UGAMI Bibliography
Journal Articles
Adams, T., Vu, H.D. and Pennings, S.C. 2021. Variation in Densities of the Salt Marsh Katydid Orchelimum fidicinium over Space and Time. Estuaries and Coasts.:12.
Abstract
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 (5 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 five sites where O. fidicinium was common, densities varied greatly among years. Regression models 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 nutrients may 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.
Abstract
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‐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‐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.
Alberts, J.J. and Filip, Z. 1989. Sources and characteristics of fulvic and humic acids from a salt marsh estuary. Science of the Total Environment. 81/82:353-361.
Alberts, J.J. and Filip, Z. 1994. Humic substances in rivers and estuaries of Georgia, USA. Trends in Chemical Geology. 1:143-162.
Alberts, J.J. and Filip, Z. 1998. Metal binding in estuarine humic and fulvic acids: FTIR analysis of humic acid-metal complexes. Environmental Technology. 19:923-931.
Alberts, J.J. and Griffin, C. 1996. Formation of particulate organic carbon (POC) from dissolved organic carbon (DOC) in salt marsh estuaries of the Southeastern United States. Archiv fur Hydrobiologie Special Issues Advances in Limnology. 47:401-409.
Alberts, J.J. and Takacs, M. 1999. Characterization of natural organic matter from eight Norwegian surface waters: The effect of ash on molecular size distributions and CHN content. Environment International. 25(2/3):237-244.
Alberts, J.J. and Takacs, M. 1999. Importance of humic substances for carbon and nitrogen transport into southeastern United States estuaries. Organic Geochemistry. 30:385-395.
Alberts, J.J. and Takacs, M. 2004. Comparison of the natural fluorescence distribution among size fractions of terrestrial fulvic and humic acids and aquatic natural organic matter. Organic Geochemistry. 35(10):1141-1149.
Alberts, J.J. and Takacs, M. 2004. Total luminescence spectra of IHSS standard and reference fulvic acids, humic acids and natural organic matter: Comparison of aquatic and terrestrial source terms. Organic Geochemistry. 35(3):243-256.
Alberts, J.J., Bowling, J.W. and Emmons, M. 1988. Dissolved carbohydrate distribution and dynamics in two southeastern United States reservoirs. Canadian Journal of Fisheries and Aquatic Sciences. 45:325-332.
Alberts, J.J., Bowling, J.W., Schindler, J.E. and Kyle, D.E. 1988. Seasonal dynamics of physical and chemical properties of a warm monomictic reservoir. Verhandlungen Internationale Vereinigung Limnololgie. 23:176-180.
Alberts, J.J., Ertell, J.R. and Case, L. 1990. Characterization of organic matter in rivers of the southeastern United States. Verhandlungen Internationale Vereinigung Limnologie. 24:260-262.
Alberts, J.J., Filip, Z. and Hertkorn, N. 1992. Fulvic and humic acids isolated from groundwater: compositional characteristics and cation binding. Journal Contaminant Hydrology. 11:317-330.
Alberts, J.J., Filip, Z. and Leversee, G.J. 1989. Interaction of estuarine organic matter with copper and benzo(a)pyrene. Marine Chemistry. 28:77-87.
Alberts, J.J., Filip, Z., Price, M.T., Hedges, J.I. and Jacobsen, T.R. 1992. CuO-oxidation products, acid hydrolyzable monosaccharides and amino acids of the humic substances occurring in a salt marsh estuary. Organic Geochemistry. 18:171-180.
Alberts, J.J., Filip, Z., Price, M.T., Williams, D.J. and Williams, M.C. 1988. Elemental composition, stable carbon isotope ratios and spectrophotometric properties of humic substances occurring in a salt marsh estuary. Organic Geochemistry. 12:455-467.
Alberts, J.J., Halverson, J.E. and Orlandini, K.A. 1986. The distribution of plutonium, americium and curium isotopes in pond and stream sediment of the Savannah River plant, South Carolina, USA. Journal of Environmental Radioactivity. 3:249-271.
Alberts, J.J., Hatcher, P.G., Price, M.T. and Filip, Z. 1991. Carbon-13 nuclear magnetic resonance analysis, lignin content and carbohydrate composition of humic substances from salt marsh estuaries. Lecture Notes in Earth Science. 33:195-203.
Alberts, J.J., Pinder, J.E., Bowling, J.W., Nelson, D.M. and Orlandini, K.A. 1986. 239, 240Pu, 241Am and 232Th in lakes: The effects of seasonal anoxia. Journal of Environmental Radioactivity. 4:167-176.
Alberts, J.J., Price, M.T. and Kania, M. 1990. Metal concentrations in tissues of Spartina alterniflora (Loisel.) and sediments of Georgia salt marshes. Estuarine, Coastal and Shelf Science. 30:47-58.
Alberts, J.J., Price, M.T. and Lewis, S. 1991. Lignin oxidation product and carbohydrate composition of plant tissues from the South-eastern United States. Estuarine, Coastal and Shelf Science. 33:213-222.
Alberts, J.J., Takacs, M. and Egeberg, P.K. 2002. Total luminescence spectral characteristics of natural organic matter (NOM) size fractions as defined by ultrafiltration and high performance size exclusion chromatography (HPSEC). Organic Geochemistry. 33:817-828.
Alberts, J.J., Takacs, M. and Pattanayek, M. 2000. Influence of IHSS standard and reference materials on copper and mercury toxicity to Vibrio fischeri. Acta Hydrochimica et Hydrobiologica. 28(7):428-435.
Alberts, J.J., Takacs, M. and Schalles, J. 2004. Ultraviolet-visible and fluorescence spectral evidence of natural organic matter (NOM) changes along an estuarine salinity gradient. Estuaries. 27(2):296-310.
Alberts, J.J., Wahlgren, M.A., Orlandini, K.A. and Durbahn, C.A. 1989. The distributions of 239, 240Pu, 241Am, and 137Cs among chemically-defined components of sediments, settling particulates and net plankton of Lake Michigan. Journal of Environmental Radioactivity. 9:89-103.
Alberts, J.J., Weber, M.F. and Evans, D.W. 1988. The effect of pH and contact time on the concentration of As(III) and As(V) in coal ash systems. Environmental Technology Letters. 9:63-70.
Albright, L.J., Sherr, E.B., Sherr, B.F. and Fallon, R.D. 1987. Grazing of ciliated protozoa on free and particle-attached bacteria. Marine Ecology-Progress Series. 38:125-129.
Altin, D.Z., Habura, A. and Goldstein, S.T. 2009. A NEW ALLOGROMIID FORAMINIFER NIVEUS FLEXILIS NOV GEN., NOV SP., FROM COASTAL GEORGIA, USA: FINE STRUCTURE AND GAMETOGENESIS. Journal of Foraminiferal Research. 39(2):73-86.
Abstract
Allogromiids (sensu lato) occupy diverse habitats, including marine, brackish, freshwater, and terrestrial environments, serve a suite of trophic functions within their communities, and are modern descendents of the earliest diverging foraminiferal lineages. Allogromiids appear to be morphologically simplistic, but they have diverse, intricate shell architectures at the fine structural level. They are not well known from the fossil record and are sometimes difficult to recognize in modern systems. Recent molecular work on small subunit ribosomal DNA (SSU rDNA) sequences by others has delineated 13 genetic clades, most of which unite taxa that do not share a common general morphology. Here, we present ultrastructural and molecular results on an undescribed allogromiid, Niveus flexilis nov. gen., nov. sp., collected from low-salinity marshes along coastal Georgia, USA. Partial SSU phylogenetic analyses indicate that this taxon is a member of Clade E Allogromiid Foraminifera. This taxon is small (<300 mu m), generally ovate in shape, and has a single aperture. The flexible test is composed of a thin (<0.5 mu m), outer agglutinated layer of fine clay particles predominantly arranged parallel to the shell surface. The outer surface of the test is crenulated and irregular. The agglutinated layer is underlain by a thick (3-8 mu m), inner organic lining (IOL), which is in direct contact with the cell membrane. The IOL contains numerous small electron-dense particles along with long, fine fibers generally arranged parallel to the outer surface of the shell. Small vesicles lie just beneath the plasma membrane and appear to release test construction materials at the base of the IOL. The nuclear membrane is surrounded by a thick layer (1.5 mu m) of endoplasmic reticulum overlain by a layer of vesicles of unknown function. Gamonts release many small biflagellated gametes through the aperture directly into surrounding seawater. Fine cytological examination of the test suggests that this new allogromiid shares a similar constructional theme with other Clade E allogromiids examined to date, particularly Psammophaga spp. Ultrastructural data for additional Clade E taxa are necessary to identify fine morphological characters that may be synapomorphies for this group.
Altin-Ballero, D.Z., Habura, A. and Goldstein, S.T. 2013. PSAMMOPHAGA SAPELA N. SP., A NEW MONOTHALAMOUS FORAMINIFERAN FROM COASTAL GEORGIA, USA: FINE STRUCTURE, GAMETOGENESIS, AND PHYLOGENETIC PLACEMENT. Journal of Foraminiferal Research. 43(2):113-126.
Abstract
We describe a new monothalamous species, Psammophaga sapela, collected from salt marshes and mudflats along the coast of Georgia, U.S.A. Partial small subunit ribosomal DNA (SSU rDNA) phylogenetic analyses assign this species to Clade E, one of a series of clades of monothalamous foraminifera. Psammophaga sapela joins three previously described species in this genus: P. simplora Arnold, the type species, P. magnetica Pawlowski and Majewski, and the reassigned Allogromia crystallifera Dahlgren. This new species is of moderate size (<= 500 mu m in length), is generally pyriform in shape, and has a single, flexible aperture, which may occur at the end of a very short neck. The flexible test is composed of a relatively thick (10-15 mu m), smooth, outer agglutinated layer of fine clay particles arranged loosely parallel to the plasma membrane of the cell body. The agglutinated layer is underlain by a moderately thick (2-5 mu m), inner organic lining (IOL), which is in direct contact with the cell membrane. The IOL contains numerous electron-dense particles with elongated fine fibers similar to other previously reported Clade E taxa. Small vesicles lie just beneath the cell membrane and merge with the plasma membrane to release test construction materials at the base of the IOL. This species is gametogamous, where gamonts release biflagellated gametes either through the aperture or within membrane-bound packets that open following release. Budding was also observed. True to its generic name Psammophaga (sand-eating), this taxon avidly ingests and maintains sediment grains of orthoclase, pyrrhotite, basaluminite, pseudobrookite, anatase, and ilmenite, the latter rendering it magnetic.
Alvarez, M., Foust, C.M., Robertson, M., Ainouche, M., Ferreira De Carvalho, J., Meals, C., Preite, V., Salmon, A., Shayter, A., Schrey, A., Verhoeven, K.J.F. and Richards, C.L. 2015. MOLECULAR RESPONSE TO CHALLENGING ENVIRONMENTAL CONDITIONS IN SPARTINA ALTERNIFLORA: AN INTEGRATED APPROACH.
Abstract
Native populations of the invasive grass, Spartina alterniflora, provide a unique opportunity to explore mechanisms of phenotypic response to a range of stressors, including persistent environmental gradients and periodic disturbance events, that may inform our understanding of the global S. alterniflora invasion. Here, we use Amplified Fragment Length Polymorphism (AFLP), methylation sensitive-AFLP (MS-AFLP), and microarrays to examine genetic, epigenetic, and transcriptional response to natural and anthropogenic stressors in native populations of S. alterniflora. Preliminary data from these experiments suggests that epigenetic variation is at least partially structured by predictable natural gradients in environmental factors, whereas response to the severe disturbance of the Deepwater Horizon oil spill changed the genetic make-up of populations and had a strong effect on gene expression. These findings suggest that the ability of S. alterniflora to persist across a range of conditions may be due to a combination of epigenetic and genetic molecular mechanisms. Invasive species often display high phenotypic variation and are successful in a wide range of habitats. Our results indicate that both epigenetic and genetic molecular mechanisms may provide insight into the regulation of phenotype in response to the novel stressors present in an invaded habitat.
Andersen, D.O., Alberts, J.J. and Takacs, M. 1999. Nature of natural organic matter (NOM) in acidified and limed surface waters. Water Research. 34(1):266-278.
Abstract
natural organic matter
Anderson, J.M. and Cormier, M.J. 1973. Lumisomes: the cellular sight of bioluminescence in coelenterates. Journal of Biological Chemistry. 248:2937-2943.
Anderson, J.M. and Cormier, M.J. 1976. Transductive coupling in bioluminescence: Effects of monovalent cations and ionophores on the calcium-triggered luminescence of Renilla lumisomes. Biochemical and Biophysical Reseaech Communications. 68:1234-1241.
Anderson, J.M., Charbonneau, H. and Cormier, M.J. 1974. Mechanism of calcium induction of Renilla bioluminescence involvement of a calcium-triggered luciferin binding protein. Biochemistry. 13:1195-1199.
Antlfinger, A.E. and Dunn, E.L. 1979. Seasonal patterns of CO2 and water vapor exchange of three salt marsh succulents. Oecologia. 43:249-260.
Antlfinger, A.E. and Dunn, E.L. 1983. Water use and salt balance in three salt marsh succulents. American Journal of Botany. 70:561-567.
Antoine, J.W. and Henry, V.J.J. 1965. Seismic refraction study of shallow part of continental shelf off Georgia coast. Bulletin of the American Association of Petroleum Geologists. 49:601-604.
Arsuffi, T.L. and Suberkropp, K. 1988. Effects of fungal mycelia and enzymatically degraded leaves on feeding and performance of caddisfly (Trichoptera) larvae. Journal of the North American Benthological Society. 7:205-211.
Arsuffi, T.L. and Suberkropp, K. 1989. Selective feeding by shredders on leaf-colonizing stream fungi: comparison of macroinvertebrate taxa. Oecologia. 79:30-37.
Ashworth, R.B. and Cormier, M.J. 1967. Isolation of 2,6-dibromophenol from the marine hemichordate, Balanoglossus biminiensis. Science. 155:1558-1559.
Bacic, M.K., Newell, S.Y. and Yoch, D.C. 1998. Release of dimethylsulfide from dimethylsulfoniopropionate by plant-associated salt marsh fungi. Applied and Environmental Microbiology. 64(4):1484-1489.
Baerlocher, F., Arsuffi, T.L. and Newell, S.Y. 1989. Digestive enzymes in the salt marsh periwinkle Littorina irrorata (Gastropoda). Oecologia. 80:39-43.
Baerlocher, F., Newell, S.Y. and Arsuffi, T. 1989. Digestion of Spartina alterniflora material with and without fungal constituents by the periwinkle Littorina irrorata (Mollusca: Gastropoda). Journal Experimental Marine Biology and Ecology. 130:45-53.
Balderston, W.L., Sherr, B. and Payne, W.J. 1976. Blockage by acetylene of nitrous oxide reduction in Pseudomonas perfectomarinus. Applied and Environmental Microbiology. 31:504-508.
Bancroft, K., Paul, E.A. and Wiebe, W. 1976. The extraction and measurement of adenosine triphosphate from marine sediments. Limnology and Oceanography. 21:473-480.
Barlocher, F. and Newell, S.Y. 1994. Growth of the saltmarsh periwinkle Littoraria irrorata on fungal and cordgrass diets. Marine Biology. 118:109-114.
Barlocher, F. and Newell, S.Y. 1994. Phenolics and Proteins affecting Palatability of Spartina Leaves to the Gastropod Littoraria irrorata. Marine Ecology. 15:65-75.
Basan, P.B. 1979. Classification of low marsh habitat in a Georgia salt marsh. Georgia Journal of Science. 37:139-154.
Basan, P.B. and Frey, R.W. 1982. Size reduction with deliccation of modern internal molds of the mussel Geukensia demissa. Journal of Paleontology. 56:970-972.
Benke, A.C., Chaubey, I., Ward, G.M. and Dunn, E.L. 2000. Flood pulse dynamics of an unregulated river floodplain in the southeastern U.S. coastal plain. Ecology. 81(10):2730-2741.
