane was observed in the freshwater lens near the center of Cabretta Island (median = 587 µM) supported by high rates of methanogenesis (22.2 ±10.6 mmol m-2 day-1). However, most of this methane was consumed before it could be exported to the ocean due to active methanotrophy (18 ± 2.1 mmol m-2 day-1) in surficial beach sand. Finally, submarine groundwater discharge was shown to export roughly the same quantity of greenhouse gases from salt marsh soils as direct efflux to the atmosphere, the only export pathway recognized previously in theliterature.
%A Schutte, Charles
%K Nitrogen cycling, shallow coastal aquifers, SINERR Publication, Student Publication, UGAMI Publication

%0 Book Section
%T Development of wetland plant communities
%D 2014
%P 133-150
%I University of California Press
%B Ecology of Freshwater and Estuarine Wetlands
%7 Second edition
%9 Article
%Z published
%M GCE.919
%A Sharitz, Rebecca R.
%A Pennings, Steven C.
%K wetlands, plants, hydrology, SINERR Publication, UGAMI Publication

%0 Book Section
%T Ecology of Freshwater and Estuarine Wetlands: An Introduction
%D 2014
%P 1-22
%I University of California Press
%B Ecology of Freshwater and Estuarine Wetlands
%7 Second edition
%9 Article
%Z published
%M GCE.918
%A Sharitz, Rebecca R.
%A Batzer, Darold
%A Pennings, Steven C.
%K wetlands, plants, hydrology, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Alternating Effects of Climate Drivers on Altamaha River Discharge to Coastal Georgia, USA
%D 2014
%V 37
%P 772–788
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.745
%R 10.1007/s12237-013-9715-z
%X Freshwater delivery is an important factor determining estuarine character and health and may be influenced by large-scale climate oscillations. Variability in freshwater delivery (precipitation and discharge) to the Altamaha River estuary (GA, USA) was examined in relation to indices for several climate signals: the Bermuda High Index (BHI), the Southern Oscillation Index (SOI), the Improved El Nińo Modoki Index (IEMI), the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO), the Pacific Decadal Oscillation (PDO), and the Pacific/North American Pattern (PNA). Discharge to this estuary has been linked to key ecosystemproperties (e.g., salinity regime, water residence time, nutrient inputs, and marsh processes), so understanding how climate patterns affect precipitation and river discharge will help elucidate how the estuarine ecosystem may respond to climate changes. Precipitation patterns in the Altamaha River watershed were described using empirical orthogonal functions (EOFs) of the combined multidecadal time series of precipitation at 14 stations. The first EOF (67 % of the variance) was spatially uniform, the second EOF (11%) showed a spatial gradient along the long axis of the watershed (NW–SE), and the third EOF (6 %) showed a NE–SWpattern. We compared the principal components (PCs) associated with these EOFs, monthly standardized anomalies of Altamaha River discharge at the gauge closest to the estuary, and the climate indices. Complex, seasonally alternating patterns emerged. The BHI was correlated with June–January discharge and precipitation PC 1. The SOI was correlated with January–April discharge and precipitation PC 2, and also weakly correlated with PC 1 in November–December. The AMO was correlated with river discharge and precipitation PC 3 mainly in December–February and June. The correlation patterns of precipitation PCs with PDO and PNAwere similar to those with SOI, but weaker. There were no consistent relationships with two NAO indices or IEMI. Connections between climate signals and estimates of nutrient loading were consistent with the connections to discharge. The occurrence of tropical storms in the region was strongly related to the BHI but not to the other climate indices, possibly representing the influence of storm tracking more than the rate of storm formation. Comparison with the literature suggests that the patterns found may be typical of southeastern USA estuaries but are likely to be different from those outside the region.
%U http://link.springer.com/article/10.1007/s12237-013-9715-z/fulltext.html
%A Sheldon, Joan E.
%A Burd, Adrian B.
%K Climate signals, Precipitation, Discharge, Altamaha River, Estuary, Tropical storms

%0 Conference Proceedings
%T Example Workflows for Sensor Data Processing and QA/QC
%D 2014
%I Earth Science Information Partners (ESIP)
%C Copper Mountain, Colorado
%B Federation of Earth Science Information Partners Summer Meeting 2014
%S Avoid Tech Regret: Let a Workflow Turn the Crank
%8 July 8-11, 2014
%9 Presentation
%Z presented
%M GCE.806
%U http://gce-lter.marsci.uga.edu/public/uploads/SheldonWorkflowExamples2014_20140718T161816.pdf
%A Sheldon, Wade M., Jr.
%K archives, LTER-IMC, data, metadata, workflows, software, GCE Data Toolbox, MATLAB

%0 Conference Proceedings
%T Putting the Archives to Work: Workflow and Metadata-driven Analysis in LTER Science
%D 2014
%I Earth Science Information Partners (ESIP)
%C Copper Mountain, Colorado
%B Federation of Earth Science Information Partners Summer Meeting 2014
%S Enabling Technologies for the Ecological Data Lifecycle
%8 July 8-11, 2014
%9 Presentation
%Z presented
%M GCE.805
%U http://gce-lter.marsci.uga.edu/public/uploads/WSheldon_LTER_Archive_Workflows_20140718T161428.pdf
%A Sheldon, Wade M., Jr.
%K archives, LTER-IMC, data, metadata, workflows, software, GCE Data Toolbox, MATLAB

%0 Conference Proceedings
%T The GCE Data Toolbox
%D 2014
%I CUAHSI
%C WWW (https://www.cuahsi.org/VW-Solutions)
%B CUAHSI Virtual Workshop on Field Data Management Solutions
%S Tools, tricks and techniques for handling data in the field
%9 Presentation
%Z presented
%M GCE.838
%U http://gce-lter.marsci.uga.edu/public/uploads/WSheldon_CUAHSI_Workshop_Oct2014_20141014T83308.pdf
%A Sheldon, Wade M., Jr.
%K data, LTER-IMC, metadata, MATLAB, processing, management, archiving, database, sensor

%0 Newspaper Article
%T Using the GCE Data Toolbox as an EML-compatible workflow engine for PASTA
%D 2014
%I LTER Network
%C Albuquerque, NM
%B LTER Databits – Information management Newsletter of the Long Term Ecological Research Network
%S Fall 2014
%9 Article
%Z published
%M GCE.892
%X The GCE Data Toolbox for MATLAB was initially developed in 2000 to process, quality control and document environmental data collected at the then-new Georgia Coastal Ecosystems LTER site (Sheldon, 2001). Development of this software framework has continued steadily since then, adding graphical user interface dialogs (Sheldon, 2002), data indexing and search (Sheldon, 2005), web-based data mining (Sheldon, 2006; Sheldon, 2011b), dynamic QA/QC (Sheldon, 2008), and a growing suite of tools for automating data harvesting and publishing (Sheldon et al. 2013; Gries et al., 2013). We began distributing a compiled version of the toolbox to the public in 2002, and in 2010 we released the complete source code under an open source GPL license (Sheldon, 2011a). Today, the GCE Data Toolbox is used at multiple LTER sites and other research programs across the world for a wide variety of environmental data management tasks, and we are actively working to make it a more generalized tool for the scientific community (Chamblee et al., 2013).The toolbox can be leveraged in many ways, but it has proven particularly useful for designing automated data processing, quality control and synthesis workflows (Sheldon et al., 2013; Cary and Chamblee, 2013; Gries et al., 2013). Key factors include broad data format support, a flexible metadata templating system, dynamic rule-based QA/QC, automated metadata generation and metadata-based semantic processing (fig.1). Consequently, the GCE Data Toolbox was one of the technologies chosen for a 2012 LTER NIS workshop convened to test the PASTA Framework for running analytical workflows (see http://im.lternet.edu/im_practices/data_management/nis_workflows). The lack of built-in support for EML metadata proved to be a significant barrier to fully utilizing this toolbox for PASTA workflows during the workshop; however, complete EML support has since been implemented. This article describes how the GCE Data Toolbox can now be used as a complete workflow engine for PASTA and other EML-compatible frameworks.
%U https://lternet.edu/wp-content/uploads/2017/12/2014-fall-lter-databits.pdf
%A Sheldon, Wade M., Jr.
%K LTER-IMC, metadata, EML, MATLAB, toolbox, workflows, PASTA, NIS

%0 Journal Article
%T Salt marshes
%D 2014
%V 24
%N 9
%P 348-350
%B Current Biology
%9 Article
%Z published
%M GCE.877
%R 10.1016/j.cub.2014.03.001
%X Salt marshes are lush, intertidal grasslands renowned for their productivity. The yearly accumulation of plant and animal tissue in salt marshes rivals and often exceeds that observed in other highly productive ecosystems, including coral reefs and tropical rain forests. Although the local diversity of plants and animals found in salt marshes is comparatively low, the abundance of organisms that do occur in marshes is often breathtaking. The abundance per square meter of one species of fiddler crab or snail routinely reaches 100–400 individuals, at times over 1000, and over larger spatial scales the density of one species of non-insect invertebrate (mussels, crabs and snails) can often reach 50,000,000 per square kilometer. Globally, plant species richness in salt marshes is surprisingly high, with over 500 salt marsh plant species known.
%U http://www.cell.com/current-biology/pdf/S0960-9822(14)00256-5.pdf
%A Silliman, Brian R.
%K salt marshes

%0 Journal Article
%T Livestock as a Biological Control Agent for an Invasive Wetland Plant.
%D 2014
%V 2
%P 567
%B PeerJ
%9 Article
%Z published
%M GCE.878
%R 10.7717/peerj.567
%X Invasive species threaten biodiversity and incur costs exceeding billions of US$. Eradication efforts, however, are nearly always unsuccessful. Throughout much of North America, land managers have used expensive, and ultimately ineffective, techniques to combat invasive Phragmites australis in marshes. Here, we reveal that Phragmites may potentially be controlled by employing an affordable measure from its native European range: livestock grazing. Experimental field tests demonstrate that rotational goat grazing (where goats have no choice but to graze Phragmites) can reduce Phragmites cover from 100 to 20% and that cows and horses also readily consume this plant. These results, combined with the fact that Europeans have suppressed Phragmites through seasonal livestock grazing for 6,000 years, suggest Phragmites management can shift to include more economical and effective top-down control strategies. More generally, these findings support an emerging paradigm shift in conservation from high-cost eradication to economically sustainable control of dominant invasive species.
%A Silliman, Brian R.
%A Mozdzer, C.
%A Angelini, Christine
%A Brundage, J.E.
%A Bakker, J.P.
%A Esselink, P.
%A van de Koppel, Johan
%A Baldwin, A.H.
%K Top-down control, Salt marshes, Invasive species, Biocontrol, Student Publication

%0 Journal Article
%T Independent and combined effects of multiple predators across ontogeny of a dominant grazer
%D 2014
%V 123
%N 9
%P 1081-1090
%B OIKOS
%9 Article
%Z published
%M GCE.867
%R 10.1111/oik.01579
%X Ecosystems host multiple coexisting predator species whose interactions may strengthen or weaken top–down control of grazers. Grazer populations often exhibit size-structure, but the nature of multiple predator effects on suppression of size-structured prey has seldom been explicitly considered. In a southeastern US salt-marsh, we used both field (additive design) and mesocosm (additive-substitutive design) experiments to test the independent and combined effects of two species of predatory crab on the survival and predator-avoidance behavior (i.e. a non-consumptive effect) of both juveniles and adults of a dominant grazing snail. Results showed: 1) juvenile snails were more vulnerable to predation; 2) consumptive impacts of predators were hierarchically nested, i.e. the larger predator consumed both juvenile and adult snails, while the smaller-bodied predator consumed only juvenile snails; 3) there were no emergent multiple predator effects on snail consumption; and 4) non-consumptive effects differed from consumptive effects, with only the large predator inducing predator-avoidance behavior of individuals within either snail ontogenetic class. The smaller predator therefore played a functionally redundant trophic role across the prey classes considered, augmenting and potentially stabilizing trophic regulation of juvenile snails. Meanwhile, the larger predator played a complementary and functionally unique role by both expanding the size-spectrum of prey trophic regulation and non-consumptively altering prey behavior. While our study suggests that nestedness of consumptive interactions determined by predator and prey body sizes may allow prediction of the functional redundancy of particular predator species, it also shows that traits beyond predator body size (e.g. habitat domain) may be required to predict potentially cascading non-consumptive effects. Future studies of multiple predators (and predator biodiversity) should continue to strive towards greater realism by incorporating not only size-structured prey, but also other aspects of resource and environmental heterogeneity typical of natural ecosystems.
%A Soomdat, Nicole
%A Griffin, John N.
%A McCoy, M.
%A Hensel, Marc Simon
%A Buhler, Stephanie
%A Chejanovski, Zachary A.
%A Silliman, Brian R.
%K grazer, predator, salt marsh, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Fluvial Morphology and Bedform Migration in the Ebb Tidal Dominated Duplin River, Georgia
%D 2014
%I AGU
%C San Francisco
%B 2014 AGU Fall Meeting
%8 December, 2014
%9 Abstract
%Z presented
%M GCE.832
%X The Duplin River is an ebb-domintated, salt marsh drainage system west of Sapelo Island, Georgia. With no riverine input, flow in the Duplin is dependent on local surface run off, groundwater discharge and tidal flushing. Repeat multibeam bathymetry surveys within this system provide insight into sediment transport, current dynamics, and the migration of bottom features. Examination of bathymetric changes and the rate of bedform migration can be used to help estimate net sediment transport in fluvial and tidal systems. The swath bathymetry data presented here were collected during December 2009, March 2013, and June 2013 (high and low tide) aboard a small survey vessel, using a pole-mounted Kongsberg EM3002d multibeam bathymetry system.  Along-stream profiles from bathymetry data collected during a single spring tidal cycle show little bedform migration, while the more temporally distant profiles record significant shifts in both small (cm-scale) and large (m-scale) bedform position, as well as changes in the morphology of large erosional scour depressions.  Previous work has suggested the larger bedforms, which maintain an ebb-oriented geometry through both ebb and flood tide, are indicative of sediment transport rates that are an order of magnitude greater during the ebb tide (Zarillo, 1985). The new data suggest punctuated events, such as storm surges, may also play an important role in the fluvial transport, although more analysis is needed to determine how sediment storage changes in the Duplin river system over multiple tidal cycles. Integration of topographic LiDAR data, vegetation patterns, sediment composition, groundwater inputs and planform river morphology will also provide insight into sediment storage and transport within the system.
%A Straub, Jessamin A.
%A Hill, Jenna, C.
%A Viso, Richard F.
%A Peterson, Richard N.
%A Carter, Matthew
%K bathymetry, Duplin River, geomorphology, Student Publication

%0 Journal Article
%T Gastric nematode diversity between estuarine and inland freshwater populations of the American alligator (Alligator mississippiensis ,daudin 1802), and the prediction of intermediate hosts
%D 2014
%V 3
%P 227-235
%B International Journal for Parasitology:Parasites and Wildlife
%9 Article
%Z published
%M GCE.913
%R 10.1016/j.ijppaw.2014.07.001
%X We examined the variation of stomach nematode intensity and species richness of Alligator mississippiensis from coastal estuarine and inland freshwater habitats in Florida and Georgia, and integrated prey content data to predict possible  intermediate hosts. Nematode parasitism within inland freshwater inhabiting populations was found to have a higher intensity and species richness than those inhabiting coastal estuarine systems. This pattern potentially correlates with the difference and diversity of prey available between inland freshwater and coastal estuarine habitats. Increased consumption of a diverse array of prey was also correlated with increased nematode intensity in larger alligators. Parasitic nematodesDujardinascaris waltoni, Brevimulticaecum tenuicolle, Ortleppascaris antipini, Goezia sp., and Contracaecum sp. were present in alligators from both habitat types. Dujardinascaris waltoni, B. tenuicolle, and O. antipini had a significantly higher abundance among inland inhabiting alligators than hosts from estuarine populations.Our findings also suggest that host specific nematode parasites of alligators may have evolved to infect multiple intermediate hosts, particularly fishes, crabs, and turtles, perhaps in response to the opportunistic predatory behaviors of alligators
%U https://www.ncbi.nlm.nih.gov/pubmed/25426417
%A Tellez, M.
%A Nifong, James C.
%K Alligator mississippiensis, Ascarididae, Georgia, Florida, Intermediate hosts, Stomach &#64258, ushing, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Forty years of experiments on invasive species: are biases limiting our understanding of impacts?
%D 2014
%V 22
%P 1-22
%B NeoBiota
%9 Article
%Z published
%M GCE.880
%R 10.3897/neobiota.22.6224
%X Invasions by non-native species are a threat to biodiversity because invaders can impact native populations, communities and entire ecosystems. To manage this threat, it is necessary to have a strong mechanistic understanding of how non-native species affect local species and communities. We reviewed 259 published papers (1972–2012) that described field experiments quantifying the impact of aquatic non-native species, to examine whether various types of study biases are limiting this understanding. Our review revealed that invasion impacts had been experimentally quantified for 101 aquatic non-native species, in all major freshwater and marine habitats, on all continents except Antarctica and for most higher taxonomic groupings. Over one-quarter (26%) of studies included tests for impacts on local biodiversity. However, despite this extensive research effort, certain taxa, habitats and regions remain poorly studied. For example, of the over one hundred species examined in previous studies, only one was a marine fish and only six were herbivores. Furthermore, over half (53%) of the studies were from the USA and two-thirds (66%) were from experiments conducted in temperate latitudes. By contrast, only 3% of studies were from Africa and <2% from high latitudes. We also found that one-fifth (20%) of studies were conducted in estuaries, but only 1% from coral reefs. Finally, we note that the standard procedure of pooling or not reporting non-significant treatments and responses is likely to limit future synthetic advancement by biasing meta-analysis and severely limiting our ability to identify non-native species with none or negligible ecological impacts. In conclusion, a future focus on poorly-studied taxa, habitats and regions, and enhanced reporting of results, should improve our understanding and management of impacts associated with aquatic non-native species.
%A Thomsen, M. S
%A Wernberg, T.
%A Olden, J.
%A Byers, James
%A Bruno, John F.
%A Silliman, Brian R.
%A Schiel, D.R.
%K Biotic homogenization, alien species, exotic species, review

%0 Thesis
%T The influence of environmental factors including reactive oxygen species on the spatial and temporal distribution of marine Thaumarchaeota
%D 2014
%P 418
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.907
%X Thaumarchaeota ? formerly known as Marine Group I Crenarchaeota ? are highly abundant in the world?s oceans, making up ~20% of the total prokaryotic population. Members of the Thaumarchaeota are capable of oxidizing ammonia using the ammonia monooxygenase enzyme (amoA), which is the first step in nitrification and a key process in the global nitrogen cycle. They are most abundant in deeper, colder waters with appearances in surface waters generally limited to higher latitudes and polar oceans in winter. Reasons for this distribution have been postulated, but no definitive explanation has been found to date. A hypothesis tested with this work is that reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2), play a role in exclusion of Thaumarchaeota from surface waters. This dissertation examines the spatial distribution of Thaumarchaeota in coastal and open-ocean, polar and temperate marine environments, where correlations with increased depth and decreased oxygen were common regardless of sample site. We also investigated the temporal distribution of Thaumarchaeota on Sapelo Island, Georgia, where annual spikes in abundance correlated to summer conditions (increased temperature; decreased pH, oxygen). The potential for Thaumarchaeota to use urea as an alternate substrate for ammonia oxidation was also investigated; our findings suggest that this is not a widespread attribute and is most likely due to removal of amine groups that are subsequently oxidized. Additionally, we found that nitrification is inhibited with increased [H2O2] in open ocean samples, with the most sensitive populations coming from the Southern Ocean. Populations from Sapelo Island, Georgia, were not as sensitive, but these microbial communities encounter high daily H2O2 concentrations. In conclusion, we have found that Thaumarchaeota distributions correlate to a variety of environmental factors and it is unlikely that any single one can be used to predict dynamics of the entire group. However, evidence from this work indicates that clades of Thaumarchaeota could be differentially affected by certain conditions, justifying the separation of this group into ecotypes for future studies. We have shown that direct oxidation of urea by Thaumarchaeota is unlikely, and that ROS can inhibit ammonia oxidation. This may explain why Thaumarchaeota are typically absent from surface waters.
%A Tolar, Bradley
%K Thaumarchaeota, Ammonia oxidation, Ammonia-oxidizing Archaea, Nitrification, 16S rRNA, ammonia monooxygenase (amoA), Reactive oxygen species (ROS), Ammonia, Urea, Nitrite, Nitrate, Nitrogen cycle, Quantitative PCR (qPCR), Student Publication

%0 Journal Article
%T Climate Drivers of Spartina alterniflora Saltmarsh Production in Georgia, USA
%D 2014
%V 17
%N 3
%P 473-484
%B Ecosystems
%9 Article
%Z published
%M GCE.802
%R 10.1007/s10021-013-9732-6
%X Tidal wetlands are threatened by global changes related not only to sea level rise but also to altered weather patterns. To predict consequences of these changes on coastal communities, it is necessary to understand how temporally varying abiotic conditions drive wetland production. In 2000–2011, we conducted annual surveys of Spartina alterniflora biomass in tidal marshes at nine sites in and around the Altamaha river estuary on the coast of Georgia, USA. End of the year live biomass was assessed in the creek bank and midmarsh zones to estimate annual net primary production (ANPP). River discharge was the most important driver of S. alterniflora ANPP, especially in creek bank vegetation. Increased river discharge reduces water column salinity, and this was most likely the proximate driver of increased production. In the midmarsh zone, the patterns were less distinct, although river discharge was again the best predictor, but maximum temperature had similar predictive ability. In contrast to results from terrestrial grasslands, we found no consistent evidence for a sharply delimited critical period for any climate driver in the tidal marsh,which indicates that plant growth was responsive to abiotic drivers at any time during the growing season. Results were broadly consistent across multiple sites within a geographic region. Our results differ from previous analyses of production in S. alterniflora marshes, which either identified oceanic drivers of S. alterniflora production or were unable to identify any drivers, likely because the low-latitude sites we studied were hotter and more affected by river discharge than those in previous studies.
%U http://link.springer.com/article/10.1007%2Fs10021-013-9732-6
%A Wieski, Kazimierz
%A Pennings, Steven C.
%K Spartina, productivity, river discharge, salt marsh, ANPP, sea level, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Latitudinal variation in resistance and tolerance to herbivory of a salt marsh shrub
%D 2014
%V 37
%P 763-769
%B Ecography
%9 Article
%Z published
%M GCE.804
%R 10.1111/ecog.00498
%X Interactions between plants and herbivores often vary on a geographic scale. Although theory about plant defenses and tolerance is predicated on temporal or spatial variation in herbivore damage, no single study has compared the pattern of herbivory, plant defenses and tolerance to herbivory of a single species across a latitudinal gradient. In 2002–2005 we surveyed replicate salt marshes along the Atlantic coast of the United States from Florida to Maine. At each field site we scored leaves of Iva frutescens for herbivore damage. In laboratory experiments we measured constitutive resistance and induced resistance in I. frutescens from high and low latitude sites along the Atlantic Coast. In another common garden experiment we studied tolerance to herbivory of I. frutescens from various sites. Theory predicts that constitutive resistance should matter more when damage is high, and induced resistance when herbivory is high but variable. In the field, average levels of herbivore damage, and spatial and temporal variation in herbivore damage were all greater at low versus high latitudes, indicating that constitutive as well as induced resistance should be stronger at low latitudes. Consistent with this prediction, constitutive resistance to herbivory was stronger at low latitudes. Induced resistance to herbivores was also stronger at low latitudes: it was deployed faster and lasted longer. Theory also predicts that tolerance to herbivory should be greater where average herbivory damage is greater; however, tolerance to herbivory in Iva did not depend on geographic origin. Our results emphasize the value of considering multiple ways in which plants respond to herbivores when examining geographic variation in plant–herbivore interactions.
%U http://onlinelibrary.wiley.com/doi/10.1111/ecog.00498/abstract
%A Wieski, Kazimierz
%A Pennings, Steven C.
%K induced defense, constitutive defense, Iva frutescens, high marsh, Cross-site Research, SINERR Publication, UGAMI Publication

%0 Report
%T Listening for / Learning from ecological knowledge: a social science pilot study in McIntosh County, GA
%D 2013
%I Sapelo Island NERR
%C Sapelo Island, Georgia
%B South Atlantic Regional Sea Grant - NERRS Fellowship Report
%9 Report
%Z presented
%M GCE.894
%X The Georgia Coastal Ecosystem (GCE) is 1 of 11 Maps and Locals (MALS) LTER sites nationwide. MALS research combines spatial analysis and social science to study socio-ecological change near LTER sites. Spatial analysis of McIntosh County was completed in 2011.
%U http://gce-lter.marsci.uga.edu/public/uploads/GCEPub894_Addes-Poster-May-2013-csh_20150304T135511.pdf
%A Addes, Danyel
%K social science, pilot, listening, citizens, McIntosh, anthropology, SINERR Publication, Student Publication

%0 Journal Article
%T Coastal Long Term Ecological Research: Introduction to the Special Issue.
%D 2013
%V 26
%N 3
%P 14 - 17
%B Oceanography
%S Coastal Long Term Ecological Research
%9 Article
%Z published
%M GCE.840
%X The US National Science Foundation's Long Term Ecological Research (LTER) network was established in 1980 to provide the scientific expertise, research platforms, and long-term data sets necessary to document and analyze environmental change (http://www.lternet.edu). There are currently 25 sites in the US LTER network representing a range of ecosystems, including deserts, prairies, forests, tundra, lakes, urban areas, estuaries, coastal reefs, the pelagic ocean, and production agriculture. Although the research questions being addressed vary across the network, each site collects data on primary production, population dynamics, the cycling of both organic and inorganic matter, and disturbance patterns. Long-term data in these core areas enable changes in critical ecological processes to be tracked over time and facilitate comparisons among different ecosystem types.
%A Alber, Merryl
%A Reed, D.J.
%A McGlathery, K. 
%K oceanography, coastal LTER

%0 Conference Proceedings
%T High-Resolution Assessment of Salt Marsh Development in Response to Sea Level Rise in the Southeastern United States.
%D 2013
%I Coastal and Estuarine Research Federation
%C San Diego, CA
%B Coastal and Estuarine Research Federation Biennial Meeting.
%8 4-7 November 2013
%9 Abstract
%Z published
%M GCE.827
%A Alexander, Clark R., Jr.
%A Blanton, Jackson O.
%A Garrett, A.
%A Brandes, J.
%A Hodgson, J.
%K Sea level rise, salt marsh, Southeastern United States

%0 Journal Article
%T The changing carbon cycle of the coastal ocean
%D 2013
%V 504
%P 61-70
%B Nature
%9 Article
%Z published
%M GCE.884
%R 10.1038/nature12857
%X The carbon cycle of the coastal ocean is a dynamic component of the global carbon budget. But the diverse sources and sinks of carbon and their complex interactions in these waters remain poorly understood. Here we discuss the sources, exchanges and fates of carbon in the coastal ocean and how anthropogenic activities have altered the carbon cycle. Recent evidence suggests that the coastal ocean may have become a net sink for atmospheric carbon dioxide during post-industrial times. Continued human pressures in coastal zones will probably have an important impact on the future evolution of the coastal ocean's carbon budget.
%U http://www.nature.com/nature/journal/v504/n7478/full/nature12857.html
%A Bauer, J.E.
%A Cai, Wei-Jun
%A Raymond, P.
%A Bianchi, Thomas S.
%A Hopkinson, Charles S.
%A Regnier, Pierre A. G.
%K carbon cycle

%0 Book
%T Marine Community Ecology and Conservation
%D 2013
%P 560
%I Sinauer Associates, Inc.
%9 Book
%Z ISBN-10: 1605352284 ISBN-13: 978-1605352282
%M GCE.853
%A Bertness, Mark D.
%A Bruno, John F.
%A Silliman, Brian R.
%A Stachowicz, John J.
%K Marine ecology, conservation

%0 Journal Article
%T Quantity is Nothing without Quality: Automated QA/QC for Streaming Environmental Sensor Data
%D 2013
%V 63
%N 7
%P 574-585
%B BioScience
%9 Article
%Z published
%M GCE.772
%R 10.1525/bio.2013.63.7.10
%X Sensor networks are revolutionizing environmental monitoring by producing massive quantities of data that are being made publicly available in near-real-time. These new data streams pose a challenge for ecologists because traditional approaches to quality assurance and quality control are no longer practical when confronted with extremely large data sets. Automated methods for rapidly identifying and (ideally) correcting problematic data are necessary for handling the volume of data generated by streaming sensor networks. Advances in sensor hardware have outpaced software, creating a need for tools to implement automated quality assurance and quality control procedures, produce graphical and statistical summaries for review, and track the provenance of the data. Use of automated tools would enhance data integrity and reliability, and reduce delays in releasing data products. Development of community-wide standards for quality assurance and quality control can instill confidence in sensor data and improve interoperability across environmental sensor networks.
%U http://www.nrs.fs.fed.us/pubs/43678
%A Campbell, John L.
%A Rustad, Lindsey E.
%A Porter, John H.
%A Taylor, Jeffrey R.
%A Dereszynkski, Ethan W.
%A Shanley, James B.
%A Gries, Corinna
%A Henshaw, Donald L.
%A Martin, Mary E.
%A Sheldon, Wade M., Jr.
%A Boose, Emery R.
%K quality control, qualifiers, sensor data, streaming, QA/QC, flagging, data management, LTER-IMC, Cross-site Research

%0 Conference Proceedings
%T Tidal Pumping as a Driver of Groundwater Discharge to a Back Barrier Salt Marsh Ecosystem
%D 2013
%I AGU
%C San Francisco
%B 2013 AGU Fall Meeting
%S Hydrologic Controls on Biogeochemical and Ecosystem Processes at the Land-Sea Interface III
%8 9-13 December, 2013
%9 Poster
%Z presented
%M GCE.830
%X Submarine groundwater discharge (SGD) typically consists of both terrestrial groundwater and recirculated seawater and has been shown to be a significant pathway of dissolved substances to the coastal zone. The fresh and saline water mixture in the subsurface creates a salinity gradient that can impact biogeochemical processes. Located along the South Atlantic Bight, Georgia’s coastline is an approximately 100-mile stretch of complex primary and secondary barrier islands resulting from geologic interactions driven by long-term sea level rise and retreat, accretion, seasonal tidal events, storm overwash, and wave driven erosion. Our study site is located in the Duplin River near Sapelo Island, GA and is part of the Georgia Coastal Ecosystems Long Term Ecosystem Research (GCE-LTER) program. This area is considered mesotidal (2-4m) and tidal pumping may be a dominating process in controlling SGD rates. The Duplin River is connected to the Atlantic Ocean through Doboy Sound to the south. To the north, the river terminates in extensive salt marsh and therefore has no overland freshwater input. Previous studies show a salinity gradient within the Duplin River indicating that SGD must be present as a source of brackish water. To place constraints on SGD processes, we employ a combination of geochemical and geophysical techniques to determine the magnitude of SGD in the Duplin River. Together these techniques permit a more complete understanding of the groundwater system. Three time series stations at the upper, mid and lower reaches of the Duplin River were deployed in June of 2013 to measure groundwater influences during daily and fortnightly tidal cycles. At each station, continuous radon-222 measurements were conducted at 30 minute intervals along with measurements of water level, temperature and conductivity using standard hydrological data loggers. During this period, eight time series resistivity profiles using a 56 electrode (110m long) cable were recorded to provide detailed imagery of fluid interactions at the ground/surface water interface during a tidal cycle. The resistivity profiles are presented as color contoured tomograms representing the shallow aquifer system to depths exceeding 20 meters. Measurements took place during a series of large precipitation events, including immediately before and after a tropical storm, as well as during relatively dry conditions. Taking into account the metrological variability, our initial results indicate that the SGD process is most strongly influenced by tidal pumping. Radon analysis and resistivity measurements reveal strong inverse relationships with water level. Percent difference resistivity models indicate substantial tidally controlled pore fluid flushing and mixing within the shallow aquifer system. These measurements will be further used to construct a water budget within the Duplin River and to delineate the extent of variability in salinity of shallow marsh sediments. In addition, these measurements will provide accurate rates and flow geometries useful as constraints on ongoing reactive transport modeling efforts.
%A Carter, Matthew
%A Viso, Richard F.
%A Peterson, Richard N.
%A Hill, Jenna, C.
%K Groundwater/surface water interaction, estuarine processes, radioactivity and radioisotopes, Student Publication

%0 Newspaper Article
%T GCE and CWT Host Successful Workshop to Demonstrate, Improve, and Promote the Adoption of the GCE Data Toolbox for Matlab
%D 2013
%I LTER Network
%C Albuquerque, NM
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Spring 2013
%9 Article
%Z published
%M GCE.775
%X As the volume and diversity of ecological data grows, scientific discovery demands ecological scientists and anthropologists develop common tools to solve common problems so that data, as well as published literature, can be used to frame and envision next-generation research. From November 27-30, 2012, the Coweeta (CWT) and Georgia Coastal Ecosystems (GCE) information managers pursued this goal by leading a workshop on the GCE Data Toolbox for MATLAB. At this workshop, information and data managers from 11 universities and federal agencies were provided a potentially critical step in meeting the need for a common set of tools. The workshop was organized so that attendees were offered time for hands-on instruction that not only provided an introductory framework, but also a considerable amount of unstructured time in which information managers could interact with the software and its developer using their own data to solve their own problems.
%U https://lternet.edu/wp-content/uploads/2018/01/2013-spring-lter-databits.pdf
%A Chamblee, John F.
%A Sheldon, Wade M., Jr.
%A Cary, Richard
%K LTER-IMC, software, data, database, streaming, middleware, MATLAB

%0 Journal Article
%T Coastal Adaptation Defense with Ecological Engineering.
%D 2013
%V 3
%P 787 - 791
%B Nature Climate Change
%9 Article
%Z published
%M GCE.841
%R 10.1038/NCLIMATE1854
%X The use of combined approaches to coastal adaptation in lieu of a single strategy, such as sea-wall construction, allows for better preparation for a highly uncertain and dynamic coastal environment. Although general principles such as mainstreaming and no- or low-regret options exist to guide coastal adaptation and provide the framework in which combined approaches operate, few have examined the interactions, synergistic effects and benefits of combined approaches to adaptation. This Perspective provides three examples of ecological engineering — marshes, mangroves and oyster reefs — and illustrates how the combination of ecology and engineering works.
%A Cheong, S. M. 
%A Silliman, Brian R.
%A Wong, P.P.
%A Wesienback, B.
%A Kim, C.
%A Guannel, G.
%K ecological engineering, coastal adaptation

%0 Conference Proceedings
%T Promoting a balance between societal demands and coastal ecosystem sustainability.
%D 2013
%I ASLO
%C New Orleans, Louisiana
%B ASLO Aquatic Sciences Meeting
%8 February, 2013
%9 Presentation
%Z presented
%M GCE.858
%A Cherrier, J.
%A Kelly, B.
%A Abazinge, M.
%A Jagoe, C.
%A Callender, R.
%A Schalles, John F.
%A Tunnell, W.
%K coastal ecosystem

%0 Book Section
%T Emergent biomass production
%D 2013
%P 137-154
%I Soil Science Society of America
%C Madison, WI
%B Methods in Biogeochemistry of Wetlands
%9 Article
%Z published
%M GCE.793
%A Craft, Christopher B.
%E DeLaune, R.D.
%E Reddy, K.R.
%E Richardson, C.
%E Megonigal, P.
%K Aboveground biomass, harvest, belowgound biomass, roots, rhizomes, non-destructive measurements, UGAMI Publication

%0 Book Section
%T Past Shorelines of the Georgia Coast
%D 2013
%V 98
%P 145-167
%I Anthropological Papers of the American Museum of Natural History, New York
%B Life Among the Tides: Recent Archaeology on the Georgia Bight
%9 Article
%Z published
%M GCE.633
%A DePratter, Chester
%A Thompson, Victor D.
%K Sea Level Rise, Archaeology, Shoreline

%0 Journal Article
%T The Dynamical Response of Salinity to Freshwater Discharge and Wind Forcing in Adjacent Estuaries on the Georgia Coast
%D 2013
%V 26
%N 3
%P 44–51
%B Oceanography
%S Coastal Long Term Ecological Research
%9 Article
%Z published
%M GCE.785
%R 10.5670/oceanog.2013.44
%X Ten years of oceanic and meteorological monitoring data were collected in order to understand the spatial and temporal patterns of salinity distribution across three adjacent estuaries in the Georgia Coastal Ecosystems Long Term Ecological Research domain. Empirical orthogonal function analysis shows that 95% of the subtidal salinity variability can be explained by two principle modes. The first mode is dominated by river discharge, and causes system-wide freshening throughout the domain. The second mode, which explains 8% of the variability, is correlated with subtidal sea surface height and, hence, alongshore winds. The response in Sapelo and Doboy Sounds to this second mode, however, is out of phase with that of Altamaha Sound. During upwelling-favorable winds when coastal sea surface height decreases, Altamaha Sound freshens, and salinity increases in Doboy and Sapelo Sounds. On the other hand, freshening in Doboy and Sapelo Sounds and a salinity increase in Altamaha Sound accompany downwelling-favorable winds. A regional ocean model of a highly idealized coastal domain of three adjacent estuaries connected by the Intracoastal Waterway is consistent with the observations—river discharge and upwelling-favorable winds freshen the coastal domain so that when downwelling-favorable winds occur, the coastal freshwater originating in the Altamaha River is transported into Sapelo and Doboy Sounds. Model results suggest that the Intracoastal Waterway and the complex network of channels that connects the sounds play a dominant role in water exchange between the adjacent estuaries.
%U https://tos.org/oceanography/article/the-dynamical-response-of-salinity-to-freshwater-discharge-and-wind-forcing
%A Di Iorio, Daniela
%A Castelao, Renato
%K wind forcing, buoyancy transport

%0 Conference Proceedings
%T Quantifying spatial variability of microbenthic algae using optical reflectance measurements.
%D 2013
%I Coastal and Estuarine Research Federation
%C San Diego, CA
%B Coastal and Estuarine Research Federation Biennial Meeting
%S SCI-068P Estuarine Shallows : Biophysical Interactions
%8 November, 2012
%9 Poster
%Z presented
%M GCE.836
%X Tidal mudflats are inhabited by communities of microbenthic algae that contribute to the productivity and biogeochemical processes of coastal wetlands and estuaries. These algae migrate vertically, surfacing at low tide, and a fraction of the algae slough off the mud surfaces and drain into tidal streams. These algae can represent a significant proportion of water column algal communities and provide trophic support for grazing invertebrates (mud snails) and, in suspensions, for filter feeders (oysters). Variation in microbenthic algal pigment features were evident in 2006 AISA Eagle aerial imagery acquired at Sapelo Island, Georgia. In the summers of 2012 and 2013, hyperspectral scans were taken at close range over different areas of Georgia coastal mudflats using an Ocean Optics USB 2000 spectroradiometer. Chlorophyll a and cyanobacteria phycocyanin signals were clearly discernable. Sediment samples were collected from the upper 5 mm and analyzed for chlorophyll and accessory pigment concentrations. We found substantial spatial variability in algal densities within and between sites. We have produced provisional predictive algorithms for estimating the microbenthic algal densities on exposed mudflats using selective wavelengths, and are working to parameterize these algorithms for use with high spatial and spectral resolution airborne spectroscopy. 
%A Gilson, Gina F.
%A Schalles, John F.
%A O'Donnell, J.P.
%K Microbenthic algae, Georgia salt marshes, intertidal zone, algal pigments, field spectroscopy, hyperspectral remote sensing, Student Publication

%0 Newspaper Article
%T Integrating Open Source Data Turbine with the GCE Data Toolbox for MATLAB
%D 2013
%I LTER Network
%C Albuquerque, NM
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Spring 2013
%9 Article
%Z published
%M GCE.774
%X North Temperate Lakes LTER's streaming sensor data are being used as one of three "science experiments" in a NSF Software Infrastructure for Sustained Innovation (SI2) project led by Tony Fountain (CalIT2, UCSD). A major focus of this collaborative project is software integration in complex science environments. This involves strategic software development, systems integration, and testing through demonstration projects (i.e., science experiments). Major requirements for the software developed by this project include performance, usability, interoperability, and cyber-security. In addition to NTL LTER, these software products will be integrated into production research infrastructures at Purdue University, the University of Connecticut, and the Monterey Bay Aquarium Research Institute to answer important science questions, including: (1) What is the impact of uncertainty in the design of civil infrastructure? (2) How sensitive are ocean systems to pH changes? (3) What is the variability of lake metabolic parameters such as gross primary productivity and respiration?One goal of this collaboration is to make integrating the Open Source Data Turbine (OSDT) streaming data middleware with other environmental community software tools more robust and accessible to information managers. In the first project phase, the existing OSDT - MATLAB interface was improved by developing a toolkit (DTMatlabTK) of easy-to-use MATLAB functions for interacting with Data Turbine servers. Building on these improvements, code was developed to directly access data in OSDT using the GCE Data Toolbox for MATLAB (developed at Georgia Coastal Ecosystems LTER) to provide a robust, automated and configurable QA/QC environment for harvesting real-time sensor data. The GCE Data Toolbox was then used to transform data to be compatible with the CUAHSI Observations Data Model (ODM, see Resources section below for links), and insert processed OSDT data into an ODM database to support an end-to-end workflow from NTL data buoys to a CUAHSI Hydrologic Information Server.
%U https://lternet.edu/wp-content/uploads/2018/01/2013-spring-lter-databits.pdf
%A Gries, Corinna
%A Sheldon, Wade M., Jr.
%A Fountain, Tony
%A Sebranek, Chad
%A Miller, Matthew
%A Tilak, Sameer
%K LTER-IMC, software, data, database, streaming, middleware, MATLAB, Java, Data Turbine, RBNB