Benner, R., Fogel, M.L. and Sprague, E.K. 1991. Diagenesis of belowground biomass of Spartina alterniflora in salt-marsh sediments. Limnology and Oceanography. 36:1358-1374.
Benner, R., Fogel, M.L., Sprague, E.K. and Hodson, R.E. 1987. Depletion of 13C in lignin and its implications for stable carbon isotope studies. Nature. 329:708-710.
Benner, R., Maccubbin, A.E. and Hodson, R.E. 1984. Anaerobic biodegradation of the lignin and polysaccharide components of lignocellulose and synthetic lignin by sediment microflora. Applied and Environmental Microbiology. 47:998-1004.
Benner, R., Maccubbin, A.E. and Hodson, R.E. 1984. Preparation, characterization, and microbial degradation of specifically radiolabeled (14C) lignocelluloses from marine and freshwater macrophytes. Applied and Environmental Microbiology. 47:381-389.
Benner, R., Maccubbin, A.E. and Hodson, R.E. 1986. Temporal relationship between the deposition and microbial degradation of lignocellulosic detritus in a Georgia salt marsh and the Okefenokee Swamp. Microbial Ecology. 12:291-298.
Benner, R., Moran, M.A. and Hodson, R.E. 1985. Effects of pH and plant source on lignocellulose biodegradation rates in two wetland ecosystems, the Okefenokee Swamp and a Georgia salt marsh. Limnology and Oceanography. 30:489-499.
Benner, R., Moran, M.A. and Hodson, R.E. 1986. Biogeochemical cycling of lignocellulosic carbon in marine and freshwater ecosystems: relative contributions of procaryotes and eucaryotes. Limnology and Oceanography. 31:89-100.
Benner, R., Newell, S.Y., Maccubbin, A.E. and Hodson, R.E. 1984. Relative contributions of bacteria and fungi to rates of degradation of lignocellulosic detritus in salt-marsh sediments. Applied and Environmental Microbiology. 48:36-40.
Bergbauer, M. and Newell, S.Y. 1992. Contribution to lignocellulose degradation and DOC formation from a salt marsh macrophyte by the ascomycete Phaeosphaeria spartinicola. FEMS Microbiol Ecology. 86:341-348.
Berman, T.B. 1983. Phosphorous uptake by microplankton in estuarine and coastal shelf water near Sapelo Island, Georgia, U.S.A. Estuaries. 6:160-166.
Berresheim, H. 1993. Distribution of atmospheric sulphur species over various wetland regions in the southeastern U.S.A. Atmospheric Environment. 27a:211-221.
Biers, E.J., Zepp, R.G. and Moran, M.A. 2007. The role of nitrogen in chromophoric and fluorescent dissolved organic matter formation. Marine Chemistry. 103:46-60.
Bishop, T.D., Miller, H.L., Walker, R.L., Hurley, D.H., Menken, T. and Tilburg, C.E. 2010. Blue Crab (Callinectes sapidus Rathbun, 1896) Settlement at Three Georgia (USA) Estuarine Sites. Estuaries and Coasts. 33(3):688-698.
Abstract
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=0.5461, lag _0-2 days) between wind events, temperature, salinity, maximum tidal height, and settlement.
Bohlool, B.B. and Wiebe, W.J. 1978. Nitrogen-fixing communities in an intertidal ecosystem. Canadian Journal of Microbiology. 24:932-938.
Bostrom, C., Pittman, S.J., Simenstad, C. and Kneib, R.T. 2011. Seascape ecology of coastal biogenic habitats: advances, gaps, and challenges. Marine Ecology Progress Series. 427:191-217.
Abstract
We review the progress made in the emerging field of coastal seascape ecology, i.e. the application of landscape ecology concepts and techniques to the coastal marine environment. Since the early 1990s, the landscape ecology approach has been applied in several coastal subtidal and intertidal biogenic habitats across a range of spatial scales. Emerging evidence indicates that animals in these seascapes respond to the structure of patches and patch mosaics in different ways and at different spatial scales, yet we still know very little about the ecological significance of these relationships and the consequences of change in seascape patterning for ecosystem functioning and overall biodiversity. Ecological interactions that occur within patches and among different types of patches (or seascapes) are likely to be critically important in maintaining primary and secondary production, trophic transfer, biodiversity, coastal protection, and supporting a wealth of ecosystem goods and services. We review faunal responses to patch and seascape structure, including effects of fragmentation on 5 focal habitats: seagrass meadows, salt marshes, coral reefs, mangrove forests, and oyster reefs. Extrapolating and generalizing spatial relationships between ecological patterns and processes across scales remains a significant challenge, and we show that there are major gaps in our understanding of these relationships. Filling these gaps will be crucial for managing and responding to an inevitably changing coastal environment. We show that critical ecological thresholds exist in the structural patterning of biogenic ecosystems that, when exceeded, cause abrupt shifts in the distribution and abundance of organisms. A better understanding of faunal-seascape relationships, including the identifications of threshold effects, is urgently needed to support the development of more effective and holistic management actions in restoration, site prioritization, and forecasting the impacts of environmental change.
Bradley, P. and Dunn, E.L. 1989. Effects of sulfide on the growth of three salt marsh halophytes of the southeastern United States. American Journal of Botany. 76:1707-1713.
Brittain, R.A. and Craft, C.B. 2012. Effects of Sea-Level Rise and Anthropogenic Development on Priority Bird Species Habitats in Coastal Georgia, USA. Environmental Management. 49(2):473-482.
Abstract
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.
Brittain, R.A., Meretsky, V.J. and Craft, C.B. 2010. AVIAN COMMUNITIES OF THE ALTAMAHA RIVER ESTUARY IN GEORGIA, USA. Wilson Journal of Ornithology. 122(3):532-544.
Abstract
We surveyed male breeding birds in five habitats (bottomland forest, maritime oak [Quercus spp.], pine [Pious 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 (Panda 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 (similar to 0.2%) and had three PIF priority species, including Painted Bunting (Passerina ciris), the only PIF species with extremely high priority in this study.
Brittain, R.A., Schimmelmann, A., Parkhurst, D.F. and Craft, C.B. 2012. Habitat Use by Coastal Birds Inferred from Stable Carbon and Nitrogen Isotopes. Estuaries and Coasts. 35(2):633-645.
Abstract
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 C-13 and delta N-15. 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.
Buchan, A., Collier, L.S., Neidle, E.L. and Moran, M.A. 2000. Key aromatic-ring-cleaving enzyme, Protocatechuate 3,4-Dioxygenase, in the ecologically important marine Roseobacter lineage. Applied and Environmental Microbiology. 66(11):4662-4672.
Buchan, A., Newell, S.Y., Butler, M., Biers, E.J., Hollibaugh, J.T. and Moran, M.A. 2003. Dynamics of bacterial and fungal communities on decaying salt marsh grass. Applied and Environmental Microbiology. 69(11):6676-6687.
Buchan, A., Newell, S.Y., Moreta, J.I.L. and Moran, M.A. 2002. Analysis of internal transcribed spacer (ITS) regions of rRNA genes in fungal communities of a southeastern U.S. salt marsh. Microbial Ecology. 43(3):329-340.
Buck, T.L., Breed, G.A., Pennings, S.C., Chase, M.E., Zimmer, M. and Carefoot, T.H. 2003. Diet choice in an omnivorous salt-marsh crab: different food types, body size, and habitat complexity. Journal of Experimental Marine Biology and Ecology. 292:103-116.
Burkholder, P.R. 1956. Studies on the nutritive value of Spartina grass growing in the marsh areas of coastal Georgia. Bulletin of the Torrey Botanical Club. 83:327-334.
Burkholder, P.R. and Bornside, G.H. 1957. Decomposition of marsh grass by aerobic marine bacteria. Bulletin of the Torrey Botanical Club. 84:366-383.
Burkholder, P.R. and Burkholder, L.M. 1956. Vitamin B12 in suspended solids and marsh muds collected along the coast of Georgia. Limnology and Oceanography. 1:202-208.
Burns, C.J., Alber, M. and Alexander, C.R. 2020. Historical Changes in the Vegetated Area of Salt Marshes. Estuaries and Coasts. 44(1):162-177.
Abstract
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.
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Abstract
We used field and laboratory measurements, geographic information systems, and simulation modeling to investigate the potential effects of accelerated sea-level rise on tidal marsh area and delivery of ecosystem services along the Georgia coast. Model simulations using the Intergovernmental Panel on Climate Change (IPCC) mean and maximum estimates of sea-level rise for the year 2100 suggest that salt marshes will decline in area by 20% and 45%, respectively. The area of tidal freshwater marshes will increase by 2% under the IPCC mean scenario, but will decline by 39% under the maximum scenario. Delivery of ecosystem services associated with productivity (macrophyte biomass) and waste treatment (nitrogen accumulation in soil, potential denitrification) will also decline. Our findings suggest that tidal marshes at the lower and upper salinity ranges, and their attendant delivery of ecosystem services, will be most affected by accelerated sealevel rise, unless geomorphic conditions (ie gradual increase in elevation) enable tidal freshwater marshes to migrate inland, or vertical accretion of salt marshes to increase, to compensate for accelerated sea-level rise.
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Craft, C.B. 2012. Tidal freshwater forest accretion does not keep pace with sea level rise. Global Change Biology. 18(12):3615-3623.
Abstract
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 C-137 and Pb-210 averaged 1.3 and 2.2 mm yr(-1), respectively, and was substantially lower than the recent rate of SLR along the Georgia coast (3.0 mm yr(-1)). Healthy tidal forest soils sequestered C (4982 g m(-2) yr(-1)), accumulated N (3.25.3 g m(-2) yr(-1)) and P (0.290.56 g m(-2) yr(-1)) and trapped mineral sediment (340650 g m(-2) yr(-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.
Abstract
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 = 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 mm/year) and in tidal fresh and brackish marshes (4.7–5.4 mm/year) of the estuary. Accretion rates were considerably lower in alluvial and tidal fresh forests and salt marshes (0.9–2.5 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 g C/m2/year, 7.1–9.5 g 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 g/m2/year) and P burial (2.75 g P/m2/year) than other wetlands along the waterway (180–1730 g sediment/m2/year, 0.23–0.90 g 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.
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Abstract
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.
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Abstract
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.
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Filip, Z. and Alberts, J.J. 1994. Adsorption and transformation of salt marsh related humic acids in quartz and clay minerals. Science of the Total environment. 153:141-150.
Filip, Z. and Alberts, J.J. 1994. Microbial utilization resulting in early diagenesis of salt marsh humic acids. Science of the Total Environment. 144:121-135.
Filip, Z., Alberts, J.J., Chesire, M.V., Goodman, B.A. and Bacon, J.R. 1988. Comparison of salt marsh humic acid with humic-like substances from the indigenous plant species Spartina alterniflora (Loisel.). Science of the Total Environment. 71:157-172.
Filip, Z., Newman, R.H. and Alberts, J.J. 1991. Carbon-13 nuclear magnetic resonance characterization of humic substances associated with salt marsh environments. Science of the Total Environment. 101:191-199.
Filip, Z., Trubetskoj, O.A. and Alberts, J.J. 1995. Electrophoretic evidence of the structural similarity of different salt marsh related humic substances. Scientia Agriculturae Bohemica. 26(3):219-225.
First, M.R. and Hollibaugh, J.T. 2008. Protistan bacterivory and benthic microbial biomass in an interridal creek mudflat. Marine Ecology Progress Series. 361:59-68.
Abstract
We examined 8 sediment samples collected at 3 h intervals at Dean Creek (Sapelo Island, Georgia) to assess the impact of protist bacterivory on the standing crops of benthic bacterial biomass. The combined biomass of the benthic microalgae (BMA), bacteria, heterotrophic protists, and meiofauna ranged from 0.41 to 0.57 mg C g–1 wet sediment (gws) in the samples examined. BMA represented >80% of total biomass and remained relatively stable throughout the study period. Bacterial biomass ranged from 28 to 91 μg C gws–1 (5 to 16% of total biomass) in the samples. Heterotrophic protists (mainly ciliates, flagellates, and testate amoeba) and meiofauna (mainly nematodes) each contributed small (<1% each) amounts to the total biomass. Protist grazing accounted for the loss of <1.1 and <4.7% h–1 of the total and enzymatically active bacterial standing stock, respectively. Grazing rates were highest in the morning samples, concurrent with the highest portion of potentially active bacteria. However, there was no statistically significant change in grazing impact throughout the day and in most cases bacterivory would not reduce the standing bacterial biomass. Food web simulations demonstrate that the confluence of protist loss factors (such as meiofaunal predation) and reduced grazing at low bacterial concentrations can limit the production of bacterivorous protists and, in turn, their use of the large store of benthic bacterial biomass.
First, M.R. and Hollibaugh, J.T. 2009. The model high molecular weight DOC compound, dextran, is ingested by the benthic ciliate Uronema marinum but does not supplement ciliate growth. Aquatic Microbial Ecology. 57:79-87.
Abstract
Phagotrophic ciliates are capable of growth solely on dissolved compounds in laboratory cultures. Whether ciliates use dissolved compounds in the environment for growth is unclear. We investigated the ability of the marine benthic ciliate Uronema marinum to ingest a model high molecular weight dissolved organic carbon (HMW-DOC) compound, dextran, at concentrations typical for coastal salt marsh sediments (3 μM to 3 mM C). Ingestion was measured by incubating ciliates with fluorescein-labeled dextran (2000 kDa) and measuring the fluorescence signal of the labeled compound in cells via flow cytometry. Ciliates accumulated dextran (relative to formalin-killed controls) at concentrations as low as 0.1 mg l–1 dextran (3 μM C). Labeled dextran accumulated in food vacuoles and near the buccal cavity; thus, the ingestion of dextran appears to be a consequence of feeding activities rather than transport across the cell membrane via parasomal sac formation. Dextran accumulation did not increase with higher bacterial ingestion rates. Instead, dextran accumulation was greatest at intermediate bacterial concentrations and grazing rates. Ciliate growth rates were measured in treatments amended with model carbon compounds—soluble starch, acetate, and glucose (3 mM C, final concentrations). There was no significant increase in ciliate growth rates with these compounds in either bacteria-free or bacteria-enriched treatments. Rather, growth rates were significantly lower in treatments with DOC addition, indicating that processing of these DOC compounds may incur some energetic cost to these ciliates.
First, M.R. and Hollibaugh, J.T. 2010. Diel depth distributions of microbenthos in tidal creek sediments: high resolution mapping in fluorescently labeled embedded cores. Hydrobiologia. 655:149–158.
Abstract
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 lE m-2 s-1). More than 91% of organisms mapped were\22 lm 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.
First, M.R. and Hollibaugh, J.T. 2010. Environmental factors shaping microbial community structure in salt marsh sediments. Marine Ecology Progress Series. 399:15-26.
Abstract
We examined benthic microbial communities in 3 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 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: 3.4 × 103, range: 0.1 to 9.3 × 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: 4.2 × 109; range: 0.6 to 16 × 109 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.
Fischer, J.M., Reed-Andersen, T., Klug, J.L. and Chalmers, A.G. 2000. Spatial pattern of localized disturbance along a southeastern salt marsh tidal creek. Estuaries. 23(4):565-571.
Fitt, W.K. and Coon, S.L. 1992. Evidence for ammonia as a natural cue for recruitment of oyster larvae to oyster beds in a Georgia salt marsh. Biological Bulletin. 182:401-408.
Fitz, H.C. and Wiegert, R.G. 1991. Tagging juvenile blue crabs, Callinectes sapidus, with microwire tags: retention, survival, and growth through multiple molts. Journal Crustacean Biology. 11:229-235.
Fitz, H.C. and Wiegert, R.G. 1991. Utilization of the intertidal zone of a salt marsh by the blue crab, Callinectes sapidus: density, return frequency, and feeding habits. Marine Ecology-Progress Series. 76:249-260.