%0 Journal Article
%T Biotic interactions mediate the expansion of black mangrove (Avicennia germinans) into salt marshes under climate change.
%D 2013
%V 19
%P 2765 - 2744
%B Global Change Biology
%9 Article
%Z published
%M GCE.1111
%R 10.1111/gcb.12221
%X Many species are expanding their distributions to higher latitudes due to global warming. Understanding the mechanisms underlying these distribution shifts is critical for better understanding the impacts of climate changes. The climate envelope approach is widely used to model and predict species distribution shifts with changing climates. Biotic interactions between species, however, may also influence species distributions, and a better understanding of biotic interactions could improve predictions based solely on climate envelope models. Along the northern Gulf of Mexico coast, USA, subtropical black mangrove (Avicennia germinans) at the northern limit of its distribution grows sympatrically with temperate salt marsh plants in Florida, Louisiana, and Texas. In recent decades, freeze&#8208;free winters have led to an expansion of black mangrove into salt marshes. We examined how biotic interactions between black mangrove and salt marsh vegetation along the Texas coast varied across (i) a latitudinal gradient (associated with a winter&#8208;temperature gradient); (ii) the elevational gradient within each marsh (which creates different marsh habitats); and (iii) different life history stages of black mangroves (seedlings vs. juvenile trees). Each of these variables affected the strength or nature of biotic interactions between black mangrove and salt marsh vegetation: (i) Salt marsh vegetation facilitated black mangrove seedlings at their high&#8208;latitude distribution limit, but inhibited black mangrove seedlings at lower latitudes; (ii) mangroves performed well at intermediate elevations, but grew and survived poorly in high&#8208; and low&#8208;marsh habitats; and (iii) the effect of salt marsh vegetation on black mangroves switched from negative to neutral as black mangroves grew from seedlings into juvenile trees. These results indicate that the expansion of black mangroves is mediated by complex biotic interactions. A better understanding of the impacts of climate change on ecological communities requires incorporating context&#8208;dependent biotic interactions into species range models.
%A Guo, Hongyu
%A Zhang, Yihui
%A Lan, Zhenjiang
%A Pennings, Steven C.
%K climate change, salt marshes, black mangrove, Student Publication

%0 Thesis
%T Cross-kingdom consumer diversity enhances multifunctionality of a coastal ecosystem
%D 2013
%P 34
%I University of Florida
%C Gainesville, FL
%9 M.S. Thesis
%Z published
%M GCE.910
%X The global biodiversity crisis impairs the valuable benefits ecosystems provide human society. These nature-generated benefits (i.e. services) are defined by a multitude of different ecosystem functions that operate simultaneously. How species extinctions, either globally or locally, will affect simultaneous functioning (i.e. multifunctionality), remains unstudied in real-world food-web assemblages. Here, we investigated experimentally the extinction impacts of dominant and phylogenetically diverse salt marsh consumers (i.e., Kingdom Animalia and Fungi) and reveal that a diverse consumer assemblage significantly enhances ecosystem multifunctionality. High functional turnover among consumers was found to drive a positive diversity-function relationship, where each marsh consumer affected at least one different ecosystem function, but no individual function was affected by more than two consumers. Although overlooked in past food web-diversity studies, microbes (i.e. fungi) were significant forces driving enhanced ecosystem functioning. These results provide the first experimental evidence that maximizing ecosystem multifunctionality depends on maintaining high-levels of both functional and taxonomic consumer diversity. Moreover, it emphasizes the need to incorporate both micro- and macro-components of food webs to accurately predict biodiversity declines on integrated-ecosystem functioning.
%A Hensel, Marc Simon
%K biodviersity, foodweb, functioning, fungus, marsh, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Consumer diversity across kingdoms supports multiple functions in a coastal ecosystem
%D 2013
%V 110
%N 51
%P 20621-20626
%B Proceedings of the National Academy of Sciences of the United States of America
%9 Article
%Z published
%M GCE.866
%R 10.1073/pnas.1312317110
%X The global biodiversity crisis impairs the valuable benefits ecosystems provide humans. These nature-generated benefits are defined by a multitude of different ecosystem functions that operate simultaneously. Although several studies have simulated species loss in communities and tracked the response of single functions such as productivity or nutrient cycling, these studies have involved relatively similar taxa, and seldom are strikingly different functions examined. With the exception of highly managed ecosystems such as agricultural fields, rarely are we interested in only one function being performed well. Instead, we rely on ecosystems to deliver several different functions at the same time. Here, we experimentally investigated the extinction impacts of dominant consumers in a salt marsh. These consumers are remarkably phylogenetically diverse, spanning two kingdoms (i.e., Animalia and Fungi). Our field studies reveal that a diverse consumer assemblage significantly enhances simultaneous functioning of disparate ecosystem processes (i.e., productivity, decomposition, and infiltration). Extreme functional and phylogenetic differences among consumers underlie this relationship. Each marsh consumer affected at least one different ecosystem function, and each individual function was affected by no more than two consumers. The implications of these findings are profound: If we want ecosystems to perform many different functions well, it is not just number of species that matter. Rather, the presence of species representing markedly different ecologies and biology is also essential to maximizing multiple functions. Moreover, this work emphasizes the need to incorporate both microcomponents and macrocomponents of food webs to accurately predict biodiversity declines on integrated-ecosystem functioning.
%A Hensel, Marc Simon
%A Silliman, Brian R.
%K multifunctionality, fungus, Sesarma reticulatum, Litoraria irrorata, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Salt marsh elevation and habitat mapping using hyperspectral and LIDAR data
%D 2013
%V 139
%P 318 - 330
%B Remote Sensing of the Environment
%9 Article
%Z published
%M GCE.851
%R 10.1016/j.rse.2013.08.003
%X Accurate mapping of both elevation and plant distributions in salt marshes is important for management and conservation goals. Although light detection and ranging (LIDAR) is effective at measuring surface elevations, laser penetration is limited in dense salt marsh vegetation. In a previous study, we found that LIDAR-derived digital elevation model (DEM) error varied with vegetation cover. We derived cover-class-specific correction factors to reduce these errors, including separate corrections for three different height classes of Spartina alterniflora, the dominant macrophyte in southeastern U.S. salt marshes. In order to apply these cover class-specific corrections, it is necessary to have information on the distribution of cover classes in a LIDAR-derived DEM. Hyperspectral imagery has been shown to be suitable for the separation of salt marsh vegetation species by spectral signatures, and can be used to determine cover classes; however, there is persistent confusion both among the different height classes of S. alterniflora and between plants and mud (the Spartina problem). This paper presents a method to overcome the respective limitations of LIDAR and hyperspectral imagery through the use of multisensor data. An initial classification of hyperspectral imagery based on the maximum likelihood classification algorithm was used in a decision tree in combination with elevation and normalized difference vegetation index (NDVI) derived from the hyperspectral imagery to map nine salt marsh cover classes. The decision tree appreciably reduced the Spartina problem by reassigning classes using these ancillary data and resulted in a final overall classification accuracy of 90%, with a quantity disagreement of 1% and an allocation disagreement of 9%. The resulting hyperspectral image classification was then used as the basis for applying cover class-specific elevation correction factors to the LIDAR-derived DEM. Applying these correction factors greatly improved the accuracy of the DEM: overall mean error decreased from 0.10 ± 0.12 (SD) to &#8722; 0.003 ± 0.10 m, and root mean squared error from 0.15 to 0.10 m. Our results suggest that the use of decision trees to combine elevation and spectral information can aid both hyperspectral image classification and DEM elevation mapping.
%U https://www.sciencedirect.com/science/article/abs/pii/S0034425713002617
%A Hladik, Christine M.
%A Schalles, John F.
%A Alber, Merryl
%K LIDAR, Digital elevation model (DEM), Hyperspectral imagery, Salt marshes, Multisensor data, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Preference and performance in plant-herbivore interactions across latitude – a study in U.S. Atlantic salt marshes
%D 2013
%V 8
%N 3
%B PLoS One
%9 Article
%Z published
%M GCE.771
%R 10.1371/journal.pone.0059829
%X High-latitude plants are often more palatable to herbivores than low-latitude conspecifics. Does increased plant palatability lead to better herbivore performance? Our field and laboratory work investigated (A) whether high-latitude plants have traits indicating that they should be higher-quality foods for herbivores; (B) whether geographic differences in plant quality are more important than local adaptation of herbivores. We studied 3 plant species and 6 invertebrate herbivores in U.S. Atlantic Coast. Past studies had shown high-latitude individuals of these plants are more palatable than low-latitude conspecifics. We documented plant traits and herbivore performance (body size) in the field across latitude. We collected individuals from different latitudes for factorial (plant region x herbivore region) laboratory experiments, examining how herbivore performance was affected by plant region, herbivore region, and their interaction (i.e., local adaptation). Field surveys suggested high-latitude plants were likely of higher quality to herbivores. Leaf nitrogen content in all plant species increased toward high latitudes, consistent with lower leaf C/N and higher leaf chlorophyll content at high latitudes. Furthermore, leaf toughness decreased toward higher latitudes in 1 species. The body size of 4 herbivore species increased with latitude, consistent with high-latitude leaves being of higher quality, while 2 grasshopper species showed the opposite pattern, likely due to life-history constraints. In the laboratory, high-latitude plants supported better performance in 4 herbivore species (marginal in the 5th). The geographic region where herbivores were collected affected herbivore performance in all 6 species; however, the pattern was mixed, indicating a lack of local adaptation by herbivores to plants from their own geographic region. Our results suggest that more-palatable plants at high latitudes support better herbivore growth. Given that geographic origin of either plants or herbivores can affect herbivore performance, the nature of plant-herbivore interactions is likely to change if climate change “reshuffles” plant and herbivore populations across latitude.
%U http://gce-lter.marsci.uga.edu/public/uploads/Ho_and_Pennings_2013_Preference_and_performance_across_latitude_PLOS_One_20130506T160838.pdf
%A Ho, Chuan-Kai
%A Pennings, Steven C.
%K latitude, herbivory, Spartina, Solidago, Iva, Prokelisia, aphid, beetle, grasshopper, insect, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Seasonal variation in the metratranscriptomes of a Thaumarchaeota population from SE USA coastal waters
%D 2013
%V 8
%P 685 - 698
%I ASLO
%C New Orleans, Louisiana
%B ASLO Aquatic Sciences Meeting
%8 17-22 February, 2013
%9 Abstract
%Z published
%M GCE.860
%R 10.1038/ismej.2013.171
%A Hollibaugh, James T.
%A Gifford, Scott
%A Moran, Mary Ann
%A Ross, Meredith
%A Sharma, S.
%A Tolar, Bradley
%K ammonia oxidation, nitrification, estuary, Thaumarchaeota, nitrite, diurnal, Student Publication

%0 Journal Article
%T Influence of terrestrial inputs on continental shelf carbon dioxide
%D 2013
%V 10
%P 839 - 849
%B Biogeosciences
%9 Article
%Z published
%M GCE.846
%R 10.5194/bg-10-839-2013
%X The US South Atlantic Bight (SAB) is a low-latitude shallow continental shelf bordered landward by abundant salt marshes and rivers. Based on previously published data on sea surface partial pressure of carbon dioxide (pCO2) and new dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) data, a model analysis is presented to identify and quantify the contributions of various terrestrial carbon inputs on SAB sea surface pCO2. After removal of pCO2 variations due to annual temperature variability and air–sea gas exchange from the in situ pCO2, the temperature- and gas-exchange-corrected pCO2 (TG-corrected pCO2) is derived. Contributions from rivers, salt marshes, and the continental shelf to the TG-corrected pCO2 are then calculated. Our findings demonstrate that although additions of CO2 from within shelf waters (i.e., &#916;pCO2(shelf)) were the greatest of the three components and underwent the largest seasonal changes, &#916;pCO2(shelf) showed smaller onshore–offshore gradients than rivers and marshes. In contrast, CO2 contributions from river (&#916;pCO2(river)) and salt marsh (&#916;pCO2(marsh)) components were greatest closest to the coast and decreased with distance offshore. In addition, the magnitude of &#916;pCO2(marsh) was about three-fold greater than &#916;pCO2(river). Our findings also revealed that decomposition of terrestrial organic carbon was an important factor regulating the seasonal pattern of pCO2 on the inner shelf. Despite large uncertainties, this study demonstrates the importance of terrestrial inputs, in particular those from coastal wetlands, on coastal ocean CO2 distributions.
%A Jiang, Liqing
%A Cai, Wei-Jun
%A Wang, Yongchen
%A Bauer, J.E.
%K carbon dioxide, continental shelf, Student Publication

%0 Journal Article
%T Effects of Increased Salinity and Inundation on Inorganic N and P Exchange by Tidal Freshwater Floodplain Forest Soils, Georgia (USA).
%D 2013
%V 36
%P 508-518
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.559
%R 10.1007/s12237-012-9449-6
%X We investigated the effects of increasing salinity and inundation on inorganic N exchange and P sorption/precipitation in soils of tidal freshwater floodplain forests (TFFF) of coastal Georgia, USA. Our objectives were to better understand how sea level rise, increasing inundation, and saltwater intrusion will affect the ability of TFFFs to retain nitrogen (N) and phosphorus (P). We collected soil cores (0–5 cm) from three TFFFs that do not currently experience saltwater intrusion and from one TFFF currently experiencing saltwater intrusion and measured NH4-N exchange and PO4-P removal over five simulated 6-h tidal cycles using nutrient-enriched freshwater (30 µM NH4-N and 5 µM PO4-P). In a second experiment, we exposed soil cores to three salinities (0, 2, and 5) and two inundation depths (5 and 10 cm) using the same nutrient enrichment. When flooded with nutrient-enriched freshwater, soils from the three TFFFs that do not experience saltwater intrusion removed inorganic N and P in amounts ranging from 5.2 to 10.7 and 2.3 to 4.4 mg/m2, respectively, and the TFFF soils experiencing saltwater intrusion removed 2.1 to 3.8 mg P/m2. However, TFFF soils experiencing saltwater intrusion released inorganic N to the water column in amounts ranging from 7.1 to 67.5 mg/m2. In the second experiment, soils from TFFFs not experiencing saltwater intrusion released NH4-N to the water column when exposed to 2 and 5 salinity, and the amount of N released increased with salinity and number of tidal cycles. In contrast, the same TFFF soils sorbed two and three times more PO4-P when exposed to 2 and 5 salinity than when exposed to 0 salinity. P removal on a mass basis was greater under 10 cm of inundation, but the efficiency of removal was greater under the 5 cm flooding depth. Our findings suggest that saltwater intrusion caused by sea level rise will promote N release into the water column through organic matter mineralization and/or ion exchange and may promote P sorption, or precipitation of P with metal cations. In addition, release of N and resulting increased N/P could exacerbate eutrophication of estuaries in the future.
%A Jun, Mi hee
%A Altor, A.
%A Craft, Christopher B.
%K tidal forests, nutrients, nitrogen, phosphorus, sorption, desorption, salt water intrusion

%0 Generic
%T Delineating the drivers of groundwater flow at a Back Barrier island – marsh Transect in coastal Georgia
%D 2013
%B Georgia Water Resources Conference, April 10-11, 2013 in Athens GA
%9 Article
%Z published
%M GCE.790
%X Groundwater plays an important role in coastal regions by delivering freshwater and nutrients tonear shore and salt marsh environments. To quantify groundwater flow, salinity, temperature and pressure, sensors were installed in shallow piezometers along a transect behind Blackbeard Island, GA. Located approximately 90 m from the nearest tidal creek, the transect reaches from a back barrier island to a hammock and into the adjacent marsh. Coincident with each well, vibracores were takenand sediment permeability was estimated from grain size measurements. Combined with horizontal pressure gradients, this allowed quantification of groundwater flow. Subsequently, the impact of forces that govern groundwater movement such as tidal inundation, subsurface propagation of pressure signals, and variations in fluid density was assessed. First, the propagation of pressure in the subsurface was investigated using a one-dimensional model and was found to likely only have a minor effect at the location of the well transect. Then, measured pressure gradients were separated into contributions from piezometric head changes and density changes. Density changes were responsible for typically <10% of groundwater flow and the effect was most dominant at the hammock. Todelineate the contribution of tidal flushing, a classical harmonic analysis of the pressure time series was performed. Results of this ongoing effort show that tidal flushing plays the primary role. Alternate drivers, including precipitation events, are most evident in periods with low tidal forcing. Understanding current drivers of groundwater movement will help predict hydrological response to changing forces and the potential for saltwater intrusion.
%A Ledoux, Jonathan G.
%A Alexander, Clark R., Jr.
%A Meile, Christof
%K groundwater driver marsh, Student Publication

%0 Journal Article
%T The impact of change in vegetation structure on the ecological functions of salt marshes: The example of the Yangtze River
%D 2013
%V 14
%N 2
%P 623-632
%B Regional Environmental Change
%9 Article
%Z published
%M GCE.820
%R 10.1007/s10113-013-0520-9
%X Salt marshes worldwide are faced with threats from rising sea levels and coastal development. We measured changes in salt marsh vegetation structure using remote sensing and its consequences for carbon sequestration, wave attenuation, and sediment trapping ability using remotely sensed imaging, field measurement data, and the published literature data pertaining to the Yangtze Estuary, a rapidly urbanizing area in Eastern China. From 1980 to 2010, the total area of vegetated salt marsh decreased by 17 %, but the vegetation structure changed more dramatically, with the ratio of Phragmites/Spartina/Scirpus changing from 24:0:76, to 77:0:23, 44:13:43, and 33:39:28 in 1980, 1990, 2000, and 2010, respectively. Carbon sequestration increased slightly from 1980 to 2010, with the dramatic shifts in plant species composition. The total length of seawall inadequately protected by salt marsh vegetation increased from 44 km in 1980 to 300 km in 2010. Sediment accretion increased (from 8 to 14 million m3/year) due to the spread of Spartina, which to some extent compensated the loss of total vegetated area in the salt marsh. Changes in the delivery of functions were not linearly related to the change in the area of vegetated salt marsh, but more from the combined effect of changing vegetation structure, sediment input, and land reclamation. Under threat of sea-level rise, protection and maintenance of vegetation structure outside the seawall are of great importance for the safe economic development inside the seawall.
%A Li, X.
%A Ren, Y
%A Lui, Y
%A Craft, Christopher B.
%A Mander, U
%A Tang, S
%K carbon sequestration, sediment accumulation, wave attenuation

%0 Journal Article
%T Rapid degradation of Deepwater Horizon spilled oil by indigenous microbial communities in Louisiana salt marsh sediments.
%D 2013
%V 47
%N 23
%P 13303-13312
%B Environmental Science and Technology
%9 Article
%Z published
%M GCE.881
%R 10.1021/es4036072
%X The Deepwater Horizon oil spill led to the severe contamination of coastal environments in the Gulf of Mexico. A previous study detailed coastal saltmarsh erosion and recovery in a number of oil-impacted and nonimpacted reference sites in Barataria Bay, Louisiana over the first 18 months after the spill. Concentrations of alkanes and polyaromatic hydrocarbons (PAHs) at oil-impacted sites significantly decreased over this time period. Here, a combination of DNA, lipid, and isotopic approaches confirm that microbial biodegradation was contributing to the observed petroleum mass loss. Natural abundance 14C analysis of microbial phospholipid fatty acids (PLFA) reveals that petroleum-derived carbon was a primary carbon source for microbial communities at impacted sites several months following oil intrusion when the highest concentrations of oil were present. Also at this time, microbial community analysis suggests that community structure of all three domains has shifted with the intrusion of oil. These results suggest that Gulf of Mexico marsh sediments have considerable biodegradation potential and that natural attenuation is playing a role in impacted sites.
%A Mahmoudi, N.
%A Porter, T.
%A Zimmerman, A.
%A Fulthopre, R.
%A Kasozi, G.
%A Slater, G.
%A Silliman, Brian R.
%K salt marshes, microbial communities, Deepwater Horizon

%0 Journal Article
%T Importance of local vs. geographic variation in salt marsh plant quality for arthropod herbivore communities
%D 2013
%V 101
%P 1169-1182
%B Journal of Ecology
%9 Article
%Z published
%M GCE.782
%R 10.1111/1365-2745.12137
%X 1. An important recent advance in food web ecology has been the application of theory regarding spatial gradients to studies of the factors that affect animal population dynamics. Building on extensive studies of the Spartina alterniflora food web at the local scale, we hypothesized that geographic variation in S. alterniflora quality is an important bottom-up control on food web structure and that geographic variation in S. alterniflora quality would interact with the presence of predators and top omnivores to mediate herbivore densities.2. We employed a four-factor fully crossed experiment in which we (i) collected plants from high and low-latitude locations and grew them in a common garden and varied (ii) plant fertilization status (mimicking the plant quality differences due to marsh elevation), (iii) mesopredator density and (iv) omnivore density.3. Our results suggest that the single most important factor mediating insect herbivore densities is local variation in plant quality – induced in our experiment by fertilization and demonstrated repeatedly as a consequence of marsh elevation.4. Top-down effects were generally weak and in those cases where predators did exert a significant suppressing effect on herbivores, that impact was itself mediated by host-plant characteristics.5. Finally, despite observed variation in plant quality with latitude, and the separately measurable effects of this variation on herbivores, geographic-scale variation in plant quality was overwhelmed by local conditions in our experiments.6. Synthesis. We suggest that a first-order understanding of variation across large latitudinal ranges in the Spartina alterniflora arthropod food web must begin with local variation in plant quality, which provides strong bottom-up forcing to herbivore populations. A second-order understanding of the arthropod food web should consider the role of predation in controlling herbivores feeding on low quality plants. Finally, while latitudinal variation in plant quality probably explains some variation in herbivore densities, it is probably more of a response to herbivore pressure than a driver of the herbivore dynamics. Although extrapolating from local to geographic scales presents multiple challenges, it is an essential task in order for us to develop an understanding that is general rather than site-specific.
%A Marczak, Laurie
%A Wieski, Kazimierz
%A Denno, Robert
%A Pennings, Steven C.
%K latitude, herbivory, herbivore, Spartina, top-down, bottom-up, Prokelisia, spider, Cross-site Research, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Foliar DMSO:DMSP ratio and metal content as indicators of stress in Spartina alterniflora
%D 2013
%V 474
%P 1-13
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.734
%R 10.3354/meps10184
%X We evaluated 2 potential indicators of stress, viz. the ratio of dimethylsulfoxide to dimethylsulfoniopropionate (DMSO:DMSP) and foliar metals, in Spartina alterniflora collected from areas affected by 4 different disturbances (sudden marsh dieback,horse grazing, increased snail densities, wrack deposition) across 20 marshes in Georgia, USA. The DMSO:DMSP ratio was a stronger and more consistent indicator of stress than either DMSP or DMSO concentrations alone, with significantly higher ratios occurring in leaves and stems collected from affected compared to healthy areas in all 4 disturbance types. Foliar metal concentrations also differed in affectedcompared to healthy areas. Of 20 metals evaluated, concentrations of 19 were increased in leaves collected from edge and affected areas. Multidimensional scaling using the entire suite of metals showed separation between plants from affected and healthy areas, but no difference among disturbance types. In contrast, chlorophyll a concentrations were not significantly different between affected and healthy areas, and did not correlate with variation in either of the 2 indicators. These results suggest that the DMSO:DMSP ratio and foliar metal suite are sensitive indicators of sublethal stress in Spartina, capable of identifying stress before there are visible signs such as chlorophyll loss. The fact that both indicators were consistent across a variety of disturbance types suggests that they may be primarily responsive to general oxidative stress and thus, broadly useful tools for evaluating the health of salt marsh habitat in the field.
%A McFarlin, Caroline R.
%A Alber, Merryl
%K Spartina, stress, disturbance, metal, DMSO:DMSP ratio, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Shoreline armoring in coastal Georgia: Do landscape characteristics matter?
%D 2013
%I Georgia Coastal Ecosystems LTER
%C Athens, GA
%B Georgia Coastal Ecosystems Annual Meeting
%8 9-10 January 2013
%9 Poster
%Z published
%M GCE.828
%A McLenaghan, Natalie Ann
%A Alber, Merryl
%A Hepinstall-Cymerman, J.
%A Alexander, Clark R., Jr.
%K Shoreline armoring, Coastal Georgia, landscape characteristics, Student Publication

%0 Journal Article
%T Impacts of a large-bodied, apex predator (Alligator mississippiensis Daudin 1801) on salt marsh food webs
%D 2013
%V 440
%N 2013
%P 185-191
%B Journal of Experimental Marine Biology and Ecology.
%9 Article
%Z published
%M GCE.844
%R 10.1016/j.jembe.2013.01.002
%X Large-bodied apex predators (e.g., sharks, wolves, crocodilians) are believed to regulate food web structure and drive ecosystem processes, but there remains relatively little experimental evidence. Here we use field surveys and a mesocosm experiment to evaluate the cascading effects of an apex predator (American alligator) on a salt marsh food web. Consistent with previous studies (n = 10), field surveys revealed blue crabs (Callinectes sapidus Rathbun 1896), an important marsh mesopredator, were a frequent component of estuarine-occurring alligators' diet (mean ± SD, 47 ± 20%, n = 1384). In mesocosms, we examined potential consequences of this interaction in a simplified salt marsh community. We experimentally isolated alligator effects on the abundance (consumptive effect) and behavior (non-consumptive effect) of blue crabs and on blue crab consumption of plant-grazing snails and ribbed mussels. Alligators reduced blue crab abundance by ~ 40% over 3 days and induced behavioral changes, resulting in decreased foraging activity and increased refuge use by blue crabs. The combined effects of reduced crab abundance and altered behavior translated into increased survival of both a keystone grazer (snails) and a mutualist (mussels) within the salt marsh food web. Our findings experimentally demonstrate that a large-bodied, apex predator has the potential to 1) generate a trophic cascade, 2) elicit behavioral changes (i.e., non-consumptive effects) in mesopredator prey, and 3) indirectly affect the potential for both grazing and mutualism to occur in this food chain. Our results generate testable hypotheses regarding the broad-scale effects of alligator presence and top-down forcing in salt marsh ecosystems.
%U https://www.sciencedirect.com/science/article/pii/S0022098113000063
%A Nifong, James C.
%A Silliman, Brian R.
%K apex predator, Alligator mississippiensis Daudin, salt marsh, food webs, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Attachment and deployment of remote video/audio recording devices (Crittercam) on wild American alligators (Alligator mississippiensis Duadin 1801).
%D 2013
%V 44
%N 2
%P 243-247
%B Herpetological Review
%9 Article
%Z published
%M GCE.843
%X Historically, researchers have used direct observation, often with the assistance of specialized equipment (e.g., binoculars, telescopes, remote video/audio recorders), to document animal behavior and ecology (Altmann 1974). However, these observerbased techniques typically cause disturbance to animals via presence of observers or equipment, are limited in the data that can be collected (e.g., field of view, magnification), and often occur over short temporal scales, all of which restrict the inferences that can be gleaned from the data (Marsh and Hanlon 2004; Samuel et al. 1987). Documenting the behavior of aquatic species, such as crocodilians, presents additional complications because the majority of their interactions occur below the water’s surface where direct observation can be even more challenging (Dickens et al. 2011). To overcome these limitations and increase the quality and quantity of observational data, researchers have utilized technological advances to develop devices that can be attached to animals and are capable of collecting video and audio data from the animal’s point-of-view. Collectively known as “animalborne imagery,” this field has flourished in the past 20 years, inpart due to the success of the National Geographic Remote Imaging (NGRI) Crittercam program (Marshall 1998). To date, their animal-borne imaging systems have been used to study the behavior of over 60 species spanning a wide range including aquatic vertebrates and invertebrates, such as large sharks, sea turtles, and Humboldt squid, as well as terrestrial species such as lions, bears, and various species of birds (Marshall, unpubl. data). Crittercam, in addition to other animal-borne imaging systems, has revolutionized the field of animal behavior and ecology by permitting the observation of novel natural history characteristics, such as cryptic foraging behaviors or subtle species interactions, and by expanding the range of response variables available for ecological studies, such as diving, foraging, and prey capture success rates (Moll et al. 2007).
%A Nifong, James C.
%A Lowers, R.H.
%A Silliman, Brian R.
%A Abernathy, K.
%A Marshall, G.
%K American alligators, Alligator mississippiensis Duadin, crittercam, Student Publication

%0 Journal Article
%T Drought impacts on biogeochemistry and microbial processes in salt marsh sediments: a flow-through reactor approach
%D 2013
%V 112
%N 1-3
%P 389-407
%B Biogeochemistry
%9 Article
%Z published
%M GCE.868
%R 10.1007/s10533-012-9734-z
%X The effects of drought on salt marsh sediments from Sapelo Island, Georgia, were examined in flow-through reactor experiments. Three hydrological treatments were employed: a continuously flooded anoxic control, a periodic drought treatment that experienced alternate periods of flooding and drying, and a severe drought treatment, where sediment was exposed to drought (drying) for several weeks and then flooded; the effect of both buffered and non-buffered flooding solutions were examined. In permanently anoxic sediments as well as in sediments exposed to drought, organic carbon oxidation was dominated by SO4 2&#8722; reduction (SR) and SR rates increased over time. The shift from anoxic to oxic conditions in drought treatments significantly altered sediment geochemistry and pathways of microbial metabolism. Drought conditions favored suboxic mineralization processes, such as Fe(III) reduction and denitrification, which was fueled by NH4 + oxidation promoted by O2 delivered during drought conditions. Other major drought-induced changes included pH decrease, and altered concentrations of solid phase adsorbed metals.
%A Palomo, Laura
%A Meile, Christof
%A Joye, Samantha B.
%K Drought Salt marsh Organic matter mineralization D

%0 Book Section
%T Forging collaborations between ecology and historical ecology
%D 2013
%P 167-175
%I The University Press of Florida
%C Gainesville
%B The archaeology and historical ecology of small scale economies
%9 Article
%Z published
%M GCE.736
%A Pennings, Steven C.
%E Thompson, Victor D.
%E Waggoner, Jamie
%K anthropogenic impact, SINERR Publication, UGAMI Publication

%0 Conference Proceedings
%T Computer science meets biology: using volunteer scientists to map salt marsh plant communities
%D 2013
%I University of La Rochelle
%C La Rochelle, France
%B Workshop on complex adaptive systems
%8 21 October, 2013
%9 Presentation
%Z presented
%M GCE.798
%A Pennings, Steven C.
%K plants, map, volunteer scientists

%0 Journal Article
%T Development of a sparging chamber for field radon analysis
%D 2013
%V 298
%P 1347-1357
%B Journal of Radioanalytical and Nuclear Chemistry
%9 Article
%Z published
%M GCE.794
%R 10.1007/s10967-013-2589-5
%X Radon-222 has become a widely used tracer of submarine groundwater discharge.  However, remote field studies are often limited by the need to pump water to a spray chamber which degasses dissolved radon for subsequent analysis in the gaseous phase.  We develop here a new method of degassing dissolved 222Rn, utilizing a stream of bubbles driven by the internal air pump of a commercial radon analyzer to achieve air:water partitioning equilibrium, eliminating the need to pump water.  This system utilizes a sparging chamber, comprised of a slotted vertically-oriented pipe with bubbles produced in the bottom.  A non-slotted section of the pipe at the top of the chamber forms a sealed headspace, allowing air to be circulated in a closed loop between the sparging chamber and a radon-in-air monitor.  We found that such a sparging chamber needs to allow bubbles to rise through at least 45 cm of water column to function at equal efficiency as the standard protocol of the spray chamber.  Under our optimized configuration, the sparging chamber operates as efficiently as the standard protocol at measuring dissolved 222Rn activities when encountering increasing 222Rn activities, and offers even greater gas exchange efficiency when dissolved 222Rn activities decrease.  The sparging chamber offers a more field-friendly alternative to measuring 222Rn activities, as it eliminates the need to maintain a submersible pump throughout the measurement and it offers increased temporal resolution when variable 222Rn activities are expected.
%A Peterson, Richard N.
%A Breier, John C.
%A Harmon, Lindsay R.
%A Brusa, Jamie
%A Hutchins, Patrick R.
%K radon, groundwater, methods, field measurements, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Predation on speared lionfish /Pterois volitans/ by spotted moray /Gymnothorax moringa.
%D 2013
%V 76
%N 3-4
%P 391-394
%B Florida Scientist
%9 Article
%Z published
%M GCE.882
%X Little is known about predation on the red lionfish, Pterois volitans, in invaded habitats. In this note, we report for the first time a spotted moray, Gymnothorax moringa, successfully attacking and eating a still alive, but injured (speared) adult red lionfish in San Salvador, Bahamas. We describe the consumption of the red lionfish and the response behavior of the predator. Understanding predation pressures on red lionfish in the western Atlantic Ocean is of great significance given the rapid growth of this invasive species and its potential effects on populations of coral reef fish. This important problem is exacerbated by the fact that top predators have largely been overfished in the western Atlantic, thus removing potential predators for this invasive species. Our observation suggests that the spotted moray and, by extrapolation, other morays might represent a naturally occurring top-down control agent of invasive red lionfish. Muraenids in general eould play a critical role as bio-control forces because moray eel populations have been largely spared the effects of over fishing.
%U https://www.jstor.org/stable/24321994?seq=1#page_scan_tab_contents
%A Pimiento, C.
%A Monaco, Eric
%A Barbour, A.
%A Silliman, Brian R.
%K non-native species, opportunistic predation, prey, reef, western Atlantic Ocean, Student Publication

%0 Journal Article
%T Frugivory and seed dispersal by crocodilians: an overlooked form of saurochory?
%D 2013
%P 13
%B Journal of Zoology
%9 Article
%Z published
%M GCE.792
%R 10.1111/jzo.12052
%X Saurochory (seed dispersal by reptiles) among crocodilians has largely beenignored, probably because these reptiles are generally assumed to be obligatecarnivores incapable of digesting vegetable proteins and polysaccharides. Hereinwe review the literature on crocodilian diet, foraging ecology, digestive physiologyand movement patterns, and provide additional empirical data from recent dietarystudies of Alligator mississippiensis. We found evidence of frugivory in 13 of 18(72.2%) species for which dietary information was available, indicating this behavioris widespread among the Crocodylia. Thirty-four families and 46 genera ofplants were consumed by crocodilians. Fruit types consumed by crocodiliansvaried widely; over half (52.1%) were fleshy fruits. Some fruits are consumed asgastroliths or ingested incidental to prey capture; however, there is little doubt thaton occasion, fruit is deliberately consumed, often in large quantities. Sensory cuesinvolved in crocodilian frugivory are poorly understood, although airborne andwaterborne cues as well as surface disturbances seem important. Crocodilianslikely accrue nutritional benefits from frugivory and there are no a priori reasonsto assume otherwise. Ingested seeds are regurgitated, retained in the stomach forindefinite and often lengthy periods, or passed through the digestive tract andexcreted in feces. Chemical and mechanical scarification of seeds probably occursin the stomach, but what effects these processes have on seed viability remainunknown. Because crocodilians have large territories and undertake lengthymovements, seeds are likely transported well beyond the parent plant before beingvoided. Little is known about the ultimate fate of seeds ingested by crocodilians;however, deposition sites could prove suitable for seed germination. Althoughthere is no evidence for a crocodilian-specific dispersal syndrome similar to thatdescribed for other reptiles, our review strongly suggests that crocodilians functionas effective agents of seed dispersal. Crocodilian saurochory offers a fertileground for future research.
%U https://www.researchgate.net/publication/258242110_Frugivory_and_seed_dispersal_by_crocodilians_An_overlooked_form_of_saurochory
%A Platt, Steve G. 
%A Elsey, Ruth M.
%A Liu, H.
%A Rainwater, Thomas R.
%A Nifong, James C.
%A Rosenblatt, Adam E.
%A Heithaus, M.R.
%A Mazzotti, Frank J.
%K Alligator mississippiensis, Crocodylia, diet, foraging ecology, frugivory, saurochory, seed dispersal., Student Publication

%0 Journal Article
%T The Roles of Large Top Predators in Coastal Ecosystems: New Insights from Long Term Ecological Research
%D 2013
%V 26
%N 3
%P 156 - 167
%B Oceanography
%S Coastal Long Term Ecological Research
%9 Article
%Z published
%M GCE.842
%R 10.5670/oceanog.2013.59
%X During recent human history, human activities such as overhunting and habitat destruction have severely impacted many large top predator populations around the world. Studies from a variety of ecosystems show that loss or diminishment of top predator populations can have serious consequences for population and community dynamics and ecosystem stability. However, there are relatively few studies of the roles of large top predators in coastal ecosystems, so that we do not yet completely understand what could happen to coastal areas if large top predators are extirpated or significantly reduced in number. This lack of knowledge is surprising given that coastal areas around the globe are highly valued and densely populated by humans, and thus coastal large top predator populations frequently come into conflict with coastal human populations. This paper reviews what is known about the ecological roles of large top predators in coastal systems and presents a synthesis of recent work from three coastal eastern US Long Term Ecological Research (LTER) sites where long-term studies reveal what appear to be common themes relating to the roles of large top predators in coastal systems. We discuss three specific themes: (1) large top predators acting as mobile links between disparate habitats, (2) large top predators potentially affecting nutrient and biogeochemical dynamics through localized behaviors, and (3) individual specialization of large top predator behaviors. We also discuss how research within the LTER network has led to enhanced understanding of the ecological roles of coastal large top predators. Highlighting this work is intended to encourage further investigation of the roles of large top predators across diverse coastal aquatic habitats and to better inform researchers and ecosystem managers about the importance of large top predators for coastal ecosystem health and stability.
%A Rosenblatt, A. E.
%A Heithaus, M.R.
%A Mather, M.E.
%A Matich, P.
%A Nifong, James C.
%A Ripple, W.J.
%A Silliman, Brian R.
%K Top predators, coastal ecosystems, Cross-site Research, Student Publication

%0 Journal Article
%T Measuring the temporal instability of land change using the Flow matrix
%D 2013
%V 27
%N 9
%P 1696-1716
%B International Journal of Geographical Information Science
%9 Article
%Z published
%M GCE.1008
%R 10.1080/13658816.2013.792344
%X This article introduces the Flow matrix, which expresses the sizes of transitions among categories between two time points. We use the Flow matrix to create a metric R that measures the instability of annual change among time intervals that partition the time extent. Specifically, R is the proportion of change that would need to be reallocated to different time interval(s) to achieve uniform change during the time extent. This article computes R for 10 Long Term Ecological Research (LTER) sites and for seven case studies from published land change data. Of the 10 LTER sites analyzed, the Andrews site in Oregon had the highest R value (37.1% of change), while the Luquillo site in Puerto Rico had the lowest (1.7% of change). We analyze the mathematical behavior of R, especially with respect to how the partitioning of the time extent into intervals can influence R.
%A Runfola, Dan
%A Pontius, Robert G.
%K temporal stability, model assumptions, land-change science, Markov, LTER, Cross-site Research, Student Publication

%0 Journal Article
%T Exploring siliceous subfossils as a tool for inferring past water level and hydroperiod in Everglades marshes
%D 2013
%V 45
%P 49-66
%B Journal of Paleolimnology
%9 Article
%Z published
%M GCE.728
%R 10.1007/s10933-012-9624-3
%X Successfully rehabilitating drained wetlands through hydrologic restoration is dependent on defining restoration targets, a process that is informed by pre-drainage conditions, as well as understanding linkages between hydrology and ecosystem structure. Paleoecological records can inform restoration goals by revealing long-term patterns of change, but are dependent on preservation of biomarkers that provide meaningful interpretations of environmental change. In the Florida Everglades, paleohydrological hind-casting could improve restoration forecasting, but frequent drying of marsh soils leads to poor preservation of many biomarkers. To determine the effectiveness of employing siliceous subfossils in paleohydrological reconstructions, we examined diatoms, plant and sponge silico-sclerids from three soil cores in the central Everglades marshes. Subfossil quality varied among cores, but the abundance of recognizable specimens was sufficient to infer 1,000–3,000 years of hydrologic change at decadal to centennial resolution. Phytolith morphotypes were linked to key marsh plant species to indirectly measure fluctuations in water depth. A modern dataset was used to derive diatom-based inferences of water depth and hydroperiod (R2 = 0.63, 0.47; RMSE = 14 cm, 120 days, respectively). Changes in subfossil quality and abundances at centennial time-scales were associated with mid-Holocene climate events including the Little Ice Age and Medieval Warm Period, while decadal-scale fluctuations in assemblage structure during the twentieth century suggested co-regulation of hydrology by cyclical climate drivers (particularly the Atlantic Multidecadal Oscillation) and water management changes. The successful reconstructions based on siliceous subfossils shown here at a coarse temporal scale (i.e., decadal to centennial) advocate for their application in more highly resolved (i.e., subdecadal) records, which should improve the ability of water managers to target the quantity and variability of water flows appropriate for hydrologic restoration.
%A Sanchez, C.
%A Gaiser, E.E.
%A Saunders, C.J.
%A Wachnicka, A.H.
%A Oehm, N.
%A Craft, Christopher B.
%K siliceous subfossils, Everglades marshes

%0 Conference Proceedings
%T Sources and dynamics of dissolved organic carbon outwelling on the Georgia coast into the South Atlantic Bight: Research and Student Training.
%D 2013
%I ASLO
%C New Orleans, Louisiana
%B ASLO 2013 Aquatic Sciences Meeting
%8 Feburary, 2013
%9 Presentation
%Z presented
%M GCE.857
%A Schalles, John F.
%A Alberts, James J.
%A Takacs, Monika
%A Fichot, C.G.
%K dissolved organic carbon, South Atlantic Bight

%0 Conference Proceedings
%T Invasive mangroves in Texas: Surveys and high resolution imagery to map distribution, canopy height and cover, and response to a severe freeze.
%D 2013
%I Coastal and Estuarine Research Federation Biennial Meeting
%C San Diego, CA
%B Coastal and Estuarine Research Federation Biennial Meeting
%S SCI 072 - Mangrove Expansion into Salt Marsh Habitats: Causes and Consequences
%8 November, 2012
%9 Presentation
%Z presented
%M GCE.834
%X In 2008, high resolution (1 m, 67 bands) AISA Eagle imagery was obtained for Redfish Bay, in the Mission-Aransas National Estuarine Research Reserve on the Coastal Bend of Texas. The imagery was used, in part, to map the spatial and size distributions of invasive Black Mangrove. In our study area, mangroves have displaced greater than 90% of the salt marsh cover in recent decades, and occupy about 640 hectares. An algorithm to predict mangrove canopy height was developed from an extensive field survey in 2008 regressed again a vegetation index applied to the 2008 AISA imagery. Most plants are relatively small, with a median canopy height of about 79 cm. We detected a gradient of freeze damage following two hard freezes in February, 2011, with nearly total above-ground dieback nearest the mainland and areas of intermediate and minimal damage extending across the bay to the barrier islands. Field surveys one month after the freeze found vegetation canopy cover reduced to nearly 0% at high damage sites, and about 59% and 16% at intermediate and low damage sites. We documented rapid recovery in visits 8 months and 23 months after the freeze. By January, 2013 canopy cover was 67% and 78% of pre-freeze values, and canopy height was 62% and 76% of pre-freeze values at high and intermediate damage sites. We recently obtained and are currently analyzing two WorldView 2 satellite scenes (2 m, 8 band resolution) acquired 10 months and 23 months after the freeze, and are using vegetation indices to further document and quantify the damage gradient and recovery rates across the Redfish Bay study area.
%A Schalles, John F.
%A Carpenter, Eryn J.
%A Hart, Alissa C.
%A Altrichter, Adam E.
%A Vichienwanitchkul, Prem
%K Black Mangrove, coastal wetland cmmunities, remote sensing, global change, hyperspectral remote sensing