Fitz, H.C. and Wiegert, R.G. 1992. Local population dynamics of estuarine blue crabs: abundance, recruitment and loss. Marine Ecology-Progress Series. 87:23-40.
Forbes, A.E. 2004. Spines and Natural History of Three Cenchrus Species. American Midland Naturalist. 153:80-86.
Foust, C.M., Preite, V., Schrey, A.W., Alvarez, M., Robertson, M.H., Verhoeven, K.J.F. and Richards, C.L. 2016. Genetic and epigenetic differences associated with environmental gradients in replicate populations of two salt marsh perennials. Molecular Ecology.
Abstract
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 gra- dients occurs at epigenetic, but not genetic loci in two salt marsh perennials. We detected a 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 signifi- cant correlations between epigenetic and/or genetic variation and habitat in four of five populations when populations were analysed individually, but there was no sig- nificant correlation between genetic or epigenetic variation and habitat when analysed jointly across the five populations. These analyses suggest that epigenetic mecha- nisms are involved in the response to salt marsh habitats, but also that the relation- ships among genetic and epigenetic variation and habitat vary by species. Site- specific conditions may also cloud our ability to detect response in replicate popula- tions 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.
Frankenberg, D. 1965. A new species of Cyathura (Isopoda, Anthuridae) from coastal waters off Georgia, U.S.A. Crustaceana. 8:206-212.
Frankenberg, D. 1965. An anomalous position for the appendix masculina of an anthurid isopod. Crustaceana. 8:111-112.
Frankenberg, D. 1966. Southern limit of Nassarius trivittatus. Nautilus. 79:89-90.
Frankenberg, D. 1968. Seasonal aggregation in Amphioxus. BioScience. 18:877-878.
Frankenberg, D. 1971. Dynamics of benthic communities off Georgia, U.S.A. Thalassia Jugoslavica, Special Volume. 7:49-55.
Frankenberg, D. 1976. Oxygen in a tidal river: low tide concentration correlates linearly with location. Estuarine and Coastal Marine Science. 4:455-460.
Frankenberg, D. and Burbanck, W.D. 1963. A comparison of the physiology and ecology of the estuarine isopod Cyathura polita in Massachusetts and Georgia. Biological Bulletin. 125:81-95.
Frankenberg, D. and Giles, R.T. 1970. Acid treatment of organic materials and the removal of calcium carbonate. Journal of Sedimentary Petrology. 40:1046-1048.
Frankenberg, D. and Menzies, R.J. 1966. A new species of asellote marine isopod, Munna (Uromunna) reynoldsi (Crustacea: Isopoda). Bulletin of Marine Science. 16:200-208.
Frankenberg, D. and Smith, K.L.J. 1967. Coprophagy in marine animals. Limnology and Oceanography. 12:443-450.
Frankenberg, D. and Westerfield, C. 1968. Oxygen demand and oxygen depletion capacity of sediments from Wassaw Sound, Georgia. Bulletin of the Georgia Academy of Science. 26:160-171.
Frankenberg, D., Coles, S.L. and Johannes, R.E. 1967. The potential trophic significance of Callianassa major fecal pellets. Limnology and Oceanography. 12:113-120.
Franks, S.J. 2003. Competitive and facilitative interactions within and between two species of coastal dune perennials. Canadian Journal of Botany. 81:330-337.
Franks, S.J. 2003. Facilitation in multiple life-history stages: evidence for nucleated succession in coastal dunes. Plant Ecology. 168:1-11.
Frey, R.W. 1969. New observations on Tisoa, a trace fossil from the Lincoln Creek formation (mid-Tertiary) of Washington. The Compass. 47:10-22.
Frey, R.W. 1970. The lebensspuren of some common marine invertebrates near Beaufort, North Carolina. II. Anemone burrows. Journal of Paleontology. 44:308-311.
Frey, R.W. 1971. Ichnology--The study of fossil and recent lebensspuren. LSU School of Geosciences Misc. Publ. 71-1:91-125.
Frey, R.W. 1972. Review of "Coastal Lagoons, A Symposium". A. S. Castanares and F. B. Phlegar (eds.). Journal of Paleontology. 46:461-462.
Frey, R.W. 1973. Concepts in the study of biogenic sedimentary structures. Journal of Sedimentary Petrology. 43:6-19.
Frey, R.W. 1987. Distribution of ark shells (Bivalvia: Anadara), Cabretta Island Beach, Georgia. Southeastern Geology. 27:155-163.
Frey, R.W. 1987. Hermit crabs: Neglected factors in taphonomy and palaeoecology. Palaios. 2:313-322.
Frey, R.W. and Basan, P.B. 1981. Taphonomy of relict Holocene salt marsh deposits, Cabretta Island, Georgia. Senckenbergiana Maritima. 13:111-155.
Frey, R.W. and Dorjes, J. 1988. Carbonate skeletal remains in beach-to-offshore sediments, Pensacola, Florida. Senckenbergiana Maritima. 20:31-57.
Frey, R.W. and Dorjes, J. 1988. Fair- and foul-weather shell accumulations on a Georgia beach. Palaios. 3:561-576.
Frey, R.W. and Henderson, S.W. 1987. Left-right phenomena among bivalve shells: Examples from the Georgia Coast. Senckenbergiana Maritima. 19:223-247.
Frey, R.W. and Howard, J.D. 1969. A profile of biogenic sedimentary structures in a Holocene barrier island-salt marsh complex, Georgia. Transactions-Gulf Coast Association of Geological Societies. 19:427-444.
Frey, R.W. and Howard, J.D. 1972. Georgia Coastal Region, Sapelo Island, U.S.A.: Sedimentology and Biology. VI. Radiographic study of sedimentary structures made by beach and offshore animals in aquaria. Senckenbergiana Maritima. 4:169-182.
Frey, R.W. and Howard, J.D. 1986. Mesotidal estuarine sequences: A perspective from the Georgia Bight. Journal of Sedimentary Petrology. 56:911-924.
Frey, R.W. and Howard, J.D. 1986. Taphonomic characteristics of offshore mollusk shells, Sapelo Island, Georgia. Tulane Studies in Geology and Paleontology. 19:51-62.
Frey, R.W. and Howard, J.D. 1988. Beaches and beach-related facies, Holocene barrier island of Georgia. Geological Magazine. 125:621-640.
Frey, R.W. and Mayou, T.V. 1971. Decapod burrows in Holocene barrier island beaches and washover fans, Georgia. Senckenbergiana Maritima. 3:53-77.
Frey, R.W. and Pemberton, S.G. 1986. Vertebrate lebensspuren in intertidal and supratidal environments, Holocene barrier islands, Georgia. Senckenbergiana Maritima. 18:45-95.
Frey, R.W. and Pemberton, S.G. 1987. The Psilonichnus ichnocoenose, and its relationship to adjacent marine and nonmarine ichnocoenoses along the Georgia coast. Bulletin of Canadian Petroleum Geology. 35:333-357.
Frey, R.W. and Pinet, P.R. 1978. Calcium-carbonate content of surficial sands seaward of Altamaha and Doboy Sounds, Georgia. Journal of Sedimentary Petrology. 48:1249-1256.
Frey, R.W., Basan, P.B. and Scott, R.M. 1973. Techniques for sampling salt marsh benthos and burrows. American Midland Naturalist. 89:228-234.
Frey, R.W., Basan, P.B. and Smith, J.M. 1987. Rheotaxis and distribution of oysters and mussels, Georgia tidal creeks and salt marshes, U.S.A. Palaeogeography, Palaeoclimatology, Palaeoecology. 61:1-16.
Frey, R.W., Curran, H.A. and Pemberton, S.G. 1984. Tracemaking activities of crabs and their environmental significance: the ichnogenus Psilonichnus. Journal of Paleontology. 58:333-350.
Frey, R.W., Howard, J.D. and Pryor, W.A. 1978. Ophiomorpha: Its morphologic, taxonomic, and environmental significance. Palaeogeography, Palaeoclimatology, Palaeoecology. 23:119-229.
Frey, R.W., Voorhies, M.R. and Howard, J.D. 1975. Estuaries of the Georgia coast, U.S.A.: Sedimentology and biology. VIII. Fossil and recent skeletal remains in Georgia estuaries. Senckenbergiana Maritima. 7:257-295.
Frost, J.W., Schleicher, T. and Craft, C. 2009. EFFECTS OF NITROGEN AND PHOSPHORUS ADDITIONS ON PRIMARY PRODUCTION AND INVERTEBRATE DENSITIES IN A GEORGIA (USA) TIDAL FRESHWATER MARSH. Wetlands. 29(1):196-203.
Abstract
We added nitrogen (N), phosphorus (P), and N+P to a Zizaniopsis miliacea (Giant Cutgrass) dominated tidal freshwater marsh in Georgia USA to investigate nutrient limitation of tidal freshwater marsh primary production and invertebrate densities. After two years, aboveground biomass was significantly greater in the plots receiving N (2130 g m22), and N+P (2066 g m22) than in the control (886 g m22) and P (971 g m22) only treatments. We observed no enrichment of leaf N or P in response to nutrient additions. Rather leaf N decreased and C:N increased in plots receiving N, suggesting that leaf N was diluted by increased production of carbon laden structural components used to support increased plant height. N:P ratios (mol:mol) of the plant tissue were consistently , 30 (14–27) in the treatment plots, also suggesting N limitation of primary production. Total densities of benthic invertebrates and oligochaete worms (primarily Tubificidae and Lumbriculidae) were significantly greater in the N+P plots than in the other treatments after two years of nutrient additions. There were no clear differences in diversity of benthic invertebrates among treatments. Our results suggest that tidal freshwater marsh primary and secondary production is limited or co-limited by N, and thus, like estuaries and salt marshes, are susceptible to N enrichment and eutrophication.
Fry, B. and Sherr, E.B. 1984. 13C measurements as indicators of carbon flow in marine and freshwater ecosystems. Contributions in Marine Science. 27:13-47.
Abstract
In the nutrient-rich region surrounding marine phytoplankton cells, heterotrophic bacterioplankton transform a major fraction of recently fixed carbon through the uptake and catabolism of phytoplankton metabolites. We sought to understand the rules by which marine bacterial communities assemble in these nutrient-enhanced phycospheres, specifically addressing the role of host resources in driving community coalescence. Synthetic systems with varying combinations of known exometabolites of marine phytoplankton were inoculated with seawater bacterial assemblages, and communities were transferred daily to mimic the average duration of natural phycospheres. We found that bacterial community assembly was predictable from linear combinations of the taxa maintained on each individual metabolite in the mixture, weighted for the growth each supported. Deviations from this simple additive resource model were observed but also attributed to resource-based factors via enhanced bacterial growth when host metabolites were available concurrently. The ability of photosynthetic hosts to shape bacterial associates through excreted metabolites represents a mechanism by which microbiomes with beneficial effects on host growth could be recruited. In the surface ocean, resource-based assembly of host-associated communities may underpin the evolution and maintenance of microbial interactions and determine the fate of a substantial portion of Earth''s primary production.
Gaeta, J.W. and Kornis, M.S. 2011. Stem Borer Frequency and Composition in Healthy Spartina alterniflora (smooth cordgrass) and Dieback Zones in a Southern Atlantic Coast Salt Marsh. Estuaries and Coasts. 34(5):1078-1083.
Abstract
Unprecedented Spartina alterniflora (smooth cordgrass) dieback has recently plagued Atlantic and Gulf coast US salt marshes. The hypothesized drivers of dieback vary geographically but include drought and herbivory. Stem-boring insect larvae may also contribute to dieback, but have thus far been overlooked. Here we describe stem borer frequency and composition among healthy S. alterniflora morphs (tall and short) and dieback zones in Dean Creek Marsh on Sapelo Island, GA. Overall stem borer frequency was highest in tall morph S. alterniflora and dieback zones (present in 46.7% and 39.5%, respectively). Healthy habitat types were characterized by six stem borer families with only two of those families observed in dieback zones. Taxa from these two families, previously reported by others to cause stem death, were found at their highest frequency in dieback zones. Although we cannot infer causation, our results raise the possibility of stem borers contributing to the formation of dieback zones, meriting further research.
Gallagher, J.L. 1974. Sampling macro-organic matter profiles in salt marsh plant root zones. Soil Science Society of America Proceedings. 38:154-155.
Gallagher, J.L. 1975. Effect of an ammonium nitrate pulse on the growth and elemental composition of natural stands of Spartina alterniflora and Juncus roemerianus. American Journal of Botany. 62:644-648.
Gallagher, J.L. 1975. The significance of the surface film in salt marsh plankton metabolism. Limnology and Oceanography. 20:120-123.
Gallagher, J.L. 1979. Growth and element compositional responses of Sporobolus virginicus (L.) Kunth. to substrate salinity and nitrogen. American Midland Naturalist. 102:68-75.
Gallagher, J.L. and Kibby, H. 1980. Marsh plants as vectors in trace mineral dynamics in Oregon tidal marshes. American Journal of Botany. 67:1069-1074.
Gallagher, J.L. and Pfeiffer, W.J. 1977. Aquatic metabolism of the communities associated with attached dead shoots of salt marsh plants. Limnology and Oceanography. 22:562-565.
Gallagher, J.L. and Plumley, F.G. 1979. Underground biomass profiles and productivity in Atlantic coastal marshes. American Journal of Botany. 66:156-161.
Gallagher, J.L., Pfeiffer, W.J. and Pomeroy, L.R. 1976. Leaching and microbial utilization of dissolved organic carbon from leaves of Spartina alterniflora. Estuarine and Coastal Marine Science. 4:467-471.
Gallagher, J.L., Reimold, R.J., Linthurst, R.A. and Pfeiffer, W.J. 1980. Aerial production, mortality, and mineral accumulation dynamics in Spartina alterniflora and Juncus roemerianus in a Georgia salt marsh. Ecology. 61:303-312.
Gallagher, J.L., Robinson, S.E., Pfeiffer, W.J. and Seliskar, D.M. 1979. Distribution and movement of toxaphene in anaerobic saline marsh soils. Hydrobiologia. 63:3-9.
Gallagher, J.L., Wolf, P.L. and Pfeiffer, W.J. 1984. Rhizome and root growth rates and cycles in protein and carbohydrate concentrations in Georgia Spartina alterniflora Loisel. plants. American Journal of Botany. 71:165-169.
Ge, Z., Brown, C.W. and Alberts, J.J. 1995. Infrared fiber optic sensor for petroleum. Environmental Science and Technology. 29(4):878-882.
Gebrehiwet, T., Koretsky, C.M. and Krishnamurthy, R.V. 2008. Influence of Spartina and Juncus on saltmarsh sediments. III. Organic geochemistry. Chemical Geology. 255(1-2):114-119.
Abstract
Total organic carbon, C/N ratios of sediment organic matter and delta(13)C of sediment organic matter (delta(13)C(org)) were measured as a function of depth at four sites in a saltmarsh on Sapelo Island, GA during summer 2006. The goal of this study is to assess the sources of sediment organic matter at each site and to investigate the influence of macrophytes and macrofauna on the observed carbon isotopic signatures and C/N ratios at each site. The four sites include two adjacent creekside sites, one densely vegetated by tall-form Spartina alterniflora and the other mostly unvegetated, together with two adjacent sites higher in the marsh, including a site with sparse short-form Spartina and a neighboring site densely vegetated with Juncus roemarianus. Total organic carbon in the sediments of these sites varies between 2.1 and 6.4%, with the highest values observed at shallow depths at the unvegetated creek bank and the lowest at the short Spartina site. C/N ratios of the sediment organic matter vary between 10.6 and 17.3, with higher values at the short Spartina site compared to the other three sites. delta(13)C(org) varies little with depth, averaging -20.1 +/- 0.2 parts per thousand at the Juncus, tall Spartina and adjacent unvegetated sites, and -17.8 +/- 0.6 parts per thousand at the short Spartina site. Mixing calculations completed with the depth-averaged C/N and delta(13)C(org) for each site, assuming three endmember organic matter sources (C(3) plants, C(4) plants, phytoplankton), suggest that up to 75% of the organic matter at all four sites is derived from phytoplankton. Surprisingly, the average delta(13)C(org) and C/N values, and therefore the calculated contributions of the three endmember organic matter sources to the total sediment organic matter, are very similar at the Juncus, tall Spartina and unvegetated creekbank sites. The greater delta(13)C(org) and C/N of the short Spartina sediments is consistent with little or no inclusion of C(3)-derived organic matter in the sediments at this site, in spite of the close proximity to the densely-vegetated Juncus site, and with less degradation of the organic matter compared to the other three sites. (C) 2008 Elsevier B.V. All rights reserved.
Gehman, A.L.M., Mahaffey, M. and Byers, J.E. 2021. Influences of land use and ecological variables on trematode prevalence and intensity at the salt marsh-upland ecotone. Ecosphere. 12(8):13.
Abstract
Human-altered shorelines make up approximately 14% of the coastline in the United States, with consequences for marsh ecosystems ranging from altered physical and biological variables, to direct loss of intertidal marsh habitat, to diminished land-sea connectivity. Trophically transmitted parasites that require connectivity between upland host species and marsh host species to complete their complex lifecycles could be particularly sensitive to the effects of shoreline alterations. They can additionally respond to gradients in natural physical and biological factors, including the host communities, that are often sharp at the land-sea ecotone. Across 27 salt marshes over 45 km, we evaluated the effects of environmental variables and three types of land use (undeveloped; single-house adjacent to the marsh with small-scale shoreline armoring; and single-house adjacent to the marsh without shoreline armoring), on infection prevalence and intensity of the trematode Microphallus basodactylophallus in its second intermediate crab host, Minuca pugnax. The first intermediate hosts of M. basodactylophallus are Hydrobiid snail species that are obligate marsh residents, while the definitive hosts are terrestrial rodents and raccoons. Thus, trematode transmission must depend on cross-boundary movement by the definitive hosts. We found that although there was a trend of lower infection prevalence at undeveloped forested sites, there was no significant effect of adjacent land development on infection prevalence or intensity. Instead host, biotic and abiotic factors were correlated with infection; namely, larger M. pugnax had higher prevalence and intensity of M. basodactylophallus, and higher soil moisture and lower density of the ribbed mussel (Geukensia demissa) were associated with increased M. basodactylophallus prevalence. The small, indirect influence of upland development suggests that movement of definite hosts across the ecotone may be largely unaffected. Further, the robust trematode levels signify the ecosystem and the species interactions, upon which its complex lifecycle depends, are largely intact.
Giblin, A.E. and Howarth, R.W. 1984. Porewater evidence for a dynamic sedimentary iron cycle in salt marshes. Limnology and Oceanography. 29:47-63.
Giesy, J.P. and Alberts, J.J. 1989. Conditional stability constants and binding capacities for copper(II) by ultrafilterable material isolated from six surface waters of Wyoming, USA. Hydrobiologia. 188/189:659-679.
Gifford, S.M., Sharma, S., Booth, M. and Moran, M.A. 2013. Expression patterns reveal niche diversification in a marine microbial assemblage. Isme Journal. 7(2):281-298.
Abstract
Resolving the ecological niches of coexisting marine microbial taxa is challenging due to the high species richness of microbial communities and the apparent functional redundancy in bacterial genomes and metagenomes. Here, we generated over 11 million Illumina reads of protein-encoding transcripts collected from well-mixed southeastern US coastal waters to characterize gene expression patterns distinguishing the ecological roles of hundreds of microbial taxa sharing the same environment. The taxa with highest in situ growth rates (based on relative abundance of ribosomal protein transcripts) were typically not the greatest contributors to community transcription, suggesting strong top-down ecological control, and their diverse transcriptomes indicated roles as metabolic generalists. The taxa with low in situ growth rates typically had low diversity transcriptomes dominated by specialized metabolisms. By identifying protein-encoding genes with atypically high expression for their level of conservation, unique functional roles of community members emerged related to substrate use (such as complex carbohydrates, fatty acids, methanesulfonate, taurine, tartrate, ectoine), alternative energy-conservation strategies (proteorhodopsin, AAnP, V-type pyrophosphatases, sulfur oxidation, hydrogen oxidation) and mechanisms for negotiating a heterogeneous environment (flagellar motility, gliding motility, adhesion strategies). On average, the heterotrophic bacterioplankton dedicated 7% of their transcriptomes to obtaining energy by non-heterotrophic means. This deep sequencing of a coastal bacterioplankton transcriptome provides the most highly resolved view of bacterioplankton niche dimensions yet available, uncovering a spectrum of unrecognized ecological strategies. The ISME Journal (2013) 7, 281-298; doi: 10.1038/ismej.2012.96; published online 30 August 2012
Giles, R.T. and Pilkey, O.H. 1965. Atlantic beach and dune sediments of the southern United States. Journal of Sedimentary Petrology. 35:900-910.
Gilligan, M.R., Verity, P.G., Cook, C.B., Cook, S.B., Booth, M.G. and Frischer, M.E. 2007. Building a diverse and innovative ocean workforce through collaboration and partnerships that integrate research and education: HBCUs and Marine Laboratories. Journal of Geoscience Education. 55(6):531-540.
Abstract
Historically Black Colleges and Universities (HBCUs) attract, retain and award science degrees to African Americans at a higher rate than majority institutions. Because they offer life-changing and career-orienting experiences for students, field stations and marine laboratories are well positioned to help increase the number of students opting for science, technology, engineering and mathematics (STEM) careers and ocean science and education careers, in particular. Two kinds of partnerships have developed between Savannah State University (SSU), an HBCU, and marine laboratories as a result of federal funding: a Research Experiences for Undergraduates (REU) program between SSU and the Harbor Branch Oceanographic Institution, and an internship/graduate program between SSU and the Skidaway Institute of Oceanography. These collaborations and other funded projects since 1998 have resulted in an increase in the percent of graduates from SSU''s Bachelor of Science in Marine Science degree who had a significant research experience from 25% before 1999 to 66% percent afterwards and an increase in the number graduating with honors from 30% prior to 1999 to 41% after 1999. The growth and productivity of marine science degree and research experience programs at Savannah State University illustrates how collaboration and partnerships can be an effective way to increase access and eventually pay big dividends by increasing diversity in geoscience professions.
Giurgevich, J.R. and Dunn, E.L. 1978. Seasonal patterns of CO2 and water vapor exchange of Juncus roemerianus Scheele in a Georgia salt marsh. American Journal of Botany. 65:502-510.
Giurgevich, J.R. and Dunn, E.L. 1979. Seasonal patterns of CO2 and water vapor exchange of the tall and short height forms of Spartina alterniflora Loisel. in a Georgia salt marsh. Oecologia. 43:139-156.
Giurgevich, J.R. and Dunn, E.L. 1981. A comparative analysis of the CO2 and water vapor responses of two Spartina species from Georgia coastal marsh. Estuarine and Coastal Marine Science. 12:561-568.
Giurgevich, J.R. and Dunn, E.L. 1982. Seasonal patterns of daily net phytosynthesis, transpiration, and net primary productivity of Juncus roemerianus and Spartina alterniflora in a Georgia salt marsh. Oecologia. 52:404-410.
Gjessing, E.T., Alberts, J.J., Bruchet, A., Egeberg, P.K., Lydersen, E., McGown, L.B., Mobed, J.J., Munster, U., Pempkowiak, J., Perdue, M., Ratnawerra, H., Rybacki, D., Takacs, M. and Abbt-Braun, G. 1998. Multi-method characterisation of natural organic matter isolated from water: Characterisation of reverse osmosis-isolates from water of two semi-identical dystrophic lakes basins in Norway. Water Research. 32(10):3108-3124.
Goldstein, S. and Bagwell-Harben, E. 1993. Taphofacies implications of infaunal foraminiferal assemblages in a Georgia salt marsh, Sapelo Island. Micropaleontology. 39:53-62.
Goldstein, S. and Weinmann, A. 2016. Landward directed dispersal of benthic foraminiferal propagules at two shallow-water sites in the Doboy Sound area (Georgia, U.S.A.). Journal of Foraminiferal Research. 47(4):325–336.
Abstract
Transport of foraminiferal propagules is an important mode of dispersal in benthic foraminifera. Known to occur from tidal marshes and estuaries to deep-water environments, the former are particularly vulnerable to ongoing climate change. Because rising sea levels can have profound implications on local salinity and associated faunal compositions, transport of foraminiferal propagules within these environments can be crucial for local assemblages to respond to changing conditions. Here we focus on a shallow-water environment in southeastern Georgia to evaluate whether propagule transport occurs evenly or whether it shows a predominant direction, such as land- or seaward. Two sites were sampled in the Doboy Sound area: the southern tip of Sapelo Island and a site on the North River located approximately 10 km inland. We applied the propagule method using the fine fraction of the sediments that contains the propagule bank. Experimental conditions in the laboratory included three temperatures (18, 24 and 30â—¦C) and three salinities (15, 25 and 35) to simulate a range of environments that might trigger the growth of various foraminiferal species. While adult in situ assemblages of both sites were at least partly influenced by the adjacent salt marshes, experimentally grown assemblages were dominated by mudflat, estuarine or more open marine species. Thus, propagule transport from the more terrestrial side of the assemblage gradient is limited, while propagules of more marine species can be transported far into the extensive estuarine system of the study area, where they can remain viable within the local propagule banks.Results provide important insights into possible changes in foraminiferal assemblages with rising sea-level on the Georgia coast.
Goldstein, S.T. 1997. Gametogenesis and the antiquity of reproductive pattern in the foraminiferida. Journal of Foraminiferal Research. 27(4):319-328.
Goldstein, S.T. and Alve, E. 2011. Experimental assembly of foraminiferal communities from coastal propagule banks. Marine Ecology Progress Series. 437:1-11.
Abstract
Benthic foraminifera (protists) have long been recognized as sensitive indicators in studies on natural and human-induced environmental, paleo-environmental, and climate change. These wide-ranging applications are founded on more than a century of field-based investigations in which environmental data were related to species distributions, and have subsequently been refined by the development of chemical proxies and a variety of culture-based studies. The recent discovery of foraminiferal propagule banks that occur in the fine-sediment fraction of marine depositional settings provides a novel experimental tool for examining the ecology of benthic foraminifera, their processes of dispersal, and the responses of multi-species assemblages to changing environmental conditions. In the ''propagule method'' presented here, we use experimental arrays in which foraminifera are grown from propagule banks under different controlled abiotic conditions. We examined the roles of temperature, salinity, and site (exposed vs. protected) in structuring coastal assemblages and show that, because individual species respond differently, distinct assemblages grew from the same propagule bank under different environmental regimes. Temperature was the most important factor distinguishing experimental assemblages, whereas exposure of the collection site (e.g. to waves and currents, that promote or limit species dispersal to and from each site) was most important in determining species richness. The diversity of the propagule bank therefore imparts resilience to foraminiferal associations and provides a rapid-response mechanism for changing environments. This method further provides a tool for documenting changes in coastal assemblages that potentially result from warming or cooling climates.
Goldstein, S.T. and Barker, W.W. 1988. Test ultrastructure and taphonomy of the monothalamous agglutinated foraminifer Cribrothalammina n. gen. Alba (Heron-Allen Earland). Journal of Foraminiferal Research. 18:130-136.
Goldstein, S.T. and Barker, W.W. 1990. Gametogenesis in the monothalamous agglutinated foraminifer. Journal of Protozoology. 37:20-27.
Goldstein, S.T. and Frey, R.W. 1986. Salt marsh foraminifera, Sapelo Island, Georgia. Senckenbergiana Maritima. 18:97-121.
Goldstein, S.T. and Moodley, L. 1993. Gametogenesis and the life cycle of the foraminifer Ammonia beccarii (Linne) forma Tepida (Cushman). Journal of Foraminiferal Research. 23:213-220.
Goldstein, S.T. and Watkins, G.T. 1998. Elevation and the distribution of salt-marsh foraminigera, St. Catherines Island, Georgia: a taphonomic approach. Palaios. 13:570-580.
Goldstein, S.T. and Watkins, G.T. 1999. Taphonomy of salt marsh foraminifera: an example from coastal Georgia. Palaeogeography Palaeoclimatology Palaeoecology. 149:103-114.
Goldstein, S.T., Habura, A., Richardson, E.A. and Bowser, S.S. 2010. XIPHOPHAGA MINUTA, AND X. ALLOMINUTA, NOV GEN., NOV SPP., NEW MONOTHALAMID FORAMINIFERA FROM COASTAL GEORGIA (USA): CRYPTIC SPECIES, GAMETOGENESIS, AND AN UNUSUAL FORM OF CHLOROPLAST SEQUESTRATION. Journal of Foraminiferal Research. 40(1):3-15.
Abstract
The biodiversity of modern monothalamid Foraminifera (predominantly agglutinated taxa as well as naked and organic-walled forms) is considerably higher than that recognized in most previous studies. The numerous mudflats associated with salt marshes of Sapelo Island, Georgia, host an extensive array of mainly undescribed monothalamids (allogromiids and astrorhizids), in addition to the better-known, multi-chambered forms. Among these monothalamids are two new cryptic species, Xiphophaga minuta and X. allominuta, nov. gen., nov. spp., which may be distinguished by SSU rDNA sequences, but are closely similar in morphology. These new species are small (typically similar to 200 pm), translucent, and comparable in shape and shell construction. Both agglutinate clay platelets and have a single aperture located on a distinct neck. Both species belong to the monothalamid clade E of Pawlowski and others (2002). Xiphophaga minuta occurred abundantly on Sapelo''s back-barrier mudflats during the summer of 2003, and X. allominuta was recovered from the same mudflats during the summers of 2005 and 2007. Xiphophaga minuta is the primary focus of this report. Gametogenesis, common in populations of both species during the summer, occurs in uninucleate individuals and follows a comparable pattern. Some foreign material is egested at the onset, but most is sequestered within a large, highly vacuolated central region. Gametogenesis occurs in the peripheral cytoplasm around this central region, producing numerous biflagellated gametes that are released directly into the surrounding seawater via the aperture. Xiphophaga minuta and X. allominuta therefore are gametogamous, as are most species of Foraminifera. Non-reproductive individuals of both species appear golden-brown in color, reflecting the ingestion of numerous pennate diatoms within the cytoplasm. Such individuals are packed with diatoms, which, although mainly digested, retain intact chloroplasts. We suggest that these foraminiferans, which lack hard mineralized structures, are unable to fracture diatoms and remove their chloroplasts. Rather, they ingest entire diatoms as a form of chloroplast sequestration.
Goldstein, S.T., Watkins, G.T. and Kuhn, R.M. 1995. Microhabitats of salt marsh foraminifera: St. Catherines Island, Georgia, U.S.A. Marine Micropaleontology (759). 26:17-29.
Gonzalez, J., Whitman, W.B., Hodson, R.E. and Moran, M.A. 1996. Identifying numerically abundant culturable bacteria from complex communities: an example from a lignin enrichment culture. Applied and Environmental Microbiology. 62(12):4433-4440.
Gonzalez, J.M. 1999. Bacterivory rate estimates and fraction of active bacterivores in natural protist assemblages from aquatic systems. Applied and Environmental Microbiology. 65(4):1463-1469.
Gonzalez, J.M. and Moran, M.A. 1997. Numerical dominance of a group of marine bacteria in the a-subclass of the class Proteobacteria in coastal seawater. Applied and Environmental Microbiology. 63(11):4237-4242.
Gonzalez, J.M., Kiene, R.P. and Moran, M.A. 1999. Transformation of sulfur compounds by an abundant lineage of marine bacteria in the -subclass of the class Proteobacteria. Applied and Environmental Microbiology. 65(9):3810-3819.