%0 Journal Article
%T Landscape estimates of habitat types, plant biomass, and invertebrate densities in a Georgia salt marsh
%D 2013
%V 26
%P 88-97
%B Oceanography
%S Coastal Long Term Ecological Research
%9 Article
%Z published
%M GCE.795
%R 10.5670/oceanog.2013.50
%X Salt marshes often contain remarkable spatial heterogeneity at multiple scales across the landscape. A combination of advanced remote-sensing approaches (hyperspectral imagery and lidar) and conventional field survey methods was used to produce detailed quantifications and maps of marsh platform geomorphology, vegetation composition and biomass, and invertebrate patterns in a Georgia (USA) salt marsh. Community structure was largely related to hydrology, elevation, and soil properties. Both abiotic drivers and community patterns varied among subwatersheds and across the landscape at larger spatial scales. The authors conclude that measurements of marsh ecosystem structure and processes are spatially contextual and not scalable without detailed geospatial analysis. Efforts to protect and restore coastal marshes must strive to document, understand, and conserve this inherent spatial complexity.
%U https://doi.org/10.5670/oceanog.2013.50
%A Schalles, John F.
%A Hladik, Christine M.
%A Lynes, Alana R.
%A Pennings, Steven C.
%K remote sensing, spartina, Littoraria, Geukensia, Melampus, Student Publication, UGAMI Publication

%0 Journal Article
%T Patterns and controls of nutrient concentrations in a southeastern United States tidal creek.
%D 2013
%V 26
%N 3
%P 12-139
%B Oceanography
%S Coastal Long Term Ecological Research
%9 Article
%Z published
%M GCE.791
%R 10.5670/oceanog.2013.55
%X Terrestrial inputs largely govern nutrient delivery to the coastal ocean, and subsequent processes transform these nutrients in the land-ocean transition zone. Here, we describe spatial and temporal patterns in surface water chemistry from the Duplin, a salt marsh/tidal creek system located in coastal Georgia, USA. Key drivers of nutrient concentration patterns in the Duplin include discharge from the nearby Altamaha River, groundwater inputs, exchange with the marsh platform, and biological processes within the tidal creek. Altamaha River discharge is correlated with salinity in the Duplin, but the processes taking place within the Duplin watershed regulate the distribution of other dissolved and particulate materials. Long-term data sets advance our understanding of the relative importance of these processes in generating the observed patterns in surface water chemistry. This knowledge improves our ability to predict how coastal systems will respond to anthropogenic perturbations.
%A Schutte, Charles
%A Hunter, Kimberley S.
%A McKay, Paul
%A Di Iorio, Daniela
%A Joye, Samantha B.
%A Meile, Christof
%K Nutrient Duplin Groundwater Altamaha, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Impact of electron acceptor availability on the anaerobic oxidation of methane in coastal freshwater and brackish wetland sediments
%D 2013
%V 115
%P 15 - 30
%B Geochimica et Cosmochimica Acta
%9 Article
%Z published
%M GCE.849
%R 10.1016/j.gca.2013.03.029
%X Methane, a powerful greenhouse gas, is both produced and consumed in anoxic coastal sediments via microbial processes. Although the anaerobic oxidation of methane (AOM) is almost certainly an important process in coastal freshwater and salt marsh sediments, the factors that control the rates and pathways of AOM in these habitats are poorly understood. Here, we present the first direct measurements of AOM activity in freshwater (0 PSU) and brackish (25 PSU) wetland sediments. Despite disparate sulfate concentrations, both environments supported substantial rates of AOM. Higher sulfate reduction (SR) rates were measured in the freshwater site and SR at both sites was of sufficient magnitude to support the observed AOM activity. Laboratory incubations of freshwater and brackish tidal, wetland sediments amended with either nothing [control], sulfate, nitrate, manganese oxide (birnessite) or iron oxide (ferrihydrite) and supplied with a methane headspace were used to evaluate the impact(s) of electron acceptor availability on potential AOM rates. Maximum AOM rates in brackish slurries occurred in the sulfate amendments. In contrast, addition of sulfate and several possible electron acceptors to the freshwater slurries decreased AOM rates relative to the control. High ratios of AOM activity relative to SR activity in the nitrate, birnessite, and ferrihydrite treatments of both the brackish and freshwater slurries provided evidence of AOM decoupled from SR. This study demonstrates that both freshwater and brackish coastal wetland sediments support considerable rates of anaerobic methanotrophy and provides evidence for sulfate-independent AOM that may be coupled to nitrate, iron, or manganese reduction in both environments.
%A Segarra, Katherine
%A Comerford, Christopher
%A Slaughter, Julia B.
%A Joye, Samantha B.
%K anaerobic oxidation, methane, wetland sediments, Student Publication

%0 Journal Article
%T Seasonal variations of methane fluxes from an unvegetatedtidal freshwater mudflat (Hammersmith Creek, GA)
%D 2013
%V 115
%P 349 - 361
%B Biogeochemistry
%9 Article
%Z published
%M GCE.848
%R 10.1007/s10533-013-9840-6
%X Wetlands are estimated to contribute nearly 40 % of global annual methane (CH4) emissions to the atmosphere. However, because CH4 fluxes from these systems vary spatially, seasonally, and by wetland type, there is a large uncertainty associated with scaling up the CH4 flux from these environments. We monitored seasonal patterns of CH4 cycling from tidal mudflat wetland sediments adjacent to a vegetated freshwater wetland in coastal Georgia between 2008 and 2009. CH4 emissions were significantly correlated with CH4 production and sediment saturation state with respect to CH4 but not with temperature. CH4 cycling displayed distinct seasonal patterns. Winter months were characterized by low CH4 production and emissions. During the spring, summer and fall, CH4 fluxes exceeded CH4 production in the top 40 cm. Comparison of CH4 sources and sinks in conjunction with the interpretation of CH4 concentration profiles using a 1D reactive transport model indicated that CH4 delivered via lateral tidal pumping likely provided additional CH4 to the upper sediment column. Seasonally high CH4 ebullition rates reflected increased CH4 production and decreased CH4 solubility. The annual CH4 flux was estimated to be on the order of 10 mol CH4 m&#8722;2 y&#8722;1 which is 2–4 times the global average for wetland CH4 emissions. Thus, even though tidal freshwater mudflats are of limited spatial extent, these environments may serve as globally significant sources of CH4 to the atmosphere. This study highlights the importance of these dynamic environments to the global CH4 cycle and their relevance to climate change.
%A Segarra, Katherine
%A Samarkin, Vladimir
%A King, E.
%A Meile, Christof
%A Joye, Samantha B.
%K Methane  Greenhouse gas  Methane flux  Freshwater , Student Publication

%0 Conference Proceedings
%T Managing Data, Provenance and Chaos through Standardization and Automation at the Georgia Coastal Ecosystems LTER Site
%D 2013
%C San Francisco, California
%B American Geophysical Union Fall Meeting 2013
%S IN53C: Data Stewardship in Theory and Practice
%8 13-Dec-2013
%9 Abstract
%Z presented
%M GCE.800
%X Managing data for a large, multidisciplinary research program such as a Long Term Ecological Research (LTER) site is a significant challenge, but also presents unique opportunities for data stewardship. LTER research is conducted within multiple organizational frameworks (i.e. a specific LTER site as well as the broader LTER network), and addresses both specific goals defined in an NSF proposal as well as broader goals of the network; therefore, every LTER data can be linked to rich contextual information to guide interpretation and comparison. The challenge is how to link the data to this wealth of contextual metadata.At the Georgia Coastal Ecosystems LTER we developed an integrated information management system (GCE-IMS) to manage, archive and distribute data, metadata and other research products as well as manage project logistics, administration and governance (figure 1). This system allows us to store all project information in one place, and provide dynamic links through web applications and services to ensure content is always up to date on the web as well as in data set metadata. The database model supports tracking changes over time in personnel roles, projects and governance decisions, allowing these databases to serve as canonical sources of project history. Storing project information in a central database has also allowed us to standardize both the formatting and content of critical project information, including personnel names, roles, keywords, place names, attribute names, units, and instrumentation, providing consistency and improving data and metadata comparability. Look up services for these standard terms also simplify data entry in web and database interfaces.We have also coupled the GCE-IMS to our MATLAB- and Python-based data processing tools (i.e. through database connections) to automate metadata generation and packaging of tabular and GIS data products for distribution. Data processing history is automatically tracked throughout the data life-cycle, from initial import through quality control, revision and integration by our data processing system (GCE Data Toolbox for MATLAB), and included in metadata for versioned data products. This high level of automation and system integration has proven very effective in managing the chaos and scalability of our information management program.
%U http://gce-lter.marsci.uga.edu/public/uploads/WSheldon_AGU_Dec2013_20131218T122659.pdf
%A Sheldon, Wade M., Jr.
%K data management, LTER-IMC, provenance, standardization, automation, database, informatics

%0 Newspaper Article
%T Automating Data Harvests with the GCE Data Toolbox
%D 2013
%I LTER Network
%C Albuquerque, NM
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Fall 2013
%9 Article
%Z published
%M GCE.891
%X As described in the Spring 2013 issue of Databits, infusions of funding from the ARRA award to the LTER Network (Chamblee, 2013a) plus an NSF SI2 grant to Tony Fountain and colleagues (Gries, 2013) allowed us to make quantum leaps in both the functionality and usability of the GCE Data Toolbox for MATLAB software in 2012-2013. Accompanying funding for user training and support also allowed us to introduce more potential users to this software, and to work directly with new and existing users to take full advantage of this tool (Chamblee, 2013a; Henshaw and Gries, 2013; Peterson, 2013). This intensive work on the toolbox not only resulted in major improvements to the software, but allowed us to develop critical user support resources (https://gce-svn.marsci.uga.edu/trac/GCE_Toolbox/wiki/Support) and establish an email list and Wiki pages to encourage ongoing peer support and collaboration.  This process also provided the necessary momentum to remove remaining GCE-specific code from the main distribution and open the Subversion repository to public access, completing a 12-year transition from the toolbox being a proprietary GCE-LTER software tool to an open source community software package.
%U https://lternet.edu/wp-content/uploads/2018/01/2013-fall-lter-databits.pdf
%A Sheldon, Wade M., Jr.
%A Chamblee, John F.
%A Cary, Richard
%K data, LTER-IMC, informatics, sensors, automation, processing, quality control, database, management

%0 Conference Proceedings
%T GCE Data Toolbox for MATLAB – a software framework for automating environmental data processing, quality control and documentation
%D 2013
%C San Francisco, California
%B American Geophysical Union Fall Meeting 2013
%S ED53B: Managing Ecological Data for Effective Use and Reuse
%8 13-Dec-2013
%9 Poster
%Z presented
%M GCE.801
%X Environmental scientists are under increasing pressure from funding agencies and journal publishers to release quality-controlled data in a timely manner, as well as to produce comprehensive metadata for submitting data to long-term archives (e.g. DataONE, Dryad and BCO-DMO). At the same time, the volume of digital data that researchers collect and manage is increasing rapidly due to advances in high frequency electronic data collection from flux towers, instrumented moorings and sensor networks. However, few pre-built software tools are available to meet these data management needs, and those tools that do exist typically focus on part of the data management lifecycle or one class of data.The GCE Data Toolbox has proven to be both a generalized and effective software solution for environmental data management in the Long Term Ecological Research Network (LTER). This open source MATLAB software library, developed by the Georgia Coastal Ecosystems LTER program, integrates metadata capture, creation and management with data processing, quality control and analysis to support the entire data lifecycle. Raw data can be imported directly from common data logger formats (e.g. SeaBird, Campbell Scientific, YSI, Hobo), as well as delimited text files, MATLAB files and relational database queries. Basic metadata are derived from the data source itself (e.g. parsed from file headers) and by value inspection, and then augmented using editable metadata templates containing boilerplate documentation, attribute descriptors, code definitions and quality control rules. Data and metadata content, quality control rules and qualifier flags are then managed together in a robust data structure that supports database functionality and ensures data validity throughout processing. A growing suite of metadata-aware editing, quality control, analysis and synthesis tools are provided with the software to support managing data using graphical forms and command-line functions, as well as developing automated workflows for unattended processing. Finalized data and structured metadata can be exported in a wide variety of text and MATLAB formats or uploaded to a relational database for long-term archiving and distribution.The GCE Data Toolbox can be used as a complete, light-weight solution for environmental data and metadata management, but it can also be used in conjunction with other cyber infrastructure to provide a more comprehensive solution. For example, newly acquired data can be retrieved from a Data Turbine or Campbell LoggerNet Database server for quality control and processing, then transformed to CUAHSI Observations Data Model format and uploaded to a HydroServer for distribution through the CUAHSI Hydrologic Information System. The GCE Data Toolbox can also be leveraged in analytical workflows developed using Kepler or other systems that support MATLAB integration or tool chaining. This software can therefore be leveraged in many ways to help researchers manage, analyze and distribute the data they collect.
%U http://gce-lter.marsci.uga.edu/public/uploads/WSheldon_Toolbox_Poster_AGU2013_20131218T123041.pdf
%A Sheldon, Wade M., Jr.
%A Chamblee, John F.
%A Cary, Richard
%K data management, LTER-IMC, provenance, standardization, automation, database, informatics, MATLAB, logger

%0 Book Section
%T Salt Marshes Under Global Siege
%D 2013
%B Coastal Marine Conservation: Science and Policy
%9 Article
%Z published
%M GCE.575
%A Silliman, Brian R.
%E Ray, G.C.
%E McCormick-Ray, J.
%E Wiley, Jon
%K Salt Marsh

%0 Newspaper Article
%T Quality of biodiversity, not just quantity, is key: Right mix of species is needed for conservation
%D 2013
%B Science Daily
%8 December 8, 2013
%9 Article
%Z published
%M GCE.883
%X A new study of biodiversity loss in a salt marsh finds that it's not just the total number of species preserved that matters; it's the number of key species. If humans want to reap the benefits of the full range of functions that salt marshes and other coastal ecosystems provide, we need to preserve the right mix of species.
%U https://www.sciencedaily.com/releases/2013/12/131208090631.htm
%A Silliman, Brian R.
%A Hensel, Marc Simon
%K biodiversity, Student Publication

%0 Journal Article
%T Consumer Fronts, Global Change, and Runaway Collapse in Ecosystems
%D 2013
%V 44
%P 503 - 538
%B Annual Review of Ecology, Evolution, and Systematics
%9 Article
%Z published
%M GCE.854
%R 10.1146/annurev-ecolsys-110512-135753
%X Consumer fronts occur when grazers or predators aggregate in bands along the edges of a resource. Our review reveals that consumer fronts are a common phenomenon in nature, occur in many different ecosystems, and are triggered by universal mechanisms: External forces locally increase top-down control beyond prey carrying and/or renewal capacity, and resource-dependent movement leads to consumer aggregation along the edge of the remaining prey population. Once formed, consumer fronts move through systems as spatially propagating waves, self-reinforced via intense overexploitation and amplified by density-dependent feedbacks. When consumer fronts are spatially restricted, they generate patchiness. In contrast, when consumer fronts are expansive, they can lead to runaway responses that cause large-scale ecosystem degradation and regime shifts. We conceptualize a synergistic stress hypothesis and model that highlight how coupled intensification of physical stress and enhanced consumer pressure can trigger increased occurrence of consumer fronts and decreased system stability and resilience. With escalating climate change and food-web modification, the physical and biological conditions favoring consumer-front formation will likely become a common feature of many ecosystems.
%A Silliman, Brian R.
%A McCoy, M.
%A Angelini, Christine
%A Holt, Robert D.
%A Griffin, John N.
%A van de Koppel, Johan
%K top-down control, predation, ecosystem resilience, catastrophic collapse, spatial processes, thresholds, climate change, resource-dependent movement, density-dependent, aggregation, behavior, wave propagation, Student Publication

%0 Thesis
%T Factors influencing groundwater and surface water hydrogeochemistry with a special emphasis on the importance of sediment geology
%D 2013
%I University of Georgia
%C Athens, GA
%9 M.S. Thesis
%Z published
%M GCE.887
%X Historical data on groundwater and surface water nutrients and trace metal concentrations and water quality indicators were collected and examined in concert with aquifer, surficial geology and land use characteristics. A meta-analysis was conducted to better understand the factors affecting groundwater and surface water hydrogeochemistry and nutrients across variable conditions and scales. The primary goals were to compare (1) groundwater hydrogeochemistry and (2) groundwater vs. surface water geochemistry and nutrients for geologically and environmentally distinct wetland areas along the U.S Atlantic coast. The results demonstrate the influences of site geology, land use type, wetland extent and proximity to seawater inputs on the chemical signatures of the groundwater and surface water. Differences in microbial processes, oxygen and organic matter supply, and sources and sinks of dissolved constituents in groundwater and surface water wetland areas likely contribute to the variations in dissolved inorganic nutrients. These findings indicate the value of future studies of this nature.
%A Slaughter, Julia B.
%K Groundwater, Student Publication

%0 Book Section
%T Whispers on the Landscape
%D 2013
%I University Press of Florida
%B The Archaeology and Historical Ecology of Small Scale Economies
%9 Article
%Z published
%M GCE.635
%A Thompson, Victor D.
%E Thompson, Victor D.
%K Anthropogenic Landscape, Hammock, Native American, Shellfish

%0 Journal Article
%T Using Oxygen Isotope Sclerochronology to Evaluate the Role of Small Islands among the Guale of the Georgia Coast, USA
%D 2013
%V 8
%P 190-209
%B Journal of Island and Coastal Archaeology
%9 Article
%Z published
%M GCE.714
%R 10.1080/15564894.2012.708007
%X In this article, we present the results of sequential oxygen isotope analysis performed on hard clam, Mercenaria spp. (n = 5) and eastern oyster, Crassostrea virginica (n = 13) valves excavated from Pumpkin Hammock (9MC350). These data are used to evaluate Guale models of settlement and subsistence along the Georgia coast during the late pre-Contact and early Colonial eras (ca. AD 1325 to 1700). Season of collection data indicate shells were collected and deposited on the island during all four seasons, suggesting year-round occupation of the site. In addition, oxygen isotope values imply the Guale exploited mollusks from habitats over a wide range of salinity. We interpret this to signify that the Guale ranged broadly over the coastal landscape and that they were able to exploit these distant resources due to their use of watercraft. Finally, we place these findings within the broader context of the changing social landscape during the late pre-Contact and Colonial eras of the Georgia coast.
%A Thompson, Victor D.
%A Andrus,  C. F.T.
%K Pumpkin Hammock, marsh islands, archaeology

%0 Book
%T Coastal Landscapes and their Relationship to Human Settlement on the Georgia Coast
%D 2013
%V 98
%P 494
%I American Museum of Natural History—Scientific Publications
%C New York, NY
%B Life Among the Tides - Recent Archaeology on the Georgia Bight
%9 Book
%Z published
%M GCE.777
%X Although this volume covers a broad range of temporal and methodological topics, the chapters are unified by a geographic focus on the archaeology of the Georgia Bight. The various research projects span multiple time periods (including Archaic, Woodland, Mississippian, and contact periods) and many incorporate specialized analyses (such as petrographic point counting, shallow geophysics, and so forth). The 26 contributors conducting this cutting-edge work represent the full spectrum of the archaeological community, including museum, academic, student, and contract archaeologists. Despite the diversity in professional and theoretical backgrounds, temporal periods examined, and methodological approaches pursued, the volume is unified by four distinct, yet interrelated, themes. Contributions in Part I discuss a range of analytical approaches for understanding time, exchange, and site layout. Chapters in Part II model coastal landscapes from both environmental and social perspectives. The third section addresses site-specific studies of late prehistoric architecture and village layout throughout the Georgia Bight. Part IV presents new and ongoing research into the Spanish mission period of this area. These papers were initially presented and discussed at the Sixth Caldwell Conference, cosponsored by the American Museum of Natural History and the St. Catherines Island Foundation, held on St. Catherines Island, Georgia, May 20-22, 2011. TABLE OF CONTENTS: Revising the ą&#8308;C reservoir correction for St. Catherines Island, Georgia / David Hurst Thomas, Matthew C. Sanger, and Royce H. Hayes -- An assessment of coastal faunal data from Georgia and northeast Florida / Alexandra L. Parsons and Rochelle A. Marrinan -- Archaeological geophysics on St. Catherines Island : beyond prospection / Ginessa J. Mahar -- Paste variability and clay resource utilization at the Fountain of Youth site, St. Augustine, 8SJ31 / Ann S. Cordell and Kathleen A. Deagan -- Petrographic analysis of pottery and clay samples from the Georgia Bight : evidence of regional social interactions / Neill J. Wallis and Ann S. Cordell -- Past shorelines of the Georgia coast / Chester B. DePratter and Victor D. Thompson -- Coastal landscapes and their relationship to human settlement on the Georgia coast / John A. Turck and Clark R. Alexander -- The role of small islands in foraging economies of St. Catherines Island / Matthew F. Napolitano -- Ever-shifting landscapes : tracking changing spatial usage along coastal Georgia / Matthew C. Sanger -- A paleoeconomic model of the Georgia coast (4500-300 B.P.) / Thomas G. Whitley -- A survey of Irene phase architecture on the Georgia coast / Deborah A. Keene and Ervan G. Garrison -- Life and death on the Ogeechee : a view from the Redbird Creek village / Ryan O. Sipe -- Mission San Joseph de Sapala : mission-period archaeological research on Sapelo Island / Richard W. Jefferies and Christopher R. Moore -- The Guale landscape of Mission Santa Catalina de Guale : 30 years of geophysics at a Spanish colonial mission / Elliot H. Blair -- Missions San Buenaventura and Santa Cruz de Guadalquini : retreat from the Georgia coast / Keith H. Ashley, Vicki L. Rolland, and Robert L. Thunen -- Entangling events : the Guale coastal landscape and the Spanish missions / Victor D. Thompson, John A. Turck, Amanda D. Roberts Thompson, and Chester B. DePratter -- Island and coastal archaeology on the Georgia Bight / Scott M. Fitzpatrick.
%U http://digitallibrary.amnh.org/dspace/handle/2246/6435
%A Thompson, Victor D.
%A Thomas, David Hurst
%K anthropology, geology, settlement, humans, coast, landscapes

%0 Book
%T The Archaeology and Historical Ecology of Small Scale Economies
%D 2013
%P 240
%I University of Press of Florida
%9 Book
%Z ISBN-10: 0813042429 ISBN-13: 978-0813042428
%M GCE.852
%A Thompson, Victor D.
%A Waggoner, James C.
%K Archaeology, Historical Ecology, Small-Scale Economies

%0 Book Section
%T Cumulative Actions and the Historical Ecology of Islands along the Georgia Coast
%D 2013
%P 79-95
%I University Press of Florida
%C Gainesville
%B The Archaeology and Historical Ecology of Small Scale Economies
%9 Article
%Z published
%M GCE.572
%A Thompson, Victor D.
%A Turck, John A.
%A DePratter, Chester
%E Thompson, Victor D.
%K archaeology, historical ecology, hammocks, Student Publication

%0 Book Section
%T Entangling Events: The Guale Landscape and the Spanish Missions
%D 2013
%V 98
%P 423-437
%I Anthropological Papers of the American Museum of Natural History
%C New York
%B Life among the Tides: Recent Archaeology of the Georgia Bight
%9 Article
%Z published
%M GCE.708
%A Thompson, Victor D.
%A Turck, John A.
%A Thompson, Amanda R.
%A DePratter, Chester
%E Thompson, Victor D.
%E Thomas, David Hurst
%K Regional Archaeology, Contact Period, Guale, Spanish Missions, Agency, Structure, Student Publication

%0 Journal Article
%T Decomposition of leaf litter in a U.S. saltmarsh is driven by dominant species, not species complementarity
%D 2013
%V 33
%P 83-89
%B Wetlands
%9 Article
%Z published
%M GCE.768
%R 10.1007/s13157-012-0353-1
%X To add to our understanding of species richness effectson ecosystem processes, we studied the importanceof species complementarity in driving decomposition in asaltmarsh in Georgia, USA. We studied pair-wise interactionsof both detritivores and plant litter species and howthey affect decomposition rates in an experiment located onthe mid-marsh platform. Needle rush, Juncus roemerianus,had 2-3 times higher decomposition rates thancordgrass, Spartina alterniflora, or live oak, Quercusvirginiana. Mixing litter types did not promote decompositionrates. Cordgrass decomposition was 1.5-timeshigher when periwinkles, Littoraria irrorata, were presentthan in detritivore-free controls. In contrast, neithercoffee-bean snails, Melampus bidentatus, nor wharfcrabs, Armases cinereum, increased cordgrass decompositionrates. Mixing detritivore species did not increasecordgrass mass loss beyond expected rates from anadditive model. We conclude that in this system, speciesdo not act complementarily with each other, but thatdecomposition rates are controlled by the dominant speciesof angiosperms and invertebrate detritivores.
%A Treplin, Malte
%A Pennings, Steven C.
%A Zimmer, Martin
%K salt marsh, decomposition, Spartina, Juncus, Quercus, Littoraria, Melampus, Armases, snails, crabs, SINERR Publication, Student Publication, UGAMI Publication

%0 Book Section
%T Coastal Landscapes and their Relationship to Human Settlement on the Georgia Coast
%D 2013
%V American Museum of Natural History Anthropological
%P 169-189
%I American Museum of Natural History—Scientific Publications
%C New York, NY
%B Life Among the Tides - Recent Archaeology on the Georgia Bight
%9 Article
%Z published
%M GCE.776
%X Local geomorphology and geology are important to understanding human settlement patterns (Rossignol, 1992; Stafford, 1995, 2004; Dodonov, A.W. Kandel, A.N. Simakova, et al., 2007). The geomorphology of a landscape reveals when elements of the landscape initially formed, the processes involved in their formation, and the processes involved in subsequent landscape changes over time. Understanding these factors allows for a better interpretation of the archaeological record. Ideally, the analysis of the archaeological record should be separate from the geomorphology, but they are sometimes so intertwined that it is necessary to analyze them simultaneously. This is especially true in dynamic coastal settings, where environmental changes can occur yearly, seasonally, and even daily (Wells, 2001; also see Jordan and Maschner, 2000; Peros, Graham, and Davis, 2006; Dickinson and Burley, 2007; Bicho and Haws, 2008; Pollard, 2009; Erlandson and Braje, 2011).To refine our understanding of Georgia coastal evolution, a campaign of vibracoring, dating (radiocarbon and optically stimulated luminescence), and sediment analyses were performed in four diverse intertidal settings: back-barrier, nondeltaic interbarrier, deltaic interbarrier, and southern end barrier/recurved spit. The results were then compared to the archaeological records of these areas, noting the implication of landscape history for settlement patterns, as well as how archaeology can speak to geomorphological studies.
%U http://digitallibrary.amnh.org/dspace/handle/2246/6435
%A Turck, John A.
%A Alexander, Clark R., Jr.
%E Thompson, Victor D.
%E Thomas, David H.
%K anthropology, geology, settlement, humans, coast, landscapes, Student Publication

%0 Report
%T An Archaeological Survey of Pumpkin Hammock (9MC350), McIntosh County, Georgia.
%D 2013
%I Report on file, Georgia Archaeological Site File
%C Athens
%9 Report
%Z published
%M GCE.788
%A Turck, John A.
%A Thompson, Victor D.
%K Archaeology, Pumpkin Hammock, Survey, Student Publication

%0 Conference Proceedings
%T Sea Level Fluctuations, Landscape Evolution, and the Late Archaic Population of the Georgia Coast
%D 2013
%C Tampa, FL
%B 70th Annual Meeting of the Southeastern Archaeological Conference
%9 Presentation
%Z presented
%M GCE.803
%X The relationship among shell rings, shell middens, and non-shell sites is one of the more enduring problems of coastal archaeology. This paper evaluates settlement patterns among these site types within the Late Archaic period along the Georgia coast in comparison to landscape change. New evidence addressed includes site locational data, ceramic distributions, landscape changes due to changes in seal level, recent radiocarbon dates, and re-evaluation and re-calibration of older radiocarbon dates. Analysis indicates that at certain times, non-shell sites may have played a more important role in the social and economic landscape than previously thought.
%A Turck, John A.
%A Thompson, Victor D.
%K Archaeology, Radiocarbon Dates, Shell, Coastal Zone, Student Publication

%0 Book Section
%T Entangling Events: The Guale Landscape and the Spanish Missions
%D 2013
%I Anthropological Papers of the American Museum of Natural History
%C New York
%B Life among the Tides: Recent Archaeology of the Georgia Bight
%9 Article
%Z published
%M GCE.706
%A Turck, John A.
%A Thompson, Amanda R.
%A DePratter, Chester
%E Thompson, Victor D.
%E Thomas, David Hurst
%K Regional archaeology, back-barrier area, contact period, Spanish Missions, agency, structure, Student Publication

%0 Conference Proceedings
%T Biophysical feedbacks in tidal creek formation
%D 2013
%I Coastal and Estuarine Research Federation
%C San Diego, CA
%B Coastal and Estuarine Research Federation 2013
%8 3-7 November 2013
%9 Presentation
%Z presented
%M GCE.799
%A Vu, Huy
%A Pennings, Steven C.
%K creek, crab, erosion, hydrology, Student Publication

%0 Report
%T Water quality metadatabase for the South Atlantic Landscape Conservation Cooperative
%D 2012
%I National Park Service
%C Fort Collins, Colorado
%B Natural Resource Report NPS/SECN/NRR—2012/581
%9 Report
%Z published
%M GCE.767
%X Department of Interior Secretarial Order 3289 established a Department-wide approach for applying scientific tools to increase understanding of climate change and to coordinate an effective response to its impacts on tribes and on the land, water, ocean, fish and wildlife, and cultural heritage resources that the Department manages. Working at the landscape, regional, and national scales through the establishment of DOI Climate Science Centers and Landscape Conservation Cooperatives, the Department is defining and implementing a vision that integrates DOI science and management expertise with that of our partners, providing information and best management practices available to support strategic adaptation and mitigation efforts on both public and private lands across the U.S. and internationally. In FY 2010, the Southeast Coast Network received additional program funds to (a) expand monitoring efforts that will improve understanding of the effects of climate change on park resources, and (b) expand partnerships with other federal, state, academic, and NGO institutions to conduct resource conservation within the context of the DOI-led Landscape Conservation Cooperatives program. As a part of this effort, the Georgia Coastal Research Council developed a metadata-level database of existing water quality monitoring programs across the South Atlantic Landscape Conservation Cooperative (SALCC) geographic range. Specific objectives of this project were to expand the SECN’s coastal metadatabase project to: 1. Incorporate water quality metadata information from national databases into the database. 2. Identify project partners from the region, and work with them to provide descriptions of water quality sampling programs. 3. Enter water quality metadata for new programs. 4. Host the database and web portal until such time as it can be transferred to NPS. This report describes the updates that were made to the system and the website since the original project, summarizes the results of each project objective, and includes a discussion of challenges faced in meeting those objectives.
%U https://irma.nps.gov/App/Reference/DownloadDigitalFile?code=456748&file=Alber_et_al_2012_Water_Quality_Metadatabase_II.pdf
%A Alber, Merryl
%A Sheldon, Wade M., Jr.
%A Laporte, Christine
%A Douce, Travis
%K database, LTER-IMC, water quality, SALCC, web portal, metadata

%0 Journal Article
%T Determining the Habitats of Mollusk Collection at the Sapelo Island Shell Ring Complex, USA using Oxygen Isotope Sclerochronology
%D 2012
%V 39
%P 215-228
%B Journal of Archaeological Science
%9 Article
%Z published
%M GCE.715
%R 10.1016/j.jas.2011.08.002
%X Sequential oxygen isotope analysis was performed on Mercenaria spp. (n = 41) and Crassostrea virginica (n = 17) valves excavated from the Sapelo Island Shell Ring complex, coastal Georgia, USA. The data were analyzed to determine the habitats in which the mollusks were harvested in order to gain insight into the subsistence practices of the site occupants. The rationale for this study is based on the observation that temperatures are similar in all of the habitats surrounding the island, but the &#948;18Owater trends across the habitats co-vary with salinity. Accordingly, the shells grown in these habitats contain sinusoidal oscillations in &#948;18O through ontogeny due primarily to seasonal temperature variation, but the absolute values reflect the salinity ranges of each habitat. Assuming a relatively constant oxygen isotope/salinity gradient since the time of site occupation, it appears that both of these mollusks were exploited over nearly the full range of their salinity tolerances. While a precise estimate of travel distance during collection cannot be made, these data suggest that mollusks were harvested at distances from the site greater than would be predicted using terrestrial foraging models. In addition to providing insight into past subsistence strategies in this region, this research establishes a new method of assessing catchment area and mobility practices.
%A Andrus,  C. F.T.
%A Thompson, Victor D.
%K Georgia, Archaeology

%0 Journal Article
%T Patch size-dependent community recovery after massive disturbance
%D 2012
%V 93
%N 1
%P 101–110
%B Ecology
%9 Article
%Z published
%M GCE.721
%R 10.1890/11-0557.1
%X Massive anthropogenic and climate-related disturbances are now common in ecosystems worldwide, generating widespread die-off and subsequent community recovery dominated by remnant-patch dynamics rather than open-gap dynamics. Whether communities can recover and, if so, which factors mediate recolonization rate and extent remain unresolved. Here we evaluate recolonization dynamics of southern U.S. salt marshes that experienced extensive, drought-induced die-off of the foundation species Spartina alterniflora over the previous decade. Surveys of Georgia (USA) salt marshes showed little seedling recruitment in die-off areas but persistence of Spartina particularly in large, rather than small, remnant patches. Given this natural variation in remnant patch size, we conducted field experiments to test whether key plant-controlling biotic (grazing, plant neighbor presence) and abiotic (water availability) factors differentially impact Spartina recolonization at small and large-patch scales. In the small-patch (,1 m2) experiment in 2009, removing grazers and plant neighbors prompted dramatically higher expansion and growth of Spartina relative to controls, while adding freshwater to reduce water limitation had little effect. In contrast, large-patch (.20 m2) borders advanced significantly over the same time period regardless of grazer or neighbor removal. We continued the large-patch experiments in 2010, a year that experienced drought, and also added freshwater or salt to borders to modify ambient drought stress; overall, borders advanced less than the previous year but significantly more where neighbors were removed or freshwater added. Thus, water availability appears to mediate Spartina recovery by fueling large-patch expansion during wet summers and intensifying interspecific competition during drought. Combined, these findings suggest ecosystems can recover from massive disturbance if remnant foundation species’ patches are large enough to overcome biotic inhibition and successfully expand during periods of relaxed abiotic stress.
%U https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/11-0557.1
%A Angelini, Christine
%A Silliman, Brian R.
%K climate change, competition, drought, foundation species, herbivory, mudflats, patch dynamics, resilience, salt marshes, Georgia, USA, size-dependent recolonization processes, Spartina alterniflora, succession, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Effects of Sea-Level Rise and Anthropogenic Development on Priority Bird Species Habitats in Coastal Georgia, USA
%D 2012
%V 49
%P 473-482
%B Environmental Management
%9 Article
%Z published
%M GCE.704
%R 10.1007/s00267-011-9761-x
%X We modeled changes in area of five habitats, tidal-freshwater forest, salt marsh, maritime shrub-scrub (shrub), maritime broadleaf forest (oak) and maritime narrowleaf (pine) forest, in coastal Georgia, USA, to evaluate how simultaneous habitat loss due to predicted changes in sea level rise (SLR) and urban development will affect priority bird species of the south Atlantic coastal plain by 2100. Development rates, based on regional growth plans, were modeled at 1% and 2.5% annual urban growth, while SLR rates, based on the Intergovernmental Panel on Climate Change’s A1B mean and maximum scenarios, were modeled at 52 cm and 82 cm, respectively. SLR most greatly affected the shrub habitat with predicted losses of 35–43%. Salt marsh and tidal forest also were predicted to lose considerable area to SLR (20–45 and 23–35%, respectively), whereas oak and pine forests had lesser impact from SLR, 18–22% and 11–15%, respectively. Urban development resulted in losses of considerable pine (48–49%) and oak (53–55%) habitat with lesser loss of shrub habitat (21–24%). Under maximum SLR and urban growth, shrub habitat may lose up to 59–64% compared to as much as 62–65% pine forest and 74–75% oak forest. Conservation efforts should focus on protection of shrub habitat because of its small area relative to other terrestrial habitats and use by Painted Buntings (Passerina ciris), a Partners In Flight (PIF) extremely high priority species. Tidal forests also deserve protection because they are a likely refuge for forest species, such as Northern Parula and Acadian Flycatcher, with the decline of oak and pine forests due to urban development.
%A Brittain, Ross
%A Craft, Christopher B.
%K Birds, Coast, Conservation planning, Land-use change, GIS model, Sea-level rise, Urban development, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Habitat Use by Coastal Birds Inferred from Stable Carbon and Nitrogen Isotopes
%D 2012
%V 35
%P 633-645
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.732
%X Conservationists need to know the degree of habitat fidelity for species of conservation concern. Stable Isotope Analysis in R quantified the contribution of terrestrial vs. saltmarsh primary production sources to terrestrial passerine food webs from four habitats of Sapelo Island, Georgia (USA), saltmarsh, maritime scrub–shrub, maritime broadleaf (oak), and maritime narrowleaf (pine) forests, using delta-13C and delta-15N. Models suggested Northern Parula (Parula americana) in oak forests, White-eyed Vireos (Vireo griseus) in shrub, and Brown-headed Nuthatches (Sitta pusilla) in pine forests derived most of their food from habitats they occupied (53–100%). Saltmarsh provided 47–94% of Painted Bunting (Passerina ciris) food sources, supporting previous findings by Springborn and Meyers (2005). Thus, Painted Bunting conservation in the Southeastern USA should focus on Springborn and Meyers' suggestion of maritime scrub–shrub habitat and forests with <75% canopy, >50% ground cover, and patches of shrubs that are within 700 m of saltmarsh.
%A Brittain, R.A.
%A Schimmelmann, A.
%A Parkhurst, D.
%A Craft, Christopher B.
%K coastal birds, food webs, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Tidal freshwater forest accretion does not keep pace with sea level rise
%D 2012
%V 18
%P 3615-3623
%B Global Change Biology
%9 Article
%Z published
%M GCE.726
%R 10.1111/gcb.12009
%X Soil properties, accretion, and accumulation were measured in tidal freshwater forests (tidal forests) of the Ogeechee, Altamaha, and Satilla rivers of the South Atlantic (Georgia USA) coast to characterize carbon (C) sequestration and nutrient (nitrogen-N, phosphorus-P) accumulation in these understudied, uncommon, and ecologically sensitive wetlands. Carbon sequestration and N and P accumulation also were measured in a tidal forest (South Newport River) that experiences saltwater intrusion to evaluate the effects of sea level rise (SLR) and saltwater intrusion on C, N and P accumulation. Finally, soil accretion and accumulation of tidal forests were compared with tidal fresh, brackish and salt marsh vegetation downstream to gauge how tidal forests may respond to SLR. Soil accretion determined using 137C and 210Pb averaged 1.3 and 2.2 mm yr&#8722;1, respectively, and was substantially lower than the recent rate of SLR along the Georgia coast (3.0 mm yr&#8722;1). Healthy tidal forest soils sequestered C (49–82 g m&#8722;2 yr&#8722;1), accumulated N (3.2–5.3 g m&#8722;2 yr&#8722;1) and P (0.29–0.56 g m&#8722;2 yr&#8722;1) and trapped mineral sediment (340–650 g m&#8722;2 yr&#8722;1). There was no difference in long-term accretion, C sequestration, and nutrient accumulation between healthy tidal forests and tidal forests of the South Newport River that experience saltwater intrusion. Accelerated SLR is likely to lead to decline of tidal forests and expansion of oligohaline and brackish marshes where soil accretion exceeds the current rate of SLR. Conversion of tidal forest to marshes will lead to an increase in the delivery of some ecosystem services such as C sequestration and sediment trapping, but at the expense of other services (e.g. denitrification, migratory songbird habitat). As sea level rises in response to global warming, tidal forests and their delivery of ecosystem services face a tenuous future unless they can migrate upriver, and that is unlikely in most areas because of topographic constraints and increasing urbanization of the coastal zone.
%U http://onlinelibrary.wiley.com/doi/10.1111/gcb.12009/abstract
%A Craft, Christopher B.
%K tidal freshwater forest accretion, sea level rise, UGAMI Publication

%0 Journal Article
%T Genetic structure and connectivity patterns of two Caribbean rocky-intertidal gastropods
%D 2012
%V 78
%P 112 - 118
%B Journal of Molluscan Studies
%9 Article
%Z published
%M GCE.756
%R 10.1093/mollus/eyr050
%X The extent of gene flow in Caribbean marine communities has been investigated primarily in taxa from coral reef habitats, particularly in corals and reef fishes. Results from empirical population genetic studies in those taxa have indicated the presence of an east–west genetic break between 67° and 70°W longitude, and isolation of populations in the Bahamas. Hydrodynamic modelling has further suggested the presence of four connectivity regions that may contribute to genetic isolation. In this study we test for the presence of genetic structure in two gastropods (Cenchritis muricatus and Echinolittorina ziczac) from poorly sampled rocky-intertidal habitats, using mitochondrial sequence data. Significant genetic structure was found in C. muricatus (Snn = 0.29, P< 0.001; Fst = 0.022, P< 0.001), but not in E. ziczac (Snn = 0.17, P= 0.48; Fst = 0.022, P= 0.48), in spite of similar larval life histories. The pattern of differentiation does not match a simple east–west model in either species, nor a four-region model, nor do the Bahamas show evidence of isolation. However, the genetic differentiation of Bonaire from other sites that is observed in C. muricatus and E. ziczac is consistent with the previously observed isolation of this location in the trochid gastropod Cittarium pica.
%A Diaz-Ferguson, Edgardo
%A Haney, A.
%A Wares, John P.
%A Silliman, Brian R.
%K genetics, gastrods, snails, population ecology

%0 Journal Article
%T Predator/prey-interactions promote decomposition of low-quality detritus
%D 2012
%V 32
%P 931-938
%B Wetlands
%9 Article
%Z published
%M GCE.737
%R 10.1007/s13157-012-0326-4
%X Predation on detritivores is expected to decelerate detritivore-mediated decomposition processes. In field mesocosms, we studied whether the decomposition of leaf and needle litter of live oak (Quercus virginiana) and loblolly pine (Pinus taeda), respectively, was affected by saltmarsh detritivores (Gastropoda: Littoraria irrorata and Melampus bidentatus) and predacious omnivores (Decapoda: Armases cinereum) and their interactions. Both crabs and snails alone increased decomposition (mass loss) rates of oak litter, while a combination of both resulted in the same mass loss as in animal-free controls, probably due to crabs feeding on snails rather than litter. Neither crabs nor snails alone affected mass loss of pine litter, but a combination of both significantly increased decomposition rates. Irrespective of the litter type, crabs significantly increased mortality of the snails but gained biomass only on pine litter and only when detritivorous snails were present. Our findings suggest that unidirectional facilitation of omnivorous semi-terrestrial crabs by their detritivorous prey (saltmarsh snails) promotes the decomposition of low-quality (pine) litter. On high-quality (oak) litter, by contrast, negative effects of the predator prevail, resulting in a drop of decomposition rates when crabs were present, probably owing to predation on detritivorous snails. Thus, the effects of predator/prey-interactions on decomposition processes are context-dependent and are controlled by resource quality.
%U http://link.springer.com/article/10.1007/s13157-012-0326-4
%A Ewers, Christine
%A Beiersdorf, Anika
%A Wieski, Kazimierz
%A Pennings, Steven C.
%A Zimmer, Martin
%K predation, detritivory, Littoraria, Melampus, Armases, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Numerical models of salt marsh evolution: Ecological, geomorphic and climatic factors
%D 2012
%V 50
%N RG1002
%B Reviews of Geophysics
%9 Article
%Z published
%M GCE.717
%R 10.1029/2011RG000359
%X Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise.
%U http://onlinelibrary.wiley.com/doi/10.1029/2011RG000359/abstract
%A Fagherazzi, Sergio
%A Kirwan, Matthew Lynn
%A Mudd, Simon Marius
%A Guntenspergen, Glenn R.
%A Temmerman, Stijn
%A D'Alpaos, Andrea
%A van de Koppel, Johan
%A Craft, Christopher B.
%A Rybczyk, John
%A Reyes, Enrique
%A Clough, Jonathan
%K models, salt marsh, geomorphology, climate

%0 Journal Article
%T Ciliate Ingestion and Digestion: Flow Cytometric Measurements and Regrowth of a Digestion-Resistant Campylobacter jejuni
%D 2012
%V 59
%N 1
%P 12 - 19
%B Journal of Eukaryotic Microbiology
%9 Article
%Z Collaborative with USDA, ecology of infectious diseases
%M GCE.845
%R 10.1111/j.1550-7408.2011.00589.x
%X We measured ingestion and digestion rates of the pathogenic bacterium Campylobacter jejuni by a freshwater ciliate Colpoda sp. to determine whether Campylobacter is able to resist protist digestion. Campylobacter and the nonpathogenic bacterium Pseudomonas putida LH1 were labeled with a 5-chloromethylfluorescein diacetate, which fluoresces in intact and active cells but fades when exposed to low pH environments, such as protistan food vacuoles. Ingestion and digestion rates were measured via flow cytometry as the change in ciliate fluorescence over time, which corresponded to the quantity of intracellular bacteria. The rate of Campylobacter ingestion exceeded the digestion rate. Ciliates retained labeled Campylobacter 5 h after ingestion was stopped. In contrast, ciliates grazing upon P. putida returned to baseline fluorescence within 5 h, indicating that P. putida were completely digested. The ability of intracellular Campylobacter to remain viable after ingestion was tested by sorting individual ciliates and bacterial cells into Campylobacter-selective media. Campylobacter growth occurred in 15% (± 5 SE) of wells seeded with highly fluorescent ciliates, whereas only 4% (± 1) of wells seeded with free-living Campylobacter exhibited growth. A key advantage of this approach is that it is rapid and should be applicable to other phagocytotis studies.
%U https://www.ncbi.nlm.nih.gov/pubmed/22092598
%A First, Matthew R.
%A Park, N. Y.
%A Berrang, M. E.
%A Meinersmann, R. J.
%A Bernhard, J. M.
%A Gast, R. J.
%A Hollibaugh, James T.
%K Bacterivory, cell metabolism, CellTracker Green, pathogen survival, Trojan horse protist., Student Publication

%0 Conference Proceedings
%T Large scale simulations of virtual prairies with volunteer computing
%D 2012
%I LTER National Network
%C Estes Park, CO
%B 2012 LTER All Scientist Meeting
%S Modeling wetland processes
%8 September 10-13, 2012
%9 Presentation
%Z presented
%M GCE.743
%A Garbey, Marc
%A Bittebiere, Anne-Kristel
%A Smaoui, M
%A Rinsurongkawong, W
%A Clement, B.
%A Pennings, Steven C.
%A Mony, Cendrine
%K simulation, modeling, grassland

%0 Thesis
%T A fish tale: comparison of the gut microbiome of 15 fish species and the influence of diet and temperature on its composition
%D 2012
%P 229
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.908
%X This dissertation addresses four aspects of the biology of the fish gut. 1) What bacteria constitute the fish gut microbiome, how variable is the composition within a species; how different are the gut microflora of different fish species; and how do fish gut microbiomes different from those of other organisms that have been studied? 2) How do food quality and diet-associated bacteria affect the composition of the gut microbiome? 3) Ocean temperatures are expected to rise in the future in response to increased atmospheric CO2 concentrations, we know that the incidence of marine pathogenic Vibrios is higher during warm summer months and we know that Vibrios are common, and often dominant, taxa in the gut microbiome. Does increased habitat temperature influence the composition of the gut microbiome and specifically does the abundance of potentially pathogenic Vibrios increase when fish are held at higher water temperatures? 4) Conversely, can fish serve as refuges for these Vibrios when growth conditions are less favorable and as vectors for their distribution? We used 454-pyrosequencing to survey the 16S rRNA ribotypes in the gut microbiomes of 12 finfish and 3 shark species. Fish were selected to encompass herbivorous and carnivorous lifestyles, to have varied digestive physiologies, to represent pelagic and demersal species, and as representatives of a range of habitats from estuarine to marine. Proteobacteria ribotypes were present in all fish and often dominated the gut microflora community of many fish species. Firmicutes were also prevalent within the fish gut community, but at a lower relative abundance. Each species had a core gut microflora; however, no individual ribotype was present among all species suggesting that the gut microflora community is adapted to the autecological properties and physiological conditions of each fish species. We determined the effects of both diet quality and food-associated bacteria on gut microflora using mummichogs (F. heteroclitus) and pinfish (L. rhomboides) as model organisms. We identified a core gut microflora for these species and determined that food-associated microbiota strongly influenced the composition of the gut microflora in mummichogs, but not pinfish. We also tested the effect of temperature on the composition of gut microflora and on the occurrence of Vibrio spp. 16S rRNA and V. vulnificus vvh genes in the two model fish (mummichogs and pinfish) using clone libraries and quantitative PCR (qPCR). In a related set of experiments, we asked whether fish guts might serve as a refuge for Vibrio parahaemolyticus and Vibrio vulnificus during periods of sub-optimal environmental conditions. We found that both of these Vibrio species were present in the gut microbiome and that they could be transferred to other environmental reservoirs, implicating fish in the persistence and dispersal of these potential pathogens. Lastly, we examined the microbiome of the Atlantic blue crab (Callinectes sapidus) to address how the crab-associated bacterial community may affect crab, fish, and human health.
%A Givens, Carrie
%K Fish gut, Gut microbiome, 16S rRNA, Gut microflora, 454-pyrosequencing, Shark gut, Blue crab microbiome, core gut microbiome, Proteobacteria, Firmicutes, Tenericutes, Vibrio sp., Vibrio parahaemolyticus, Vibrio vulnificus, Trinectes maculatus, Bairdiella chrysoura, Lagodon rhomboides, Paralichthys lethostigma, Fundulus heteroclitus, Centropristis striata, Sciaeops ocellatus, Caranx hippos, Scomberomorus maculatus, Scomberomorus cavalla, Coryphaena hippurus, Sphyraena barracuda, Carcharhinus brevipinna, Rhizoprionodon terraenovae, Carcharhinus plumbeus, Quantitative PCR (qPCR), 16S rRNA clone library, fish health, crab health, human health, Student Publication

%0 Journal Article
%T Incorporating clonal growth form clarifies the role of plant height in response to nitrogen addition
%D 2012
%V 169
%P 1053-1062
%B Oecologia
%9 Article
%Z published
%M GCE.722
%R 10.1007/s00442-012-2264-5
%X Nutrient addition to grasslands consistentlycauses species richness declines and productivity increases.Competition, particularly for light, is often assumed to producethis result. Using a long-term dataset from North Americanherbaceous plant communities, we tested whether heightand clonal growth form together predict responses to fertilizationbecause neither trait alone predicted species loss in aprevious analysis. Species with a tall-runner growth formcommonly increased in relative abundance in response toadded nitrogen, while short species and those with a tallclumpedclonal growth form often decreased. The ability toincrease in size via vegetative spread across space, whilesimultaneously occupying the canopy, conferred competitiveadvantage, although typically only the abundance of a singlespecies within each height-clonal growth form significantlyresponded to fertilization in each experiment. Classifyingspecies on the basis of two traits (height and clonal growthform) increases our ability to predict species responses tofertilization compared to either trait alone in predominantlyherbaceous plant communities.
%A Gough, Laura
%A Gross, Katherine L.
%A Cleland, Elsa E.
%A Clark, Christopher M.
%A Collins, Scott L.
%A Fargione, Joseph E.
%A Pennings, Steven C.
%A Suding, Katherine N.
%K clonal growth, competition, grassland, nitrogen addition, productivity, Cross-site Research, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Mechanisms mediating plant distributions across estuarine landscapes in a low-latitude tidal estuary
%D 2012
%V 93
%N 1
%P 90-100
%B Ecology
%9 Article
%Z published
%M GCE.676
%R 10.1890/11-0487.1
%X Understanding of how plant communities are organized and will respond to global changes requires an understanding of how plant species respond to multiple environmental gradients. We examined the mechanisms mediating the distribution patterns of tidal marsh plants along an estuarine gradient in Georgia using a combination of field transplant experiments and monitoring. Our results could not be fully explained by the “competition-to-stress hypothesis” (the current paradigm explaining plant distributions across estuarine landscapes). This hypothesis states that the upstream limits of plant distributions are determined by competition, and the downstream limits by abiotic stress. We found that competition was generally strong in freshwater and brackish marshes, and that conditions in brackish and salt marshes were stressful to freshwater marsh plants, results consistent with the competition-to-stress hypothesis. Four other aspects of our results, however, were not explained by the competition-to-stress hypothesis. First, several halophytes found the freshwater habitat stressful, and performed best (in the absence of competition) in brackish or salt marshes. Second, the upstream distribution of one species was determined by the combination of both abiotic and biotic (competition) factors. Third, marsh productivity (estimated by standing biomass) was a better predictor of relative biotic interaction intensity (RII) than was salinity or flooding, suggesting that productivity is a better indicator of plant stress than salinity or flooding gradients. Fourth, facilitation played a role in mediating the distribution patterns of some plants. Our results illustrate that even apparently simple abiotic gradients can encompass surprisingly complex processes mediating plant distributions.
%U https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/11-0487.1
%A Guo, Hongyu
%A Pennings, Steven C.
%K biotic interaction, competition, estuary, facilitation, flooding, physical gradient, salinity, zonation, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Post-mortem ecosystem engineering by oysters creates habitat for a rare marsh plant
%D 2012
%V 170
%P 789-798
%B Oecologia
%9 Article
%Z published
%M GCE.738
%R 10.1007/s00442-012-2356-2
%X Oysters are ecosystem engineers in marine ecosystems, but the functions of oyster shell deposits in intertidal salt marshes are not well understood. The annual plant Suaeda linearis is associated with oyster shell deposits in Georgia salt marshes. We hypothesized that oyster shell deposits promoted the distribution of Suaeda linearis by engineering soil conditions unfavorable to dominant salt marsh plants of the region (the shrub Borrichia frutescens, the rush Juncus roemerianus, and the grass Spartina alterniflora). We tested this hypothesis using common garden pot experiments and field transplant experiments. Suaeda linearis thrived in Borrichia frutescens stands in the absence of neighbors, but was suppressed by Borrichia frutescens in the with-neighbor treatment, suggesting that Suaeda linearis was excluded from Borrichia frutescens stands by interspecific competition. Suaeda linearis plants all died in Juncus roemerianus and Spartina alterniflora stands, regardless of neighbor treatments, indicating that Suaeda linearis is excluded from these habitats by physical stress (likely water-logging). In contrast, Borrichia frutescens, Juncus roemerianus, and Spartina alterniflora all performed poorly in Suaeda linearis stands regardless of neighbor treatments, probably due to physical stresses such as low soil water content and low organic matter content. Thus, oyster shell deposits play an important ecosystem engineering role in influencing salt marsh plant communities by providing a unique niche for Suaeda linearis, which otherwise would be rare or absent in salt marshes in the southeastern US. Since the success of Suaeda linearis is linked to the success of oysters, efforts to protect and restore oyster reefs may also benefit salt marsh plant communities.
%U http://link.springer.com/article/10.1007%2Fs00442-012-2356-2
%A Guo, Hongyu
%A Pennings, Steven C.
%K oyster, Spartina, Suaeda, Juncus, Borrichia, ecosystem engineer, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Use of Remote Sensing Data for Evaluating Elevation and Plant Distribution in a Southeastern Salt Marsh
%D 2012
%P 205
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.759
%X Salt marshes are valuable ecosystems that are susceptible to habitat loss due to changes in sea level and coastal flooding, and there is growing interest in obtaining accurate habitat and elevation maps for these areas.  Remote sensing techniques such as Light Detection and Ranging (LIDAR) can produce digital elevation models (DEMs), but the accuracy of LIDAR in salt marshes is limited by a combination of sensor resolution, instrument errors, and poor laser penetration in dense vegetation.  I assessed the accuracy of a LIDAR-derived DEM for the salt marshes surrounding Sapelo Island, GA using real time kinematic (RTK) GPS.  These observations were used to develop and validate species-specific correction factors for ten marsh cover classes, which ranged from 0.03 to 0.25 m.  In order to apply these corrections to the 13 km2 study site, I classified hyperspectral imagery by cover class and combined this information with elevation in a decision tree.  This produced both an accurate habitat classification (nine salt marsh habitat classes were mapped with a 90% overall accuracy) and a corrected DEM (overall mean error was reduced from 0.10 ± 0.12 (SD) to -0.003 ± 0.10 m (SD) and root mean squared error at the 68% confidence level decreased from 0.15 to 0.10 m) when validated with ground truth data.  Finally, I evaluated the use of remote sensing-derived variables (DEM elevation, slope, distance metrics) versus field collected edaphic variables (soil organic matter, water content, salinity, redox) to develop predictive models of plant distributions with both linear discriminant analysis (LDA) and classification and regression trees (CART).  Models that used remote sensing variables had accuracies of 0.78 and 0.79, whereas those for edaphic models were 0.63 and 0.72 for LDA and CART, respectively.  Accuracies improved only slightly in the best models which combined remote sensing variables and soil organic matter (to 0.82 and 0.83 for LDA and CART, respectively), suggesting that remote sensing-derived variables alone can be effective predictors of marsh vegetation.  Taken together, these findings show the potential for appropriately analyzed remote sensing data for evaluating elevation and habitat in marshes.
%A Hladik, Christine M.
%K Remote sensing, LIDAR, digital elevation model (DEM), hyperspectral imagery, salt marsh, habitat mapping, linear discriminant analysis (LDA), classification and regression trees (CART), Sapelo Island, LTER, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Accuracy assessment and correction of a LIDAR-derived salt marsh digital elevation model
%D 2012
%V 121
%P 234-235
%B Remote Sensing of the Environment
%9 Article
%Z published
%M GCE.663
%R 10.1016/j.rse.2012.01.018
%X Accurate habitat mapping in salt marshes is critical for both management and conservation goals.  Information on marsh elevation is important to coastal managers, particularly for flood inundation mapping, coastal hazard assessments and modeling sea level rise.  Elevation is also an important determinant of the frequency and duration of tidal flooding, which in turn affects species patterns in marshes: elevation differences of less than 10 cm can affect plant distributions and productivity.  Light Detection and Ranging (LIDAR) can provide synoptic elevation information in many environments, but its accuracy in salt marshes is limited by a combination of sensor resolution, instrument errors, and poor laser penetration in dense vegetation.  This means that uncorrected digital elevation models (DEM) are generally not accurate enough to distinguish elevation changes in salt marsh environments at the resolution that can be used to determine tidal flooding or vegetation patterns.  In this study, we used a LIDAR-derived DEM for the salt marshes surrounding Sapelo Island, GA obtained with a state-of- the- art Optech Gemini ALTM LIDAR system with a high laser pulse rate frequency of 125 kHz and evaluated its accuracy with elevations collected using real time kinematic (RTK) GPS.  We found that LIDAR offsets for different cover classes ranged from 0.03 to 0.25 m in comparison to the RTK ground truth data, with the larger offsets for taller vegetation.  We developed species-specific correction factors for ten cover classes and used these correction factors to modify the LIDAR-derived DEMs in four test areas of the study domain.  Application of the derived correction factors greatly improved the accuracy of the LIDAR DEM, reducing the overall mean LIDAR error from 0.10 ± 0.12 (SD) to -0.01 ± 0.09 m (SD), and the Root Mean Square Error from 0.16 m to 0.10 m. In the corrected DEM, the elevations of all vegetation classes were no longer significantly different than the true RTK ground elevations.  Our results suggest that these types of corrections can greatly improve the accuracy of DEMs in salt marshes and further emphasize the importance of accuracy assessments before LIDAR data are used, especially in environments such as salt marshes where small differences in elevation can have significant effects on inundation patterns and plant distributions.
%U http://www.sciencedirect.com/science/article/pii/S0034425712000557
%A Hladik, Christine M.
%A Alber, Merryl
%K salt marsh, remote sensing, LIDAR, DEM, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Carbon sequestration in wetland dominated coastal systems — aglobal sink of rapidly diminishing magnitude
%D 2012
%V 4
%P 186 - 194
%B Current Opinions in Environmental Sustainability
%9 Article
%Z published
%M GCE.847
%R 10.1016/j.cosust.2012.03.005
%X Coastal vegetated wetlands have recently been identified asvery important global C sinks but vulnerable to degradation bydirect human alteration of their habitats. While their expanse issmall globally, areal rates of C burial, or sequestration, areamong the highest of Earth’s ecosystems. There isconsiderable uncertainty in the magnitude of total globalsequestration in these systems for two reasons: poor estimatesof their global areas and high variability and uncertainty in arealrates of burial between systems. The magnitude of C burial invegetated coastal systems has been decreasing rapidly overthe past century due primarily to human disturbances such asdredging, filling, eutrophication, and timber harvest. Thesesystems continue to be lost globally at rates ranging from 1% to7% annually. We find that climate change including globalwarming, human engineering of river systems, continuedagricultural expansion, and sea level rise will also negativelyimpact C burial of coastal vegetated wetlands. A decrease inglobal C burial in these systems will ultimately exacerbate CO2emissions, and further contribute to climate change in thefuture.
%U http://www.researchgate.net/publication/232716383_Carbon_sequestration_in_wetland_dominated_coastal_systems__a_global_sink_of_rapidly_diminishing_magnitude
%A Hopkinson, Charles S.
%A Cai, Wei-Jun
%A Hu, Xinping
%K carbon sequestration, wetland, coastal ecosystems

%0 Journal Article
%T Effects of an omnivorous katydid, salinity, and nutrients on a planthopper-Spartina food web
%D 2012
%V 35
%P 475-485
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.719
%R 10.1007/s12237-011-9458-7
%X Top–down and bottom–up effects interact tostructure communities, especially in salt marshes, whichcontain strong gradients in bottom–up drivers such assalinity and nutrients. How omnivorous consumers respondto variation in prey availability and plant quality is poorlyunderstood. We used a mesocosm experiment to examinehow salinity, nutrients, an omnivore (the katydid Orchelimumfidicinium) and an herbivore (the planthopper Prokelisiaspp.) interacted to structure a simplified salt marsh food webbased on the marsh grass Spartina alterniflora. Bottom–upeffects were strong, with both salinity and nutrientsdecreasing leaf C/N and increasing Prokelisia abundance.Top–down effects on plants were also strong, with both theherbivore and the omnivore affecting S. alterniflora traitsand growth, especially when nutrients or salt were added. Incontrast, top–down control by Orchelimum of Prokelisia wasindependent of bottom–up conditions. Orchelimum grewbest on a diet containing both Spartina and Prokelisia, and incontrast to a sympatric omnivorous crab, did not shift to ananimal-based diet when prey were present, suggesting that itis constrained to consume a mixed diet. These results suggestthat the trophic effects of omnivores depend on omnivorebehavior, dietary constraints, and ability to suppress lowertrophic levels, and that omnivorous katydids may play apreviously unrecognized role in salt marsh food webs.
%A Jimenez, J. M.
%A Wieski, Kazimierz
%A Marczak, Laurie
%A Ho, Chuan-Kai
%A Pennings, Steven C.
%K top-down bottom-up, Orchelimum, omnivory, Prokelisia, Spartina, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Modeling the production of salt marsh grasses
%D 2012
%B 2012 LTER ASM
%9 Poster
%Z presented
%M GCE.770
%A Jung, Yeajin
%A Burd, Adrian B.
%K Modeling the production of salt marsh grasses, Student Publication

%0 Conference Proceedings
%T Drivers of Groundwater Flow at a Back Barrier Island - Marsh Transect
%D 2012
%I University of Georgia, Marine Sciences
%B 2012 LTER ASM
%9 Poster
%Z presented
%M GCE.765
%X Groundwater plays an important role in coastal regions by delivering nutrients to near shore and salt marsh environments.  To quantify groundwater flow, salinity, temperature, and pressure sensors were installed in shallow piezometers along a transect located behind Blackbeard Island, GA, approximately 90 m from the nearest tidal creek, reaching from a back barrier island to a hammock and into the adjacent marsh.  Coinciding with each well, vibracores were also collected and sediment permeability was estimated from grain size measurements.  Combined with pressure gradients, this allowed an estimate of groundwater flow.  To better understand groundwater dynamics, pressure data was normalized to a fixed datum.  Subsequently, forces that govern groundwater movement such as tidal inundation, tidal propagation, and variations in fluid density were quantified.  First, the role of the propagation pressure waves in the subsurface was investigated using a one-dimensional model.  Results show that pressure propagation would only have a minor effect at a distance of 70m from the tidal creek.  To investigate the role of variations in salinity, measured pressure gradients between adjacent wells were then separated into freshwater head and density changes.  Density changes are only responsible for up to 14% of groundwater flow.  In order to investigate the drivers influencing pressure gradients due to head changes, and to delineate the contribution of tidal flushing, the pressure time series were studied using Fourier analysis.  Preliminary results of this ongoing effort indicate that tidal flushing plays the primary role.  Understanding these drivers of groundwater today will help predict the response to changing forces, e.g. due to storms, changes in surface runoff due to coastal development or sea level rise.
%A Ledoux, Jonathan G.
%A Alexander, Clark R., Jr.
%A Meile, Christof
%K Groundwater, Darcy's Law, Student Publication

%0 Journal Article
%T Effects of Salinity on Denitrification and Greenhouse Gas Production from Laboratory-incubated Tidal Forest Soils
%D 2012
%V 32
%P 347-357
%B Wetlands
%9 Article
%Z published
%M GCE.705
%R 10.1007/s13157-012-0270-3
%X We measured ambient and potential denitrification in tidal freshwater floodplain forest (tidal forests) soils along the Altamaha, Ogeechee, and Satilla Rivers in southeast Georgia to characterize nitrogen removal from these understudied systems. Further, we measured the response of denitrification, greenhouse gas production (CO 2 , CH 4 , N 2 O), and the formation of reduced inorganic sulfur species following laboratory incubations simulating saltwater intrusion with salinity levels of 2 and 5. Ambient denitrification ranged from 0.03 µg N 2 O/g/hr in the Satilla River to 0.40 µg N 2 O/g/hr in the Altamaha River. Potential denitrification was two to eight times greater than ambient denitrification. Denitrification from Satilla River soils increased with salinity, while Altamaha and Ogeechee River soils were unaffected. Methane production, however, was inhibited by salinity, decreasing by 77% in the 2 treatment and 89% in the 5 treatment whereas CO 2 generally increased with salinity, though exhibited a variable response between the three rivers. Formation of reduced sulfur species followed a similar trend to CO 2 production. Our findings suggest that tidal forests are effective sinks for N, capable of producing anywhere from 0.032 to 1.9 µg N 2 O/g soil/hr. Overall, salinity increased the amount of C mineralized suggesting that low levels of salinity can alter the short-term C dynamics of tidal freshwater forests.
%A Marton, John
%A Herbert, Ellen
%A Craft, Christopher B.
%K Tidal forests, Denitrification, Greenhouse gases, CO2, CH4, Salt water intrusion, Student Publication, UGAMI Publication

%0 Thesis
%T Ecosystem services of restored wetlands and riparian buffers---USDA conservation practices in the glaciated interior plains
%D 2012
%P 138
%I Indiana University
%C Bloomington, IN
%9 Ph.D. Dissertation
%Z published
%M GCE.909
%X Wetlands provide valuable ecosystem services such as water quality improvement, carbon (C) sequestration, nutrient (nitrogen [N] and phosphorus [P]) retention, and biodiversity support. Throughout the Midwest, wetlands and riparian areas have been drained and cleared for conversion to row-crop agriculture. Through the United States Department of Agriculture, programs such as the Wetlands Reserve Program (WRP) and Conservation Reserve Program (CRP) provide landowners an opportunity to restore wetlands and riparian buffers with the goal of reintroducing ecosystem services lost during the conversion to agriculture. However, there has been little research on the effectiveness of WRP and CRP sites in returning ecosystem services to the landscape.To fill this knowledge gap, I measured water quality improvement functions (denitrification and P sorption), C sequestration, and nutrient (N,P) accumulation in natural and restored wetlands and riparian buffers in Indiana and Ohio. I also evaluated which of three USDA conservation practices (e.g., restored wetland, restored riparian, conserved riparian) provided the greatest relative level of water quality improvement functions. I then characterized fine-scale spatial variability of denitrification and associated soil properties in natural and restored wetlands to determine if restored wetlands had comparable heterogeneity relative to natural wetlands.Overall, riparian areas had higher rates of denitrification, P sorption, and C sequestration than depressional wetlands. Restored and natural riparian areas provided comparable services, whereas natural wetlands provided greater services than restored wetlands. Water quality improvement functions (N and P removal) were dependent upon the interactions between parent material (clayey vs. sandy soils), hydrologic connectivity (depressional vs. pulsed), and disturbance regime. First, greater connectivity to adjacent aquatic systems increased N and P removal and C sequestration. Second, finer-textured clayey soils facilitated greater denitrification and P sorption relative to sandier soils. Third, prescribed fires in the restored wetlands inhibited the accumulation of soil organic matter, which influences denitrification and P sorption. Continued enrollment of agricultural land into conservation practices will return ecosystem services to the landscape, although whether wetlands or riparian buffers should be restored will depend upon the desired ecosystem service.
%A Marton, John M.
%K Biological sciences, Crp, Denitrification, Restoration, Riparian buffers, Wetlands, Wrp, Glaciated interior plains, Student Publication

%0 Journal Article
%T Disturbance and recovery of salt marsh arthropod communities following BP Deepwater Horizon oil spill
%D 2012
%B PLoS ONE
%9 Article
%Z published
%M GCE.720
%R 10.1371/journal.pone.0032735
%X Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Samplingoccurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littorariasnails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods areboth quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy.
%U http://gce-lter.marsci.uga.edu/public/uploads/McCall_and_Pennings_2012_BP_oil_spill_PLOS_20120307T184551.pdf
%A McCall, Brittany DeLoach
%A Pennings, Steven C.
%K Spartina, arthropods, insects, spiders, oil spill, BP Deepwater Horizon, Student Publication

%0 Journal Article
%T Geographic variation in salt marsh structure and function
%D 2012
%V 170
%P 777-787
%B Oecologia
%9 Article
%Z published
%M GCE.739
%R 10.1007/s00442-012-2352-6
%X We examined geographic variation in the structure and function of salt marsh communities along the Atlantic and Gulf coasts of the United States. Focusing on the arthropod community in the dominant salt marsh plant Spartina alterniflora, we tested two hypotheses: first, that marsh community structure varies geographically, and second, that two aspects of marsh function (response to eutrophication and addition of dead plant material) also vary geographically. We worked at eleven sites on the Gulf Coast and eleven sites on the Atlantic Coast, dividing each coast up into two geographic areas. Abiotic conditions (tidal range, soil organic content, and water content, but not soil salinity), plant variables (Spartina nitrogen content, height, cover of dead plant material, but not live Spartina percent cover or light interception), and arthropod variables (proportional abundances of predators, sucking herbivores, stem-boring herbivores, parasitoids, and detritivores, but not total arthropod numbers) varied among the four geographic regions. Latitude and mean tidal range explained much of this geographic variation. Nutrient enrichment increased all arthropod functional groups in the community, consistent with previous experimental results, and had similar effects in all geographic regions, contrary to our hypothesis, suggesting widespread consistency in this aspect of ecosystem function. The addition of dead plant material had surprisingly little effect on the arthropod community. Our results caution against the uncritical extrapolation of work done in one geographic region to another, but indicate that some aspects of marsh function may operate in similar ways in different geographic regions, despite spatial variation in community structure.
%U http://link.springer.com/article/10.1007/s00442-012-2352-6
%A McCall, Brittany DeLoach
%A Pennings, Steven C.
%K biogeography, Spartina, insect, spider, soils, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Salt Marsh Dieback: The response of Spartina alterniflora to disturbances and the consequences for marsh invertebrates
%D 2012
%P 238
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.761
%X Spartina alterniflora is a foundation species that plays a disproportionately critical role in salt marshes, as it ameliorates chemical and physical stress to other plants and animals, provides essential habitat, protection from predators, and a source of organic matter to associated fauna.  Disturbances including sudden dieback, herbivore overgrazing, and wrack deposition can lead to a loss of Spartina and thus, indirectly affect the invertebrate community. My goals were 1) to examine the effects on the invertebrate communities in 2 different geographical regions (GA, LA) and among 4 different disturbances within a region (GA), 2) to determine whether various disturbances would elicit a similar and predictable physiological response (the DMSO:DMSP ratio, and metal load) in Spartina that could be used as a sensitive and predictable indicator of stress among various disturbance types, and 3) to document the never before described long-term trajectory and patterns of recovery from sudden dieback in a Spartina and Juncus roemerianus marsh. Spartina loss in GA and LA led to similar decreases in Littoraria irrorata (periwinkle snails), but there were strong differences in the responses of infauna between the states and among years.  These results suggested context-dependency in both the effect of foundation species within a geographical region and in the evaluation of the ecosystem service provided at the time of sampling.  Overall and despite differing results, it was found that Spartina was ultimately important in maintaining the invertebrate communities in both states.  However, within a geographical region, both the physiological response of Spartina and the indirect response of the invertebrates to Spartina loss were similar and predictable among four different disturbances. The DMSO:DMSP ratio and metal loads were increased in affected Spartina plants (often responsive in otherwise green leaves) and periwinkle snails and benthic macroinfauna (density, taxon richness, and diversity) were significantly decreased in affected areas, regardless of disturbance type.  Vegetation recovery at sudden dieback is occurring slowly (on the order of a decade) via rhizomes extension from healthy areas, and thus understanding the effects to invertebrates is important, as disturbances such as these are expected to increase with climate change and anthropogenic effects.
%U http://gce-lter.marsci.uga.edu/public/files/pubs/McFarlin_Caroline_PhD_2012.pdf
%A McFarlin, Caroline R.
%K foundation species, salt marsh dieback, Spartina alterniflora, Juncus roemerianus, benthic macroinfauna, Littoraria irrorata, DMSP, DMSO, metals, chlorophyll a, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T American Alligators Digestion Rate of Blue Crabs and its Implications for Stomach Contents Analysis.
%D 2012
%V 2012
%N 3
%P 419-423
%B Copeia
%9 Article
%Z published
%M GCE.746
%R 10.1643/CE-11-177
%X Stomach contents analysis (SCA) provides a snap-shot observation of a consumer's diet. Interpretation of SCA data can be complicated by many factors, including variation in gastric residence times and digestion rates among prey taxa. Although some SCA methods are reported to efficiently remove all stomach contents, the effectiveness of these techniques has rarely been tested for large irregular shaped prey with hard exoskeletons. We used a controlled feeding trial to estimate gastric residency time and decomposition rate of a large crustacean prey item, the Blue Crab (Callinectes sapidus), which is consumed by American Alligators (Alligator mississippiensis), an abundant apex predator in coastal habitats of the southeastern United States. The decomposition rate of C. sapidus in the stomachs of A. mississippiensis followed a predictable pattern, and some crab pieces remained in stomachs for at least 14 days. We also found that certain portions of C. sapidus were prone to becoming caught within the stomach or esophagus, meaning not all crab parts are consistently recovered using gastric lavage techniques. However, because the state of decomposition of crabs was predictable, it is possible to estimate time since consumption for crabs recovered from wild alligators. This information, coupled with a detailed understanding of crab distributions and alligator movement tactics could help elucidate patterns of cross-ecosystem foraging by the American Alligator in coastal habitats. © 2012 by the American Society of Ichthyologists and Herpetologists.
%U http://www.bioone.org/doi/pdf/10.1643/CE-11-177
%A Nifong, James C.
%A Rosenblatt, A. E.
%A Johnson, N.
%A Barichivich, W. 
%A Silliman, Brian R.
%A Heithaus, M.R.
%K Alligator mississippiensis, Callinectes sapidus, feeding, gastric lavage, predator-prey interactions, Student Publication

%0 Conference Proceedings
%T Boat-borne remote sensing and HPLC analysis of coastal phytoplankton populations along the Atlantic and Gulf Coasts.
%D 2012
%I The Oeans Society, American Society of Limnology and Oceanography, and American Geophysics Union
%C Salt Lake City, Utah
%B TOS/ASLO/AGU 2012 Ocean Sciences Meeting
%S Biological oceanography -  aquatic biology
%8 February 20 - 24, 2012
%9 Presentation
%Z presented
%M GCE.698
%X Remote estimation of chlorophyll <em>a</em> is increasing globally, yet turbid, Case 2 waters present challenges. We are focusing on optical measures in diverse estuarine and nearshore waters. In 2011, we collected a set of water quality measurements and phytoplankton samples from 140 stations, located between Texas and Virginia, while simultaneously obtaining hyperspectral reflectance measurements.  Chlorophyll <em>a</em> concentration varied from 2.0 - 441.3 µg/L, total suspended matter (TSM) concentrations from 0.9 - 105.0 mg/L, and colored dissolved organic matter (CDOM) absorbance at 440 nm from 0.08 - 4.71 m <sup>-1</sup>. We are using HPLC to quantify the pigments and their composite absorption at each station and light microscopy to identify the taxonomic composition of each sample.  The pigment and taxonomic composition of diverse phytoplankton populations, including lower diversity blooms (dinoflagellates, cyanobacteria, and diatoms), are being compared to reflectance spectra using optical models. We are assessing the ability of remote sensing to taxonomically discriminate these coastal phytoplankton communities and to better parameterize our algorithms for Case 2 chlorophyll estimation.
%A Olley, J.T.
%A O'Donnell, J.P.
%A Schalles, John F.
%K Phytoplankton, algal pigments, close-range remote sensing, estuarine & coastal waters, Student Publication

%0 Journal Article
%T Estimating global "blue carbon" emissions from conversion and degradation of coastal ecosystems
%D 2012
%V 7
%P 1-7
%B PLoS-ONE
%9 Article
%Z published
%M GCE.733
%X Recent attention has focused on the high rates of annual carbon sequestration in vegetated coastal ecosystems—marshes, mangroves, and seagrasses—that may be lost with habitat destruction (‘conversion’). Relatively unappreciated, however, is that conversion of these coastal ecosystems also impacts very large pools of previously-sequestered carbon. Residing mostly in sediments, this ‘blue carbon’ can be released to the atmosphere when these ecosystems are converted or degraded. Here we provide the first global estimates of this impact and evaluate its economic implications. Combining the best available data on global area, land-use conversion rates, and near-surface carbon stocks in each of the three ecosystems, using an uncertainty-propagation approach, we estimate that 0.15–1.02 Pg (billion tons) of carbon dioxide are being released annually, several times higher than previous estimates that account only for lost sequestration. These emissions are equivalent to 3–19% of those from deforestation globally, and result in economic damages of $US 6–42 billion annually. The largest sources of uncertainty in these estimates stems from limited certitude in global area and rates of landuse conversion, but research is also needed on the fates of ecosystem carbon upon conversion. Currently, carbon emissions from the conversion of vegetated coastal ecosystems are not included in emissions accounting or carbon market protocols, but this analysis suggests they may be disproportionally important to both. Although the relevant science supporting these initial estimates will need to be refined in coming years, it is clear that policies encouraging the sustainable management of coastal ecosystems could significantly reduce carbon emissions from the land-use sector, in addition to sustaining the wellrecognized ecosystem services of coastal habitats.
%A Pendleton, L.
%A Donato, D.
%A Murray, B.
%A Crooks, S.
%A Jenkins, W.
%A Sifleet, S.
%A Craft, Christopher B.
%A Fourequrean, J.
%A Kaufman, J.
%A Marba, N.
%A Megonigal, P.
%A Pidgeon, E.
%A Bilbao-Bastida, V.
%A Ullman, R.
%A Herr, D.
%A Gordon, D.
%A Baldera, A.
%K blue carbon emissions, coastal ecosystems, conversion and degradation

%0 Conference Proceedings
%T Distributed graduate courses in the LTER network
%D 2012
%I U.S. LTER Network
%C Estes Park, CO
%B 2012 LTER All Scientist Meeting
%S LTER graduate student training: Innovations and cross-site opportunities
%8 September 10-13
%9 Presentation
%Z presented
%M GCE.741
%A Pennings, Steven C.
%K education, graduate students

%0 Conference Proceedings
%T Stability of salt marsh plant communities
%D 2012
%I U.S. LTER Network
%C Estes Park, CO
%B 2012 LTER All Scientist Meeting
%S PDTNet
%8 September 10-13
%9 Presentation
%Z presented
%M GCE.740
%A Pennings, Steven C.
%K salt marsh, plant, community

%0 Book Section
%T South Atlantic Tidal Wetlands
%D 2012
%P 45-61
%I University of California Press
%C Berkeley, California
%B Wetland Habitats of North America: Ecology and Conservation Concerns
%7 1
%9 Article
%Z published
%M GCE.576
%U http://www.ucpress.edu/book.php?isbn=9780520271647
%A Pennings, Steven C.
%A Alber, Merryl
%A Alexander, Clark R., Jr.
%A Booth, Melissa G.
%A Burd, Adrian B.
%A Cai, Wei-Jun
%A Craft, Christopher B.
%A DePratter, Chester
%A Di Iorio, Daniela
%A Hollibaugh, James T.
%A Hopkinson, Charles S.
%A Joye, Samantha B.
%A Meile, Christof
%A Moore, Willard S.
%A Silliman, Brian R.
%A Thompson, Victor D.
%A Wares, John P.
%E Batzer, Darold P.
%E Baldwin, A.H.
%K wetlands, tidal, ecology, SINERR Publication, UGAMI Publication

%0 Conference Proceedings
%T Assessment and mapping phytoplankton chlorophyll patterns in inland and coastal habitats.
%D 2012
%C University of Stirling, Stirling, Scotland, UK
%B The 1st Globolakes Scientific Workshop
%8 2012
%9 Presentation
%Z presented
%M GCE.859
%A Schalles, John F.
%A Gilerson, A.
%K phytoplankton, chlorophyll

%0 Journal Article
%T Mapping phytoplankton chlorophyll in turbid, Case 2 estuarine and coastal waters.
%D 2012
%V 60
%N 1-2
%P 169-192
%B Israel Journal of Plant Science
%S VIS-NIR Spectroscopy in Plant Sciences
%9 Article
%Z published
%M GCE.694
%R 10.1560/IJPS.60.1-2.169
%X We tested variants of semianalytic algorithms for estimating phytoplankton chlorophyll pigment in Case 2 waters. Since 2002 we sampled 279 stations in 22 estuaries, bays and near shore at seven National Estuarine Research Reserves between Delaware and Texas (USA). The following median values and ranges were observed: chlorophyll a = 17.4 µg/L3 (0.2 – 490.1); total suspended solids = 23.4 mg/L dry weight (0.7 – 191.1); and CDOM absorbance (440 nm) = 3.11 m-1 (0.00 – 21.08). Spectroradiometers measured volume reflectance at each station. Sampling was designed to capture upriver to coastal mixing gradients. Algorithms utilized features in the red and lower NIR, with interference adjustments for CDOM absorption and non-algal particle scatter using bands in either the green (550 nm) or NIR between 723-739 nm. Our best two algorithms were re-parameterized using matchups with AISA Eagle imagery. Examples of pigment classification using these adjusted models are presented for five studies: dinoflagellate bloom in Maryland, tidal watershed in Georgia, estuarine reserve and neighboring refinery in Mississippi, shallow ponds important to Whooping Cranes in Texas, and transect capturing transitions between the Nueces River and Corpus Christi Bay in Texas. These analyses were useful in addressing issues important to coastal management.
%U http://www.tandfonline.com/doi/abs/10.1560/IJPS.60.1-2.169
%A Schalles, John F.
%A Hladik, Christine M.
%K Phytoplankton, Chlorophyll a, Remote Sensing, Estuarine, Coastal, Mapping, Cross-site Research, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Cranes, Planes, and Planktonic Meals: Habitat Characterizations in Gulf and East Coast NOAA National Estuarine Research Reserves
%D 2012
%I National Oceanographic and Atmospheric Association
%C Silver Springs, Maryland
%B 2012 NOAA EPP Cooperative Science Center Seminar Series
%8 November 08, 2012
%9 Presentation
%Z presented
%M GCE.769
%X The wise management of NOAA's Estuarine Research Reserves and other coastal sites requires accurate and timely information on the spatial extent, ecosystem health, and geospatial relationships of diverse habitats. Tools to delineate habitats using high resolution imagery, masking techniques, and the unique spectral characteristics of micro and macro vegetation to map wetlands, water, mudflats, and other habitats can provide a solution.
%U http://gce-lter.marsci.uga.edu/public/uploads/ONENOAA_Schalles_08-Nov-2012_20121210T103111.pdf
%A Schalles, John F.
%A Hladik, Christine M.
%A Seminara, D.N.
%K NOAA, hyperspectral, AISA, remote sensing, habit, coast, NERR, Student Publication