Gonzalez, J.M., Moran, M.A., Hodson, R.E. and Whitman, W.B. 1997. Microbulbifer hydrolyticus gen. nov., sp. nov., and marinobacterium georgiense gen. nov., sp. nov., two marine bacteria from a lignin-rich pulp mill waste enrichment community. Int. J. Syst. Bacteriol. 47:369-376.
Gonzalez, J.M., Moran, M.A., Hodson, R.E. and Whitman, W.B. 1997. Sagittula stellata gen. nov., sp. nov., a lignin-transforming bacterium from a coastal environment. Int. J. Syst. Bacteriol. 47:773-780.
Gonzalez, J.M., Sherr, E.B. and Sherr, B.F. 1990. Size-selective grazing on bacteria by natural assemblages of estuarine flagellates and ciliates. Applied and Environmental Microbiology. 56:583-589.
Goranson, C.E., Ho, C.K. and Pennings, S.C. 2004. Environmental gradients and herbivore feeding preferences in coastal salt marshes. Oecologia. 140(4):591-600.
Gormally, C.L. and Donovan, L.A. 2010. Responses of Uniola paniculata L. (Poaceae), an Essential Dune-Building Grass, to Complex Changing Environmental Gradients on the Coastal Dunes. Estuaries and Coasts. 33(5):1237-1246.
Abstract
Coastal dunes are well known for plant species zonation but less is known about species-specific responses to underlying environmental gradients. We investigated variation in morphological traits and tissue nutrient concentration in Uniola paniculata, along a shoreline-to-landward gradient (transects spanning from the dunes directly behind the high tide mark to 40-100 m inland) in the southeast USA. Several environmental factors decreased with distance from the shoreline (soil B, K, Mg, Na; salinity, pH, and sand accretion), and differences were most pronounced between the 10 m closest to the shoreline and the remainder of the transect. In the 10 m closest to the shoreline, 94% more sand accumulated, which was 31% more saline. Additionally, plants here were taller, contained higher aboveground tissue N and K, and a higher percentage tended to flower. This contrasts with patterns found in salt marshes and saline desert dunes, where plant size is often negatively correlated with salinity. During the 2 years following the planned study, storms washed out <= 25 m of the transects. Resampling of the remaining sites demonstrated that even after erosion of the dune profile, a higher percentage of the plants in the 10 m closest to the shoreline plants tended to flower, relative to populations located further from the shore. Our findings suggested that the environment and plant response in the shoreward 10 m can re-establish relatively quickly.
Gormally, C.L. and Donovan, L.A. 2011. No Evidence of Local Adaptation in Uniola paniculata L. (Poaceae), a Coastal Dune Grass. Southeastern Naturalist. 10(4):751-760.
Abstract
Studies of local adaptation generally investigate plants growing in relatively stable habitats. We asked whether populations of the long-lived clonal grass Uniola paniculata (Sea Oats) are locally adapted to microhabitats in the southeastern US coastal dunes, a habitat characterized by dynamic environmental gradients spanning relatively small distances. Although vegetative zonation is well characterized across these gradients, little is known about intraspecifi c evolutionary responses of species spanning the gradients. Plants from the foredune and backdune areas of the gradient (<10 m and 40-60 m from the shoreline, respectively) were reciprocally transplanted into experimental plots in both habitats. Although foredune plots were washed away by storms before harvest, the foredune plants demonstrated no early advantage in stem diameter or height growth, and thus there was no support for local adaptation in foredune plants. In the backdune plots, the backdune plants demonstrated no early growth advantage, and additionally demonstrated no advantage in survival, nor in growth or total biomass of surviving plants at harvest. Thus, there was again no support for local adaptation. In frequently disturbed environments such as the coastal dunes, plants may be more likely to respond with phenotypic plasticity than through local adaptation.
Gormally, C.L., Hamrick, J.L. and Donovan, L.A. 2011. GENETIC STRUCTURE OF A WIDELY DISPERSED BEACH ANNUAL, CAKILE EDENTULA (BRASSICACEAE). American Journal of Botany. 98(10):1657-1662.
Abstract
Premise of the study: Genetic structure of coastal plant species is influenced by the homogenizing effects of long-distance seed dispersal and the isolating effects of fragmented geographic distribution. Although dispersed coastal annuals play a significant role in establishing healthy dune communities, relatively little is known about their population genetic structure. Methods: We investigated the population genetic structure of Cakile edentula, an annual colonizer of beaches of coastal North America and the Great Lakes. We surveyed 22 populations for 24 allozyme loci across a geographic range encompassing three infraspecific taxa: two subspecies (C. edentula subsp. edentula and subsp. harperi) and two varieties of subsp. edentula (var. edentula and var. lacustris). Key results: Genetic diversity in C. edentula (H(es) = 0.118) is equivalent to mean estimates for other annual mixed-mating species, but is much lower (H(ep) = 0.041) within its populations. UPGMA identified three groups that are consistent with previously described subspecies and possibly consistent with the two varieties. An AMOVA indicates that variation among taxonomic groups explains 54% of total genetic diversity within the species. Although pairwise F(ST) estimates indicate moderate rates of gene flow between populations within groups, there was no evidence of significant isolation by distance. Conclusions: Genetic structure of C. edentula is strongly related to previously described phenotypically and geographically based infraspecific taxa. Within taxa, the effects of long-distance dispersal of its buoyant propagules are balanced by the isolating effects of fragmented geographic distribution and a mixed-mating system.
Abstract
Understanding the underlying causes of phe- notypic trait variation among populations is important for informing conservation decisions. This knowledge can be used to determine whether locality matters when sourcing populations for habitat restoration. Uniola paniculata is a federally protected coastal dune grass native to the south- eastern Atlantic and the Gulf coasts of the USA that is often used to stabilize restored dune habitats. This study uses neutral genetic markers (allozymes) and a greenhouse common garden study to determine the relative contribu- tions of neutral evolutionary processes and natural selec- tion to patterns of phenotypic variation among natural populations of U. paniculata. Seeds were sourced from foredune and backdune populations spanning shoreline-to- landward environmental gradients on each of four Georgia barrier islands. Based on previous work, we expected to find evidence of divergent selection among populations located on the shoreline-to-landward environmental gradi- ent. However, differences among islands, rather than intra- island habitat differences, drive divergent selection on aboveground and total biomass. The lack of evidence for divergent selection across the shoreline-to-landward gra- dient suggests that previously documented intra-island trait variation is likely due to phenotypic plasticity. Our findings have implications for conservation and restoration efforts involving U. paniculata, as there is evidence for divergent selection among populations located on neighboring islands.
Goshorn, D.M. and Epifanio, C.E. 1991. Development, survival, and growth of larval weakfish at different prey abundances. Transactions of the American Fisheries Society. 120:693-700.
Goshorn, D.M. and Epifanio, C.E. 1991. Diet of larval weakfish and prey abundance in Delaware Bay. Transactions of the American Fisheries Society. 120:684-692.
Gosselink, J.G., Hatton, R. and Hopkinson, C.S. 1984. Relationships among bulk density and organic and inorganic material in Louisiana marsh soils. Soil Science. 137:177-180.
Graca, M.A.S., Newell, S.Y. and Kneib, R.T. 2000. Grazing rates of organic matter and living fungal biomass of decaying Spartina alterniflora by three species of saltmarsh invertebrates. Marine Biology. 136(2):281-289.
Gregory, M.R., Campbell, K.A., Zuraida, R. and Martin, A.J. 2006. Plant traces resembling Skolithos. Ichnos. 13:205-216.
Abstract
The ichnogenus Skolithos Haldeman 1840 is a simple tubular trace fossil that was initially described as a “fucoid” or seaweed impression, i.e., a fossilized marine plant. Today the tracemaker is commonly considered to have been a vermiform marine invertebrate, although this interpretation is not acceptable to all. It is the name giver to the archetypal, Seilacherian Skolithos ichnofacies, which is a widely acknowledged indicator of relatively high energy, shallow water, nearshore to marginal marine environments. Here we record and describe analogous cylindrical structures, unquestionably reflecting plant tracemakers. These have been recognized in Quaternary consolidated “coffee” sandrock and Recent coastal dune, marsh or swamp, and salt meadow settings from northern New Zealand and Sapelo Island, USA. We conclude that Skolithos is not an unequivocal indicator of shallow marine settings. Our observations confirm the opinions of a number of previous workers who have expressed the need for caution when using this ichnotaxon as a shallow-water, higher energy palaeoenvironmental indicator, especially when supporting evidence is otherwise lacking. In particular we note that in high intertidal and non-aquatic settings, Skolithos may be a plant trace fossil rather than serve as evidence for invertebrate activities. At the present time there is pressing need for a thorough systematic revision of the Skolithos ichnotaxon.
Gregory, M.R., Martin, A.J. and Campbell, K.A. 2004. Compound trace fossils formed by plant and animal interactions: Quaternary of northern New Zealand and Sapelo Island, Georgia (USA). Fossils and Strata. 51:88-105.
Gross, M.F., Hardisky, M.A., Wolf, P.L. and Klemas, V. 1991. Relationship between aboveground and belowground biomass of Spartina alterniflora (smooth cordgrass). Estuaries. 14:180-191.
Guo, H., Chamberlain, S.A., Elhaik, E., Jalli, I., Lynes, A.-R., Marczak, L., Sabath, N., Vargas, A., Wieski, K., Zelig, E.M. and Pennings, S.C. 2015. Geographic variation in plant community structure of salt marshes: species, functional and phylogenetic perspectives. PloS one. 10(5):e0127781.
Abstract
In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes 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 relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in ecosystems with low species diversity, functional and phylogenetic approaches may not provide additional insight over a species-based approach.
Guo, H.Y. and Pennings, S.C. 2012. Mechanisms mediating plant distributions across estuarine landscapes in a low-latitude tidal estuary. Ecology. 93(1):90-100.
Abstract
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 (USA) 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.
Guo, H.Y. and Pennings, S.C. 2012. Post-mortem ecosystem engineering by oysters creates habitat for a rare marsh plant. Oecologia. 170(3):789-798.
Abstract
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.
Guo, H.Y., Wieski, K., Lan, Z.J. and Pennings, S.C. 2014. Relative influence of deterministic processes on structuring marsh plant communities varies across an abiotic gradient. Oikos. 123(2):173-178.
Abstract
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 that deterministic 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 community structure. 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.
Gwak, W.-S. 2003. Effects of shelter on growth and survival in age-0 black sea bass, Centropristis striata (L.). Aquaculture Research. 34:1387-1390.
Hackney, C.T. and Haines, E.B. 1980. Stable carbon isotope composition of fauna and organic matter collected in a Mississippi estuary. Estuarine and Coastal Marine Science. 10:703-708.
Haddad, R.I., Newell, S.Y., Martens, C.S. and Fallon, R.D. 1992. Early diagenesis of lignin-associated phenolics in the saltmarsh grass Spartina alterniflora. Geochimica et Cosmochimica Acta. 56:3751-3764.
Hails, J.R. and Hoyt, J.H. 1968. Barrier development of submerged coasts: Problems of sea-level changes from a study of the Atlantic coastal plain of Georgia, U.S.A., and parts of the east Australian coast. Zeitschrift fĂĽr Geomorphologie. 7:24-55.
Hails, J.R. and Hoyt, J.H. 1969. An appraisal of the evolution of the lower Atlantic coastal plain of Georgia, U.S.A. The Institute of British Geographers Publications. Trans. Publ. No. 46:53-68.
Hails, J.R. and Hoyt, J.H. 1969. The significance and limitations of statistical parameters for distinguishing ancient and modern sedimentary environments of the lower Georgia coastal plain. Journal of Sedimentary Petrology. 39:559-580.
Hails, J.R. and Hoyt, J.H. 1971. The question of late Quaternary changes of sea level in New South Wales, Australia. Quaternaria. 14:255-264.
Haines, B.L. and Dunn, E.L. 1976. Growth and resource allocation responses of Spartina alterniflora Loisel. to three levels of NH4-N, Fe, and NaCl in solution culture. Botanical Gazette. 137:224-230.
Haines, E.B. 1976. Nitrogen content and acidity of rain on the Georgia coast. Water Resources Bulletin. 12:1223-1231.
Haines, E.B. 1976. Relation between the stable carbon isotope composition of fiddler crabs, plants and soils in a salt marsh. Limnology and Oceanography. 21:880-883.
Haines, E.B. 1976. Stable carbon isotope ratios in the biota, soils, and tidal water of a Georgia salt marsh. Estuarine and Coastal Marine Science. 4:609-619.
Haines, E.B. 1977. The origin of detritus in Georgia salt marsh estuaries. Oikos. 29:254-260.
Haines, E.B. 1979. Growth dynamics of cordgrass, Spartina alterniflora Loisel., on control and sewage sludge fertilized plots in a Georgia salt marsh. Estuaries. 2:50-53.
Haines, E.B. 1979. Nitrogen pools in Georgia coastal waters. Estuaries. 2:34-39.
Haines, E.B. and Hanson, R.B. 1979. Experimental degradation of detritus made from the salt marsh plants Spartina alterniflora Loisel., Salicornia virginica L., and Juncus roemerianus Scheele. Journal Experimental Marine Biology and Ecology. 40:27-40.
Haines, E.B. and Montague, C.L. 1979. Food sources of estuarine invertebrates analyzed using 13C/12C ratios. Ecology. 60:48-56.
Hall, A.M. and Fritz, W.J. 1984. Armored mud balls from Cabretta and Sapelo Barrier Islands, Georgia. Journal of Sedimentary Petrology. 54:831-835.
Hanson, R.B. 1977. Comparison of nitrogen fixation activity in tall and short Spartina alterniflora salt marsh soils. Applied and Environmental Microbiology. 33:596-602.
Hanson, R.B. 1977. Nitrogen fixation (acetylene reduction) in a salt marsh amended with sewage sludge and organic carbon and nitrogen compounds. Applied and Environmental Microbiology. 33:846-852.
Hanson, R.B. 1977. Pelagic Sargassum community metabolism: Carbon and nitrogen. Journal Experimental Marine Biology and Ecology. 29:107-118.
Hanson, R.B. 1983. Nitrogen fixation activity (acetylene reduction) in the rhizosphere of salt marsh angiosperms, Georgia, USA. Botanica Marina. 26:49-59.
Hanson, R.B. and Snyder, J. 1979. Microheterotrophic activity in a salt-marsh estuary, Sapelo Island, Georgia. Ecology. 60:99-107.
Hanson, R.B. and Snyder, J.S. 1979. Enzymatic determination of glucose in marine environments: Improvement and note of caution. Marine Chemistry. 7:353-362.
Hanson, R.B. and Snyder, J.S. 1980. Glucose exchanges in a salt marsh estuary: Biological activity and chemical measurement. Limnology and Oceanography. 25:633-642.
Hanson, R.B. and Wiebe, W.J. 1977. Heterotrophic activity associated with particulate size fractions in a Spartina alterniflora salt-marsh estuary, Sapelo Island, Georgia U.S.A., and the continental shelf waters. Marine Biology. 42:321-330.
Hanson, R.B., Robertson, C.Y., Yoder, J.A., Verity, P.G. and Bishop, S.S. 1990. Nitrogen recycling in coastal waters of southeastern U. S. during summer of 1986. Journal of Marine Research. 48:641-660.
Abstract
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.
Hardy, D. and Heynen, N. 2020. "I am Sapelo:" Racialized Uneven Development and Land Politics within the Gullah/Geechee Corridor. Environment and Planning E: Nature and Space.
Harriss, R.C. and Pilkey, O.H. 1966. Temperature and salinity control of the concentration of skeletal Na, Mn, and Fe in Dendraster excentricus. Pacific Science. 20:235-238.
Harvey, C.J. 1998. Use of sandy beach habitat by Fundulus majalis, a surf-zone fish. Marine Ecology Progress Series. 164:307-310.
Harvey, H.R., Fallon, R.D. and Patton, J.S. 1986. The effect of organic matter and oxygen on the degradation of bacterial membrane lipids in marine sediments. Geochimica et Cosmochimica Acta. 50:795-804.
Harvey, H.R., Fallon, R.D. and Patton, J.S. 1989. Methanogenesis and microbial lipid synthesis in anoxic salt marsh sediments. Biogeochemistry. 7:111-130.
Hattin, D.E. and Frey, R.W. 1969. Facies relations of Crossopodia sp., a trace fossil from the Upper Cretaceous of Kansas, Iowa, and Oklahoma. Journal of Paleontology. 43:1435-1440.
Abstract
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 ÎĽg gâ’1 hrâ’1 in the mature marshes to 0.094 ± 0.03 ÎĽg gâ’1 hrâ’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.
Healy, B. 1994. New species of Marionina (Annelida:Oligochaeta: Enchytraeidae) from Spartina marshes on Sapelo Island, Georgia, USA. Proceedings of the Bilogical Society of Washington. 107:164-173.
Healy, B. and Walters, K. 1994. Oligochaeta in Spartina stems:the microdistribution of Enchytraeidae and Tubificidae in a salt marsh, Sapelo Island, USA. Hydrobiologia. 278:111-123.
Heard, R.W. 1970. Parasites of the clapper rail, Rallus longirostris Boddaert. II. Some trematodes and cestodes from Spartina marshes of the eastern United States. Proceedings Helminthological Society Washington. 37:147-153.
Heard, R.W. 1975. Feeding habits of white catfish from a Georgia estuary. Florida Scientist. 38:20-28.
Heard, R.W.I. and Sikora, W. 1971. A new species of Corophium Latreille, 1806 (Crustacea:Amphipoda) from Georgia brackish waters with some ecological notes. Proceedings of the Biological Society of Washington. 84:467-476.
Heard, R.W.I. and Sikora, W.B. 1969. Probolocoryphe otagaki, 1958 (Trematoda:Microphallidae), a senior synonym of Mecynophallus Cable, Connor, and Balling, 1960, with notes on the genus. Journal of Parasitology. 55:674-675.
Henderson, S.W. and Frey, R.W. 1986. Taphonomic redistribution of mollusk shells in a tidal inlet channel, Sapelo Island, Georgia. Palaios. 1:3-16.
Henry, V.J.J. 1971. Origin of capes and shoals along the southeastern coast of the United States: Reply. Geological Society of America Buletin. 82:3541-3542.
Henry, V.J.J. and Hoyt, J.H. 1968. Quaternary paralic and shelf sediments of Georgia. Southeastern Geology. 9:195-214.
Hensel, M.J.S. and Silliman, B.R. 2013. Consumer diversity across kingdoms supports multiple functions in a coastal ecosystem. Proceedings of the National Academy of Sciences of the United States of America. 110(51):20621-20626.
Abstract
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.
Herbert, E.R., Schubauer-Berigan, J. and Craft, C. 2018. Differential effects of chronic and acute seawater intrusion on tidal freshwater marsh carbon cycling. Biogeochemistry.
Abstract
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 (SO42â’, Clâ’, organic C, inorganic nitrogen and phosphorus), ecosystem CO2 and CH4exchange, 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.
Herbert, E.R., Schubauer-Berigan, J. and Craft, C.B. 2018. Effects of ten years of nitrogen and phosphorus fertilization in tidal freshwater marshes. Limnology and Oceanography. IN REVISION.
Hermeno, E., Knowlton, M.K., Krueger, J.P., Lerberg, S., Nomann, B.E., Page, T., Richards, C.L., Stallins, J.A. and Townsend, H. 1996. Abstracts of research reports from the University of Georgia Marine Institute Student Intern Program, 1992-1995. Georgia Journal of Science. 54(2):91-98.
Hicks, R.E. and Newell, S.Y. 1982. Gas chromatographic analysis of muramic acid and glucosamine for microbial biomass determinations. University of Georgia Sea Grant Technical Report 82-2. 51 p.
Hicks, R.E. and Newell, S.Y. 1983. An improved gas chromatographic method for measuring glucosamine and muramic acid concentrations. Analytical Biochemistry. 128:438-445.
Hicks, R.E. and Newell, S.Y. 1984. A comparison of glucosamine and biovolume conversion factors for estimating fungal biomass. Oikos. 42:355-360.
Hicks, R.E. and Newell, S.Y. 1984. The growth of bacteria and the fungus Phaeosphaeria typharum (Desm.) Holm (Eumycota:Ascomycotina) in salt-marsh microcosms in the presence and absence of mercury. Journal Experimental Marine Biology and Ecology. 78:143-155.
Hladik, C., Schalles, J. and Alber, M. 2013. Salt marsh elevation and habitat mapping using hyperspectral and LIDAR data. Remote Sensing of Environment. 139:318-330.
Abstract
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 MAR 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 derision 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 -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. (C) 2013 Elsevier Inc. All rights reserved.
Ho, C.-K. and Pennings, S.C. 2008. CONSEQUENCES OF OMNIVORY FOR TROPHIC INTERACTIONS ON A SALT MARSH SHRUB. Ecology. 89(6):1714-1722.
Abstract
Although omnivory is common in nature, its impact on trophic interactions is variable. Predicting the food web consequences of omnivory is complicated because omnivores can simultaneously produce conflicting direct and indirect effects on the same species or trophic level. We conducted field and laboratory experiments testing the top-down impacts of an omnivorous salt marsh crab, Armases cinereum, on the shrub Iva frutescens and its herbivorous and predatory arthropod fauna. Armases is a â€â€true omnivore,’’ consuming both Iva and arthropods living on Iva. We hypothesized that Armases would benefit Iva through a top-down trophic cascade, and that this benefit would be stronger than the direct negative effect of Armases on Iva. A field experiment on Sapelo Island, Georgia (USA), supported this hypothesis. Although Armases suppressed predators (spiders), it also suppressed herbivores (aphids), and benefited Iva, increasing leaf number, and reducing the proportion of dead shoots. A one-month laboratory experiment, focusing on the most common species in the food web, also supported this hypothesis. Armases strongly suppressed aphids and consumed fewer Iva leaves if aphids were available as an alternate diet. Armases gained more body mass if they could feed on aphids as well as on Iva. Although Armases had a negative effect on Iva when aphids were not present, Armases benefited Iva if aphids were present, because Armases controlled aphid populations, releasing Iva from herbivory. Although Armases is an omnivore, it produced strong top-down forces and a trophic cascade because it fed preferentially on herbivores rather than plants when both were available. At the same time, the ability of Armases to subsist on a plant diet allows it to persist in the food web when animal food is not available. Because omnivores feed on multiple trophic levels, their effects on food webs may differ from those predicted by standard trophic models that assume that each species feeds only on a single trophic level. To better understand the complexity of real food webs, the variable feeding habits and feeding preferences of different omnivorous species must be taken into consideration.
Ho, C.-K. and Pennings, S.C. 2013. Preference and Performance in Plant-Herbivore Interactions across Latitude-A Study in US Atlantic Salt Marshes. PLoS One. 8(3):e59829.
Abstract
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.
Ho, C.K., Pennings, S.C. and Carefoot, T.H. 2010. Is Diet Quality an Overlooked Mechanism for Bergmann's Rule? American Naturalist. 175(2):269-276.
Abstract
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.
Ho, H.H., Nakagiri, A. and Newell, S.Y. 1992. A new species of Halophytophthora from Atlantic and Pacific subtropical islands. Mycologia. 84:548-554.
Hodson, R.E., Christian, R.R. and Maccubbin, A.E. 1984. Lignocellulose and lignin in the salt marsh grass Spartina alterniflora: initial concentrations and short-term, post-depositional changes in detrital matter. Marine Biology. 81:1-7.
Hoese, H.D. 1966. Ectoparasitism by juvenile sea catfish, Galeichthys felis. Copeia. 4:880-881.
Hoese, H.D. 1967. Effect of higher than normal salinities on salt marshes. Contributions in Marine Science. 12:249-261.
Hoese, R. 1971. Dolphin feeding out of water in a salt marsh. Journal of Mammalogy. 52:222-223.
Hopkinson, C.S. 1985. Shallow-water benthic and pelagic metabolism: evidence of heterotrophy in the nearshore Georgia Bight. Marine Biology. 87:19-32.
Hopkinson, C.S. 1987. Nutrient regeneration in shallow-water sediments of the estuarine plume region of the nearshore Georgia Bight, USA. Marine Biology. 94:127-142.
Hopkinson, C.S. 1992. A comparison of ecosystem dynamics in freshwater wetlands. Estuaries. 15:549-562.
Hopkinson, C.S. and Dunn, E.L. 1984. Rapid sampling of organic matter in flooded soils and sediments. Estuaries. 7:181-184.
Hopkinson, C.S. and Schubauer, J.P. 1984. Static and dynamic aspects of nitrogen cycling in the salt marsh graminoid Spartina alterniflora. Ecology. 65:961-969.
Hopkinson, C.S. and Wetzel, R.L. 1982. In situ measurements of nutrient and oxygen fluxes in a coastal benthic community. Marine Ecology-Progress Series. 10:29-35.
Hopkinson, C.S., Day, J.W. and Kjerfve, B. 1985. Ecological significance of summer storms in a shallow water estuarine system. Contributions in Marine Science. 28:69-77.
Hopkinson, C.S., Fallon, R.D., Jansson, B.O. and Schubauer, J.P. 1991. Community metabolism and nutrient cycling of Gray's Reef, a hard bottom habitat in the Georgia Bight. Marine Ecology-Progress Series. 73:105-120.
Hopkinson, C.S., Sherr, B.F. and Ducklow, H.W. 1987. Microbial regeneration of ammonium in the water column of Davies Reef, Australia. Marine Ecology-Progress Series. 41:147-153.
Hopkinson, C.S., Sherr, B.F. and Wiebe, W.J. 1989. Size-fractionated metabolism of coastal microbial plankton. Marine Ecology-Progress Series. 51:155-166.
Hori, K. and Cormier, M.J. 1965. Studies on the bioluminescence of Renilla reniformis. V. Absorption and fluorescence characteristics of chromatographically pure luciferin. Biochimica et Biophysica Acta. 102:386-396.
Hori, K. and Cormier, M.J. 1966. Studies on the bioluminescence of Renilla reniformis. VI. Some chemical properties and the tentative partial structure of luciferin. Biochimica et Biophysica Acta. 130:420-425.
Hori, K., Anderson, J.M., Ward, W.W. and Cormier, M.J. 1975. Renilla luciferin as the substrate for calcium induced photoprotein bioluminescence. Assignment of luciferin tautomers in aequorin and mnemiopsin. Biochemistry. 14:2371-2376.
Hori, K., Charbonneau, H., Hart, R.C. and Cormier, M.J. 1977. Structure of native Renilla reniformis luciferin. Proceedings of the National Academy of Science of the USA. 74:4285-4287.
Hori, K., Nakano, Y. and Cormier, M.J. 1972. Studies on the bioluminescence of Renilla reniformis. XI. Location of the sulfate group in luciferyl sulfate. Biochimica et Biophysica Acta. 256:638-644.
Hori, K., Wampler, J.E., Matthews, J.C. and Cormier, M.J. 1973. Identification of the product excited states during the chemiluminescent and bioluminescent oxidation of Renilla (sea pansy) luciferin and certain of its analogs. Biochemistry. 12:4463-4468.
Howard, J.D. 1966. Characteristic trace fossils in Upper Cretaceous sandstones of Book Cliffs and Wasatch Plateau. Coals of Central Utah Bulletin Utah Geological Survey. 80:35-53.
Howard, J.D. 1966. Patterns of sediment dispersal in the Fountain Formation of Colorado. The Mountain Geologist. 3:147-153.
Howard, J.D. 1966. Sedimentation of the Panther Sandstone Tongue. Coals of Central Utah Bulletin Utah Geological Survey. 80:23-33.
Howard, J.D. 1968. X-ray radiography for examination of burrowing in sediments by marine invertebrate organisms. Sedimentology. 11:249-258.
Howard, J.D. 1969. Depositional control of Upper Cretaceous coal units. Mountain Geologist. 6:143-146.
Howard, J.D. 1969. Radiographic examination of variations in barrier island facies: Sapelo Island, Georgia. Transactions-Gulf Coast Association of Geological Societies. 19:217-232.
Howard, J.D. and Frey, R.W. 1973. Characteristic physical and biogenic sedimentary structures in Georgia estuaries. Bulletin of the American Association of Petroleum Geologists. 57:1169-1184.
Howard, J.D. and Frey, R.W. 1975. Estuaries of the Georgia coast, U.S.A.: Sedimentology and biology. I. Introduction. Senckenbergiana Maritima. 7:1-31.
Howard, J.D. and Frey, R.W. 1975. Estuaries of the Georgia coast, U.S.A.: Sedimentology and biology. II. Regional animal-sediment characteristics of Georgia estuaries. Senckenbergiana Maritima. 7:33-103.
Howard, J.D. and Frey, R.W. 1985. Physical and biogenic aspects of backbarrier sedimentary sequences, Georgia coast, U.S.A. Marine Geology. 63:77-127.
Howard, J.D. and Henry, V.J.J. 1966. Sampling device for semiconsolidated and unconsolidated sediments. Journal of Sedimentary Petrology. 36:818-820.
Howard, J.D. and Henry, V.J.J. 1967. Use of X-radiography in the study of bioturbate textures. Preprint, 7th International Sedimentological Congress.:4.
Howard, J.D. and Lohrengel, C.F.I. 1969. Large non-tectonic deformational structures from Upper Cretaceous rocks of Utah. Journal of Sedimentary Petrology. 39:1032-1039.
Howard, J.D., Frey, R.W. and Reineck, H.E. 1972. Georgia coastal region, Sapelo Island, U.S.A.: Sedimentology and biology. IV. Physical and biogenic sedimentary structures of the nearshore shelf. Senckenbergiana Maritima. 4:81-123.
Howarth, R.W. and Giblin, A. 1983. Sulfate reduction in the salt marshes at Sapelo Island, Georgia. Limnology and Oceanography. 28:70-82.
Howarth, R.W. and Merkel, S. 1984. Pyrite formation and the measurement of sulfate reduction in salt marsh sediments. Limnology and Oceanography. 29:598-608.
Hoyt, J.H. 1962. High angle beach stratification, Sapelo Island, Georgia. Journal of Sedimentary Petrology. 32:309-311.
Hoyt, J.H. 1966. Air and sand movements to the lee of dunes. Sedimentology. 7:137-143.
Hoyt, J.H. 1967. Barrier island formation. Geological Society of America Bulletin. 78:1125-1136.
Hoyt, J.H. 1967. Intercontinental correlation of late Pleistocene sea levels. Nature. 2l5:612-614.
Hoyt, J.H. 1967. Occurrence of high-angle stratification in littoral and shallow neritic environments, central Georgia coast, U.S.A. Sedimentology. 8:229-238.
Hoyt, J.H. 1967. Review of "Processes of Coastal Development" by V. P. Zenkowich. Journal of Geology. 76:606-607.
Hoyt, J.H. 1968. Barrier island formation: Reply. Geological Society of America Bulletin. 79:1427-1432.
Hoyt, J.H. 1968. Barrier island formation: Reply. Geological Society of America Bulletin. 79:947.
Hoyt, J.H. 1969. Chenier versus barrier, genetic and stratigraphic distinction. American Association of Petroleum Geologists. 53:299-306.
Hoyt, J.H. 1969. Late Cenozoic structural movements, northern Florida. Transactions of the Gulf Coast Association Geological Society. 19:1-9.
Hoyt, J.H. 1970. Development and migration of barrier islands, northern Gulf of Mexico: Discussion. Geological Society of America Bulletin. 81:3779-3782.
Hoyt, J.H. 1972. Shoreline processes. Journal of Geological Education. 10:16-22.