%0 Conference Proceedings
%T Assessing chlorophyll patterns in tidal tributary streams and rivers and in estuary to near shore transition zones.
%D 2012
%I Institute of Electrical and Electronics Engineers
%C Munich, Germany
%B IEEE International Geoscience and Remote Sensing Symposium
%S FR4.5.5: Invited Session - Hyperspectral remote sensing in shallow waters
%8 July 22 - 27, 2012
%9 Presentation
%Z presented
%M GCE.697
%X (From Extended Abstract): In this paper we summarize extensive field measurements in Case 2 waters between 2002 and 2011 at greater than 450 stations located between Southeastern Texas and Delaware Bay on the Gulf and Atlantic Coasts of the United States. Most of these measurements accompanied acquisition of AISA hyperspectral imagery in estuaries and adjacent coastal waters at or in proximity to seven NOAA National Estuarine Research Reserves (NERR). Our objectives were: (1) to build a spectral library for turbid, Case 2 brackish and near shore marine waters using consistent field measured spectra and ancillary measurements of bulk water properties for diverse coastal waters; (2) utilize our library to test and parameterize algorithms for phytoplankton chlorophyll prediction in diverse Case 2 waters; and (3) re-parameterize and apply our best algorithms to classify AISA water pixels to map and examine patterns of chlorophyll concentrations at our field survey sites. The AISA imagery was collected to provide habitat assessments and address management objectives of our NOAA NERR partner sites. In this paper, results of imagery classifications within and in proximity to four NERR sites (Mission-Aransas, Texas; Grand Bay, Mississippi; Sapelo Island, Georgia; and Chesapeake Bay, Maryland) are presented within the context of coastal research and management issues important at these locations and at many others. Nutrient induced eutrophication was a common theme across sites, whereas site specific topics included the following: Whooping Crane foraging habitats are Mission-Aransas, marsh / tidal creek interactions at Sapelo Island, and industrial impacts on the Texas and Mississippi coasts. The sites have different tidal and climate regimes.
%A Schalles, John F.
%A Olley, J.T.
%A O'Donnell, J.P.
%A Hladik, Christine M.
%K Phytoplankton, chlorophyll mapping, remote sensing, estuarine and near shore waters, Student Publication

%0 Conference Proceedings
%T Physical and biogeochemical patterns in a saltmarsh/river system (Duplin River, GA)
%D 2012
%B 2012 LTER ASM
%9 Poster
%Z presented
%M GCE.760
%X Salt marshes are among the most productive habitats on Earth, and constitute a critical interface between the land and the sea. These intertidal ecosystems are home to a unique assemblage of fauna and flora, and play a critical role in the transformation of biogeochemically active elements and the export of nutrients to the coastal ocean (Levin et al. 2001, Ecosystems 4(5): 430-451). It is therefore critical to quantify the transport processes and biogeochemical reactions that alter the composition of both surface and subsurface fluids within marsh-coastal river ecotones.Here, we present a synthesis of multidisciplinary data from a tidally driven saltmarsh/river system located in coastal Georgia, USA. We describe spatial and temporal patterns in river chemistry and identify the relative influence of water exchange processes (riverine and groundwater flow, precipitation, and tides) and transformation processes taking place in the saltmarsh/river system on these patterns.  We argue that understanding the tidal dynamics and mixing processes within this river/marsh/upland system is critical to understanding surface water geochemical patterns, and that this understanding is facilitated by the type of multi-disciplinary research conducted at LTER sites.
%A Schutte, Charles
%A Meile, Christof
%A Di Iorio, Daniela
%A McKay, Paul
%A Hunter, Kimberley S.
%A Blanton, Jackson O.
%A Joye, Samantha B.
%K Salt marsh processes, marsh-creek intertidal dynamics, groundwater inputs, spring-neap cycles, Student Publication

%0 Thesis
%T A study of methane-related processes in freshwater ecosystems
%D 2012
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.886
%X This dissertation seeks to understand the seasonal controls of methane cycling in freshwater sediments. Using a combination of field measurements, radiotracer incubations, porewater characterization, lipid biomarker analysis, and stable carbon isotopes, pronounced seasonal variations in microbial carbon turnover were documented in a freshwater sediment and in two peat wetlands. Constraints of the methane budget in shallow (< 40 cm) sediments revealed a seasonal imbalance between methane fluxes and methane production that may be relieved through tidal pumping of methane-laden porewaters derived from adjacent high marsh through the creekbank. Rate measurements of sulfate reduction and the anaerobic oxidation of methane (AOM), two processes not typically considered relevant in low salinity habitats, revealed their importance in freshwater settings. Seasonal variations in AOM may be driven by fluctuations in hydrogen and acetate dynamics generated by variations in other microbial metabolisms (e.g. sulfate reduction and methanogenesis). Lipid biomarker analysis revealed the presence of sulfate-reducing bacteria and archaea associated with methane cycling. However, seasonal variations in microbial metabolisms were not associated with changes in the lipid distribution. Stable carbon isotope analyses revealed the imprint of AOM on the signatures of methane and dissolved inorganic carbon. The influence of methanotrophy, however, was not as pronounced in the microbial lipid signatures. A potential AOM isotopic signal may have been diluted by methanogenesis and other autotrophic and heterotrophic processes, which may mask a clear methanotrophic signature. While sulfate reduction activity is sufficient to support all observed AOM activity, no conclusive evidence was found to link these processes. Long-term enrichments of coastal sediments with various electron acceptors demonstrated a positive influence of sulfate and ferric citrate additions on AOM. Other electron acceptors such as nitrate and manganese may also support AOM in these coastal settings. These studies advance the understanding of the seasonal controls on methane emissions, methane production, and methane consumption via AOM in freshwater ecosystems. Future efforts are aimed at closer examinations of these mediating factors, especially temperature changes and substrate availability.
%A Segarra, Katherine
%K methane, sulfate, biogeochemistry, AOM, methanogenesis, freshwater, wetland, lipid, Student Publication

%0 Journal Article
%T Southeastern U.S.A. continental shelf respiratory rates revisited
%D 2012
%V 107
%P 501-506
%B Biogeochemistry
%9 Article
%Z published
%M GCE.610
%R 10.1007/s10533-010-9552-0
%X Respiratory rates on the U. S. southeastern continental shelf have been estimated several times by different investigators, most recently by Jiang et al. (Biogeochemistry 98:101–113, 2010) who report lower mean rates than were found in earlier work and attribute the differences to analytical error in all methods used in earlier studies. The differences are, instead, attributable to the differences in the geographical scope of the studies. The lower estimates of regional organic carbon flux of Jiang et al. (Biogeochemistry 98:101–113, 2010) are a consequence of their extrapolation of data from a small portion of the shelf to the entire South Atlantic Bight. This comment examines the methodologies used as well as the variability of respiratory rates in this region over space and time.
%U http://www.springerlink.com/openurl.asp?genre=article&id=doi:10.1007/s10533-010-9552-0
%A Sheldon, Joan E.
%A Griffith, Peter C.
%A Peters, Francesc
%A Sheldon, Wade M., Jr.
%A Blanton, Jackson O.
%A Amft, Julie
%A Pomeroy, Lawrence R.
%K microbial respiration, southeastern U.S.A. continental shelf, dissolved oxygen, bacteria

%0 Conference Proceedings
%T Transparent Metadata Capture for Environmental Science
%D 2012
%C Estes Park, Colorado
%B 2012 LTER All Scientists Meeting
%S Ecological research from a truly long-term perspective: What needs to be done today to support ecological analysis in 2100?
%8 September 10-13, 2012
%9 Presentation
%Z presented
%M GCE.778
%X If current trends continue, in 2100 we can expect environmental information systems will have access to vast stores of data from automated sensor systems, scientists and the public will interact with these systems using natural human interfaces (including touch, speech and 3-dimensional vision), and natural language will replace technical query languages and syntax. In short, we will be approaching the "Star Trek" era of computing where concept replaces syntax and speech replaces text as the means of requesting information. To get there, we need ubiquitous and sophisticated metadata for all environmental data we collect.
%U http://gce-lter.marsci.uga.edu/public/uploads/Sheldon_LTER2100_20130807T102125.pdf
%A Sheldon, Wade M., Jr.
%K LTER-IMC, metadata, automation, computer science, data, future

%0 Conference Proceedings
%T Using MATLAB to Analyze LTER Data in PASTA and ClimDB
%D 2012
%I Long Term Ecological Research Network
%C Estes Park, Colorado
%B 2012 LTER All Scientists Meeting
%S A Researcher’s Guide to Automating Analysis of LTER Data
%8 11-Sep-2012
%9 Presentation
%Z presented
%M GCE.758
%X Use of the GCE Data Toolbox to retrieve and analyze LTER data uploaded to the PASTA framework of the Network Information System and ClimDB climate database was described and demonstrated.
%U http://gce-lter.marsci.uga.edu/public/uploads/Sheldon_Automating_Analysis_MATLAB_ASM2012_20120921T110406.pdf
%A Sheldon, Wade M., Jr.
%K database, LTER-IMC, metadata, software, MATLAB, information management, data mining

%0 Conference Proceedings
%T GCE Data Toolbox and Metabase: A sensor-to-synthesis software pipeline for LTER data management
%D 2012
%I Long Term Ecological Research Network
%C Estes Park, Colorado
%B 2012 LTER All Scientists Meeting
%8 11-Sep-2012
%9 Poster
%Z presented
%M GCE.757
%X LTER sites use a wide range of software to acquire, process, quality control and archive data. A separate set of tools is then typically used to produce and manage metadata content and generate EML-described data packages for the LTER NIS. This separation of data and metadata processing is inefficient, risks loss of information, and often delays data release. Software developed at the GCE LTER site - the GCE Data Toolbox for MATLAB - streamlines this process by coupling metadata creation to data processing and quality control. This software also interfaces with the Metabase, a sophisticated Metadata Management System (MMS) that supports data warehousing and automatic distribution of EML-described, version-controlled data through the NIS. Used together, these systems constitute an integrated and highly automated pipeline for producing EML-described data packages for archival and synthesis efforts. This poster describes how this software is used to automate and streamline data management at the GCE and CWT LTER sites, and opportunities for use at other sites.
%U http://gce-lter.marsci.uga.edu/public/uploads/gce_cwt_pipeline_asm2012_20120926T71226.pdf
%A Sheldon, Wade M., Jr.
%A Chamblee, John F.
%A Cary, Richard
%K database, LTER-IMC, metadata, software, MATLAB, information management

%0 Conference Proceedings
%T From Scientist and Sensor to Synthesis: Metabase Metadata Management System
%D 2012
%I University of Georgia
%C Athens, Georgia
%B GCE Data Toolbox and Metabase Training Workshop
%8 Nov. 28-30, 2012
%9 Presentation
%Z presented
%M GCE.773
%X The Metabase is a generalized relational database management system for managing LTER metadata, including personnel lists, site geography (study area polygons, point locations), instrumentation, research projects and data sets (studies, methods, entities, attributes, files). The database is also linked to bibliographic and taxonomic databases, supporting automatic cross-links between personnel, research, publications and data. The database also supports reciprocal queries between resources, for example data sets by investigator, and data sets referenced in publications. This database allows centralized management of all project information, and supports automated metadata generation for data sets and cross-links between related resources on the web.
%U http://gce-lter.marsci.uga.edu/public/files/pubs/Sheldon_Metabase_Nov2012.pdf
%A Sheldon, Wade M., Jr.
%A Chamblee, John F.
%A Cary, Richard
%K database, LTER-IMC, metadata, EML, information management, software

%0 Journal Article
%T Trophic cascades across diverse plant ecosystems
%D 2012
%V 3
%N 9
%P 3
%B Nature Education Knowledge
%9 Article
%Z published
%M GCE.644
%X Trophic cascades are powerful indirect interactions that can control entire ecosystems. Trophic cascades occur when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level.
%U http://www.nature.com/scitable/knowledge/library/trophic-cascades-across-diverse-plant-ecosystems-80060347
%A Silliman, Brian R.
%A Angelini, Christine
%K trophic, ecosystems, Student Publication

%0 Journal Article
%T Degradation and resilience in Louisiana salt marshes following the BP-DHW oil spill
%D 2012
%V 109
%N 28
%P 11234-11239
%B Proceedings of the National Academy of Sciences
%9 Article
%Z published
%M GCE.747
%X More than 2 y have passed since the BP–Deepwater Horizon oilspill in the Gulf of Mexico, yet we still have little understanding ofits ecological impacts. Examining effects of this oil spill will generatemuch-needed insight into how shoreline habitats and thevaluable ecological services they provide (e.g., shoreline protection)are affected by and recover from large-scale disturbance.Here we report on not only rapid salt-marsh recovery (high resilience)but also permanent marsh area loss after the BP–DeepwaterHorizon oil spill. Field observations, experimental manipulations, andwave-propagationmodeling reveal that (i) oil coveragewas primarilyconcentrated on the seaward edge of marshes; (ii) there were thresholdsof oil coverage that were associated with severity of salt-marshdamage, with heavy oiling leading to plant mortality; (iii) oil-drivenplant death on the edges of these marshes more than doubled ratesof shoreline erosion, further driving marsh platform loss that is likelyto be permanent; and (iv) after 18 mo, marsh grasses have largelyrecovered into previously oiled, noneroded areas, and the elevatedshoreline retreat rates observed at oiled sites have decreased to levelsat reference marsh sites. This paper highlights that heavy oil coverageon the shorelines of Louisiana marshes, already experiencingelevated retreat because of intense human activities, induced a geomorphicfeedback that amplified this erosion and thereby set limits tothe recovery of otherwise resilient vegetation. It thus warns of theenhanced vulnerability of already degraded marshes to heavy oilcoverage and provides a clear example of how multiple human-inducedstressors can interact to hasten ecosystem decline.
%A Silliman, Brian R.
%A Diller, J.
%A McCoy, M.
%A Earl, Kamala
%A von de Koppel, J.
%A Zimmerman, A.
%K geomorphology, multiple stressor, wetland, human impacts, Student Publication

%0 Journal Article
%T New metrics for managing and sustaining the ocean's bounty
%D 2012
%V 36
%N 1
%P 303–306
%B Marine Policy
%9 Article
%Z published
%M GCE.651
%R 10.1016/j.marpol.2011.03.013
%X Policies are arising around the world, most recently in the United States, that mandate the implementation of marine spatial planning as a practical pathway towards ecosystem-based management. In the new United States ocean policy, and several other cases around the globe, ecosystem services are at the core of marine spatial planning, but there is little guidance on how ecosystem services should be measured, making it hard to implement this new approach. A new framework is shown here for practical, rigorous ecosystem service measurement that high lights contributions from both natural and social systems. The novel three-step framework addresses traditional shortcomings of an ecosystem services approach by giving managers and scientists the tools to assess and track: (1) the condition of the ecosystem (supply metrics),(2)the amount of ocean resources actually used or enjoyed by people (service metrics), and (3) people's preference for that level of service (value metrics). This framework will allow real world progress on marine spatial planning to happen quickly, and with a greater chance for success.
%U https://www.sciencedirect.com/science/article/pii/S0308597X11000728
%A Tallis, H.
%A Lester, S.E.
%A Ruckelshaus, M.
%A Plummer, M.
%A McLeod, K.
%A Guerry, A.
%A Andelman, S.
%A Caldwell, M.
%A Conte, M.
%A Copps, S.
%A Fox, D.
%A Fujita, R.
%A Gaines, S.D.
%A Gelfenbaum, G.
%A Gold, B.
%A Kareiva, P.
%A Kim, C.
%A Lee, K.
%A Papenfus, M.
%A Redman, S.
%A Silliman, Brian R.
%A Wainger, L.
%A White, C.
%K sustain, manage, ocean, metrics

%0 Journal Article
%T A meta-analysis of seaweed impacts on seagrasses: generalities and knowledge gaps
%D 2012
%V 7
%N 1
%B Plos ONE
%9 Article
%Z published
%M GCE.749
%X Seagrasses are important habitat-formers and ecosystem engineers that are under threat from bloom-forming seaweeds.These seaweeds have been suggested to outcompete the seagrasses, particularly when facilitated by eutrophication,causing regime shifts where green meadows and clear waters are replaced with unstable sediments, turbid waters, hypoxia,and poor habitat conditions for fishes and invertebrates. Understanding the situations under which seaweeds impactseagrasses on local patch scales can help proactive management and prevent losses at greater scales. Here, we provide aquantitative review of available published manipulative experiments (all conducted at the patch-scale), to test whichattributes of seaweeds and seagrasses (e.g., their abundances, sizes, morphology, taxonomy, attachment type, or origin)influence impacts. Weighted and unweighted meta-analyses (Hedges d metric) of 59 experiments showed generally highvariability in attribute-impact relationships. Our main significant findings were that (a) abundant seaweeds had strongernegative impacts on seagrasses than sparse seaweeds, (b) unattached and epiphytic seaweeds had stronger impacts than‘rooted’ seaweeds, and (c) small seagrass species were more susceptible than larger species. Findings (a) and (c) were ratherintuitive. It was more surprising that ‘rooted’ seaweeds had comparatively small impacts, particularly given that thiscategory included the infamous invasive Caulerpa species. This result may reflect that seaweed biomass and/or shading andmetabolic by-products like anoxia and sulphides could be lower for rooted seaweeds. In conclusion, our results representsimple and robust first-order generalities about seaweed impacts on seagrasses. This review also documented a limitednumber of primary studies. We therefore identified major knowledge gaps that need to be addressed before generalpredictive models on seaweed-seagrass interactions can be build, in order to effectively protect seagrass habitats fromdetrimental competition from seaweeds.
%A Thomsen, M. S
%A Wernberg, Thomas
%A Engelen, H. 
%A Tuya, F.
%A Vanderklift, M. 
%A Holmer, M.
%A McGlathery, K. 
%A Arenas, F. 
%A Kotta, J. 
%A Silliman, Brian R.
%K not listed

%0 Conference Proceedings
%T Action Archaeology: Applying Archaeological Research to Present-day Problems.
%D 2012
%I Southeastern Archaeological Conference
%C Baton Rogue, LA
%B 69th Annual Meeting of the Southeastern Archaeological Conference
%8 2012
%9 Presentation
%Z published
%M GCE.797
%X Applied archaeology can take many forms. A relatively recent trend in the discipline is with the application of archaeology to present-day social issues, sometimes called “action archaeology.” This is different than the typical public archaeology (which is not necessarily designed to serve the needs of the public). Action archaeology reorients research towards addressing current social problems, giving archaeology a different kind of relevance, thus making it more useful. This question of “usefulness” is not typical in academia, but is becoming necessary in these poor economic times, which have been accompanied by sentiments of anti-science (and anti-anthropology), in certain public spheres.
%A Turck, John A.
%K Public Archaeology, Activist Archaeology, Sea Level, Hammocks, Student Publication

%0 Journal Article
%T Where Were All of the Coastally Adapted People During the Middle Archaic Period in Georgia, USA?
%D 2012
%V 7
%P 404–424
%B Journal of Island and Coastal Archaeology
%9 Article
%Z published
%M GCE.707
%R 10.1080/15564894.2011.652763
%X A dramatic increase in the number of sites, compared to previous periods, has been noted for the Late Archaic (4200-3100 BP) period on the Georgia coast. This presumably larger and more sedentary population has been attributed to sea-level rise and the establishment of the marsh-estuarine system and its resources. To assess this idea, and to understand the conditions prior to the explosion of Late Archaic sites on the coast, a model of sea-level history and attendant landscape changes leading up to the Late Archaic period is created for McIntosh County, Georgia, USA. According to the model, conditions were sufficient for marsh formation prior to the Late Archaic period, suggesting that terminal Middle Archaic (~5000 cal BP) populations should have been established on the coast of Georgia. The fact that no sites dating to this period have been found further suggests that the explosion of Late Archaic period sites in the coastal zone of Georgia may have been due to a colonizing group of people who migrated in from another area.
%U http://dx.doi.org/10.1080/15564894.2011.652763
%A Turck, John A.
%K Archaeology, Middle Archaic period, McIntosh County, Sea Level Modeling, Abandonment, Migration, Student Publication

%0 Report
%T An Archaeological Survey of Little Sapelo Island (Little Sapelo S- 9MC353 and N- 9MC352), McIntosh County, Georgia.
%D 2012
%I Report on file, Georgia Archaeological Site File
%C Athens
%9 Report
%Z published
%M GCE.787
%A Turck, John A.
%A Thompson, Victor D.
%K Archaeology, Little Sapelo Island, Survey, Student Publication

%0 Conference Proceedings
%T Considering Context and Sample Selection along the Georgia Coast: Implications for Radiocarbon Dating Methods in Archaeological Settings.
%D 2012
%I Society for American Archaeology
%C Memphis, TN
%B 77th Annual Meeting of the Society for American Archaeology Conference
%9 Presentation
%Z published
%M GCE.796
%X Recent radiocarbon dates from materials on the Georgia coast suggest that not all contexts are reliable for obtaining radiocarbon samples for archaeological purposes. In this paper we compare sooted pottery sherds, carbonized material within a sherd, shell and carbonized material from midden layers, and root and carbonized material from within a core. Results indicate that dating materials from inside sherds does not correspond to the period of use, due to either older or younger inclusions. Paired shell and charcoal samples are also compared, noting implications for reservoir corrections. This research provides general guidelines for sample selection in similar archaeological settings.
%A Turck, John A.
%A Thompson, Victor D.
%A Cherkinsky, Alex
%K Archaeology, Radiocaron Dating, Hammocks, Sapelo Island, Student Publication

%0 Journal Article
%T A three-stage symbioses forms the foundation of seagrass ecosystems
%D 2012
%V 319
%P 321-323
%B Science
%9 Article
%Z published
%M GCE.748
%X Seagrasses evolved from terrestrial plants into marine foundation species around 100 million years ago. Their ecological success, however, remains a mystery because natural organic matter accumulation within the beds should result in toxic sediment sulfide levels. Using a meta-analysis,a field study, and a laboratory experiment, we reveal how an ancient three-stage symbiosis between seagrass, lucinid bivalves, and their sulfide-oxidizing gill bacteria reduces sulfide stress for seagrasses. We found that the bivalve–sulfide-oxidizer symbiosis reduced sulfide levels and enhanced seagrass production as measured in biomass. In turn, the bivalves and their endosymbionts profit from organic matter accumulation and radial oxygen release from the seagrass roots. These findings elucidate the long-term success of seagrasses in warm waters andoffer new prospects for seagrass ecosystem conservation.
%A van der Heide, Tjisse
%A Govers, Laura L.
%A de Fouw, Jimmy
%A Olff, Han
%A van der Geest, Matthiis
%A van Katwijk, Marieke M.
%A Piersma, Theunis
%A van de Koppel, Johan
%A Silliman, Brian R.
%A Smolders, Alfons J. P.
%A van Gils, Jan A.
%K symbioses, seagrass, ecology, biomass, oxygen

%0 Conference Proceedings
%T Climate drivers of Spartina marsh production on the Georgia coast
%D 2012
%C Estes Park
%B LTER All Scientists Meeting
%8 September 10-13, 2012
%9 Poster
%Z published
%M GCE.742
%X Global climate changes are altering functioning of the earth’s ecosystems. Tidal saltmarshes are threatened by sea level rise and changes in weather patterns. In order to predict the consequences of climate change on coastal communities, we need to understand how climate drivers mediate ecosystem production. In case of the tidal marshes this understanding is currently ambiguous and geographically limited to the central and northern part of the Atlantic coast.In 2000-2011 we conducted annual surveys of Spartina alterniflora biomass in tidal marshes of the coast of Georgia. Plant length was measured at permanent plots established near the creekbank and in the midmarsh zone at 9 sites located in the Altamaha river estuary. Data on plant length was converted into biomass using site specific regressions. Spartina alterniflora biomass, air temperature, precipitation, sea level and Altamaha river discharge were analyzed using multilevel modeling.Spartina ANPP strongly varied between years. River discharge had stronger effects on creekbank than mid-marsh production. A weak  effect of sea level on midmarsh ANPP had been detected. The decrease in salinity in high discharge years was most likely the proximate driver of the increased production. Our results differ from analyses from tidal marshes of the central and northern part of the Atlantic coast which can be due to differences in climate or hydrology and/or reflect differences in statistical and sampling methodology.
%A Wieski, Kazimierz
%A Pennings, Steven C.
%K critical period, Spartina alterniflora, river discharge

%0 Journal Article
%T Interactions between mangroves and exotic Spartina in an anthropogenically disturbed estuary in southern China
%D 2012
%V 93
%N 3
%P 588 - 597
%B Ecology
%9 Article
%Z published
%M GCE.1113
%R 10.1890/11-1302.1
%X Cordgrass (Spartina alterniflora) was introduced to China in 1979 from the United States for reducing coastal erosion. It grows vigorously in China and has spread over much of the Chinese coast, from Leizhou Peninsula to Liaoning, a range of more than 19 degrees of latitude. On the southern coast of China, S. alterniflora has invaded mangrove&#8208;dominated habitats during the last two decades, but little is known about interactions between native mangroves and invasive S. alterniflora.We studied the distribution and competitive interactions between native mangroves and S. alterniflora in the Zhangjiang Estuary at four tidal sites along a salinity gradient: oligohaline upstream, mesohaline, polyhaline, and euhaline downstream. S. alterniflora occurred at all four sites, and several mangrove species occurred at all but the downstream euhaline site. S. alterniflora has invaded the estuary widely and has spread to the lower tidal margins of mangroves. It has not invaded mangrove areas with a closed canopy but has established in the mangrove zone where the canopy was opened by human disturbance.Ramets of S. alterniflora transplanted into the understory of mangrove stands with closed canopies died within 10 weeks, but 37.5% survived and grew well on open mud flats. S. alterniflora had virtually no competitive effect on mangrove seedlings planted at the upstream oligohaline site. However, S. alterniflora competitively reduced biomass of mangrove seedlings to 33% over a period of 14 weeks at the mesohaline and polyhaline sites where human disturbance has opened the mangrove canopy. In contrast, S. alterniflora marginally facilitated growth and survival of experimental seedlings at the downstream euhaline site.In China, mangroves occur along the coastline south of Whenzhou, but they have been severely disturbed and removed widely, mainly by mariculture activities. Natural vegetation patterns and our experimental results suggest that, without intervention, S. alterniflora could gradually replace these mangroves in mid&#8208;salinity regions of Chinese estuaries.
%A Zhang, Yihui
%A Huang, Guanmin
%A Wang, Wenqing
%A Chen, Luzhen
%A Lin, Guanghui
%K biological invasion, human disturbance, mongroves, salt marsh, salinity gradient, Spartina alterniflora

%0 Generic
%T Water quality status of Georgia estuaries and coastal waters using recommended indicators.
%D 2011
%I Proceedings of the 2011 Georgia Water Resources Conference
%C University of Georgia, Athens, Georgia
%B Georgia Water Resources Conference
%9 Article
%Z published
%M GCE.670
%X Water quality is a concern in many estuaries, and the U.S. EPA has mandated the development of numeric nutrient criteria to assess the status of U.S. coastal waters. We have proposed a suite of seven indicators that are intended to help classify and understand the causes of water quality degradation in Georgia by covering the progression of eutrophication from nutrient over-enrichment to algal overgrowth (if present) to enhanced microbial respiration and hypoxia. Of these, we are able to assess four indicators coastwide using data collected by GA DNR CRD during 2003-2006. pH status was assessed using &#916;pH, the deviation from the expected pH according to the sample salinity and estuary type (alluvial/tidewater, blackwater, alkaline blackwater). Annual median pH deviations were classified as good at almost all sites in all years, whereas annual minimum pH deviations often ranged into the fair and poor categories. pH status generally improved from 2004 to 2006. Annual median dissolved oxygen (DO) was mainly good to fair, while annual minimum DO was mainly fair to poor, with sites classified as poor occurring sporadically along the coast. DO status generally improved from 2003 to 2006. Annual median dissolved inorganic nitrogen status was mostly fair coastwide in all years, with the few sites classified as poor concentrated in the Altamaha River estuary. Annual median total dissolved phosphorus was fair coastwide during the study period. The generally poorer water quality in 2003 compared to later years may have been due to conditions related to high rainfall after asevere drought.
%A Alber, Merryl
%A Sheldon, Joan E.
%E Carroll, G. Denise
%K water quality, indicator

%0 Conference Proceedings
%T Late Holocene Geologic Development of The Georgia Coast.
%D 2011
%I Geological Society of America
%C Wilmington, NC
%B Geological Society of America Abstracts with Programs
%S No. 2
%8 March 23-25
%9 Abstract
%Z published
%M GCE.821
%X Deposits associated with the geologic development of the Southeastern United States during the Late Holocene preserve the record of coastal response under the influence of rising sea levels and changing climates. Documenting the age, geomorphic character and stratigraphic signature of these deposits provides insight into both the sedimentary processes that formed the landforms and the timing associated with these processes. Although these issues have been investigated in the SE US over the past several decades, the Georgia coast has received relatively little study when compared to other states. Back-barrier islands (BBIs) along the Georgia coast provide a depositional record of Late Holocene coastal development, and are the focus of this study.BBIs found along the southeastern coast of the United States are poorly studied, yet common topographic highs in the back-barrier environment. These islands are presently surrounded by salt marsh, are generally of limited area and elevation (less than 10 hectares and less than 2 m above mean sea level), can be either Pleistocene, Holocene or Recent in age, and can have natural or anthropogenic origins. The characteristically long, linear BBIs are Holocene in age and preserve the record of coastal change. Stratigraphically, Holocene BBIs consist of unconsolidated sediments: fine sand beds that coarsen downcore, typically resting unconformably on older marsh muds, which grade into interbedded tidal channel deposits. Grain size and sedimentary structures in cores, document that these BBIs formed as discrete beach ridges as the coastline prograded seaward, either under the influence of a short-term sea-level fall, or an increase in sediment supply to the coast. Although far from a comprehensive dataset, existing OSL dates for Holocene BBIs associated with major barrier islands in Georgia document that the major period of coastal progradation occurred between ~1700 and ~500 years ago, during which time many sections of the Georgia coast prograded 2-5 kilometers seaward. Since ~500 year ago, rapid progradation has ceased, and the shoreline has been comparatively stable, with a coast-wide, mean shoreline change rate of +0.14 m/y. Archaeological estimates of BBI age from the 1970s, based on shell-midden ages, support these OSL results.
%A Alexander, Clark R., Jr.
%A Rink, W. J.
%A Jackson, C.W.
%A Brook, G.A.
%A Ivester, A.
%K Holocene, Georgia Cost

%0 Journal Article
%T Interactions among Foundation Species and Their Consequences for Community Organization, Biodiversity, and Conservation
%D 2011
%V 61
%N 10
%P 782-789
%B BioScience
%9 Article
%Z published
%M GCE.647
%R 10.1525/bio.2011.61.10.8
%X Foundation species create complex habitats in which associated organisms find refuge from biological and physical stress; these foundation species are thus fundamental to the structure and resilience of terrestrial and marine ecosystems. In the present article, we develop an approach to understanding foundation species' effects in communities that are maintained not by a single foundation species, as has been the focus of research to date, but by multiple, co-occurring foundation species. Using examples from diverse ecosystems, we illustrate the prevalence of multiple-foundation-species assemblages and hypothesize that the nature of foundation-species interactions has important consequences for community structure. We predict where positive and negative interactions among foundation species will occur and suggest that they organize communities hierarchically in nested or adjacent assemblages that underlie landscape-scale patterns in species distribution. Elucidating the predictable nature of foundation-species interactions may be key to understanding and managing the biodiversity and functioning of many ecosystems.
%A Angelini, Christine
%A Alteiri, A.
%A Silliman, Brian R.
%A Bertness, Mark D.
%K community, interactions, species, Student Publication

%0 Book Section
%T Estuarine and Coastal Ecosystems and Their Services
%D 2011
%V 12
%P 109–127
%I Elsevier
%B Treatise on Estuarine and Coastal Science
%7 Ecological Economics of Estuaries and Coasts
%9 Article
%Z published
%M GCE.577
%R 10.1016/B978-0-12-374711-2.01206-7
%X The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological functions and their services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. We cite estimates of the key economic values arising from these services, and discuss how the natural variability of ECE impacts their benefits, the synergistic relationships of ECE across seascapes, and the management implications.
%U http://www.sciencedirect.com/science/article/pii/B9780123747112012067
%A Barbier, Edward B.
%A Hacker, Sally D.
%A Koch, Evamaria W.
%A Stier, A.
%A Silliman, Brian R.
%E van den Belt, M.
%E Costanza, R.
%K Coral reef, Economic value, Ecosystem service, Estuarine and coastal ecosystem, Mangrove, Salt marsh, Sand dune, Seagrass, Seascape

%0 Journal Article
%T The Value of Estuarine and Coastal Ecosystem Services
%D 2011
%V 81
%P 169-193
%B Ecological Monographs
%9 Article
%Z published
%M GCE.650
%X The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. Where possible, we indicate estimates of the key economic values arising from these services, and discuss how the natural variability of ECEs impacts their benefits, the synergistic relationships of ECEs across seascapes, and management implications. Although reliable valuation estimates are beginning to emerge for the key services of some ECEs, such as coral reefs, salt marshes, and mangroves, many of the important benefits of seagrass beds and sand dunes and beaches have not been assessed properly. Even for coral reefs, marshes, and mangroves, important ecological services have yet to be valued reliably, such as cross-ecosystem nutrient transfer (coral reefs), erosion control (marshes), and pollution control (mangroves). An important issue for valuing certain ECE services, such as coastal protection and habitat–fishery linkages, is that the ecological functions underlying these services vary spatially and temporally. Allowing for the connectivity between ECE habitats also may have important implications for assessing the ecological functions underlying key ecosystems services, such coastal protection, control of erosion, and habitat–fishery linkages. Finally, we conclude by suggesting an action plan for protecting and/or enhancing the immediate and longer-term values of ECE services. Because the connectivity of ECEs across land–sea gradients also influences the provision of certain ecosystem services, management of the entire seascape will be necessary to preserve such synergistic effects. Other key elements of an action plan include further ecological and economic collaborative research on valuing ECE services, improving institutional and legal frameworks for management, controlling and regulating destructive economic activities, and developing ecological restoration options.
%U http://www.esajournals.org/doi/pdf/10.1890/10-1510.1
%A Barbier, Edward B.
%A Hacker, Sally D.
%A Koch, Evamaria W.
%A Stier, A.
%A Silliman, Brian R.
%K estuarine, coastal, ecosystem services

%0 Journal Article
%T The present and future role of coastal wetland vegetation in protecting shorelines: answering recent challenges to the paradigm
%D 2011
%V 106
%P 7-29
%B Climatic Change
%9 Article
%Z published
%M GCE.652
%X For more than a century, coastal wetlands have been recognized for their ability to stabilize shorelines and protect coastal communities. However, this paradigm has recently been called into question by small-scale experimental evidence. Here, we conduct a literature review and a small meta-analysis of wave attenuation data, and we find overwhelming evidence in support of established theory. Our review suggests that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves. In biophysical models, field tests, and natural experiments, the presence of wetlands reduces wave heights, property damage, and human deaths. Meta-analysis of wave attenuation by vegetated and unvegetated wetland sites highlights the critical role of vegetation in attenuating waves. Although we find coastal wetland vegetation to be an effective shoreline buffer, wetlands cannot protect shorelines in all locations or scenarios; indeed large-scale regional erosion, river meandering, and large tsunami waves and storm surges can overwhelm the attenuation effect of vegetation. However, due to a nonlinear relationship between wave attenuation and wetland size, even small wetlands afford substantial protection from waves. Combining man-made structures with wetlands in ways that mimic nature is likely to increase coastal protection. Oyster domes, for example, can be used in combination with natural wetlands to protect shorelines and restore critical fishery habitat. Finally, coastal wetland vegetation modifies shorelines in ways (e.g. peat accretion) that increase shoreline integrity over long timescales and thus provides a lasting coastal adaptation measure that can protect shorelines against accelerated sea level rise and more frequent storm inundation. We conclude that the shoreline protection paradigm still stands, but that gaps remain in our knowledge about the mechanistic and context-dependent aspects of shoreline protection.
%U http://www.springerlink.com/content/k200735m7g521p67/
%A Bromberg-Gedan, Keryn
%A Kirwan, M.
%A Barbier, Edward B.
%A Wolanski, Eric
%A Silliman, Brian R.
%K coastal, wetland, shoreline, protection

%0 Conference Proceedings
%T GIS And Field-Based Documentation of Armored Estuarine Shorelines In Georgia.
%D 2011
%I Geological Society of America
%C Wilmington, NC
%B Geological Society of America Abstracts with Programs
%S No. 2
%8 March 23-25
%9 Abstract
%Z published
%M GCE.824
%X Sea level rise is inundating coastal regions around the world, driving intertidal habitats onto uplands. This is not a concern in undeveloped areas, where the land/sea boundary is allowed to retreat naturally, preserving habitat, but armored shorelines block this retreat, endangering the persistence of intertidal habitats. In addition, areas of armored shoreline are likely to be further armored as sea levels rise, leading to further environmental degradation. GIS tools allow us to accurately map and attribute armored shoreline features, providing a means to delineate areas for ecological retreat and potential protection.This study delineated armored shorelines in the six coastal counties of Georgia. Armored structures identified in the coastal environment included bulkheads, revetments, jetties and groins. These features were digitized in ARCGIS 9.3 from geo-referenced aerial orthophotographs. Each county was analyzed using color imagery with better than 1 sq m pixel resolution. Photographic observations were augmented with field observations in areas where imagery was not adequate to identify shoreline character. Each county was analyzed as a separate project, with shapefiles for armored shorelines, causeways and field inspections routes. Length of armored shoreline, broken out by type, and field inspection routes, were calculated from these data.Because all land/water boundaries could not be inspected in photographs or by field inspection, the extent of armoring in this study is a minimum estimate. Within Georgia, 212 kilometers of shoreline is armored, with the most armoring found in Chatham County (109 kilometers). We examined the relationship between length of armored shoreline in each coastal county and basic demographic parameters (i.e., population, per capita income and county area) for the counties. Of these parameters, only population exhibited a significant relationship with armored shoreline length. We are currently quantifying the length of the extensive backbarrier shoreline to put length of armored shoreline into a regional context. The results of this study are being used by state and local governments for better management of the Georgia coast, including storm surge flood modeling and to plan for adaptation to climate change.
%A Bulski, K.
%A Alexander, Clark R., Jr.
%A Robinson, Michael
%A Jackson, C.W.
%K GIS, Armored Shorelines, Estuaries, Georgia

%0 Journal Article
%T Estuarine and Coastal Ocean Carbon Paradox: CO2 Sinks or Sites of Terrestrial Carbon Incineration?
%D 2011
%V 3
%P 123-145
%B Annual Review of Marine Science
%9 Article
%Z First published online as a Review in Advance on October 18, 2010
%M GCE.615
%R 10.1146/annurev-marine-120709-142723
%X Estuaries are a major boundary in the land-ocean interaction zone where organic carbon (OC) and nutrients are being processed, resulting in a high water-to-air carbon dioxide (CO2) flux (0.25 Pg C y&#8722;1). The continental shelves, however, take up CO2 (0.25 Pg C y&#8722;1) from the atmosphere, accounting for approximately 17% of open ocean CO2 uptake (1.5 Pg C y&#8722;1). It is demonstrated here that CO2 release in estuaries is largely supported by microbial decomposition of highly productive intertidal marsh biomass. It appears that riverine OC, however, would bypass the estuarine zone, because of short river-transit times, and contribute to carbon cycling in the ocean margins and interiors. Low-latitude ocean margins release CO2 because they receive two-thirds of the terrestrial OC. Because of recent CO2 increase in the atmosphere, CO2 releases from low latitudes have become weaker and CO2 uptake by mid- and high-latitude shelves has become stronger, thus leading to more dissolved inorganic carbon export to the ocean.
%U http://www.annualreviews.org/doi/abs/10.1146/annurev-marine-120709-142723?prevSearch=wei-jun%2Bcai&searchHistoryKey=
%A Cai, Wei-Jun
%K Estuarine, Carbon, Sinks, Terrestrial Carbon Incineration

%0 Newspaper Article
%T Systems Upgrade through Technology Transfer across LTERs: Who Benefits?
%D 2011
%I Long Term Ecological Research Network
%C Albuquerque, New Mexico
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Spring 2011
%9 Article
%Z published
%M GCE.620
%X In 2009, the Coweeta LTER site began planning a complete web and information system redesign. In an early preparatory step, John Chamblee (CWT IM) and Ted Gragson (CWT LPI), met with the Wade Sheldon (GCE Lead IM), to discuss potential use of GCE technology for this effort. Both CWT and GCE LTER sites are administered at the University of Georgia, and attempts to forge closer ties between CWT and GCE have been underway since GCE was first established in 2000. The need for a system upgrade presented a fresh opportunity to push the effort forward. After discussion and demos of GCE software, and with the approval of both project leaderships, we agreed to collaborate on adapting several GCE databases and web applications for Coweeta’s use, as well as the GCE Data Toolbox software for processing Coweeta field data.  Although work continues, initial products of this collaboration are now implemented on the new CWT website, unveiled in April 2011 (http://coweeta.uga.edu).
%U https://lternet.edu/wp-content/uploads/2017/12/2011-spring-lter-databits.pdf
%A Chamblee, John F.
%A Sheldon, Wade M., Jr.
%K software, development, collaboration, technology, sharing, LTER-IMC