Hoyt, J.H. and Hails, J.R. 1967. Pleistocene and shoreline sediments in coastal Georgia: Deposition and modification. Science. 155:1541-1543.
Hoyt, J.H. and Hails, J.R. 1967. Pleistocene shorelines in a relatively stable area, southeastern Georgia, U.S.A. Giornale di Geologia. XXXV:105-117.
Hoyt, J.H. and Hails, J.R. 1967. Significance of radiocarbon dates from Botany Bay Island, South Carolina. Geologic Notes. 10:61-65.
Hoyt, J.H. and Hails, J.R. 1971. Regional distortions along the southeastern United States coast. Quaternaria. 15:51-63.
Hoyt, J.H. and Henry, V.J.J. 1963. Development and geologic significance of soft beach sand. Sedimentology. 3:44-51.
Hoyt, J.H. and Henry, V.J.J. 1963. Rhomboid ripple mark, indicator of current direction and environment. Journal of Sedimentary Petrology. 33:604-608.
Hoyt, J.H. and Henry, V.J.J. 1967. Influence of island migration on barrier island sedimentation. Geological Society of America Bulletin. 78:77-86.
Hoyt, J.H. and Henry, V.J.J. 1971. Origin of capes and shoals along the southeastern coast of the United States. Geological Society of America Bulletin. 82:59-66.
Hoyt, J.H. and Weimer, R.J. 1963. Comparison of modern and ancient beaches, central Georgia coast. Bulletin of the American Association of Petrology and Geology. 47:529-531.
Hoyt, J.H., Howard, J.D. and Henry, V.J.J. 1966. Pleistocene and Holocene Sediments, Sapelo Island, Georgia and Vicinity. Geological Society of America, Southeastern Section Guidebook. 78.
Hoyt, J.H., Oostdam, B.L. and Smith, D.D. 1969. Offshore sediments and valleys of the Orange River (South and Southwest Africa). Marine Geology. 7:69-84.
Hu, J. and Forschler, B.T. 2011. Sex Ratios in Field Populations of Reticulitermes spp. (Isoptera: Rhinotermitidae) on Sapelo Island, Georgia, USA. Sociobiology. 57(3):555-563.
Abstract
Social insects provide some of the most striking examples of sexual division. Thirty termite inspection ports were sampled four times in 11 months (September 2008 - July 2009). A total of 90 collections of a not-yet described Reticulitermes spp. were examined to estimate sex ratios. The range of sex ratios (male to female) observed, by caste, were: 0.49-3.50 for workers, 0.75-5.25 for soldiers and 0.02-26.00 for nymphs. These results provide new minimum and maximum values of sex ratios for each caste in Reticulitermes and reveal that there is a great deal of variation in field population sex ratios. The variation could be attributed to sample size, termite population movement between sample dates, and species differences. The data are discussed relative to interpretation of termite sex ratio data.
Hu, J.A. and Forschler, B.T. 2011. Sample Size Requirement in the Study of Subterranean Termite (Isoptera: Rhinotermitidae) Sex Ratio. Journal of Entomological Science. 46(1):23-29.
Abstract
The choice of an appropriate sample size is a neglected topic in termite sex ratio research because the literature contains a variety of sample sizes with most < 50 individuals. We compared the effect of sample size (from 25 - 800) on matching the ratio obtained from several Reticulitermes flavipes (Kollar) populations of 1600 individuals. This study showed that a sample size of < 50 is too small to estimate the actual sex ratio of a population. A sample size of at least 100 termites is required to provide +/- 10% error in a census of Reticulitermes sex ratios. The results should improve confidence in estimates of termite colony sex ratios, and we propose a standard sample size for such studies.
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Jimenez, J.M., Wieski, K., Marczak, L.B., Ho, C.K. and Pennings, S.C. 2012. Effects of an Omnivorous Katydid, Salinity, and Nutrients on a Planthopper-Spartina Food Web. Estuaries and Coasts. 35(2):475-485.
Abstract
Top-down and bottom-up effects interact to structure communities, especially in salt marshes, which contain strong gradients in bottom-up drivers such as salinity and nutrients. How omnivorous consumers respond to variation in prey availability and plant quality is poorly understood. We used a mesocosm experiment to examine how salinity, nutrients, an omnivore (the katydid Orchelimum fidicinium) and an herbivore (the planthopper Prokelisia spp.) interacted to structure a simplified salt marsh food web based on the marsh grass Spartina alterniflora. Bottom-up effects were strong, with both salinity and nutrients decreasing leaf C/N and increasing Prokelisia abundance. Top-down effects on plants were also strong, with both the herbivore and the omnivore affecting S. alterniflora traits and growth, especially when nutrients or salt were added. In contrast, top-down control by Orchelimum of Prokelisia was independent of bottom-up conditions. Orchelimum grew best on a diet containing both Spartina and Prokelisia, and in contrast to a sympatric omnivorous crab, did not shift to an animal-based diet when prey were present, suggesting that it is constrained to consume a mixed diet. These results suggest that the trophic effects of omnivores depend on omnivore behavior, dietary constraints, and ability to suppress lower trophic levels, and that omnivorous katydids may play a previously unrecognized role in salt marsh food webs.
Johannes, R. 1965. Influence of marine protozoa on nutrient regeneration. Limnology and Oceanography. 10:434-442.
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Johannes, R.E. 1967. Ecology of organic aggregates in the vicinity of a coral reef. Limnology and Oceanography. 12:189-195.
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Jun, M., Altor, A.E. and Craft, C.B. 2013. Effects of Increased Salinity and Inundation on Inorganic Nitrogen Exchange and Phosphorus Sorption by Tidal Freshwater Floodplain Forest Soils, Georgia (USA). Estuaries and Coasts. 36(3):508-518.
Abstract
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 mu M NH4-N and 5 mu M 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/m(2), respectively, and the TFFF soils experiencing saltwater intrusion removed 2.1 to 3.8 mg P/m(2). However, TFFF soils experiencing saltwater intrusion released inorganic N to the water column in amounts ranging from 7.1 to 67.5 mg/m(2). 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.
Kale, H.W. and Teal, J.M. 1958. Royal tern nesting on Little Egg Island. The Oriole. 23:36-37.
Kale, H.W.I. 1964. Food of the long-billed marsh wren, Telmatodytes palustris griseus, in the salt marshes of Sapelo Island, Georgia. The Oriole. 29:47-66.
Kale, H.W.I. 1964. Nesting of purple martins aboard a ship. Wilson Bulletin. 76:62-67.
Kale, H.W.I. 1965. Ecology and bioenergetics of the long-billed marsh wren, Telmatodytes palustris griseus, in a salt marsh ecosystem. Nuttall Ornithological Club No. 5016. 142 p.
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Kale, H.W.I. 1967. Recoveries of black skimmers banded on Little Egg Island, Georgia. The Oriole. 32:13-16.
Kale, H.W.I. 1967. Water sources of the long-billed marsh wren in Georgia salt marshes. The Auk. 84:589-591.
Kale, H.W.I. and Hyypio, P.A. 1966. Additions to the birds of Sapelo Island and vicinity. The Oriole. 31:1-11.
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Kara, E. and Shade, A. 2009. Temporal Dynamics of South End Tidal Creek (Sapelo Island, Georgia) Bacterial Communities. Applied and Environmental Microbiology. 75(4):1058-1064.
Abstract
Bacterial community dynamics in South End tidal creek, Sapelo Island, GA, were studied over a 74-h, five-tidal-cycle period. Observations were made hourly for the first consecutive 24 hours, every 3 hours on the second day, and every 6 hours on the third day. Tide most strongly influenced bacterial community composition (high-tide versus low-tide community analysis of similarities, R = 0.41, P < 0.03). Dissolved oxygen concentration and conductivity were important proximate drivers. However, after accounting for tide and environmental variables colinear with tide, cumulative time became more important in describing community variation. In-stream physical processes, including particulate suspension and sedimentation, may explain tide-associated trends in the bacterial community composition observed.
Karkhanis, Y.D. and Cormier, M.J. 1971. Isolation and properties of Renilla reniformis luciferase, a low molecular weight energy conversion enzyme. Biochemistry. 10:317-326.
Kemp, P.F. 1986. Direct uptake of detrital carbon by the deposit-feeding polychaete Euzonus mucronata (Treadwell). Journal Experimental Marine Biology and Ecology. 99:49-61.
Kemp, P.F. 1987. Potential impact on bacteria of grazing by a macrofaunal deposit-feeder, and the fate of bacterial production. Marine Ecology-Progress Series. 36:151-161.
Kemp, P.F. 1988. Bacterivory by benthic ciliates: Significance as a carbon source and impact on sediment bacteria. Marine Ecology-Progress Series. 49:163-169.
Kemp, P.F. 1990. The fate of benthic bacterial production. Reviews in Aquatic Science. 2:109-124.
Kemp, P.F. and Swartz, R.C. 1988. Acute toxicity of interstitial and particle-bound cadmium to a marine infaunal amphipod. Marine Environmental Research. 26:135-153.
Kemp, P.F., Newell, S.Y. and Hopkinson, C.S. 1990. Importance of grazing on the salt-marsh grass Spartina alterniflora to nitrogen turnover in a macrofaunal consumer, Littorina irrorata, and to decomposition of standing-dead Spartina. Marine Biology. 104:311-319.
Kemp, P.F., Newell, S.Y. and Krambeck, C. 1990. Effects of filter-feeding by the ribbed mussel Geukensia demissa on the water-column microbiota of a Spartina alterniflora saltmarsh. Marine Ecology-Progress Series. 59:119-131.
Kemp, P.F., Swartz, R.C. and Lamberson, J.O. 1986. Response of the phoxocephalid amphipod, Rhepoxynius abronius, to a small oil spill in Yaquina Bay, Oregon. Estuaries. 9:340-347.
Ket, W.A., Schubauer-Berigan, J.P. and Craft, C.B. 2011. Effects of five years of nitrogen and phosphorus additions on a Zizaniopsis miliacea tidal freshwater marsh. Aquatic Botany. 95(1):17-23.
Abstract
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 five 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(-2) year(-1) and 10 g m(-2) year(-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 five. After two years, plots receiving N and N + P had significantly greater aboveground biomass than the control and P plots. This trend continued through the fifth year of the study and resulted in two to three times more aboveground biomass at the end of the fifth year in the N (1570 g m(-2)) and N + P (1264g m(-2)) plots relative to P (710 g m(-2)) and control (570 g m(-2)) plots. After five years of nutrient additions, macro-organic matter (MOM), the living plus dead root and rhizome mat (0-10 cm), was significantly lower in the N (1457 g m(-2)) and N + P (994g m(-2)) plots than the control (2189 g m(-2)) plots. There was less live rhizome biomass in the N + P (23 g m(-2)) plots than the control (1085 g m(-2)) plots. We observed a 31-33% increase in the N content of Z. miliacea leaves in years three through five 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 five relative to the control and P plots. These findings 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 flooding and rising sea level. (C) 2011 Elsevier B.V. All rights reserved.
Kiene, R.P. 1990. Dimethyl sulfide production from dimethylsulfoniopropionate in coastal seawater samples and bacterial cultures. Applied and Environmental Microbiology. 56:3292-3297.
Kiene, R.P. 1991. Evidence for the biological turnover of thiols in anoxic marine sediments. Biogeochemistry. 13:117-135.
Kiene, R.P. 1992. Dynamics of dimethyl sulfude and dimethylsulfoiopropionate in oceanic water samples. Marine Chemistry. 37:29-52.
Kiene, R.P. and Bates, T.S. 1990. Biological removal of dimethyl sulphide from sea water. Nature. 345:702-705.
Kiene, R.P. and Service, S.K. 1991. Decomposition of dissolved DMSP and DMS in estuarine waters: dependence on temperature and substrate concentration. Marine Ecology-Progress Series. 76:1-11.
Kiene, R.P. and Taylor, B.F. 1988. Demethylation of dimethylsulfoniopropionate and production of thiols in anoxic marine sediments. Applied and Environmental Microbiology. 54:2208-2212.
Kiene, R.P., Malloy, K.D. and Taylor, B.F. 1990. Sulfur-containing amino acids as precursors of thiols in anoxic coastal sediments. Applied and Environmental Microbiology. 56:156-161.
King, G., Klug, M., Wiegert, R.G. and Chalmers, A.G. 1982. Relation of soil water movement and sulfide concentration to Spartina alterniflora productivity in a Georgia salt marsh. Science. 218:61-63.
King, G.M. and Wiebe, W.J. 1978. Methane release from soils of a Georgia salt marsh. Geochimica et Cosmochimica Acta. 42:343-348.
King, G.M. and Wiebe, W.J. 1980. Regulation of sulfate concentration in methanogenesis in salt marsh soil. Estuarine and Coastal Marine Science. 10:215-223.
King, G.M. and Wiebe, W.J. 1980. Trace analysis of methanogenesis in salt marsh soils. Applied and Environmental Microbiology. 39:877-881.
King, G.M., Berman, T. and Wiebe, W.J. 1981. Methane formation in acidic peats of Okefenokee Swamp, Georgia. American Midland Naturalist. 105:386-389.
King, G.M., Weber, C.F., Nanba, K., Bach, E., Borowske, A., Drew, K., Euser, K., Griepenstroh, L., Haugberg, N., Moses, J., Shirakawa, Y., Wachutka, E. and Vullmahn, V. 2008. Distribution, Diversity and Activity of Marine CO-Oxidizing Bacteria in a Sapelo Island, GA Saltmarsh, and Isolation of Novel Marine CO Oxidizers. Abstracts of the General Meeting of the American Society for Microbiology. 108:398.
Kinsey, D.W. 1978. Alkalinity changes and coral reef calcification. Limnology and Oceanography. 23:989-991.
Kirchman, D. and Hodson, R.E. 1984. Inhibition by peptides of amino acid uptake by bacterial populations in natural waters: implications for the regulation of amino acid transport and incorporation. Applied and Environmental Microbiology. 47:624-631.
Kirchman, D., K'nees, E. and Hodson, R.E. 1985. Leucine incorporation and its potential as a measure of protein synthesis by bacteria in natural aquatic systems. Applied and Environmental Microbiology. 49:599-607.
Kleppel, G.S. 1993. On the diets of calanoid copepods. Marine Ecology Progress Series. 99:183-195.
Kneib, R.T. 1981. Reanalysis of conversion efficiencies for larval Fundulus heteroclitus. Marine Biology. 63:213-215.
Kneib, R.T. 1981. Size-specific effects of density on the growth, fecundity and mortality of the fish Fundulus heteroclitus in an intertidal salt marsh. Marine Ecology-Progress Series. 6:203-212.
Kneib, R.T. 1982. Habitat preference, predation, and intertidal distribution of gammaridean amphipods in a North Carolina salt marsh. Journal Experimental Marine Biology and Ecology. 59:219-230.
Kneib, R.T. 1982. The effects of predation by wading birds (Ardeidae) and blue crabs (Callinectes sapidus) on the population size structure of the common mummichog, Fundulus heteroclitus. Estuarine, Coastal and Shelf Science. 14:159-165.
Kneib, R.T. 1984. Patterns in the utilization of the intertidal salt marsh by larvae and juveniles of Fundulus heteroclitus (Limnaeus) and Fundulus luciae (Baird). Journal Experimental Marine Biology and Ecology. 83:41-51.
Kneib, R.T. 1984. Patterns of invertebrate distribution and abundance in the intertidal salt marsh: causes and questions. Estuaries. 7:392-412.
Kneib, R.T. 1985. Predation and disturbance by grass shrimp, Palaemonetes pugio Holthus, in soft-substratum benthic invertebrate assemblages. Journal Experimental Marine Biology and Ecology. 93:91-102.
Kneib, R.T. 1986. Size-specific patterns in the reproductive cycle of the killifish, Fundulus heteroclitus (Pisces: Fundulidae) from Sapelo Island, Georgia. Copeia. 1986(2):342-351.
Kneib, R.T. 1986. The role of Fundulus heteroclitus in salt marsh trophic dynamics. American Zoologist. 26:259-269.