%0 Journal Article
%T Patterns of trait convergence and divergence among native and exotic species in herbaceous plant communities are not modified by nitrogen enrichment.
%D 2011
%V 99
%P 1327-1338
%B Journal of Ecology
%9 Article
%Z published
%M GCE.735
%R 10.1111/j.1365-2745.2011.01860.x
%X 1.&#8194;Community assembly theories predict that the success of invading species into a new community should be predictable by functional traits. Environmental filters could constrain the number of successful ecological strategies in a habitat, resulting in similar suites of traits between native and successfully invading species (convergence). Conversely, concepts of limiting similarity and competitive exclusion predict native species will prevent invasion by functionally similar exotic species, resulting in trait divergence between the two species pools. Nutrient availability may further alter the strength of convergent or divergent forces in community assembly, by relaxing environmental constraints and/or influencing competitive interactions.2.&#8194;To investigate how nutrient availability influences forces of divergence and convergence during the invasion of exotic species into native communities, we conducted multivariate analyses of community composition and functional traits from naturally assembled plant communities in long-term nitrogen (N) addition experiments across North America.3.&#8194;Relative abundances of key functional traits differed between the native and exotic plant communities, consistent with limiting similarity or a trait bias in the exotic species pool. Environmental context also played an important role in invasion because sites varied in the identity of the traits that predicted dissimilarity between native and exotic communities. Nitrogen enrichment did not alter these patterns.4.&#8194;Nitrogen enrichment tended to increase exotic abundance, but this result was driven by a dramatic increase in exotics in only a few experiments. When similarity between native and exotic communities was included in the statistical model, N enrichment no longer predicted an increase in exotic relative abundance. Instead, sites with the highest abundance of exotic species were the ones where native and exotic communities had the highest trait similarity.5.&#8194;Synthesis. Our analysis of natural patterns of invasion across herbaceous communities in North America found evidence of both divergent and convergent forces on community assembly with exotic species. Together, these results suggest that while functionally dissimilar exotic species may be more likely to invade, they are unlikely to become abundant unless they have traits pre-adapting them to environmental conditions in their invaded range. Contrary to prior studies, invasion was not consistently promoted by N enrichment.
%A Cleland, Elsa E.
%A Clark, Christopher M.
%A Collins, Scott L.
%A Fargione, Joseph E.
%A Gough, Laura
%A Gross, Katherine L.
%A Pennings, Steven C.
%A Suding, Katherine N.
%K fertilize, nutrients, Cross-site Research, Student Publication

%0 Journal Article
%T Crab regulation of cross-ecosystem resource transfer by marine foraging fire ants
%D 2011
%V 166
%P 1111-1119
%B Oecologia
%9 Article
%Z published
%M GCE.654
%R 10.1007/s00442-011-1952-x
%X Permeability of boundaries in biological systems is regulated by biotic and/or abiotic factors. Despite this knowledge, the role of biotic factors in regulating resource transfer across ecosystem boundaries has received little study. Additionally, little is known about how cross-ecosystem resource transfer affects source populations. We used experiments, observations and stable isotopes, to evaluate: (1) the proportion of intertidal-foraging black fire ant (Solenopsis richteri) diet derived from marine sources, (2) how black fire ant cross-ecosystem resource transfer is altered by the dominant bioengineer in the intertidal, a burrowing crab (Neohelice granulata), (3) the topdown impact of these terrestrial ants on a marine resource, and (4) the effect of marine resources on recipient black fire ants. We found that more than 85% of the black fire ant diet is derived from marine sources, the number of intertidal foraging ants doubles in the absence of crab burrows, and that ants cause a 50% reduction in intertidal polychaetes. Also, ant mound density is three times greater adjacent to marine systems. This study reveals that cross-ecosystem foraging terrestrial ants can clearly have strong impacts on marine resources. Furthermore, ecosystem engineers that modify and occupy habitat in these ecosystem boundaries can strongly regulate the degree of cross-ecosystem resource transfer and resultant top down impacts.
%U http://www.springerlink.com/content/v2h80ut730h85424/
%A Garcia, E. A.
%A Bertness, Mark D.
%A Alberti, J.
%A Silliman, Brian R.
%K crabs, ecosystem, ants, estuarine, Student Publication

%0 Thesis
%T Microbial Ecology and Biogeochemistry of the Coastal Ocean: New Insights from Metatranscriptomics
%D 2011
%P 163
%I University of Georgia
%C Athens, Georgia
%9 Ph.D. Dissertation
%Z presented
%M GCE.687
%X In the oceans, the transfer of energy and cycling of elements is predominantly controlled by bacterioplankton, such that any understanding of marine ecosystems requires knowledge about bacterial activities and functional capabilities. Metatranscriptomics, the direct retrieval and sequencing of environmental RNA, is a powerful tool that can identify active community members and their expressed functional capabilities. This dissertation is composed of three studies that used metatranscriptomics to gain fundamental insights into the ecology and biogeochemistry of coastal microbial communities. In the first study, an internal standard approach was developed to make absolute (per liter) estimates of transcript numbers, a significant advantage over proportional estimates. Expression levels of genes diagnostic for transformations in the marine nitrogen, phosphorus and sulfur cycles were determined, as well as the total size of the mRNA pool. By representing expression in absolute units, metatranscriptomics extends beyond relative comparisons, allowing for direct comparisons with other biogeochemical measurements. In the second study, a metatranscriptomic dataset revealed an unexpected abundance of transcripts to Candidatus Nitrosopumilus maritimus, an ammonia oxidizing Archaea whose presence has significant implications in the carbon and nitrogen cycles. Reads assigned to genes for ammonia uptake and oxidation accounted for 37% of N. maritimus transcripts. In contrast, transcripts from co-occurring ammonia oxidixing Bacteria were in much lower abundance, with no transcripts related to ammonia oxidation or carbon fixation. This study suggests that these two members of the ammonia oxidizing functional guild respond differently to the same environmental cues. The third study used metatranscriptomics to examine how differences in expression among taxa can be indicative of niche diversification. The sequencing of transcripts from four coastal bacterial communities revealed the expression and activity of thousands of different taxa. The genes carried by these taxa have extensive overlap, and the majority of highly expressed genes were for redundant functions. To identify unique ecological roles for these taxa, a method was developed to classify genes both by their expression level and their frequency in genomes. The results show clear functional delineations across broad phylogenetic groupings and provide insights into the diversity of lifestyle strategies that supports complex microbial assemblages.
%U http://gce-lter.marsci.uga.edu/public/uploads/GCEPub687_Gifford_PhD_2011_20120125T92748.pdf
%A Gifford, Scott
%K microbes, microbial ecology, biogeochemistry, ocean, genomics, metatranscriptomics, RNA, DNA, molecular, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Quantitative analysis of a deeply sequenced marine microbial metatranscriptome
%D 2011
%V 5
%P 461-472
%B International Society for Microbial Ecology
%9 Article
%Z published
%M GCE.602
%R 10.1038/ismej.2010.141
%X The potential of metatranscriptomic sequencing to provide insights into the environmental factors that regulate microbial activities depends on how fully the sequence libraries capture community expression (that is, sample-sequencing depth and coverage depth), and the sensitivity with which expression differences between communities can be detected (that is, statistical power for hypothesis testing). In this study, we use an internal standard approach to make absolute (perliter) estimates of transcript numbers, a significant advantage over proportional estimates that can be biased by expression changes in unrelated genes. Coastal waters of the southeastern United States contain 1x10^12 bacterioplankton mRNA molecules per liter of seawater (~200 mRNA molecules per bacterial cell). Even for the large bacterioplankton libraries obtained in this study (~500 000 possible protein-encoding sequences in each of two libraries after discarding rRNAs andsmall RNAs from 41 million 454 FLX pyrosequencing reads), sample-sequencing depth was only 0.00001%. Expression levels of 82 genes diagnostic for transformations in the marine nitrogen, phosphorus and sulfur cycles ranged from below detection (<1x10^6 transcripts per liter) for 36 genes (for example, phosphonate metabolism gene phnH, dissimilatory nitrate reductase subunitnapA) to >2.7x10^9 transcripts per liter (ammonia transporter amt and ammonia monooxygenase subunit amoC). Half of the categories for which expression was detected, however, had too few copy numbers for robust statistical resolution, as would be required for comparative (experimental or time-series) expression studies. By representing whole community gene abundance and expressionin absolute units (per volume or mass of environment), ‘omics’ data can be better leveraged to improve understanding of microbially mediated processes in the ocean.
%U https://www.ncbi.nlm.nih.gov/pubmed/20844569
%A Gifford, Scott
%A Sharma, S.
%A Rinta-Kanto, J.M.
%A Moran, Mary Ann
%K metatranscriptomics, marine, bacterioplankton, gene expression, biogeochemistry, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Predator diversity stabilizes and strengthens trophic control of a keystone grazer
%D 2011
%V 7
%P 79-82
%B Biology Letters
%9 Article
%Z published
%M GCE.649
%R 10.1098/rsbl.2010.0626
%X Despite the global vulnerability of predators to extinction, and the critical functional role they play in many ecosystems, there have been few realistic tests of the consequences of predator species deletion (conversely, predator diversity) in natural ecosystems. We performed a four-month field experiment in a southeastern United States salt marsh to test the role of predatory crab diversity in regulating populations of a keystone grazer that can decimate marsh vegetation at high densities. Our results revealed that a combination of this system's two resident predator species, in comparison to individual species, both stabilize and strengthen predation rates on the potent grazer. Monthly monitoring of predation rates from intense, hot summer months into the cooler autumn indicate this diversity benefit arises from predators responding differentially to changing environmental conditions across seasons. This study provides some of the first experimental field support for the insurance hypothesis from marine ecosystems, suggests that predator temporal complementarity may be more common than currently perceived, and argues for conservation of predator diversity to ensure reliable and effective control of potentially habitat-destroying grazers.
%U http://rsbl.royalsocietypublishing.org/content/7/1/79
%A Griffin, John
%A Silliman, Brian R.
%K predator, diversity, trophic, keystone, SINERR Publication, UGAMI Publication

%0 Journal Article
%T Resource Partitioning and Why It Matters
%D 2011
%V 2
%N 1
%P 8
%B Nature Education Knowledge
%9 Article
%Z published
%M GCE.755
%X Similar species commonly use limiting resources in different ways. Such resource partitioning helps to explain how seemingly similar species can coexist in the same ecological community without one pushing the others to extinction through competition. Understanding resource partitioning among species may help us to predict how ongoing species declines will impact the functioning of ecosystems.
%U https://www.nature.com/scitable/knowledge/library/resource-partitioning-and-why-it-matters-17362658
%A Griffin, John
%A Silliman, Brian R.
%K None listed

%0 Journal Article
%T Top predators suppress rather than facilitate plants in a trait-mediated tri-trophic cascade
%D 2011
%V Published online
%B Biology Letters
%9 Article
%Z published
%M GCE.646
%R 10.1098/rsbl.2011.0166
%X Classical ecological theory states that in tri-trophic systems, predators indirectly facilitate plants by reducing herbivore densities through consumption, while more recent work has revealed that predators can generate the same positive effect on plants non-consumptively by inducing changes in herbivore traits (e.g. feeding rates). Based on observations in US salt marshes dominated by vast monocultures of cordgrass, we hypothesized that sit-and-wait substrate-dwelling predators (crabs) could actually strengthen per capita impacts of potent grazers (snails), by non-consumptively inducing a vertical habitat shift of snails to their predation refuge high on canopy leaves that are vulnerable to grazing. A two-month field experiment supported this hypothesis, revealing that predators non-consumptively increased the mean climbing height of snails on grasses, increased grazing damage per leaf and ultimately suppressed cordgrass biomass, relative to controls. While seemingly counterintuitive, our results can be explained by (i) the vulnerability of refuge resources to grazing, and (ii) universal traits that drove the vertical habitat shift—i.e. relative habitat domains of predator and prey, and the hunting mode of the top predator. These results underline the fact that not only should we continue to incorporate non-consumptive effects into our understanding of top-down predator impacts, but we should do so in a spatially explicit manner.
%U http://rsbl.royalsocietypublishing.org/content/early/2011/04/16/rsbl.2011.0166.full
%A Griffin, John
%A Butler, Jack
%A Soomdat, Nicole
%A Brun, K.
%A Chejanovski, Zachary A.
%A Silliman, Brian R.
%K top-predator, tropic, cascade, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Organization of plant communities across estuarine landscapes in low-latitude tidal marshes
%D 2011
%P 106
%I University of Houston
%C Houston, TX
%9 Ph.D. Dissertation
%Z published
%M GCE.956
%X Understanding the processes that influence the distribution of organisms and the structure of communities is a major goal of ecological research. The unprecedented loss of biodiversity and habitats due to the impacts from human activities and global changes has made this goal more essential to the conservation and restoration of ecosystem function and services. In this dissertation, I explored the underlying mechanisms that organize the plant communities in tidal marshes in the southeastern US, with a focus on three topics: 1) I investigated the abiotic and biotic factors that mediate plant distribution across estuarine landscapes. I found that the "competition-to-stress hypothesis" which states that the upstream limits of plant distributions are determined by competition and the downstream limits by abiotic stress, could not fully explain the plant distribution patterns. This illustrated that even apparently simple abiotic gradients can encompass surprisingly complex processes mediating plant distributions. 2) I explored the role of ecosystem engineers in influencing plant community distribution and structure. I demonstrated that oyster shell deposits play an important ecosystem engineering role in influencing salt marsh plant community by providing a unique niche for Suaeda linearis, which otherwise would be extremely rare or even absent in salt marshes in the southeastern US. 3) I evaluated the relative importance of deterministic (niche-based) and stochastic processes in structuring plant communities in tidal marshes across estuarine landscapes. I found that stochastic processes were relatively important in shaping plant community structure in freshwater marshes, whereas deterministic processes played a relatively strong role in structuring plant communities in brackish and salt marshes. At the estuarine scale, the community assembly of tidal marsh vegetation across the estuarine landscape was primarily driven by niche-based selective processes. The results of this dissertation suggest that deterministic processes related with selective forces play important roles in organizing plant communities in coastal wetlands, but that attention also needs to be paid to the non-neglectable stochastic aspects of community organization in tidal fresh marshes to better comprehend the mechanisms underlying the organization of plant communities in tidal marshes.
%A Guo, Hongyu
%K plant communities, tidal marshes, SINERR Publication, Student Publication, UGAMI Publication

%0 Generic
%T Circulation and reaction hotspots in a Georgia salt marsh: a modeling study
%D 2011
%I Proceedings of the 2011 Georgia Water Resources Conference
%C The University of Georgia, Athens, Georgia
%B Georgia Water Resources Conference
%9 Article
%Z published
%M GCE.623
%X Intertidal salt marshes are highly productive, dynamic ecosystems at the interface between the land and the ocean that can play a significant role in reducing nutrient loading to the coastal ocean. To assess the spatio-temporal patterns in salt marsh biogeochemistry, a reactive transport model describing tidally-driven flow as well as solute dynamics across a marsh cross-section was developed.Porewater residence times were computed to identify zones of rapid fluid exchange. Model simulations suggest the presence of circulation hotspots at the creek bank and the upland-marsh transition zone, whose intensity varies over a tidal cycle. The location and magnitude of these regions of rapid fluid exchange depend on the tidal amplitude, and on the presence or absence of terrestrial groundwater input from the upland. The introduction of oxygenated creek water to the marsh subsurface also promotes biogeochemical reactions and hence may be important for regulating the marsh's filter function. Reaction hotspots are located at the interface between chemically distinct water bodies such as upland-derived groundwater and the intruding tidal creek water. As a result, these hotspots develop at the fringes of circulation hotspots, but are not identical to the locations of highest infiltration. The relative importance of reaction hotspots varies substantially with tidal amplitude and their presence has important implications for the placement of monitoring wells in field studies.
%A Hagens, Mathilde
%A Meile, Christof
%E Carroll, G. Denise
%K groundwater modeling

%0 Conference Proceedings
%T Circulation and reaction hotspots in a Georgia salt marsh: a modeling study.
%D 2011
%B LTER Science Council Meeting, Jekyll Island, GA
%9 Poster
%Z presented
%M GCE.625
%A Hagens, Mathilde
%A Meile, Christof
%K groundwater marsh modeling

%0 Journal Article
%T Relationships between vegetation zonation and environmental factors in newly formed tidal marshes of the Yangtze River estuary
%D 2011
%V 19
%P 341-349
%B Wetlands Ecology and Management
%9 Article
%Z published
%M GCE.731
%X The Yangtze River delta is characterized by rapidly accreting sediments that form tidal flats that are quickly colonized by emergent vegetation including Scirpus mariqueter and the invasive species Spartina alterniflora. We measured soil surface elevation, water table depth, soil salinity, water content and compaction in the tidal flat, the Scirpus and Spartina zones and their borders to identify relationships between environmental factors and colonization by Scirpus and Spartina. With increasing elevation from tidal flat to Spartina, inundation frequency and duration, moisture and depth to water table decreased whereas soil salinity, temperature and compaction increased. High soil moisture and groundwater and low salinity were the characteristics of the tidal flat and its border with Scirpus. The Spartina zone and its border with Scirpus were characterized by greater salinity and elevation relative to the other zones. Our findings suggest that soil salinity controls patterns of plant zonation in the newly formed tidal salt marshes whereas elevation is of secondary importance. Our results suggest that patterns of vegetation zonation in tidal marshes of the Yangtze River delta are controlled by environmental factors, especially (low) salinity that favors colonization by Scirpus in the lower elevations of the marsh.
%U https://link.springer.com/article/10.1007/s11273-011-9220-8
%A He, Y.
%A Li, X.
%A Craft, Christopher B.
%A Ma, Z.
%A Sun, Y.
%K Yangtze River, tidal marshes, environmental factors

%0 Conference Proceedings
%T Assessment of salt marsh LIDAR errors and digital elevation model correction
%D 2011
%I SEERS
%C Athens, GA
%B SEERS
%8 March 16-18, 2011
%9 Presentation
%Z presented
%M GCE.700
%A Hladik, Christine M.
%A Alber, Merryl
%K LIDAR, DEM, salt marsh, Student Publication

%0 Conference Proceedings
%T Fusing hyperspectral airborne imagery and LIDAR-derived digital elevation models for the correction of salt marsh elevations.
%D 2011
%C Daytona Beach, FL
%B Coastal and Estuarine Research Federation
%8 November 6-10, 2011
%9 Poster
%Z presented
%M GCE.699
%A Hladik, Christine M.
%A Alber, Merryl
%A Schalles, John F.
%K remote sensing, LIDAR, hyperspectral, salt marsh, Student Publication

%0 Journal Article
%T Metatranscriptomic analysis of ammonia-oxidizing organisms in an estuarine bacterioplankton assemblage
%D 2011
%V 5
%P 866-878
%B ISME Journal
%9 Article
%Z published
%M GCE.552
%R 10.1038/ismej.2010.172
%X Quantitative PCR (qPCR) analysis revealed elevated relative abundance (1.8% of prokaryotes) of marine group 1 Crenarchaeota (MG1C) in two samples of southeastern US coastal bacterioplankton, collected in August 2008, compared with samples collected from the same site at different times (mean 0.026%). We analyzed the MG1C sequences in metatranscriptomes from these samples to gain an insight into the metabolism of MG1C population growing in the environment, and for comparison with ammonia-oxidizing bacteria (AOB) in the same samples. Assemblies revealed low diversity within sequences assigned to most individual MG1C open reading frames (ORFs) and high homology with ‘Candidatus Nitrosopumilus maritimus’ strain SCM1 genome sequences. Reads assigned to ORFs for ammonia uptake and oxidation accounted for 37% of all MG1C transcripts. We did not recover any reads for Nmar_1354–Nmar_1357, proposed to encode components of an alternative, nitroxyl-based ammonia oxidation pathway; however, reads from Nmar_1259 and Nmar_1667, annotated as encoding a multicopper oxidase with homology to nirK, were abundant. Reads assigned to two homologous ORFs (Nmar_1201 and Nmar_1547), annotated as hypothetical proteins were also abundant, suggesting that their unknown function is important to MG1C. Superoxide dismutase and peroxiredoxin-like transcripts were more abundant in the MG1C transcript pool than in the complete metatranscriptome, suggesting an enhanced response to oxidative stress by the MG1C population. qPCR indicated low AOB abundance (0.0010% of prokaryotes), and we found no transcripts related to ammonia oxidation and only one RuBisCO transcript among the transcripts assigned to AOB, suggesting they were not responding to the same environmental cues as the MG1C population.
%U http://www.nature.com/ismej/journal/vaop/ncurrent/abs/ismej2010172a.html
%A Hollibaugh, James T.
%A Gifford, Scott
%A Sharma, S.
%A Bano, Nasreen
%A Moran, Mary Ann
%K Crenarchaeota, ammmonia oxidation, Nitrosopumilus, nitrosomonas, Nitrosospira, Nitrosococcus, Student Publication

%0 Conference Proceedings
%T Analyzing Backbarrier Shoreline Change Along Georgia's Barrier Islands: Lessons Learned From Developing And Using Ambur.
%D 2011
%I Geological Society of America
%C Wilmington, NC
%B Geological Society of America Abstracts with Programs
%S No. 2
%8 March 23-25
%9 Abstract
%Z published
%M GCE.822
%X Georgia’s barrier coast is composed of standalone islands and multi-barrier complexes that front expansive tidal marsh and are separated by relatively large, positionally stable inlets. The backbarrier shorescape is a mixture of dense to moderately vegetated dunes and sediment banks, maritime forests, and marsh platforms dissected by laterally migrating tidal streams. The shape of the shoreline can range from curvilinear to highly sinuous depending on the processes acting upon the backbarrier shore. Most historical shoreline change studies have concentrated on the oceanfront side of the barriers. Not only because, simply, that is where the built environment is concentrated, but also because the oceanfront shoreline is mostly curvilinear and lacks highly curved segments which are difficult to analyze with currently available GIS-based analysis tools. Recently, the AMBUR (Analyzing Moving Boundaries Using R) package was developed and applied to map shoreline change for each island along the Georgia coast including backbarrier, oceanfront, and inlets. AMBUR’s transect-casting techniques simplify dealing with curved shoreline segments that have proven problematic for the traditional perpendicular-transect method. Furthermore, AMBUR’s output of data tables, graphics, and shapefiles allows for rapid identification of erosion hotspots and other areas of shoreline position flux.Preliminary results from coast-wide analyses show that approximately 65% of Georgia’s backbarrier shoreline eroded throughout the study period from 1855 to 2004 at a mean rate of -0.35 m/yr. Less than half of the backbarrier of the islands eroded from 1933 to 1974. However, during the most recent period from 1974 to 2004, there was approximately 78% backbarrier erosion coast-wide occurring at a mean rate of -0.39 m/yr. Backbarrier erosion tends to be heightened near the apex of encroaching tidal stream meanders, near the confluence of two tidal streams adjacent to the backbarrier shore, and along shorelines within close proximity to or adjacent to inlets. Furthermore, more than half of the length of the Atlantic Intracoastal Waterway is adjacent to the backbarrier shoreline and has influenced shoreline behavior through dredging activities.
%A Jackson, C.W.
%A Alexander, Clark R., Jr.
%A Bush, D.M.
%K Shoreline Change, Georgia Coast, Barrier Island, Ambur

%0 Conference Proceedings
%T Modeling the Production of Saltmarsh Grasses
%D 2011
%I Coastal and Estuarine Research Federation
%C Daytona Beach, Florida, USA
%B 21st Biennial Conference of the Coastal and Estuarine Research Federation
%S Dynamic Feedbacks between Marsh Sedimentation and Vegetation
%8 7th November 2011
%9 Presentation
%Z presented
%M GCE.702
%X Salt marsh grasses species change as one moves from high marsh areas to low marsh areas as a result of many factors including light, salinity and nutrient availability. We are developing a model to understand the factors controlling species succession from high marsh to low marsh, using data from the Georgia Coastal Ecosystems Long Term Ecological Research program at Sapelo Island. We present results from initial development of the model and comparisons of model output with long-term data. The development and accuracy of the model depends crucially on the availability of data, which is not uniform across the species being studied (Spartina alterniflora, Juncus Roemerianus and Borrichia Frustescenes). We discuss future developments and uses of the model.
%A Jung, Yeajin
%A Burd, Adrian B.
%K Spartina, model, Student Publication

%0 Thesis
%T Application of the Water Quality Analysis Simulation Program (WASP) to Evaluate Dissolved Nitrogen Concentrations in the Altamaha River Estuary, Georgia
%D 2011
%P 227
%I University of Georgia
%C Athens, Georgia
%9 M.S. Thesis
%Z published
%M GCE.675
%X The Water Quality Analysis Simulation Program (WASP v.7.4) and a water flow model, SqueezeBox, were used to model concentrations of dissolved nitrogen (DN) in the Altamaha River estuary, Georgia. Model development was guided by previous studies using WASP, literature surveys, and sensitivity analyses. The model was calibrated and validated against observations from the Georgia Coastal Ecosystems Long Term Ecological Research project. Average error between model predicted and observed concentrations was 39.8 % for NH3, 23.6 % for NO3-, and 7.8 % for DON. Results from the calibrated model showed that riverine DN input had an approximately 6-fold greater influence on predicted DN in the estuary than either flow or temperature. Overall, predicted DN concentrations were highest for high DN input, high flows, and low and medium temperatures.
%U http://gce-lter.marsci.uga.edu/public/uploads/GCEPub675_GKaufman_MS_2011_20120221T135921.pdf
%A Kaufman, Galen
%K WASP, water quality, nitrogen, Altamaha, Student Publication

%0 Journal Article
%T Effects of five years of nitrogen and phosphorus additions on a Zizaniopsis miliacea tidal freshwater marsh.
%D 2011
%V 95
%P 17-23
%B Aquatic Botany
%9 Article
%Z published
%M GCE.631
%R 10.1016/j.aquabot.2011.03.003
%X The purpose of this experiment was to determine if nitrogen (N) or phosphorus (P) acts as the limiting nutrient for tidal freshwater marsh vegetation. To answer this question, we added N, P, and N + P to a tidal freshwater marsh dominated by Zizaniopsis miliacea (Michx.) (giant cutgrass) in Georgia, USA, for &#64257;ve years to determine their effects on aboveground and belowground biomass and nutrient (N, P) uptake. Nitrogen and P were applied twice per year at an annual rate of 50 g m&#8722;2 year&#8722;1 and 10 g m&#8722;2 year&#8722;1, respectively. Aboveground biomass and leaf C, N, and P were sampled in August of each year. Belowground biomass and C, N, and P content were measured in August of year &#64257;ve. After two years, plots receiving N and N + P had signi&#64257;cantly greater aboveground biomass than the control and P plots. This trend continued through the &#64257;fth year of the study and resulted in two to three times more aboveground biomass at the end of the &#64257;fth year in the N (1570 g m&#8722;2) and N + P (1264 g m&#8722;2) plots relative to P (710 g m&#8722;2) and control (570 g m&#8722;2) plots. After &#64257;ve years of nutrient additions, macro-organic matter (MOM), the living plus dead root and rhizome mat (0–10 cm), was signi&#64257;cantly lower in the N(1457 g m&#8722;2) and N + P (994 g m&#8722;2) plots than the control (2189 g m&#8722;2) plots. There was less live rhizome biomass in the N + P (23 g m&#8722;2) plots than the control (1085 g m&#8722;2) plots. We observed a 31–33% increase in the N content of Z. miliacea leaves in years three through &#64257;ve in the N and N + P plots relative to the control plots, but observed no P enrichment of leaves. In the N-treated plots, leaf C:N decreased 20–25% whereas N:P increased 21–64% in years three through &#64257;ve relative to the control and P plots. These &#64257;ndings collectively suggest that N, rather than P, limits productivity of tidal freshwater marsh vegetation. Reduced belowground biomass that accompanies N enrichment is of special concern as it may lead to increased erosion and reduced organic matter inputs to the soil, increasing their susceptibility to disturbances associated with wind, waves, river &#64258;ooding and rising sea level.
%A Ket, Wes
%A Schubauer-berigan, Joe
%A Craft, Christopher B.
%K Nutrient limitation, Nitrogen, Phosphorus, Tidal freshwater marsh, Aboveground biomass, Belowground biomass, N:P ratio, Fertilizer, Zizaniopsis miliacea, Pontederia cordata, Sagittaria lancifolia, Student Publication, UGAMI Publication

%0 Generic
%T South Atlantic Regional Research Plan: Development and Application of Coastal Regional Priorities
%D 2011
%I Proceedings of the 2011 Georgia Water Resources Conference
%C University of Georgia, Athens, Georgia
%B Georgia Water Resources Conference
%9 Article
%Z published
%M GCE.672
%X The South Atlantic Regional Research Project (SARRP, http://www.gcrc.uga.edu/sarrp.htm) is a regional, multi-agency project to develop a coordinated coastal and ocean research plan for the southeastern United States (from NC to FL). The South Atlantic effort was funded by National Sea Grant-NOAA and was conducted in concert with similar projects in other Sea Grant regions across the US and Insular Pacific. The project's primary goals are to identify priority coastal and ocean research needs for the region and to foster productive cooperation among regional partners. The SARRP plan was released in April 2010 after a three-year process that involved federal, regional, state and academic partners from throughout the region. The plan identifies 27 research priorities, which were aligned with the four themes that are also being used by the South Atlantic Governor's Alliance: Healthy Ecosystems, Working Waterfronts, Clean Coastal and Ocean Waters, and Disaster-Resilient Communities. We are currently collecting information describing ongoing or planned activities that are relevant to each priority, as well as identifying areas specifically aligned with the missions of particular agencies and organizations. This paper will describe the process by which the plan was developed, highlighting the key research priorities identified in the research plan and presenting an update on synergy with other regional initiatives.
%A Laporte, Christine
%A Alber, Merryl
%E Carroll, G. Denise
%K water quality, indicator

%0 Journal Article
%T Guest Editorial: When teachers become scientists
%D 2011
%P 3
%B Science Scope
%9 Article
%Z published
%M GCE.616
%X Ask yourself this question: Have you ever worked on a real scientific experiment? Your thoughts may jump to the lab components of your undergraduate science courses and the research papers/assignments you completed in college, but should such structured, step-by-step exercises really be considered experiments? Is this what real scientists do? For the author, the answer to these questions about the true nature of science came in the form of two inspirational professional development courses where teachers become scientists. In this article, she describes her participation in the workshops and discusses how these experiences benefited her students back in the classroom as well.
%U https://www.nsta.org/store/product_detail.aspx?id=10.2505/4/ss11_034_06_6
%A Linsky, Catherine L.
%K Process Standards for Professional Development, UGAMI Publication

%0 Journal Article
%T Latitudinal variation in top-down and bottom-up control of a salt marsh food web
%D 2011
%V 92
%P 276-281
%B Ecology
%9 Article
%Z published
%M GCE.629
%R 10.1890/10-0760.1
%X The shrub Iva frutescens, which occupies the terrestrial border of U.S. Atlantic Coast salt marshes, supports a food web that varies strongly across latitude. We tested whether latitudinal variation in plant quality (higher at high latitudes), consumption by omnivores (a crab, present only at low latitudes), consumption by mesopredators (ladybugs, present at all latitudes), or the life history stage of an herbivorous beetle could explain continental-scale field patterns of herbivore density. In a mesocosm experiment, crabs exerted strong top-down control on herbivorous beetles, ladybugs exerted strong top-down control on aphids, and both predators benefited plants through trophic cascades. Latitude of plant origin had no effect on consumers. Herbivorous beetle density was greater if mesocosms were stocked with beetle adults rather than larvae, and aphid densities were reduced in the “adult beetle” treatment. Treatment combinations representing high and low latitudes produced patterns of herbivore density similar to those in the field. We conclude that latitudinal variation in plant quality is less important than latitudinal variation in top consumers and competition in mediating food web structure. Climate may also play a strong role in structuring high-latitude salt marshes by limiting the number of herbivore generations per growing season and causing high overwintering mortality.
%U https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/10-0760.1
%A Marczak, Laurie
%A Ho, Chuan-Kai
%A Vu, Huy
%A Denno, Robert
%A Pennings, Steven C.
%K latitude, Iva, top-down, bottom-up, predation, herbivory, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Thesis
%T Geographic Variation in the Structure of Salt Marsh Arthropod Communities
%D 2011
%P 51
%I University of Houston
%C Houston, Texas
%9 M.S. Thesis
%Z published
%M GCE.622
%X The natural environment shows variation at multiple scales, and determining how large-scale patterns relate to the local community's structure and function is a fundamental goal of ecology. Salt marshes along the Atlantic and Gulf coasts are similar in many ways, and are inhabited by the same plant and insect species. However, the Atlantic and Gulf coast areas have different tidal regimes, which may result in the two areas not functioning exactly the same. In addition, abiotic factors that vary with latitude or longitude may lead to differences between northern and southern or eastern and western sites. I hypothesized that structure and function of the coastal salt marsh varies geographically. To test this, I characterized abiotic conditions and the plant and arthropod communities at 11 sites along each coast in the late summers of 2009 and 2010. I also manipulated wrack (dead plant stems) and nutrient availability in 2 x 3 m plots at each site to evaluate geographic differences in community response. The experiment was established in 2009 and allowed to run to 2010. My sampling documented that some abiotic factors varied geographically, as did plant height, nitrogen content, and thatch cover. Although the total number of arthropods collected did not differ geographically, the trophic composition of samples showed marked variation among regions. Large-scale differences in latitude and mean tidal range are likely driving much of this variation. Arthropod community structure was little affected by wrack addition, but responded strongly to fertilization; and, the effect of fertilization varied geographically for some trophic levels. Although salt marshes are superficially similar from Maine to Texas, they may be structured differently throughout this geographic range. Therefore, extrapolating results from one geographic region to another should be done with caution.
%U http://gce-lter.marsci.uga.edu/public/files/pubs/BMcCall_MS_Thesis_2011.pdf
%A McCall, Brittany DeLoach
%K geography, arthropod, community ecology, salt marsh, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T The Effect of Horses on Cumberland Island Salt Marsh Fauna
%D 2011
%I Southeastern Estuarine Research Society
%C Athens, GA
%8 March 16-18
%9 Presentation
%Z presented
%M GCE.764
%A McFarlin, Caroline R.
%A Alber, Merryl
%K Spartina alterniflora, DMSP, chlorophyll, benthic infauna, diversity, Student Publication

%0 Conference Proceedings
%T The use of DMSO and DMSP to evaluate the physiological response of Spartina alterniflora to various disturbances
%D 2011
%I Coastal and Estuarine Research Federation
%C Daytona, FL
%S SCI-205 Ecosystem Stressors, Responses and Trends
%8 November 6-10, 2011
%9 Presentation
%Z presented
%M GCE.762
%X Research by Husband and Kiene (2007) showed that when Spartina was under stress, there was direct conversion of the secondary metabolite dimethylsulfonio- propionate (DMSP) to dimethylsulfoxide (DMSO), an oxidation product. They reported higher DMSO:DMSP ratios in senescing (yellowing) plants as compared to healthy (green) plants and also in roots, as compared to stems and leaves. Recent work by Kiehn and Morris (2010) supported the idea of a stress response, as they found that DMSP concentration of Spartina was lowest near dieback areas and increased with distance from the dieback edge. We evaluated DMSO, DMSP, and chlorophyll concentrations in the leaves, stems, and where possible, roots, of Spartina plants collected from areas affected by wrack, increased snail densities, dieback, and horse disturbances. DMSP concentrations were decreased in affected areas of all disturbances except for wrack sites, and were highest in leaves and lowest in roots. The DMSO:DMSP ratio was increased in all of the affected areas as compared to nearby healthy areas, and was also highest in roots. Regression analyses of DMSP and the DMSO:DMSP ratio against chlorophyll concentrations was very weak (r2&#8804;0.05), suggesting that DMSP was not influenced by senescence alone, and may be a more sensitive indicator of stress than the obvious signs of yellowing Spartina.
%A McFarlin, Caroline R.
%A Alber, Merryl
%K Spartina alterniflora, stress, DMSP, DMSO, metals, chlorophyll, dieback, Student Publication

%0 Conference Proceedings
%T Preliminary Observations of Groundwater Discharge Behaviors into the Duplin River
%D 2011
%C Jekyll Island, Georgia
%B 2011 LTER Science Council Meeting
%8 May 2011
%9 Poster
%Z presented
%M GCE.661
%A McHugh, Christopher
%A Peterson, Richard N.
%A Viso, Richard F.
%K Groundwater discharge, Duplin River, Radon, Resistivity, Student Publication

%0 Journal Article
%T A Blueprint for Blue Carbon: Towards an improved understanding of the role of vegetated coastal habitats in sequestering CO2
%D 2011
%V 9
%N 10
%P 552=560
%B Frontiers in Ecology and the Environment.
%9 Article
%Z published
%M GCE.648
%R 10.1890/110004
%X Recent research has highlighted the valuable role that coastal and marine ecosystems play in sequestering carbon dioxide (CO2). The carbon (C) sequestered in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds, and salt marshes, has been termed “blue carbon”. Although their global area is one to two orders of magnitude smaller than that of terrestrial forests, the contribution of vegetated coastal habitats per unit area to long-term C sequestration is much greater, in part because of their efficiency in trapping suspended matter and associated organic C during tidal inundation. Despite the value of mangrove forests, seagrass beds, and salt marshes in sequestering C, and the other goods and services they provide, these systems are being lost at critical rates and action is urgently needed to prevent further degradation and loss. Recognition of their C sequestration value provides a strong argument for their protection and restoration; however, it is necessary to improve scientific understanding of the underlying mechanisms that control C sequestration in these ecosystems. Here, we identify key areas of uncertainty and specific actions needed to address them.
%U https://esajournals.onlinelibrary.wiley.com/doi/10.1890/110004
%A Mcleod, Elizabeth
%A Chmura, Gail L.
%A Bouillon, Steven
%A Salm, Rodney
%A Bjork, Mats
%A Duarte, Carlos M.
%A Lovelock, Catherine E.
%A Schlesinger, William H.
%A Silliman, Brian R.
%K carbon, coastal, habitat

%0 Conference Proceedings
%T Geographic variation in salt marsh food webs
%D 2011
%I Coastal and Estuarine Research Federation
%C Daytona Beach, FL
%B Coastal and Estuarine Research Federation
%S Comparative studies of estuarine and coastal system properties
%8 November 6-11
%9 Presentation
%Z presented
%M GCE.690
%A Pennings, Steven C.
%A Ho, Chuan-Kai
%A Marczak, Laurie
%A McCall, Brittany DeLoach
%A Wieski, Kazimierz
%A Vu, Huy
%K latitude, salt marsh, biogeography, insect, spider, Student Publication

%0 Conference Proceedings
%T Quantifying the Impact of Recreational And Commercial Usage of the Atlantic Intracoastal Water Way (AIWW) on the Natural Resources Of Georgia.
%D 2011
%I Geological Society of America
%C Wilmington, NC
%B Geological Society of America Abstracts with Programs
%S No. 2
%8 March 23-25
%9 Abstract
%Z published
%M GCE.823
%X Estuaries are ecosystems of major importance biologically and economically. Human activities make estuaries environmentally vulnerable. Although processes like shoreline erosion and accretion are natural, human activities can increase the rate at which these processes take place. The Atlantic Intracoastal Water Way (AIWW) is a man-made estuarine shipping channel that runs from New Jersey to Florida. Wakes created by recreational and commercial vessels represent the major impact to the AIWW shoreline. These wakes cause channel widening and bury living oyster reefs in sediments, causing them to die.This study focuses on quantifying the impact of anthropogenic modification and boat wakes along the Georgia portion of the AIWW shoreline. Long-term change in the AIWW was assessed used GIS tools to examine decadal-scale shoreline behavior. The data used in this study consist of historical shorelines for the AIWW main channel and alternative routes. All shorelines were digitized in ARCGIS 9.3 using NOAA T-sheets (1860’s and 1933) and aerial imagery (1942, 1972, and 2002-04). Shorelines were analyzed using AMBUR (Analyzing Moving Boundaries Using R). To assess recreational boating impacts, creeks with significant boat traffic (e.g., near marinas or public boat ramps) were digitized and compared to nearby creeks with little boating impact. Dead oyster reefs were identified by their spectral signature for the years of 1942, 1972, and 2002-04.Within the main AIWW channel, the major shoreline movements are channel dilation and migration with high shoreline change rates. Maximum rates range from -3.00 m/y erosion to 7.62 m/y accretion. The alternate routes present lower shoreline change rates, with rates ranging between -1.49 m/y erosion and 2.48 m/y accretion, which can be attributed to lower boat traffic in these areas. Dead oyster reefs are found along the main channel of the AIWW, while the alternative routes do not exhibit a large quantity of dead oyster bars, also indicating lower boat traffic. Recreational boating activity appears to significantly increase shoreline change rates downstream (toward the next major channel) from marinas and boat ramps.
%A Perez-Sanchez, N.
%A Alexander, Clark R., Jr.
%A Venherm, Claudia
%A Jackson, C.W.
%K Introcoastal Waterway, Natural Resources

%0 Journal Article
%T Field measurements and modeling of groundwater flow and biogeochemistry at Moses Hammock, a backbarrier island on the Georgia coast
%D 2011
%V 104
%P 69-90
%B Biogeochemistry
%9 Article
%Z published
%M GCE.542
%R 10.1007/s10533-010-9484-8
%X A combination of field measurements, laboratory experiments and model simulations were used to characterize the groundwater biogeochemical dynamics along a shallow monitoring well transect on a coastal hammock. A switch in the redox status of the dissolved inorganic nitrogen (DIN) pool in the well at the upland/saltmarsh interface occurred over the spring-neap tidal transition: the DIN pool was dominated by nitrate during spring tide and by ammonium during neap tide. A density-dependent reaction-transport model was used to investigate the relative importance of individual processes to the observed N redox-switch. The observed N redox-switch was evaluated with regard to the roles of nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), ammonium adsorption, and variations in inflowing water geochemistry between spring and neap tides.Transport was driven by measured pressure heads and process parameterizations were derived from field observations, targeted laboratory experiments, and the literature. Modeling results suggest that the variation in inflow water chemistry was the dominant driver of DIN dynamics and highlight the importance of spring-neap tide variations in the high marsh, which influences groundwater biogeochemistry at the marsh-upland transition.
%U http://www.springerlink.com/content/t18x02358tt6x123/
%A Porubsky, William P.
%A Joye, Samantha B.
%A Moore, Willard S.
%A Tuncay, Kagan
%A Meile, Christof
%K Hammock groundwater, nitrogen cycle, upland-marsh transition, spring-neap tide cycle, reaction transport modeling, Student Publication

%0 Thesis
%T Smouldering oceans: on the photochemically mediated oxidation of dissolved organic matter in coastal waters
%D 2011
%P 194
%I University of Georgia
%C Athens, Georgia
%9 Ph.D. Dissertation
%Z published
%M GCE.688
%X Marine dissolved organic carbon (DOC) is one of the largest and most dynamic pools of reduced carbon on earth. Photochemical processes have the potential to significantly affect the content of this DOC pool. Photochemical oxidation to carbon monoxide and carbon dioxide are two direct pathways for the removal of DOC from the marine system. Indirectly, photochemical processes can lead to the removal of DOC through the alteration of chemical structures rendering them more biologically labile. In order to assess the influence of photochemistry on the coastal carbon cycle the variability of these processes must be well constrained. To calculate photochemical production in marine waters, it is crucial to know how light is absorbed by chromophoric dissolved organic matter (CDOM), as well as the spectral efficiency of the resulting photochemical reactions (i.e. the apparent quantum yield (AQY) spectra). The challenges of using visible wavelength CDOM absorption data to model ultraviolet absorption data are investigated. Direct measurements of ultraviolet absorption data model photochemical processes best. When this is not possible, visible data can be used with an accuracy of +/- 10% in coastal waters. Either a hyperbolic absorption model or one using correction factors applied to a traditional exponential model will allow for similar accuracy in the ultraviolet portion of the absorption spectrum. The variability of photochemical oxidation of dissolved organic carbon in a coastal system was studied in order to constrain remote sensing calculations. The variability of CO and CO2 AQY spectra were relatively well constrained in three estuaries of Georgia, USA. The AQY for CO varied within +/- 12.7% year-round while CO2 varied within +/- 33.6% year-round. Hyperspectral remote sensing reveals finescale hydrodynamic structure in estuarine systems and is readily adaptable to photochemical modeling applications. Defining the variability of photochemistry?s influence on the biological lability of DOC is a complex undertaking. Unlike direct photochemical oxidation of DOC to CO and CO2, the biologically labile products (BLPs) of incomplete oxidation can themselves be photochemically reactive. Competition between production and destruction of BLPs during irradiation is a significant consideration when determining the quantitative influence of photochemistry on marine systems.
%U http://gce-lter.marsci.uga.edu/public/files/pubs/HReader_PhD_2011.pdf
%A Reader, Heather E.
%K Photochemistry, Carbon Monoxide, Carbon Dioxide, Biological Lability, Dissolved Organic Carbon, Chromophoric Dissolved Organic Matter, Remote Sensing, Estuaries, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Acquisition of integrated, field-based, subtidal and intertidal marshlands morphology and comparison to LiDAR data.
%D 2011
%I Coastal and Estuarine Research Federation
%C Daytona Beach, FL.
%B Coastal and Estuarine Research Federation Biennial Meeting.
%S No. 2
%8 6-10 November 2011
%9 Poster
%Z published
%M GCE.826
%X Coastal Georgia is a dynamic environment. Frequently, shoreline erosion along open coastlines and bluffs of tidal streams impacts important archaeological sites by exposing, removing and destroying burials, structures, and artifacts. In this study we identified sites on barrier islands and back-barrier islands (“marsh hammocks”) in coastal Georgia that are threatened and/or are being damaged by coastal erosion, evaluated their site condition and prioritized them based on the order of site loss.All archaeological sites within a 30 m radius of a waterway or marsh environment were selected from the Georgia Archaeological Site file (GASF) database, as these were the sites that might be destroyed within the next 50 years, based on average back-barrier erosion rates. This list was evaluated by the Georgia Department of Natural Resources – Historic Resources Division (DNR-HPD) to identify sites that were potentially listable on the Federal Register of Historic Places. For each of the identified sites, individual GIS projects were generated in ARCGIS 9.3 that included a current, GPS-surveyed shoreline and shorelines derived from historic maps and aerial imagery. AMBUR (Analysis of Moving Boundaries Using “R”) was then used to calculate shoreline change rates. Using these site-specific rates, we created a prioritized list of archaeological sites based on the time until the site was destroyed by erosion and the information contained within them was lost.For the 21 selected sites on barrier islands, 11 shorelines (52%) were eroding, 8 were stable, and 2 were accreting. For the 36 selected sites on back-barrier islands, 29 shorelines (81%) were eroding, and 7 were stable. Higher shoreline change rates were observed at barrier island sites (up to -1.68 m/y erosion) when compared to back-barrier island sites (rates up to -0.72 m/y erosion), although the dynamic back-barrier environment exhibited a higher percentage of erosional sites. Consequently, archaeological sites on barrier islands experience a higher annual percentage loss of site information than sites on back-barrier islands. The projected lifetime of sites varies greatly, ranging from less than a year (and some sites had completely eroded away at the time of our survey) to several hundred years depending on shoreline change rate, site location and site size.
%A Robinson, Michael
%A Alexander, Clark R., Jr.
%A Hladik, Christine M.
%K marshlands morphology, subtidal, intertidal, LiDAR, Student Publication

%0 Conference Proceedings
%T Student training and habitat monitoring in coastal systems 
%D 2011
%I NASA Space Grant Program - Western Region
%C Fairbanks, AK
%B Western Region Space Grant Director’s Meeting
%S Teacher and Student Training
%8 August 26, 2011
%9 Presentation
%Z presented
%M GCE.686
%A Schalles, John F.
%K Outdoor education, coastal habitat monitoring, remote sensing

%0 Conference Proceedings
%T Mapping Coastal and Estuarine Chlorophyll Concentrations
%D 2011
%I American Society of Limnology and Oceanography
%C San Juan, Puerto Rico
%B 2011 ASLO Aquatic Sciences Meeting
%S S05: Ocean Color Radiometry of Coastal and Inland Water
%8 February 16, 2011
%9 Presentation
%Z presented
%M GCE.679
%X Turbid, Case 2 water conditions complicate methods for optical retrieval of chlorophyll and other water constituents. We've collected data for >300 stations (Chl 0.2 - 490 ug/L), using consistent methods for field spectroscopy and water analyses at >25 estuaries and adjacent coastal waters, with most observations at, or near seven National Estuarine Research Reserves located between Aransas Bay (Texas) and Delaware Bay. With most field measurements, NOAA-ECSC airborne hyperspectral imagery was collected with the University of Nebraska's AISA Eagle instrument. Recently, we've begun mapping trials using "on the fly" boat equipment" that includes a boom mounted optic fiber connected to spectroradiometer, YSI 6600 sonde with flow-through cell, and coupled GPS tracking. Our Case 2 water algorithm, derived from station measurements, has been re-parameterized for AISA imagery classification, to produce synoptic maps at 1 m resolution. We will present map products and geospatial analyses of the classified data, along with a critique of these approaches. Revealed geospatial patterns are leading to new, testable hypotheses for algal abundance related to estuarine circulation, nutrient sources, and intertidal benthic algae.
%A Schalles, John F.
%A Hladik, Christine M.
%A Seminara, D.N.
%A O'Donnell, J.P.
%K Coastal remote sensing, phytoplankton, chlorophyll a, Student Publication

%0 Conference Proceedings
%T Comparing algal chlorophyll spatial patterns within and between Gulf and East Coast National Estuarine Research Reserves
%D 2011
%I Coastal and Estuarine Research Federatiob
%C Daytona Beach, Florida
%B Coastal and Estuarine Research Federation
%S SCI-106, Comparative Studies of Estuarine and Coastal System Properties
%8 November 9. 2011
%9 Presentation
%Z presented
%M GCE.695
%X Since 2002, we measured water reflectance spectra and conducted simultaneous sampling of water for bulk optical properties (chlorophyll, CDOM, and seston) and other water column properties at greater than 300 stations in more than 25 estuaries and adjacent coastal waters within and proximate to seven NOAA-NERR and one NMS sites located between Texas and Delaware. In most cases, our sampling was coincident with nutrient and carbon speciation analysis and with aerial hyperspectral imagery collections using the Univ. of Nebraska - CALMIT AISA Eagle sensor. Across all stations, the average, median, and ranges for chlorophyll were 22.3, 13.0, and 0.2¬ 490.1 mg/m3, for CDOM abs (440 nm) were 3.25, 1.30, and 0.0-21.1 m-1, and for seston were 33.8, 16.9, and 0.6¬ 726.3 mg/L dry wt. Sites in Texas and Mississippi had the lowest chl averages, Florida, Georgia, and South Carolina sites were intermediate, and Maryland and Delaware the highest values and chlorophyll and nutrient levels were largely correlated across these coastal sites. Within river to estuary to offshore transects, chl generally peaked in the lower reaches of the estuary. Recently, we've also begun mapping longitudinal patterns within estuarine drainages using a boat-borne multi-instrument sonde (including chl fluorometer and turbidimeter), water reflectance with a bow-mounted fiber optic light guide and foreoptics), and high resolution GPS track logging. High spatial resolution mapping in the Duplin River tidal watershed of the Sapelo Island NERR revealed several fold greater chl concentration in tidal creeks draining marshes at low tide compared to the Duplin main channel, a behavior related to export of marsh mud benthic diatoms. Chl differences between Duplin subwatersheds may be related to nutrients in ground water seepage and marsh macrophyte production patterns.
%A Schalles, John F.
%A Olley, J.T.
%A Hladik, Christine M.
%A O'Donnell, J.P.
%K Phytoplankton, Chlorophyll a, Remote Sensing, Estuarine, Coastal, Student Publication

%0 Conference Proceedings
%T Physical and biogeochemical patterns in the Duplin saltmarsh river system: preliminary results.
%D 2011
%B LTER Science Council Meeting, Jekyll Island, GA
%9 Poster
%Z presented
%M GCE.624
%A Schutte, Charles
%A Meile, Christof
%A Di Iorio, Daniela
%A McKay, Paul
%A Joye, Samantha B.
%A Blanton, Jackson O.
%A Schalles, John F.
%K duplin, Student Publication

%0 Conference Proceedings
%T Intersite comparison of marsh spatial patterns using hyperspectral imagery at NERR sites along the Gulf and Atlantic coasts.
%D 2011
%B Coastal and Estuarine Research Federation
%S SCI-106, Comparative Studies of Estuarine and Coastal System Properties
%8 November 9, 2011
%9 Presentation
%Z presented
%M GCE.696
%X The availability of high resolution remotely sensed imagery permits improved geospatial analyses over large domains. As an effective tool for coastal mapping, remote sensed data provides the foundation for revealing distinct spatial patterns or processes unseen during small scale sampling and offers validation of localized theoretical predictions. Salt marsh communities are highly dependent on specific tolerances to several environmental conditions, providing distinct zonations of dominant species. In this study, we addressed the following: (1) how effective are selected vegetation indices and landscape metrics for revealing distinguishable salt marsh spatial patterns within and between seven National Estuarine Research Reserves along the Gulf and Atlantic coasts (TX, MS, FL, GA, SC, DL, MD), and (2) how are these patterns relatable to localized site factors, such as climatology, hydrology and water quality? Using 1.0 and 1.5 m AISA hyperspectral imagery obtained between 2002 and 2010 and ENVI 4.6 and FRAGSTATS 3.3 software, we developed procedures to delineate salt marsh habitats, calculated three vegetation indices (VIs) and applied two landscape metrics to classified images. NDVI and MSAVI indices highlighted variations in structure, relative biomass, greenness and plant vigor. The third index, VARI, showed increased sensitivity for revealing green photosynthetic capacity and phenological changes within the canopy. In general, sites with higher inorganic nitrogen and/or tidal amplitudes had the highest VI values. Furthermore, patch per unit area (PPU) and Shannon Diversity Index (SDI) metrics were applied to each site, examining the density and equitability of patches using a user defined classification scheme. The Texas site (Aransas NWR) had some of the lowest VIs but the highest PPU values. Conceptual models linking system drivers to marsh structure will be presented.
%A Seminara, D.N.
%A Schalles, John F.
%K Salt marsh, vegetation, remote sensing, community structure, vegetation index

%0 Generic
%T Recommended indicators of estuarine water quality for Georgia
%D 2011
%I Proceedings of the 2011 Georgia Water Resources Conference
%C University of Georgia, Athens, Georgia
%B Georgia Water Resources Conference
%9 Article
%Z published
%M GCE.671
%X Increasing nutrient input and subsequent eutrophication and hypoxia are concerns in many estuaries,and the U.S. EPA has mandated the development of numeric nutrient criteria to assess the status of U.S. coastal waters. However, they recognize the need for regionally appropriate criteria, as previous national-level efforts have often relied on criteria that are not equally relevant in all waters. Two pathways to eutrophication have been suggested to exist in Georgia waters: the classic phytoplankton-mediated pathway in stratified waters and an alternate pathway in which excess nutrients stimulate microbial respiration directly, resulting in low dissolved oxygenthroughout a well-mixed water column. We propose a suite of seven indicators, as well as basic ancillary data (water temperature, salinity, specific conductance), that are intended to help classify and understand the causes of water quality degradation in Georgia. We recommend two immediate indicators of poor water quality (pH and dissolved oxygen) that may indicate that a stressful and potentially lethal condition is already in progress. The remaining five (nitrogen, phosphorus, chlorophyll a, transparency, and biochemical oxygen demand (BOD)) are “early warning” indicators of potentially poor water quality that should be measured in order to anticipate problems and make appropriate management decisions. These indicators, which cover the progression of eutrophication from nutrient over-enrichment to algal overgrowth (if present) to enhanced microbial respiration and hypoxia, will help to ensure that problems will not be missed due to limited sampling frequencies. We present the rationale for choosing these indicators and the considerations for developing evaluation criteria.
%A Sheldon, Joan E.
%A Alber, Merryl
%E Carroll, G. Denise
%K water quality, indicator

%0 Newspaper Article
%T Mining Long-term Data from the Global Historical Climatology Network
%D 2011
%I Long Term Ecological Research Network
%C Albuquerque, New Mexico
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Fall 2011
%9 Article
%Z published
%M GCE.693
%X Long-term climate data are critically important for climate change research, but are also needed to parameterize ecological models and provide context for interpreting research study findings. Consequently, climate data are among the most frequently-requested data products from LTER sites. This fact was a prime motivating factor for development of the LTER ClimDB database from 1997 to 2002. However, direct climate measurements made at the Georgia Coastal Ecosystems LTER site (GCE) are currently fairly limited, both geographically and temporally, because our monitoring program began in 2001. Therefore, in order to put results from GCE studies into broader historic and geographic context and to support LTER cross-site synthesis projects, we rely on climate data collected near the GCE domain from an array of long-term National Weather Service stations operated under the Cooperative Observer Program.  Data from NWS-COOP stations are distributed through the NOAA National Climatic Data Center, so we have periodically requested data from NCDC for these ancillary weather stations to supplement GCE data. Unfortunately, this entire process ground to a halt in April 2011 when NOAA announced that it was abandoning the traditional COOP/Daily data forms, meaning that daily summary data sets would not be available from the existing web application beyond December 2010. We clearly needed to find a new source for NWS-COOP data.
%U https://lternet.edu/wp-content/uploads/2018/01/2011-fall-lter-databits.pdf
%A Sheldon, Wade M., Jr.
%K MATLAB, climate, weather, data, NCDC, NOAA, Internet, LTER-IMC

%0 Conference Proceedings
%T GCE Data Toolbox: Metadata-driven Software for Data Acquisition, Quality Control and Synthesis
%D 2011
%C Jekyll Island, Georgia
%B 2011 LTER Science Council Meeting
%8 May 18-19, 2011
%9 Poster
%Z presented
%M GCE.621
%X The effort required to process, document, and quality control raw data from sensors is often a limiting step in bringing environmental data online. Similarly, the effort required to find, download and refactor data collected by others can prove limiting in large-scale synthesis efforts. However, the GCE Data Toolbox (MATLAB-based software developed at GCE-LTER) has proven effective in overcoming both of these barriers. This software can automate processing of data collected by a wide variety of data logger systems, from initial acquisition through quality control and distribution of documented data sets and plots. It is equally adept at harvesting and integrating existing data from national monitoring programs and environmental databases (e.g. LTER ClimDB/HydroDB, USGS NWIS, NOAA NCDC, NOAA NERR). This poster provides a brief overview of the toolbox, which is freely available for use by other LTER sites.
%U http://gce-lter.marsci.uga.edu/public/files/pubs/WSheldon_Toolbox_Poster_SC2011.pdf
%A Sheldon, Wade M., Jr.
%K MATLAB, data, acquisition, quality control, synthesis, software, LTER-IMC

%0 Conference Proceedings
%T GCE Data Toolbox: Metadata-driven Software for Data Acquisition, Quality Control and Synthesis
%D 2011
%C Santa Barbara, California
%B Environmental Information Management Conference 2011
%8 September 28-29, 2011
%9 Poster
%Z accepted
%M GCE.628
%X The effort required to process, document, and quality control raw data from sensors is often a limiting step in bringing environmental data online. Similarly, the effort required to find, download and refactor data collected by others can prove limiting in large-scale synthesis efforts. However, the GCE Data Toolbox (MATLAB-based software developed at the Georgia Coastal Ecosystems LTER) has proven effective in overcoming both of these barriers. This software can automate processing of data collected by a wide variety of data logger systems, from initial acquisition through quality control and distribution of documented data sets and plots. It is equally adept at harvesting and integrating existing data from national monitoring programs and environmental databases (e.g. LTER ClimDB/HydroDB, USGS NWIS, NOAA NCDC, NOAA NERR). This poster provides a brief overview of this software, which is freely available under an open source license.
%U http://gce-lter.marsci.uga.edu/public/files/pubs/wsheldon_eimc2011_poster.pdf
%A Sheldon, Wade M., Jr.
%K software, quality, control, sensors, synthesis, MATLAB, LTER-IMC

%0 Conference Proceedings
%T Dynamic, Rule-based Quality Control Framework for Real-time Sensor Data
%D 2011
%C Hubbard Brook Experimental Forest, Woodstock, New Hampshire
%B Northeast Environmental Sensor Workshop
%S Streaming QA/QC
%8 October 24-27, 2011
%9 Presentation
%Z presented
%M GCE.691
%X Quality Control of high volume, real-time data from automated sensors is an emerging challenge. Traditional techniques (e.g. plotting, statistics) often don't scale well. As a result, data validation and quality control can be a limiting factor in getting data online. Difficulties can also lead to release delays or posting provisional data. The GCE Data Toolbox (MATLAB-based software developed at GCE-LTER) has proven useful for Q/C of real-time data. This software was designed to automate GCE data processing, QA/QC and metadata generation, but is very generalized and supports any tabular data. It also provides a dynamic, rule-based Q/C framework for data processing, analysis and synthesis.
%U http://gce-lter.marsci.uga.edu/public/uploads/Sheldon_QC_SensorNIS_Oct2011_20111114T132505.pdf
%A Sheldon, Wade M., Jr.
%K quality control, data, sensor, MATLAB, toolbox, statistics, LTER-IMC

%0 Newspaper Article
%T Putting It Out There – Making the Transition to Open Source Software Development
%D 2011
%I Long Term Ecological Research Network
%C Albuquerque, New Mexico
%B LTER Databits - Information Management Newsletter of the Long Term Ecological Research Network
%S Spring 2011
%9 Article
%Z published
%M GCE.619
%X I have spent a significant portion of my scientific career developing and customizing computer software, both to process and analyze research data, and to build systems to disseminate these data to others. Throughout this time I did what the majority of scientists do, and kept this code mostly to myself. There were many reasons for my closed development approach, from the practical ("the code isn't sufficiently documented for someone else to use") to the paranoid ("I don't have time to answer questions or help people use it") to the proprietary ("why should I give away my hard work for free"). But looking back, one of the primary drivers for my attitude was a negative experience early in my career when I found myself competing against my own software for salary money, and lost. A former research colleague found it more cost-effective to hire an undergraduate student to run my software (developed for another project and shared) than to include me on the new project as a collaborator. Although that issue was eventually overcome, it had a lasting impact on my attitude regarding giving away source code.
%U https://lternet.edu/wp-content/uploads/2017/12/2011-spring-lter-databits.pdf
%A Sheldon, Wade M., Jr.
%K software, development, open source, sharing, code, LTER-IMC

%0 Generic
%T A Coastal Water Quality Metadata Database for the Southeast U.S.A.
%D 2011
%I Proceedings of the 2011 Georgia Water Resources Conference
%C The University of Georgia, Athens, Georgia
%B Georgia Water Resources Conference
%S Watershed Informatics
%8 April 11-13, 2011
%9 Article
%Z published
%M GCE.618
%X This paper describes the development and initial implementation of a Coastal Water Quality Monitoring Metadata Database for the Southeast region (from NC to FL), which was developed with funding from the National Park Service. The database was designed to store detailed information on water quality monitoring programs operated by federal, state and municipal agencies, as well as by research institutions, including monitoring station locations, measured parameters, program contacts, and links to program web pages and data downloads. Water quality parameter records are classified into parameter groups and categories to support searches at varying levels of specificity, and are matched to US EPA STORET codes when possible for interoperability with federal databases. Fields for defining sample media, units and methodology are also provided for additional context. A prototype web portal, web services and mapping services were developed to support search and display of database contents, and to support leveraging by other database and portal efforts. Information from 41 monitoring programs in the South Atlantic was initially loaded into the database in 2009, including metadata on 16,182 stations at which 1093 distinct parameters are measured; the number of programs is currently being expanded. This database provides an ongoing inventory of monitoring activities for the southeast region and will help to facilitate identification of data gaps or under- or over-sampled areas. On a broader scale, the project’s water quality metadata database and web portal have timely relevance to the broad community of coastal managers, researchers, planners and constituents as they make significant progress in leveraging and focusing regional associations and partnerships.
%U http://gce-lter.marsci.uga.edu/public/uploads/WSheldon_GWRC2011_final_20110503T123945.pdf
%A Sheldon, Wade M., Jr.
%A Laporte, Christine
%A Douce, Travis
%A Alber, Merryl
%E Carroll, G. Denise
%K database, metadata, water quality, USGS, EPA, NPS, measurements, LTER-IMC

%0 Conference Proceedings
%T Colliding Worlds: Anthropology, Ecosystem Science, and Community
%D 2011
%B the Anthroplus Conference. Department of Anthropology, University of Maryland, College Park.
%9 Keynote Address
%Z presented
%M GCE.643
%A Thompson, Victor D.
%K Public Education, Applied Archaeology, Ecosystem Science

%0 Journal Article
%T Evaluating Mobility, Monumentality, and Feasting at the Sapelo Island Shell Ring Complex
%D 2011
%V 76
%N 2
%P 315-343
%B American Antiquity
%9 Article
%Z published
%M GCE.617
%X wo of the most salient anthropological questions regarding southeastern shell ring sites are related to the season(s) that they were occupied and whether or not the deposits represent monumental constructions and/or feasting remains. This paper addresses these questions through the analysis of growth band of clams (Mercenaria spp.) (N = 620) and stable oxygen isotope ratios of clam and oyster shells (Crassostrea virginica) (N = 58) at the Sapelo Island Shell Ring complex located on the Georgia coast, USA. The season of death and the samples 'position in the shell matrix at Sapelo provide important information on the rate of shell deposition and the season(s) the site was occupied. These data support the view that at least some portion of the human population at Sapelo occupied the site year-round. Additionally, while it appears that two shell rings at the site formed through the gradual deposition and accumulation of daily subsistence, other areas evidence short term, large-scale, shellfish processing and may lend credence to the view that at some point shell rings become monuments, commemorating rituals and gatherings.
%A Thompson, Victor D.
%A Andrus,  C. F.T.
%K shell, sapelo, mobility, monumentality

%0 Conference Proceedings
%T Assessing Habitats of Mollusk Collection and Models of Late Archaic Settlement along the Atlantic Coast, USA using Oxygen Isotope Sclerochronology
%D 2011
%B Society for Ethnobiology
%9 Article
%Z presented
%M GCE.641
%A Thompson, Victor D.
%A Andrus,  C. F.T.
%K Sclerochronology, Late Archaic, Oxygen Isotope

%0 Conference Proceedings
%T Entangling Events: The Guale Landscape and the Spanish Missions
%D 2011
%B New Perspectives on the Native American Archaeology of the Georgia Bight, the American Museum of Natural History Caldwell VI Conference. St. Catherine’s Island, Georgia.
%9 Article
%Z presented
%M GCE.642
%A Thompson, Victor D.
%A Turck, John A.
%A DePratter, Chester
%K Spanish, Guale, Back Barrier Island, Settlement, Student Publication

%0 Journal Article
%T A framework to study the context-dependent impacts of marine invasions
%D 2011
%V 400
%P 322-327
%B Journal of Experimental Marine Biology and Ecology
%9 Article
%Z published
%M GCE.653
%R 10.1016/j.jembe.2011.02.033
%X The ecological impacts of marine invasive species vary according to the spatial and temporal scale of analysis, thereby challenging the extraction of generalities about underlying mechanisms. Here, we applied a broad impact framework that addresses this scale-dependency, to test if general drivers of impacts can be identified and quantified from marine invasion experiments. This framework explains variability in impacts according to the unique (specific) and universal (general) attributes of the (1) invasive organism, (2) resident biota, (3) resource levels, and (4) abiotic conditions. In this framework, unique and universal attributes encompass the properties that are either ecologically relevant to only a few specific invasions (e.g. a unique toxin) or to most invasions (e.g. invader density, size, age or longevity), respectively. We reviewed 88 published marine invasion impact experiments, where 18 tested for effects of universal and 11 for unique attributes of the invasive organism (63 tested for presence.absence effects, where these attributes are confounded). A meta-analysis confirmed that the species identity and density (representing a unique and universal attribute, respectively) of the invader significantly predicted impacts. These attributes should, therefore, whenever possible, be treated as separate impact-modifiers. By contrast, very few experiments have tested if universal or unique attributes of the resident biota, the resource levels or the abiotic conditions modify invasion impact. This highlights a major research gap; quantitative syntheses cannot be undertaken until more factorial experiments have manipulated the invasive species and habitat-associated drivers in concert (with .2 treatments per test factor). In conclusion, to facilitate a broader understanding of marine invasion impacts, we advocate that universal and unique impact-components, whenever possible, are treated as separate test entities that should be examined for each of the four impact drivers.
%U https://www.sciencedirect.com/science/article/pii/S0022098111000815
%A Thomsen, Mads S.
%A Wernberg, Thomas
%A Olden, J.
%A Griffin, John
%A Silliman, Brian R.
%K marine, invasion, impact

%0 Journal Article
%T A broad framework to organize and compare invasive species impacts
%D 2011
%V 111
%P 899-908
%B Environmental Research
%9 Article
%Z published
%M GCE.754
%X Invasive species have transformed local, regional and global biotas; however, few generalities about the mechanisms driving impacts of invaders have emerged. To explain variation in impacts among studies, we propose a broad framework that separates drivers of impacts into universal and unique attributes of the invasive species and the invaded habitat. Universal attributes are relevant to all invasions whereas unique attributes are distinct to a specific invasion. For example, impacts associated with the abundance of any invader or the properties of a specific invader (e.g., a rare toxin) represent a universal and unique impact attribute. Through meta-analyses of aquatic field experiments, we demonstrate the utility of our framework, documenting that both the abundance and the taxonomic identity of the invader significantly influence invasion outcomes for marine and freshwater plant and animal invaders. Our review also highlights that many more experiments are needed to test for universal attributes, such as priority effects, age and size, and how the attributes of the invaded habitat further modify invasion impacts. We hope that our framework will stimulate experimental invasion ecology and begin to reconcile the idiosyncrasies that currently impede the development of a unified framework for invasion impacts.
%A Thomsen, M. S
%A Wernberg, T.
%A Olden, J.
%A Griffin, John N.
%A Silliman, Brian R.
%K Invasions-impact, Field experiments, Meta-analysis

%0 Thesis
%T Geoarchaeological analysis of two back-barrier islands and their relationship to the changing landscape of coastal Georgia, U.S.A.
%D 2011
%P 239
%I University of Georgia
%C Athens, GA
%9 Ph.D. Dissertation
%Z published
%M GCE.667
%R 10.6073/pasta/d4e6577aa7dfcc6f2f36781f162a4124
%X This study examines the past human settlement system on the coast of Georgia from 12,000-1,000 B.P. (the Paleoindian through Late Woodland periods) in relation to landscape change. I take a landscape approach to understanding settlement, incorporating geomorphology, formation processes, a distributional approach to archaeological data, and landscape ecology metrics. Archaeological surveys of two back-barrier islands, Mary Hammock (9MC351) and Patterson Island (9MC493), are combined with non-archaeological paleoenvironmental data, and compared to changes in sea level, and to archaeological surveys from other environmental settings, to understand the change in human occupation in McIntosh County, GA. Numerous environmental datasets, including present-day elevations, former surfaces under the marsh, bathymetric data, soils, and wetlands, were incorporated together. These data were combined with changes in sea level over time, creating a dynamic model of landscape change. This model is used to create predictions about human settlement patterns in relation to the marsh-estuarine system for McIntosh County in general, and the back-barrier area specifically. These predictions were then tested with prehistoric site distributions of McIntosh County, as well as to prehistoric sherd densities of various surveys. Analysis revealed that terminal Middle Archaic sites (~5,000 B.P.) with evidence of coastal adaptations should be found within present-day McIntosh County. Because there are no such sites, I suggest that there may have been an abandonment of the coast at this time. The explosion in Late Archaic sites, then, may have been from an influx of people to the Georgia coast. Back-barrier islands were always part of the settlement system. The intensity of back-barrier island utilization may be related to their proximity to larger landmasses (the mainland and major barrier islands), and the different types of settlement systems associated with those landmasses. The intense utilization of back-barrier islands at certain times suggests that they may have been permanently settled. Another explanation for their intense use may be that these are relatively small islands where activities would have been concentrated. The predictions of the model were not always substantiated, indicating that changes in sea level and marsh-estuarine resources were not the only reason for changes in settlement and subsistence patterns.
%U http://gce-lter.marsci.uga.edu/public/uploads/GCEPub667_Turck_PhD_2011_20120125T93415.pdf
%A Turck, John A.
%K Archaeology, Geomorphology, Settlement patterns, Landscape change, Sea level, Back-barrier, Marsh, Islands, Mary Hammock, Patterson Island, Student Publication

%0 Conference Proceedings
%T A Siteless Approach to Comparing Multiple Surveys on the Georgia Coast
%D 2011
%C Jacksonville, FL.
%B 68th Annual Meeting of the Southeastern Archaeological Conference
%8 11/03/2011
%9 Presentation
%Z presented
%M GCE.712
%A Turck, John A.
%K Archaeological Surveys, Back-barrier Islands, Sea Level and Marsh Modeling, Student Publication

%0 Conference Proceedings
%T Settlement, Sea Level, and Landscape: The Dynamic Interaction between Humans and Environment
%D 2011
%I Department of Anthropology, the Ohio State University
%C Columbus
%8 11/28/2011
%9 Presentation
%Z presented
%M GCE.711
%A Turck, John A.
%K Archaeological Surveys, McIntosh County, Back-barrier Islands, Sea Level and Marsh Modeling, Student Publication

%0 Conference Proceedings
%T Coastal Landscapes and their Relationship to Human Settlement on the Georgia Coast
%D 2011
%I American Museum of Natural History
%C St. Catherines Island, GA.
%B Sixth Annual Caldwell Conference
%8 05/21/2011
%9 Presentation
%Z presented
%M GCE.713
%A Turck, John A.
%A Alexander, Clark R., Jr.
%K Archaeology, Geomorphology, Vibracoring, Back-barrier, Inter-barrier, Recurved Spit, Student Publication

%0 Report
%T An Archaeological Survey of Mary Hammock (9MC351), McIntosh County, Georgia
%D 2011
%I University of Georgia
%C Athens, Georgia
%B Georgia Archaeological Site File
%9 Report
%Z published
%M GCE.709
%A Turck, John A.
%A Thompson, Victor D.
%K Mary Hammock, Back-barrier Island, Archaeological Survey, Vibracoring, Student Publication

%0 Report
%T An Archaeological Survey of Patterson Island (9MC493), McIntosh County, Georgia.
%D 2011
%I Report on file, Georgia Archaeological Site File
%C Athens
%9 Report
%Z published
%M GCE.786
%A Turck, John A.
%A Thompson, Victor D.
%K Archaeology, Patterson Island, Survey, Student Publication

%0 Conference Proceedings
%T Quantifying The Threat To Archaeological, Historic And Cultural Resources From Shoreline Change: The Georgia Coast Example.
%D 2011
%I Geological Society of America
%C Wilmington, NC
%B Geological Society of America Abstracts with Programs
%S No. 2
%8 March 23-25
%9 Abstract
%Z published
%M GCE.825
%X Coastal Georgia is a dynamic environment. Frequently, shoreline erosion along open coastlines and bluffs of tidal streams impacts important archaeological sites by exposing, removing and destroying burials, structures, and artifacts. In this study we identified sites on barrier islands and back-barrier islands (“marsh hammocks”) in coastal Georgia that are threatened and/or are being damaged by coastal erosion, evaluated their site condition and prioritized them based on the order of site loss.All archaeological sites within a 30 m radius of a waterway or marsh environment were selected from the Georgia Archaeological Site file (GASF) database, as these were the sites that might be destroyed within the next 50 years, based on average back-barrier erosion rates. This list was evaluated by the Georgia Department of Natural Resources – Historic Resources Division (DNR-HPD) to identify sites that were potentially listable on the Federal Register of Historic Places. For each of the identified sites, individual GIS projects were generated in ARCGIS 9.3 that included a current, GPS-surveyed shoreline and shorelines derived from historic maps and aerial imagery. AMBUR (Analysis of Moving Boundaries Using “R”) was then used to calculate shoreline change rates. Using these site-specific rates, we created a prioritized list of archaeological sites based on the time until the site was destroyed by erosion and the information contained within them was lost.For the 21 selected sites on barrier islands, 11 shorelines (52%) were eroding, 8 were stable, and 2 were accreting. For the 36 selected sites on back-barrier islands, 29 shorelines (81%) were eroding, and 7 were stable. Higher shoreline change rates were observed at barrier island sites (up to -1.68 m/y erosion) when compared to back-barrier island sites (rates up to -0.72 m/y erosion), although the dynamic back-barrier environment exhibited a higher percentage of erosional sites. Consequently, archaeological sites on barrier islands experience a higher annual percentage loss of site information than sites on back-barrier islands. The projected lifetime of sites varies greatly, ranging from less than a year (and some sites had completely eroded away at the time of our survey) to several hundred years depending on shoreline change rate, site location and site size.
%A Venherm, Claudia
%A Alexander, Clark R., Jr.
%A Mccabe, C.
%A Perez-Sanchez, N.
%A Jackson, C.W.
%A Crass, D.
%A Robinson, Michael
%K Archaeology, Cultural Resources, Shoreline Change, Georgia Coast

%0 Conference Proceedings
%T Crab mediated tidal creek formation in salt marshes
%D 2011
%I Coastal and Estuarine Research Federation
%C Daytona Beach, FL
%B Coastal and Estuarine Research Federation
%8 November 6-11
%9 Presentation
%Z presented
%M GCE.692
%A Vu, Huy
%A Wieski, Kazimierz
%A Pennings, Steven C.
%K Sesarma, creek, sea-level rise, Student Publication

%0 Journal Article
%T Storm-driven groundwater flow in a salt marsh
%D 2011
%V 47
%N 2
%P 1-11
%B Water Resources Research
%9 Article
%Z published
%M GCE.870
%R 10.1029/2010WR009496
%X Storms can cause significant groundwater flow in coastal settings, but prior studies of the effects of storms on groundwater flow and transport have largely focused on very large storms and used salinity as a tracer. We have little information about the effects of smaller storms on coastal flow and how storm-induced variability affects key tidal wetlands like salt marshes, which may remain saline throughout a storm. Here we show that even the distant passage of a moderate storm can strongly increase groundwater flow and transport in salt marsh ecosystems and adjacent barrier islands. Groundwater monitoring and radium isotope tracer analyses revealed significant influx of saline creek water into the confined aquifer below the marsh platform, driven by storm surge. This pulse of fluids reached depths exceeding 5 m, and surge-enhanced tides propagated through the aquifer to affect flow in the upland >100 m from the creek bank. Groundwater discharge from the marsh varied significantly prior to the storm, doubling during inundating tides compared to a period of noninundating neap tides. Storm surge then caused groundwater discharge to decline &#8764;50% compared to similar inundating tides. Ra- and nutrient-poor creek water that entered the confined aquifer below the marsh was quickly enriched in nutrients and carbon, even on 12 h tidal cycles, so that nutrient discharge was likely proportional to groundwater discharge. Storm-related flow could also drive significant contaminant discharge from developed coastlines. The enhanced transport and variability observed here likely affected hundreds of kilometers of the coastline impacted by the storm.
%U http://onlinelibrary.wiley.com/doi/10.1029/2010WR009496/pdf
%A Wilson, Alicia M.
%A Moore, Willard S.
%A Joye, Samantha B.
%A Anderson, J.
%A Schutte, Charles
%K submarine groundwater discharge, salt marsh, coastal hydrogeology, nutrient budgets, tidal fluctuations, storms, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T Geophysical Characterization of the Duplin River
%D 2011
%C Jekyll Island, Georgia
%B 2011 LTER Science Council Meeting
%8 May 2011
%9 Poster
%Z presented
%M GCE.662
%A Young, David
%A McHugh, Christopher
%A Viso, Richard F.
%A Peterson, Richard N.
%K Seismics, Chirp, geophysics, Duplin River, Resistivity, Student Publication

%0 Journal Article
%T Abiotic stress mediates top-down and bottom-up control in a Southwestern Atlantic salt marsh
%D 2010
%V 163
%P 181-191
%B Oecologia
%9 Article
%Z published
%M GCE.659
%R 10.1007/s00442-009-1504-9
%X Increasing evidence has shown that nutrients and consumers interact to control primary productivity in natural systems, but how abiotic stress affects this interaction is unclear. Moreover, while herbivores can strongly impact zonation patterns in a variety of systems, there are few examples of this in salt marshes. We evaluated the effect of nutrients and herbivores on the productivity and distribution of the cordgrass Spartina densiflora along an intertidal stress gradient, in a Southwestern Atlantic salt marsh. We characterized abiotic stresses (salinity, ammonium concentration, and anoxia) and manipulated nutrients and the presence of the herbivorous crab Neohelice (Chasmagnathus) granulata, at different tidal heights with a factorial experiment. Abiotic stress increased at both ends of the tidal gradient. Salinity and anoxia were highest at the upper and lower edge of the intertidal, respectively. Nutrients and herbivory interacted to control cordgrass biomass, but their relative importance varied with environmental context. Herbivory increased at lower tidal heights to the point that cordgrass transplants onto bare mud substrate were entirely consumed unless crabs were excluded, while nutrients were most important where abiotic stress was reduced. Our results show how the impact of herbivores and nutrients on plant productivity can be dependent on environmental conditions and that the lower intertidal limits of marsh plants can be controlled by herbivory.
%U http://www.springerlink.com/content/t2517rh1590t2812/
%A Alberti, J.
%A Casariego, A. M.
%A Daleo, P.
%A Fanjul, E.
%A Silliman, Brian R.
%A Bertness, Mark D.
%A Iribarne, O.
%K abiotic, stress, top-down, bottom-up, salt marsh, atlantic, Student Publication

%0 Conference Proceedings
%T Physical-Biological Interactions in Coastal Settings: The Georgia Coastal Ecosystem LTER Example
%D 2010
%C Foz do Iguacu, Brazil
%B American Geophysical Union - Meeting of the Americas
%8 9-13 August 2010
%9 Presentation
%Z presented
%M GCE.582
%X The goal of the Georgia Coastal Ecosystem Long-Term Ecosystem Research (GCE-LTER) project is to understand the mechanisms by which variation in the quality, source and amount of both fresh and salt water create temporal and spatial variability in estuarine habitats and processes, in order to predict directional changes that will occur in response to long-term shifts in estuarine salinity patterns.  Back-barrier islands found along the southeastern Atlantic coast of the United States, colloquially known as hammocks are common topographic highs in the back-barrier environment.  These islands are surrounded by Spartina alterniflora salt marsh, are of limited area and elevation (dominantly less than 10 hectares and less than 2 m above mean sea level), can be either Pleistocene or Holocene in age, and can have natural or anthropogenic origins.  Because of their intimate connection to the marsh, hammocks are a focus of study within the GCE-LTER.  To further understand these features, a broad survey of 50 hammocks of different origin and size was carried out to characterize their morphology, texture, general stratigraphy and adjacent vegetative communities.  The morphology of the Holocene and Pleistocene hammocks differs significantly, with the former being long and linear, with discernible topographic relief across its profile, and the latter more equidimensional and without significant topographic relief.  Stratigraphically, Holocene hammocks consist of unconsolidated sediments.  Pleistocene hammock stratigraphy is more varied and some units can be semi-indurated.  Interestingly, both hammock types appear to rest atop older marsh deposits, suggesting that in many cases their origins may be similar and stratigraphic variability is more a function of time since formation.  The formative processes of these features are being investigated by examining age control (using C-14 and OSL dating), grain size, sedimentary structure and stratigraphyThe vegetative communities surrounding hammocks within the GCE-LTER was surveyed in the summer of 2007.  Sub-meter accuracy GPS units were used to map the hammock upland border and the extent of the upper marsh (from the hammock border to the upper edge of Spartina alterniflora, i.e. the marsh “halo”), and plants within the halo were characterized.  Analysis of these data showed that marsh plant community composition directly adjacent to the upland border is affected by both the size and origin of the hammock. Additionally, there are significant differences in both the mean halo width and the dominant plant species in relation to hammock size and origin.  These hammocks and their surrounding “halos” are being altered as sea level rises (at 3 mm/y).  Loss of upland to encroaching salt marsh as sea level rises should lead to a commensurate change in the salt marsh community structure, given the positive relationship between hammock size and halo width.  With the anticipated increase in rates of sea level rise associated with climate change, we can anticipate a more rapid loss of uplands and alteration of salt marsh ecosystems in the future.
%A Alexander, Clark R., Jr.
%A Alber, Merryl
%A Hladik, Christine M.
%A Pennings, Steven C.
%K Coastal, stratigraphy, sediments, marsh, halo, borrichia, spartina, juncus, Student Publication

%0 Journal Article
%T Facilitation cascade explains positive relationship between native biodiversity and invasion success
%D 2010
%V 91
%P 1269-1275
%B Ecology
%9 Article
%Z published
%M GCE.655
%R 10.1890/09-1301.1
%X The pervasive impact of invasive species has motivated considerable research to understand how characteristics of invaded communities, such as native species diversity, affect the establishment of invasive species. Efforts to identify general mechanisms that limit invasion success, however, have been frustrated by disagreement between landscape-scale observations that generally find a positive relationship between native diversity and invasibility and smaller-scale experiments that consistently reveal competitive interactions that generate the opposite relationship. Here we experimentally elucidate the mechanism explaining the large-scale positive associations between invasion success and native intertidal diversity revealed in our landscape-scale surveys of New England shorelines. Experimental manipulations revealed this large-scale pattern is driven by a facilitation cascade where ecosystem-engineering species interact nonlinearly to enhance native diversity and invasion success by alleviating thermal stress and substrate instability. Our findings reveal that large-scale diversity–invasion relationships can be explained by small-scale positive interactions that commonly occur across multiple trophic levels and functional groups. We argue that facilitation has played an important but unrecognized role in the invasion of other well studied systems, and will be of increasing importance with anticipated climate change.
%U http://www.esajournals.org/doi/abs/10.1890/09-1301.1
%A Altieri, Andrew H.
%A van Wesenbeeck, Bregje K.
%A Bertness, Mark D.
%A Silliman, Brian R.
%K biodiversity, ecosystem engineer, facilitation cascade, foundation species, invasion paradox, invasive species, marine conservation, nonlinear ecological interactions, Student Publication

%0 Journal Article
%T Blue crab (Callinectes sapidus Rathbun, 1896) settlement at three Georgia (USA) estuarine sites.
%D 2010
%V 33
%P 688-698
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.609
%R 10.1007/s12237-009-9259-4
%X The blue crab, Callinectes sapidus Rathbun, 1896, represents the second most important fishery for coastal Georgia; yet, little is known about environmental forces that affect planktonic postlarval settlement in the region. Here, we describe a study to examine the physical mechanisms responsible for blue crab settlement in the extensive salt marsh system of coastal Georgia. Bottom and surface samplers were placed at three sites along a salinity gradient from a low-salinity site in the Altamaha River to a high-salinity area of the Duplin River, Sapelo Island, GA, USA during 2005. Megalopae and juvenile monitoring occurred from July through December. The majority of both megalopae (86.8%) and juvenile (89.3%) blue crabs were recovered in bottom samplers at the low-salinity Altamaha River site during August and early September. Few megalopae were collected at the surface of the Altamaha River or at the two higher-salinity sites in the Duplin and North Rivers. Downwelling winds were unable to explain all settlement events; however, winds with an onshore component regularly preceded settlement events. The use of a multiple-regression model revealed a lagged relationship (r&#8201;=&#8201;0.5461, lag = 0–2 days) between wind events, temperature, salinity, maximum tidal height, and settlement.
%U http://www.springerlink.com/content/w72171p1560t652v/
%A Bishop, Thomas Dale
%A Miller, H. L., III
%A Walker, Randall L.
%A Hurley, Dorset
%A Menken, Theron
%A Tilburg, Charles E.
%K Blue crab, Callinectes sapidus, Postlarvae, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Transport and retention of a conservative tracer in an isolated creek–marsh system
%D 2010
%V 87
%P 333-345
%B Estuarine, Coastal and Shelf Science
%9 Article
%Z published
%M GCE.569
%R 10.1016/j.ecss.2010.01.010
%X A study of tracer transport and retention in a small tidal creek and marsh system located in the southeastern US was conducted using a three-dimensional hydrodynamic model and data from a dye tracer release. The model simulated tidally driven flow, including inundation and drying out of the marshes and the dispersal of the dye tracer. Flow measurements in the tidal creek showed that the simulations appeared to generally duplicate the tidally driven flow into and out of the tidal creeks and marshes. The dye tracer experiment was conducted to test the hydrodynamic model’s ability to simulate dispersal of a point release of pollutants into the creek during an incoming tide. The simulations reproduced much of the experimental measurements, but bathymetric errors and lack of resolution of the smallest arms of the tidal creeks affected the ability to faithfully reproduce the initial peak in measured dye tracer concentrations at a sampling location far from the boundary. The lack of the smallest tidal creeks led to some trapping of water and dye in the marshes. Two independent estimates of flushing time yielded values between 1.6 and 2.4 days. An uncertainty analysis indicates that model simulations are sensitive to variations in parameters such as water depth and marsh grass density. On the other hand, omission of the smallest tidal creeks in simulations may be partially offset by decreasing marsh grass density. Further improvements must rely on more accurate and detailed bathymetric data that resolves the smaller arms of the tidal creeks and includes quantitative information about the density and distribution of marsh grass.
%U http://dx.doi.org/10.1016/j.ecss.2010.01.010
%A Blanton, Jackson O.
%A Garrett, A.
%A Bollinger, J.
%A Hayes, D.
%A Koffman, L.
%A Amft, Julie
%A Moore, Trent C.
%K tidal creek intertidal area flushing time conserva

%0 Journal Article
%T Avian communities of the Altamaha River estuary in Georgia, USA
%D 2010
%V 122
%N 3
%P 532–544
%B The Wilson Journal of Ornithology
%9 Article
%Z published
%M GCE.560
%R 10.1676/09-186.1
%X We surveyed male breeding birds in five habitats (bottomland forest, maritime oak [Quercus spp.], pine [Pinus spp.] forest, maritime shrub, saltmarsh) of coastal Georgia, USA using distance-sampling methods to estimate population densities. We examined species-habitat relationships using indicator species analysis (ISA). Acadian Flycatcher (Empidonax virescens) in bottomland forest, Northern Parula (Parula americana) in maritime oak, Brown-headed Nuthatch (Sitta pusilla) in pine forest, Clapper Rail (Rallus longirostris) in saltmarsh, and White-eyed Vireo (Vireo griseus) in shrub habitat ranked highest for Partners in Flight (PIF) priority species by densities. The ISA indicated fewer PIF priority species were associated with saltmarsh, but more species (6) were unique to saltmarsh than any other habitat. Indicator species occurred more often in maritime oak than bottomland forest (8 vs. 6), but both habitats had similar numbers of PIF priority species (4). Shrub habitat covered the smallest area (,0.2%) and had three PIF priority species, including Painted Bunting (Passerina ciris), the only PIF species with extremely high priority in this study.
%U https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/09-1301.1
%A Brittain, Ross
%A Meretsky, Vicky J.
%A Craft, Christopher B.
%K birds, species of concern, salt marsh, tidal forest, maritime forest, live oak forest, pine forest, SINERR Publication, Student Publication

%0 Journal Article
%T Effects of upwelling on short term variability in microbial processes in estuarine sediments
%D 2010
%V 58
%P 261-271
%B Aquatic Microbial Ecology
%9 Article
%Z published
%M GCE.477
%R 10.3354/ame01387
%X We examined short-term variability in sediment microbial processes and biogeochemistry in response to decreased irradiance accompanying an upwelling event. Potential nitrification, extractable nutrients, solid phase iron and pore water sulfide concentrations were measured several times at 3 locations in Elkhorn Slough, California, USA. Benthic fluxes of nitrate+nitrite, ammonium, phosphate, sediment oxygen consumption and denitrification from N2/Ar flux were also measured. Fog that was associated with upwelling in Monterey Bay reduced photosynthetically active radiation in Elkhorn Slough, which led to increased duration of water column hypoxia. Solid phase Fe3+ concentrations and potential nitrification rates declined while pore water sulfide increased over this period. While potential nitrification rates from this study are lower than rates from estuaries that do not experience hypoxia or anoxia, nitrifiers in Elkhorn Slough appear to be capable of adjusting to changing environmental conditions, specifically of tolerating low levels of sulfide. The nitrifying assemblage was similar to the community of ammonia-oxidizing bacteria and ammonia-oxidizing archaea that was previously reported from this system. Eutrophic shallow estuaries like Elkhorn Slough are delicately poised such that their sediment biogeochemistry responds quickly to relatively small changes in the light environment.
%U http://www.int-res.com/articles/ame_oa/a058p261.pdf
%A Caffrey, Jane M.
%A Hollibaugh, James T.
%A Bano, Nasreen
%A Haskins, John
%K AOA, AOB, nitrification, crenarchaea, ammonia oxidation, ammonia, hypoxia, upwelling, irradiance, Elk Horn Slough, Student Publication

%0 Journal Article
%T Alkalinity distribution in the western North Atlantic Ocean margins
%D 2010
%V 115
%N C08014
%P 15
%B Journal of Geophysical Research
%9 Article
%Z published
%M GCE.599
%R 10.1029/2009JC005482
%X Total alkalinity (TA) distribution and its relationship with salinity (S) along the western North Atlantic Ocean (wNAO) margins from the Labrador Sea to tropical areas are examined in this study. Based on the observed TA-S patterns, the mixing processes that control alkalinity distribution in these areas can be categorized into a spectrum of patterns that are bracketed by two extreme mixing types, i.e., alongshore current-dominated and river-dominated. Alongshore current-dominated mixing processes exhibit a segmented mixing line with a shared mid-salinity end-member. In such cases (i.e., Labrador Sea, Gulf of Maine, etc.), the y-intercept of the high salinity segment of the mixing line is generally higher than the local river alkalinity values, and it reflects the mixing history of the alongshore current. In contrast, in river-dominated mixing (Amazon River, Caribbean Sea, etc.), good linear relationships between alkalinity and salinity are generally observed, and the zero salinity intercepts of the TA-S regressions roughly match those of the regional river alkalinity values. TA-S mixing lines can be complicated by rapid changes in the river end-member value and by another river nearby with a different TA value (e.g., Mississippi-Atchafalaya/Gulf of Mexico). In the wNAO margins, regression intercepts and river end-members have a clear latitudinal distribution pattern, increasing from a low of &#8764;300 µmol kg^&#8722;1 in the Amazon River plume to a high value between &#8764;500–1100 µmol kg^&#8722;1 in the middle and high latitude margins. The highest value of &#8764;2400 µmol kg^&#8722;1  is observed in the Mississippi River influenced areas. In addition to mixing control, biological processes such as calcification and benthic alkalinity production may also affect ocean margin alkalinity distribution. Therefore, deriving inorganic carbon system information in coastal oceans using alkalinity-salinity relationships, in particular, those of generic nature, may lead to significant errors.
%U https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009JC005482
%A Cai, Wei-Jun
%A Hu, Xinping
%A Huang, Wei-Jen
%A Jiang, Liqing
%A Wang, Yongchen
%A Peng, Tsung-Hung
%K coastal ocean mixing, akalinity, biological removal, Student Publication

%0 Conference Proceedings
%T Carbon sequestration and nutrient retention in tidal- versus river-pulsed floodplain forests.
%D 2010
%C Tramore, Ireland
%B 6th Annual Meeting of the Society of Wetland Scientists European Chapter
%8 May 26-29 2010
%9 Presentation
%Z presented
%M GCE.564
%A Craft, Christopher B.
%K Flood pulsing, tidal pulsing, carbon sequestration, nitrogen, phosphorus, sediment deposition

%0 Conference Proceedings
%T Carbon sequestration and nutrient retention in tidal- versus river-pulsed floodplain forests.
%D 2010
%C Maun, Botswana
%B Symposium on Wetlands in a Flood Pulsing Environment: Effects on Responses in Biodiversity, Ecosystem Functioning and Human Society.
%8 Feb. 1-5 2010
%9 Article
%Z presented
%M GCE.562
%A Craft, Christopher B.
%K flood pulsing, tidal pulsing, carbon sequestration, nitrogen, phosphorus, sediment deposition

%0 Conference Proceedings
%T Climate change reduces nitrogen sink capacity of tidal freshwater floodplain forests.
%D 2010
%C Salt Lake City, Utah
%B Annual Meeting of the Society of Wetland Scientists
%8 June 27-July 2 2010
%9 Presentation
%Z presented
%M GCE.566
%A Craft, Christopher B.
%K Climate change, sea level rise, saltwater intrusion, nitrogen, tidal forest, brackish marsh

%0 Conference Proceedings
%T The cycle of vertical and horizontal mixing in a shallow tidal creek
%D 2010
%I Eos Trans. AGU
%C Portland Oregon
%B Ocean Sci. Meet. Suppl., Abstract  PO43B-05
%S Eos Trans. AGU, 91(26),
%8 February 22-26, 2010
%9 Presentation
%Z presented
%M GCE.597
%X An experimental study of vertical mixing and along-channel dispersion parameterized in terms of horizontal mixing near the mouth of the Duplin River, a tidal creek bordered by extensive intertidal salt marshes on Sapelo Island, Georgia, was carried out over several spring/neap cycles in the fall of 2005. Vertical mixing is modulated on both M4 and fortnightly frequencies with maximum turbulent stresses being generated near the bed on periods of maximum flood and ebb and propagating into the water column showing a linear dependence with depth. Values are significantly greater on spring tide than on neap showing that the water column is well mixed except during brief periods during neap tide. Horizontal mixing evaluated by salt fluxes is driven and dominated by tidal dispersion terms, which are also modulated by the fortnightly spring/neap cycle. Net export of salt from the lower Duplin is shown to be due to residual advection modified by upstream tidal pumping and Stokes drift. The tidal dispersion coefficient exhibits a pulsating character with greater values on spring tide followed by small values on neap tide and leads to a reversing salinity gradient in the middle section of the river.
%A Di Iorio, Daniela
%A McKay, Paul
%K Estuarine processes, Turbulence, diffusion, and mixing processes, Student Publication

%0 Journal Article
%T Comparative Phylogeography of East Coast American Salt Marsh Communities
%D 2010
%V 33
%P 828-839
%B Estuaries and Coasts
%9 Article
%Z published
%M GCE.517
%R 10.1007/s12237-009-9220-6
%X Identifying differential population structure within metacommunities is key toward describing the mechanisms that maintain biodiversity in natural systems. At both local and regional scales on the North American Atlantic coast, we assessed phylogeographic and genetic diversity patterns of six common salt marsh invertebrates using equivalent sampling schemes and sequence data from the same mitochondrial locus. In general, our results suggest little genetic structure across four previously sampled biogeographic regions and a slight increase in genetic diversity from northern to southern areas; however, two of the species (Geukensia demissa and Uca pugilator) exhibited significant differentiation between the northernmost populations and other regions, consistent with a number of previous studies. Although the minimal genetic structure recovered in this community is consistent with expectations based on the larval life history of the species examined, confirmation of this result suggests that latitudinal shifts in ecological interactions in salt marsh systems are environmentally driven, rather than due to heritable adaptation.
%A Diaz-Ferguson, Edgardo
%A Robinson, John D.
%A Silliman, Brian R.
%A Wares, John P.
%K genetics, invertebrates, salt marsh, community ecology, SINERR Publication, Student Publication, UGAMI Publication

%0 Conference Proceedings
%T PYROTAG SEQUENCING OF THREE MICROBIAL DOMAINS IN A SUBTROPICAL SHALLOW ESTUARY NEAR SAPELO ISLAND, GEORGIA, USA
%D 2010
%I International Society of Microbial Ecolog
%C Seattle, Washington, USA
%B International Society of Microbial Ecology Biennial Meeting
%S Marine Microbiology
%8 August, 2010
%9 Abstract
%Z presented
%M GCE.604
%X As part of MIRADA-LTER, an NSF-funded pyrotag sequencing project inventorying microbial diversity of the three domains of life at 13 of the aquatic Long Term Ecological Research (LTER) sites, over 300,000 sequences were generated from four locations in an estuary on the Georgia coast.  Samples were collected across a tidal cycle in a freshwater site (Altamaha River), coastal-influenced site (Sapelo Sound), marsh-influenced site (Doboy Sound), and a human-impacted site (Tolomato Development) in replicate. In the Bacteria, the V6 region of the SSU rDNA marker was sequenced, generating over 128,182 reads at an average of 8,011 reads per sample.  The V6 region was also sequenced in the Archaea, with fewer total (57,902) and average (3618) reads generated, while the V9 region was sequenced in the Eukarya with 116,411 total reads and an average of 7275 reads per sample.  Community composition in each of the domains was analyzed along with 22 ancillary environmental parameters to determine which factors are most related to community structure, and also which taxonomic groups drive the signature community of each environment sampled. We made the following observations: (1) Community composition; Sapelo Sound and Doboy Sound were highly similar, the Altamaha River site was the most divergent, and the Tolomato Development site was intermediate (2) Diversity; Tolomato Development had significantly lower bacterial diversity than all of the other sites with 2-3 fold higher numbers of bacterial cells (3) Environmental parameters; Statistical analyses reveal that the combined parameters of salinity, NO2 /NO3 concentration, and bacterial cell number are highly correlated (93%) with differences in community composition. This initial characterization of a Spartina marsh-dominated estuarine microbial community lays the groundwork to explore the previously undiscovered diversity of Bacteria, Archaea, and particularly microbial Eukarya.
%A Doherty, Mary
%A Booth, Melissa G.
%A Amaral-Zettler, L.
%K bacteria, archaea, microbial, diversity, pyrosequencing

%0 Journal Article
%T Diel depth distributions of microbenthos in tidal creek sediments: high resolution mapping in fluorescently labeled embedded cores
%D 2010
%V 655
%N 1
%P 149-158
%B Hydrobiologia
%9 Article
%Z published
%M GCE.871
%R 10.1007/s10750-010-0417-2
%X Intertidal sediments experience substantial changes in temperature, salinity, and solar irradiation over short time periods. We applied the Fluorescently Labeled Embedded Core (FLEC) technique to map distribution patterns of microbenthos in tidal creek sediments. Our aims were to determine if micro-scale distributions varied over the course of a day and to test the null hypothesis that microbenthos are randomly distributed. Eight samples were collected at 3 h intervals from an intertidal sandflat on Sapelo Island, Georgia, USA. Cores were incubated with CellTracker Green (CMFDA, hereafter, CTG), a fluorogenic compounds that accumulates in metabolically active cells. Cores were embedded with epoxy and examined with laser scanning confocal microscopy. Image analysis was used to map the vertical locations of active microbenthos, which in these sediments consisted of benthic microalgae (BMA), ciliates, and flagellates. Microbenthos were abundant over the entire depth profiled (2 cm), although O2 microelectrode profiles indicate that only the top 3 mm of sediment was oxygenated during high light (1,000 µE m&#8722;2 s&#8722;1). More than 91% of organisms mapped were <22 µm in diameter and, based upon size and cell appearance, were BMA. Microbenthos accumulated in the top 1 mm at 0800 and 1100 h, corresponding to both low tide and high solar irradiation. This pattern conforms to BMA migratory rhythms determined by other methods. The standardized Morisita’s Index of dispersion determined that CTG-positive objects were significantly clumped at all time points and at each of the three spatial scales examined. This clumping pattern likely results from the heterogeneous distribution of resources, such as prey items for phagotrophs and dissolved nutrients or growth substrates for autotrophs or heterotrophs.
%U http://gce-lter.marsci.uga.edu/public/uploads/First_and_Hollibaugh_2010b_20160906T155918.pdf
%A First, Matthew R.
%A Hollibaugh, James T.
%K Tidal creeks Sapelo Island Salt marsh Microzoobent, Student Publication, UGAMI Publication

%0 Journal Article
%T Environmental Factors Shaping Microbial Community Structure in Salt Marsh Sediments.
%D 2010
%V 399
%P 15-26
%B Marine Ecology Progress Series
%9 Article
%Z published
%M GCE.490
%R 10.3354/meps08385
%X We examined benthic microbial communities in three contrasting subtidal salt marsh sediments over the course of a year to investigate the relationship between environmental conditions and benthic microbial community structure. Samples were collected monthly from a high energy, sandy beach, a tidal creek bed, and a Spartina alterniflora marsh border. The concentrations and biomasses of benthic microalgae (BMA), total and potentially active bacteria (measured by an enzyme-activated fluorogenic compound), heterotrophic protists, and metazoan meiofauna were measured at each location. Sediment grain size and porewater pH explained most of the variability in biomass distributions; variations in benthic biomass did not correlate well with temperature. There was a seasonal shift from a BMA-dominated community in the spring and summer months to bacteria-dominated communities in the autumn at all locations, when inactive bacteria were most abundant. When normalized to sediment porewater volume, benthic protists concentrations were not significantly related to sediment porosity. Benthic protist porewater concentrations (mean: 3.4x103, range: 0.1–9.3 x 103 protists ml-1) were comparable to protist concentrations in the water column. In contrast, bacteria were several orders of magnitude more concentrated in the sediments (mean: 4.2x109; range: 0.6 – 16x109 bacteria ml-1) than the water column. Low abundances of protists relative to bacteria appear to contribute to long bacterial turnover times, especially in fine grained sediments. We hypothesize that both grazing by meiofauna and low anaerobic growth efficiency lead to relatively low biomass of bacterivorous protists.
%U http://www.int-res.com/abstracts/meps/v399/p15-26/
%A First, Matthew R.
%A Hollibaugh, James T.
%K Marine sediments, salt marsh, microzoobenthos, protists, bacteria, biomass, Student Publication, UGAMI Publication

%0 Journal Article
%T Ecosystem services as a common language for coastal ecosystem-based management
%D 2010
%V 24
%P 207-216
%B Conservation Biology
%9 Article
%Z published
%M GCE.656
%R 10.1111/j.1523-1739.2009.01355.x
%X Ecosystem-based management is logistically and politically challenging because ecosystems are inherently complex and management decisions affect a multitude of groups. Coastal ecosystems, which lie at the interface between marine and terrestrial ecosystems and provide an array of ecosystem services to different groups, aptly illustrate these challenges. Successful ecosystem-based management of coastal ecosystems requires incorporating scientific information and the knowledge and views of interested parties into the decision-making process. Estimating the provision of ecosystem services under alternative management schemes offers a systematic way to incorporate biogeophysical and socioeconomic information and the views of individuals and groups in the policy and management process. Employing ecosystem services as a common language to improve the process of ecosystem-based management presents both benefits and difficulties. Benefits include a transparent method for assessing trade-offs associated with management alternatives, a common set of facts and common currency on which to base negotiations, and improved communication among groups with competing interests or differing worldviews. Yet challenges to this approach remain, including predicting how human interventions will affect ecosystems, how such changes will affect the provision of ecosystem services, and how changes in service provision will affect the welfare of different groups in society. In a case study from Puget Sound, Washington, we illustrate the potential of applying ecosystem services as a common language for ecosystem-based management.
%U http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2009.01355.x/abstract
%A Granek, Elise F.
%A Polasky, Stephen
%A Kappel, Carrie V.
%A Reed, D.J.
%A Stoms, D.M.
%A Koch, Evamaria W.
%A Kennedy, Christopher J.
%A Cramer, Abby
%A Hacker, Sally D.
%A Barbier, Edward B.
%A Aswani, S.
%A Ruckelshaus, M.
%A Perillo, M. E.
%A Silliman, Brian R.
%A Muthiga, Nyawira
%A Bael, D.
%A Wolanski, Eric
%K ecosystem services, management, ecosystem-based management, Cross-site Research, Student Publication

%0 Conference Proceedings
%T Mechanisms mediating plant distributions in Georgia tidal marshes
%D 2010
%C Pittsburgh, PA
%B 2010 annual meeting of the Ecological Society of America
%8 August 1-6, 2010
%9 Presentation
%Z presented
%M GCE.549
%A Guo, Hongyu
%A Pennings, Steven C.
%A Wieski, Kazimierz
%K salinity, competition, facilitation, Student Publication

%0 Conference Proceedings
%T Biogeochemical dynamics in salt marsh environments: the role of intertidal hotspots
%D 2010
%B Goldschmidt Conference, Knoxville TN
%9 Poster
%Z presented
%M GCE.626
%A Hagens, Mathilde
%A Meile, Christof
%K groundwater marsh modeling

%0 Conference Proceedings
%T Salt marsh habitat mapping on Sapelo Island, GA using LIDAR and hyperspectralimagery
%D 2010
%I NEERS
%C National Conservation Training Center, Shepherdstown, WV
%B National Estuarine Research Reserve Annual Meeting
%8 October 11-15, 2010
%9 Poster
%Z presented
%M GCE.605
%X Accurate habitat mapping in salt marshes is important for management and conservation goals, as it provides information essential for identifying sensitive areas and documenting changes over time as the result of sea level rise or human perturbations. While many variables affect species patterns, elevation is one of the most important as it determines the frequency and duration of tidal flooding. Light Detection and Ranging (LIDAR) is effective at measuring surface elevations at the whole marsh scale. However, it is unable to identify species. Hyperspectral imagery in the visible range can be used to characterize species-specific spectral signatures and identify species distributions. When LIDAR is used in combination with hyperspectral imagery classification accuracies can be greatly improved. The goal of this study is to characterize patterns of marsh plant distribution in the salt marshes surrounding Sapelo Island, GA in relation to elevation using LIDAR and hyperspectral data. Aerial hyperspectral imagery for over 30 km2 of marsh and upland habitats was obtained using an AISA sensor and LIDAR data was acquired for the same area. Hyperspectral imagery was combined with groundtruthing and then used to map 6 plant species. Preliminary groundtruthing of the LIDAR suggests that elevation corrections vary with vegetation height (elevation errors range from 0.03 to 0.26 m).
%A Hladik, Christine M.
%A Alber, Merryl
%A Schalles, John F.
%A Pennings, Steven C.
%K Salt marsh, remote sensing, LIDAR, hyperspectral, Spartina alterniflora, Student Publication

%0 Conference Proceedings
%T Preference and performance in plant-herbivore interactions across latitude
%D 2010
%C Pittsburgh, PA
%B 2010 annual meeting of the Ecological Society of America
%S Organized Oral Session, “Latitudinal gradients in consumer-resource interactions: bridging the gap between pattern and process“
%8 August 1-6, 2010
%9 Presentation
%Z presented
%M GCE.548
%A Ho, Chuan-Kai
%A Pennings, Steven C.
%K latitude, herbivory, plant-herbivore, Student Publication

%0 Journal Article
%T Is Diet Quality an Overlooked Mechanism for Bergmann's Rule?
%D 2010
%V 175
%N 2
%P 269-276
%B The American Naturalist
%9 Article
%Z published
%M GCE.545
%R 10.1086/649583
%X Bergmann's rule (body size increases with latitude) has long interested biologists; however, its mechanism remains unclear. An overlooked mechanism (latitudinal variation in plant quality) might help explain Bergmann's rule. We studied three herbivores. In the field, the planthopper Prokelisia and the sea hare Aplysia, but not the long-horned grasshopper Orchelimum, were larger at high latitudes, following Bergmann's rule. In the laboratory, all three species grew larger or faster on high-latitude plants. High-latitude diets increased Prokelisia size and Aplysia growth rates by 8% and 72%, respectively, enough to explain the increase in field body size toward high latitudes. Therefore, latitudinal variation in herbivore body size could be influenced by latitudinal variation in plant quality, which may directly or indirectly also affect body size in detritivores, parasitoids, and predators. Studies of Bergmann's rule should consider the influence of biotic factors on body size in addition to abiotic factors such as temperature and precipitation.
%U http://www.journals.uchicago.edu/doi/abs/10.1086/649583
%A Ho, Chuan-Kai
%A Pennings, Steven C.
%A Carefoot, Thomas H.
%K latitude, plants, nutrition, size, Bergmann, diet, biogeography, physiology, Cross-site Research, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Nutrient enrichment enhances hidden differences in phenotype to drive a cryptic plant invasion
%D 2010
%V 119
%P 1776-1784
%B Oikos
%9 Article
%Z published
%M GCE.658
%R 10.1111/j.1600-0706.2010.18647.x
%X Many mechanisms of invasive species success have been elucidated, but those driving cryptic invasions of non-native genotypes remain least understood. In one of the most successful cryptic plant invasions in North America, we investigate the mechanisms underlying the displacement of native Phragmites australis by its Eurasian counterpart. Since invasive Phragmites’ populations have been especially prolific along eutrophic shorelines, we conducted a two-year field experiment involving native and invasive genotypes that manipulated nutrient level and competitor identity (inter- and intra-genotypic competition) to assess their relative importance in driving the loss of native Phragmites. Inter-genotypic competition suppressed above-ground biomass of both native and invasive plants regardless of nutrient treatment (&#8764; 27%), while nutrient addition disproportionately enhanced the above-ground biomass (by 67%) and lateral expansion (by > 3 × farther) of invasive Phragmites. Excavation of experimental plots indicated that nutrient addition generates these differences in above-ground growth by differentially affecting rhizome production in invasive vs native plants; invasive rhizome biomass and rhizome length increased by 595% and 32% with nutrient addition, respectively, while natives increased by only 278% and 15%. Regardless of nutrient level, native rhizomes produced twice as many roots compared to invasives, which field surveys revealed are heavily infected with mycorrhizal symbionts. These results suggest that native Phragmites competes well under nutrient-limited conditions because its rhizomes are laden with nutrient-harvesting roots and mycorrhizae. Invasive Phragmites’ vigorous above-ground response to nutrients and scarcity of lateral roots, in contrast, may reflect its historic distribution in eutrophic Eurasian wetlands and correspond to its prevalence in New England marshes characterized by elevated nutrient availability and relaxed nutrient competition. These findings reveal that discrete differences in phenotype can interact with anthropogenic modification of environmental conditions to help explain the success of cryptic invaders.
%U http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0706.2010.18647.x/abstract
%A Holdredge, Christine
%A Bertness, Mark D.
%A Wettberg, E. V.
%A Silliman, Brian R.
%K nutrient, phenotype, invasion, plant, Student Publication

%0 Conference Proceedings
%T Analysis of the meta-transcriptome of an ammonia oxidizing Archaea population
%D 2010
%I Penn State University
%C State College PA
%B US-China Workshop on Geobiological Processes in Extreme Environments
%8 20 May, 2010
%9 Presentation
%Z presented
%M GCE.556
%A Hollibaugh, James T.
%A Gifford, Scott
%A Bano, Nasreen
%A Sharma, S.
%A Moran, Mary Ann
%K Crenarchaeota, ammmonia oxidation, Nitrosopumilus, nitrosomonas, Nitrosospira, Nitrosococcus, Student Publication

%0 Conference Proceedings
%T Comparison of microdiversity in Crenarchaeota and Bacteria transcripts from a coastal plankton assemblage
%D 2010
%C Seattle Washington
%B 13th International Symposium on Microbial Ecology
%8 24-28 August, 2010
%9 Abstract
%Z presented
%M GCE.554
%A Hollibaugh, James T.
%A Gifford, Scott
%A Bano, Nasreen
%A Sharma, S.
%A Moran, Mary Ann
%K Crenarchaeota, ammmonia oxidation, Nitrosopumilus, nitrosomonas, Nitrosospira, Nitrosococcus, Student Publication

%0 Conference Proceedings
%T Meta-transcriptomic analysis of a bloom of ammonia oxidizers
%D 2010
%C Los Angeles CA
%B Invited seminar, Department of Biology, University of Southern California
%8 12 January, 2010
%9 Presentation
%Z presented
%M GCE.555
%A Hollibaugh, James T.
%A Gifford, Scott
%A Bano, Nasreen
%A Sharma, S.
%A Moran, Mary Ann
%K Crenarchaeota, ammmonia oxidation, Nitrosopumilus, nitrosomonas, Nitrosospira, Nitrosococcus, Student Publication

%0 Conference Proceedings
%T The meta-transcriptome of an ammonia oxidizing Archaea bloom in Georgia coastal waters
%D 2010
%I ASLO
%C Portland OR,
%B Ocean Sciences Meeting
%S Session B-14
%8 23-27 February 2010
%9 Abstract
%Z presented
%M GCE.553
%A Hollibaugh, James T.
%A Gifford, Scott
%A Bano, Nasreen
%A Sharma, S.
%A Moran, Mary Ann
%K Crenarchaeota, ammmonia oxidation, Nitrosopumilus, nitrosomonas, Nitrosospira, Nitrosococcus, Student Publication

%0 Conference Proceedings
%T Base Station RTK vs. Virtual Reference Station (VRS) RTK survey efficiency: anevaluation of techniques, precision and costs for establishing high resolution “z”coordinates.
%D 2010
%I NEERS
%C National Conservation Training Center, Shepherdstown, WV
%B National Estuarine Research Reserve Annual Meeting
%8 October 11-15, 2010
%9 Poster
%Z presented
%M GCE.608
%X Technologies involving the use of remote sensing and Global Navigation SatelliteSystems (GNSS) to establish high-resolution elevation (“z”) coordinates for a specificGlobal Positioning System (GPS) vertical reference datum are evolving rapidly. Thecurrently available RTK GNSS survey techniques have variable costs, time constraints,geographical availability, technology deployment and precision efficiencies. In thisshort evaluation we compare and discuss the aforementioned variables in methods,technologies and precision using two different RTK survey styles: a traditional approachusing Base Station RTK and Virtual Reference Station (VRS) RTK for establishinghigh-resolution elevation mapping using NAVD88 as the fixed vertical reference datum.
%A Hurley, Dorset
%A Scoville, Nick
%A Hladik, Christine M.
%K Real-time Kinematic (RTK), Virtual Reference Station (VRS), Global Positioning System (GPS), Global Navigation Satellite System (GNSS), elevation modeling, NAVD88, Student Publication

%0 Journal Article
%T Carbonate mineral saturation states along the U.S. east coast
%D 2010
%V 55
%N 6
%P 2424–2432
%B Limnology and Oceanography
%9 Article
%Z published
%M GCE.600
%R 10.4319/lo.2010.55.6.2424
%X To assess the impact of ocean acidification on the carbonate chemistry of the shelf waters off the southeastern United States (South Atlantic Bight [SAB]), we measured carbonate mineral saturation states from January 2005 to May 2006. The findings reveal that aragonite (Varag: 2.6–4.0) and calcite (Vcal: 4.1–6.0) saturation states were considerably higher than those recently reported along the West Coast of North America. Different water mass age between the Atlantic and Pacific Oceans during global ocean circulation is the primary reason for the higher carbonate mineral saturation states in the SAB than along the West Coast. The contrasting water temperatures in the two coasts contribute to such differences. Both upwelling and freshwater discharge also play important roles in controlling saturation state. Carbonate mineral saturation in the surface water of the West Coast is strongly controlled by the upwelling of high-salinity, low-temperature, low-oxygen, and low-pH deep water. In comparison, saturation states in the surface water of the SAB coast are rarely affected by upwelling. Instead, they are strongly influenced by the input of low-saturation-state water from rivers. Continued increases of atmospheric CO2 under the Intergovernmental Panel on Climate Change B1 emission scenario will decrease the carbonate mineral saturation states by up to 40% by the end of this century, and aragonite will approach undersaturation near the coast.
%U https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2010.55.6.2424
%A Jiang, Liqing
%A Cai, Wei-Jun
%A Feely, Richard A.
%A Wang, Yongchen
%A Guo, Xianghui
%A Gledhill, Dwight K.
%A Hu, Xinping
%A Arzayus, Felipe
%A Chen, Feizhou
%A Hartmann, Justin
%A Zhang, Longuin
%K Carbonate mineral saturation states, east coast, chemistry, Student Publication

%0 Journal Article
%T Pelagic community respiration on the continental shelf off Georgia, USA
%D 2010
%V 98
%P 101–113
%B Biogeochemistry
%9 Article
%Z published
%M GCE.467
%R 10.1007/s10533-009-9379-8
%X The South Atlantic Bight (SAB) has been a focus for the study of continental shelf ecosystem respiration during the past two decades. However, two questions concerning respiration in this area have yet to be answered. First, why do previous estimates of respiration in the SAB exceed measured carbon fixation rates by almost an order of magnitude? Second, considering that bacteria are responsible for most of the pelagic community respiration in the SAB, why is respiration almost uniform from the coastline to the shelf break, while bacterial production estimates decrease offshore? This study addresses these critical questions by presenting new pelagic community respiration data that were collected across the entire width of the continental shelf off Georgia, USA from June 2003 to May 2006. The respiration was calculated as in vitro changes of dissolved oxygen and dissolved inorganic carbon concentrations during deck incubations. The measured respiration rates ranged from 0.3(±0.1) to 21.2(±1.4) mmol m&#8722;3 day&#8722;1. They followed a clear seasonal pattern, being lowest over the entire shelf in winter and reaching maxima in summer. Summertime respiration rates were highest on the inner shelf and decreased with distance offshore. Consistent with this trend, bacterial abundance measurements taken during the sampling month of July 2005 followed a pattern of seaward decline. The SAB organic carbon fluxes calculated from the respiration data are close to the estimates for primary production, which resolves a long-standing mystery regarding perceived carbon imbalance in the SAB.
%U http://www.springerlink.com/content/n6684pw510j4627p/
%A Jiang, Liqing
%A Cai, Wei-Jun
%A Wang, Yongchen
%A Diaz, J.
%A Yager, Patricia
%A Hu, Xinping
%K respiration, oceanography, metabolism, CO2, Student Publication

%0 Conference Proceedings
%T Effects of climate change on nutrient (N, P) sorption in tidal riverine floodplain forests, Georgia, USA.
%D 2010
%C Maun, Botswana
%B Symposium on Wetlands in a Flood Pulsing Environment: Effects on Responses in Biodiversity, Ecosystem Functioning and Human Society.
%8 Feb. 1-5 2010
%9 Poster
%Z presented
%M GCE.563
%A Jun, Mi hee
%A Craft, Christopher B.
%K Tidal forests, nitrogen, phosphorus, sorption, desorption, flooding, saltwater intrusion

%0 Conference Proceedings
%T South Atlantic Regional Research Plan: A Regional Research Framework
%D 2010
%C Wilmington, North Carolina
%B The Coastal Society
%8 June 2010
%9 Presentation
%Z presented
%M GCE.587
%A Laporte, Christine
%A Alber, Merryl
%K Regional Research, Framework

%0 Journal Article
%T Carbon sequestration and nutrient (N, P) accumulation in river-dominated tidal marshes, Georgia, USA
%D 2010
%V 74
%P 1028-1038
%B Soil Science Society of America Journal
%9 Article
%Z published
%M GCE.510
%R 10.2136/sssaj2009.0171
%X Soil organic C, N, and P were measured in salt, brackish, and tidal freshwater marshes in river-dominated estuaries (Ogeechee, Altamaha, and Satilla) of the Georgia coast to evaluate the effects of salinity on C, N, and P storageand accumulation. Tidal freshwater marshes had greater concentrations of organic C (10.81% w/w) and N (0.71% w/w)than brackish (7.71% C, 0.50% N) or salt (5.95% C, 0.35% N) marshes. Soil accretion rates of ^137Cs were greaterin tidal freshwater (4.78 mm yr^1) and brackish marshes (4.41 mm yr^1) than in salt marshes (1.91 mm yr^1). Consequently, organic C and N accumulation was greater in tidal freshwater (124 and 8.2 g m^2 yr^1) and brackish (93 and 6.5 g m^2 yr^1) marshes than salt marshes (40 and 2.4 g m^2 yr^1). Phosphorus accumulation was greater in the brackish marshes. Lower salinity tidal freshwater and brackish marshes remove more C, N, and P; however, salt marshes dominate the spatial extent of the study area (60%) vs. brackish (33%) and tidal freshwater marshes (7%). Combinig measurements of C, N, and P accumulation with tidal marsh area, we estimated that tidal freshwater, brackish, and salt marshes stored or removed the equivalent of 2 to 20% of watershed N inputs entering the estuaries from the terrestrial landscape. After accounting for N2 fixation and denitrification, tidal marshes collectively removed the equivalent of 13 to 32% of the N entering estuaries. Tidal marshes, especially tidal freshwater and brackish marshes, are important for improving water quality and decreasing the impacts of Neutrophication of estuarine ecosystems.
%U https://www.soils.org/publications/sssaj/abstracts/74/3/1028
%A Loomis, Mark J.
%A Craft, Christopher B.
%K geology, soils, carbon, nutrients, nitrogen, phosphorus, marsh, SINERR Publication, Student Publication, UGAMI Publication

%0 Journal Article
%T Ascomycete fungal communities associated with early decaying leaves of Spartina spp. from central California estuaries
%D 2010
%V 162
%P 435-442
%B Oecologica.
%9 Article
%Z published
%M GCE.450
%R 10.1007/s00442-009-1460-4
%X Ascomycetous fungi play an important role in the early stages of decomposition of Spartina alterniflora, but their role in the decomposition of other Spartina species has not been investigated.  Here we use fingerprint (T-RFLP) and phylogenetic analyses of the 18S-to-28S internal transcribed spacer (ITS) region to compare the composition of the ascomycete fungal communities on early decay blades of Spartina species (S. alterniflora, S. densiflora, S. foliosa, and a hybrid (S. alterniflora x S. foliosa) collected from three salt marshes in San Francisco Bay and one in Tomales Bay, California, U.S.A.  Phaeosphaeria spartinicola was found on all samples collected and was often dominant. Two other ascomycetes, Phaeosphaeria halima and Mycosphaerella sp. strain 2, were also common.  These three species are the same ascomycetes previously identified as the dominant fungal decomposers on S. alterniflora on the east coast.  Ascomycetes appeared to exhibit varying degrees of host-specificity, demonstrated by grouping patterns on phylogenetic trees.  Neither the exotic S. alterniflora nor the hybrid supported fungal flora different from that of the native S. foliosa.  However, S. densiflora had a significantly different fungal community than the other species, and hosted at least two unique ascomycetes.  Significant differences in the fungal decomposer communities were also detected within species (two clones of S. foliosa), but these were minor and may be due to morphological differences among the plants.
%U http://www.springerlink.com/content/t7186704g8100t51/
%A Lyons, Justine I.
%A Alber, Merryl
%A Hollibaugh, James T.
%K microbiology, fungi, plant, Spartina, ascomycete, decay, Student Publication

%0 Conference Proceedings
%T Top-down control dominates latitudinal variation in bottom-up forces on a herbivore community
%D 2010
%C Pittsburgh, PA
%B 2010 annual meeting of the Ecological Society of America
%S Organized Oral Session, “Latitudinal gradients in consumer-resource interactions: bridging the gap between pattern and process
%8 August 1-6, 2010
%9 Presentation
%Z presented
%M GCE.550
%A Marczak, Laurie
%K herbivory, predation, latitude, Iva

%0 Conference Proceedings
%T Marton, J. and C. Craft.  2010.  Denitrification in tidal freshwater floodplain forests of southeast Georgia, USA.
%D 2010
%C Salt Lake City, Utah
%B Annual Meeting of the Society of Wetland Scientists
%8 June 27-July 2 2010
%9 Presentation
%Z presented
%M GCE.565
%A Marton, John
%A Craft, Christopher B.
%K Tidal forests, nitrogen, denitrification, Altamaha River, Ogeechee River, Satilla River, Student Publication

%0 Conference Proceedings
%T Varation in marsh benthic invertebrate presence and abundance related to altered Spartina alterniflora density
%D 2010
%C Wilmingon, North Carolina
%B Southeastern Estuarine Research Society meeting
%8 March 2010
%9 Poster
%Z presented
%M GCE.591
%U http://gce-lter.marsci.uga.edu/public/uploads/McFarlin_BEM_2010_20120924T114915.ppt
%A McFarlin, Caroline R.
%A Bishop, Thomas Dale
%A Alber, Merryl
%A Hester, Mark W.
%K Benthic Invertebrate, Spartina alterniflora, Student Publicat