Kneib, R.T. 1987. Predation risk and use of intertidal habitats by young fishes and shrimp. Ecology. 68:379-386.
Kneib, R.T. 1988. Testing for indirect effects of predation in an intertidal soft-bottom community. Ecology. 69:1795-1805.
Kneib, R.T. 1991. Flume weir for the quantitative collection of nekton from vegetated intertidal habitats. Marine Ecology-Progress Series. 75:29-38.
Kneib, R.T. 1991. Indirect effects in experimental studies of marine soft-sediment communities. American Zoologist. 31:874-885.
Kneib, R.T. 1992. Population dynamics of the tanaid Hargeria rapax (Crustacea:Peracarda) in a tidal marsh. Marine Biology. 113:437-445.
Kneib, R.T. 1993. Growth and mortality in successive cohorts of fish larvae within an estuarine nursery. Marine Ecology-Progress Series. 94:115-127.
Kneib, R.T. 1995. Behaviour separates potential and realized effects of decapod crustaceans in salt marsh communities. Journal of Experimental Marine Biology and Ecology (761). 193:239-256.
Kneib, R.T. 1996. The University of Georgia Marine Institute. Georgia Journal of Science. 54(2):81-89.
Kneib, R.T. 1997. Early life stages of resident nekton in intertidal marshes. Estuaries. 20(1):214-230.
Kneib, R.T. 2002. Book Review - The Ecology of Seashores. Limnology and Oceanography.
Kneib, R.T. 2003. Bioenergetic and landcape considerations for scaling expectations of nekton production from intertidal marshes. Marine Ecology Progress Series - Theme Section. 264:279-296.
Kneib, R.T. 2009. Genotypic variation does not explain differences in growth of mummichogs Fundulus heteroclitus from simple and complex tidal marsh landscapes. Marine Ecology Progress Series. 386:207-219.
Abstract
Decimal coded wire tags were used to measure individual growth rates of mummichogs (Pisces: Fundulidae) within tidal marshes on Sapelo Island, Georgia, USA. Mummichogs (n = 17 508) were marked and released at 3 sites with different levels of complexity in their tidal channel drainage networks. The proportion of recaptures (average 19%), which varied from 6.4 to 43.3% among sites and release dates, was inversely related to relative complexity of the tidal drainage networks. Gender-specific differences were detected in size metrics and growth rates. Mean (+/- SD) growth rates (mm d(-1) total length, TL) of individuals at large for 28 to 56 d prior to recapture ranged from 0.062 +/- 0.044 to 0.274 +/- 0.060 for males and 0.071 +/- 0.036 to 0.279 +/- 0.062 for females, with the least and most rapid growth rates associated with complex and simple tidal drainage networks, respectively. A ''common garden'' experiment was conducted to test the hypothesis that there were genotypic differences in growth potential seemingly associated with landscape structure. Two size classes (40-50 and 55-65 mm TL) of individually marked mummichogs from drainage networks characterized as simple (high growth) and complex (low growth) were raised in the laboratory for 42 d on each of 2 daily rations (10 and 30% wet body mass) of minced fresh-frozen grass shrimp. There was no significant difference in mean (+/- SD) daily growth rates of mummichogs from the 2 sites (simple: 0.283 +/- 0.124 and complex: 0.299 +/- 0.131) when reared under the same conditions. Although there was no evidence of a genotypic difference in growth potential between these local populations of mummichogs, a possible association between landscape structure and gene expression reflected in the spatial variation of fish growth within tidal marsh ecosystems remains to be explored.
Kneib, R.T. 2010. Oiling the wheels of system change. Frontiers in Ecology and the Environment. 8(5):227-227.
Kneib, R.T. and Craig, A.H. 2001. Efficacy of minnow traps for sampling mummichogs in tidal marshes. Estuaries. 24(6A):884-893.
Kneib, R.T. and Huggler, M.C. 2001. Tag placement, mark retention, survival and growth of juvenile white shrimp (Litopenaeus setiferus Perez Farfante, 1969) injected with coded wire tags. Journal of Experimental Marine Biology and Ecology. 266:109-120.
Kneib, R.T. and Knowlton, M.K. 1995. Stage-structured interactions between seasonal and permanent residents of an estuarine nekton community. Oecologia. 103:425-434.
Kneib, R.T. and Parker, J.H. 1991. Gross conversion efficiences of mummichog and spotfin killifish larvae from a Georgia salt marsh. Transactions of the American Fisheries Society. 120:803-809.
Kneib, R.T. and Scheele, C.E.H. 2000. Does tethering of mobile prey measure relative predation potential? An empirical test using mummichogs and grass shrimp. Marine Ecology Progress Series. 198:181-190.
Kneib, R.T. and Stiven, A.E. 1980. Stable carbon isotope ratios in Fundulus heteroclitus (L) muscle tissue and gut contents from a North Carolina Spartina salt marsh. Journal Experimental Marine Biology and Ecology. 46:89-98.
Kneib, R.T. and Stiven, A.E. 1982. Benthic invertebrate responses to size and density manipulations of the common mummichog, Fundulus heteroclitus (L.) in an intertidal salt marsh. Ecology. 63:1518-1532.
Kneib, R.T. and Wagner, S.L. 1994. Nekton use of vegetated marsh habitats at different stages of tidal inundation. Marine Ecology Progress Series. 106:227-238.
Kneib, R.T. and Weeks, C.A. 1990. Intertidal distribution and feeding habits of the mud crab, Eurytium limosum. Estuaries. 13:462-468.
Kneib, R.T., Lee, S.Y. and Kneib, J.P. 1999. Adult-juvenile interactions in the crabs Sesarma (Perisesarma) bidens and S. (Holometopus) dehaani (Decapoda: Grapsidae) from intertidal mangrove habitats in Hong Kong. Journal of Experimental Marine Biology and Ecology. 234:255-273.
Kneib, R.T., Newell, S.Y. and Hermeno, E.T. 1997. Survival growth and reproduction of the salt marsh amphipod Uhlorchestia spartinophila reared on natural diets of senescent and dead Spartina alterniflora leaves. Marine Biology. 128:423-431.
Kneib, T.R. 1987. Seasonal abundance, distribution and growth of postlarval and juvenile grass shrimp (Palaemonetes pugio) in a Georgia, USA, salt marsh. Marine Biology. 96:215-223.
Koretsky, C.M. and Miller, D. 2008. Seasonal influence of the needle rush Juncus roemarianus on saltmarsh pore water geochemistry. Estuaries and Coasts. 31(1):70-84.
Abstract
Previous studies have shown that saltmarsh macrophytes have a significant influence on sediment biogeochemistry, both through radial release of oxygen from roots and also via primary production and release of labile organic exudates from roots. To assess the seasonal influence of the needle rush, Juncus roemarianus, on saltmarsh sediment geochemistry, pore waters and sediments were collected from the upper 50 cm of two adjacent sites, one unvegetated and the other vegetated by Juncus roemarianus, in a Georgia saltmarsh during winter and summer. Pore waters collected at 1- to 2-cm intervals were analyzed for pH, alkalinity, dissolved phosphate, ammonium, Fe(II), Fe(III), Mn(II), sulfide, sulfate, and organic carbon. Sediments were collected at 5-cm intervals and analyzed for iron distribution in the solid phase using a two-step sequential extraction. The upper 50 cm of the sediment pore waters are mostly sulfidic during both winter and summer. The pore water and sediment geochemistry suggest organic matter degradation is coupled mostly to Fe (III) and sulfate reduction. In summer, there is greater accumulation of alkalinity, sulfide, ammonium, and phosphate in the pore waters and lower levels of ascorbate extractable Fe, which is presumed to be comprised primarily of readily reducible Fe(III) oxides, in the sediments, consistent with higher organic matter degradation rates in summer compared to winter. Lower pH, alkalinity, ammonium, and sulfide concentrations in sediments with Juncus, compared to nearby unvegetated sediments, is consistent with release of oxygen into the Juncus rhizosphere, especially during summer.
Koretsky, C.M., Cuellar, A., Haveman, M., Beuving, L., Shattuck, T. and Wagner, M. 2008. Influence of Spartina and Juncus on saltmarsh sediments. II. Trace element geochemistry. Chemical Geology. 255(1-2):100-113.
Abstract
Sequential sediment extractions are used to assess the partitioning of Fe, Mn, Cr, Co, Ni, Cu, Zn and Pb, as a function of depth, in the sediments of two pairs of saltmarsh sites, chosen to represent a gradient of macrophyte and macrofaunal density. One pair is located adjacent to a large tidal creek, and includes a nearly unvegetated site and a site densely vegetated by tall-form Spartina alterniflora. The other two sites, located higher in the marsh, are densely vegetated by Juncus roemarianus and sparsely vegetated by short-form S. alternifora. At each site, trace element distributions among four operationally-defined solid fractions (exchangeable, carbonate, reducible and oxidizable) were measured at 4-5 cm intervals from the sediment water interface to a depth of up to 50 cm. The operationally-defined extractions suggest that in suboxic sediments, Fe, Mn, Cr, Ni, Co and Zn occur in association with Fe and Mn oxyhydroxides. In sulfidic sediments, Fe, Co and Ni probably occur mostly in pyrite. Mn is likely pyritized and may also form rhodochrosite at two of the sites, Cr is likely bound mostly to organic matter, and Zn, Cu and Pb are inferred to occur in association with both sulfides and organic matter. The depth- and site-dependent trace element distributions are in surprisingly good agreement with variations in redox geochemistry inferred from pore water data in a companion study [Koretsky, C.M., Haveman, M., Cuellar, A., Beuving, L., Shattuck, T., Wagner, M., 2008. Influence of Spartina and Juncus on saltmarsh sediments. I. Pore water geochemistry. Chemical Geology]. This demonstrates that, in spite of their inherently operational nature, sequential sediment extractions can yield useful insights into metal speciation, especially when measured in conjunction with pore water geochemistry. Furthermore, these data demonstrate that lateral and vertical variations in saltmarsh pore water chemistry lead to distinct variability in solid phase trace metal distributions. (C) 2008 Elsevier B.V. All rights reserved.
Koretsky, C.M., Haveman, M., Cuellar, A., Beuving, L., Shattuck, T. and Wagner, M. 2008. Influence of Spartina and Juncus on Saltmarsh Sediments. I. Pore Water Geochemistry. Chemical Geology. 255(1-2):87-99.
Abstract
The influence of Spartina alterniflora and Juncus roemarianus on saltmarsh sediment pore water geochemistry was investigated during summer at four sites in a saltmarsh on Sapelo Island, GA, USA. Pore waters were collected from each site at 1-2 cm intervals, to a depth of 50 cm, and analyzed for pH, alkalinity, dissolved manganese, ferric iron, ferrous iron, total sulfide, sulfate, phosphate, ammonium, calcium, magnesium and potassium. The most compressed vertical redox stratification occurs at a short Spartina site, followed closely by an adjacent Juncus site. Both sites have shallow oxic and suboxic zones, with sulfidic conditions only a few centimeters or less from the sediment water interface. The densely vegetated Juncus site is inferred to have greater primary productivity and organic matter turnover compared to the short Spartina site. More radial oxygen loss is postulated to occur in the subsurface of the Juncus site, leading to reoxidation of reduced species, more acidic conditions and less accumulation of dissolved sulfide, ammonium and oxidizable-Fe in the solid phase compared to the adjacent short Spartina site. A creekside site vegetated by tall Spartina has the most oxidized sediments, followed by an adjacent unvegetated site. Both of these sites are dominated by suboxic pore waters in most of the upper 50 cm. Subsurface injection of oxygen via roots at the densely vegetated tall Spartina site is inferred to create more acidic pore waters with significantly less accumulation of reduced solutes, including ammonium and alkalinity, compared to the adjacent unvegetated creekside site. Fe and Mn reduction are expected to be significant processes in the bulk near-surface sediments of the tall Spartina and unvegetated sites and within rhizosphere sediments at the tall Spartina and Juncus sites. This study demonstrates the significant influence of Juncus roemarianus and Spartina alterniflora on saltmarsh sediment pore water geochemistry, with important implications for nutrient and trace metal mobility and bioavailability. Future work is needed to explore differences in organic matter concentration and especially ability in the subsurface of saltmarsh sites with varying types and densities of vegetation. (C) 2008 Elsevier B.V. All rights reserved.
Koretsky, C.M., Meile, C. and Van Cappellen, P. 2002. Quantifying bioirrigation using ecological parameters: a stochastic approach. Geochemical Transactions. 3:17-30.
Abstract
Irrigation by benthic macrofauna has a major influence on the biogeochemistry and microbial community structure of sediments. Existing quantitative models of bioirrigation rely primarily on chemical, rather than ecological, information and the depth-dependence of bioirrigation intensity is either imposed or constrained through a data fitting procedure. In this study, stochastic simulations of 3D burrow networks are used to calculate mean densities, volumes and wall surface areas of burrows, as well as their variabilities, as a function of sediment depth. Burrow networks of the following model organisms are considered: the polychaete worms Nereis diversicolor and Schizocardium sp., the shrimp Callianassa subterranea, the echiuran worm Maxmuelleria lankesteri, the fiddler crabs Uca minax, U. pugnax and U. pugilator, and the mud crabs Sesarma reticulatum and Eurytium limosum. Consortia of these model organisms are then used to predict burrow networks in a shallow water carbonate sediment at Dry Tortugas, FL, and in two intertidal saltmarsh sites at Sapelo Island, GA. Solute-specific nonlocal bioirrigation coefficients are calculated from the depth-dependent burrow surface areas and the radial diffusive length scale around the burrows. Bioirrigation coefficients for sulfate obtained from network simulations, with the diffusive length scales constrained by sulfate reduction rate profiles, agree with independent estimates of bioirrigation coefficients based on pore water chemistry. Bioirrigation coefficients for O-2 derived from the stochastic model, with the diffusion length scales constrained by O-2 microprofiles measured at the sediment/water interface, are larger than irrigation coefficients based on vertical pore water chemical profiles. This reflects, in part, the rapid attenuation with depth of the O-2 concentration within the burrows, which reduces the driving force for chemical transfer across the burrow walls. Correction for the depletion of O-2 in the burrows results in closer agreement between stochastically-derived and chemically-derived irrigation coefficient profiles.
Koretsky, C.M., Moore, C.M., Lowe, K.L., Meile, C., Dichristina, T.J. and Van Cappellen, P. 2003. Seasonal oscillation of microbial iron and sulfate reduction in saltmarsh sediments (Sapelo Island, GA, USA). Biogeochemistry. 64(2):179-203.
Abstract
Seasonal variations in anaerobic respiration pathways were investigated at three saltmarsh sites using chemical data, sulfate reduction rate measurements, enumerations of culturable populations of anaerobic iron-reducing bacteria (FeRB), and quantification of in situ 16S rRNA hybridization signals targeted for sulfate-reducing bacteria (SRB). Bacterial sulfate reduction in the sediments followed seasonal changes in temperature and primary production of the saltmarsh, with activity levels lowest in winter and highest in summer. In contrast, a dramatic decrease in the FeRB population size was observed during summer at all sites. The collapse of FeRB populations during summer was ascribed to high rates of sulfide production by SRB, resulting in abiotic reduction of bioavailable Fe(III) (hydr)oxides. To test this hypothesis, sediment slurry incubations at 10, 20 and 30degreesC were carried out. Increases in temperature and labile organic carbon availability (acetate or lactate additions) increased rates of sulfate reduction while decreasing the abundance of culturable anaerobic FeRB. These trends were not reversed by the addition of amorphous Fe(III) (hydr) oxides to the slurries. However, when sulfate reduction was inhibited by molybdate, no decline in FeRB growth was observed with increasing temperature. Addition of dissolved sulfide adversely impacted propagation of FeRB whether molybdate was added or not. Both field and laboratory data therefore support a sulfide-mediated limitation of microbial iron respiration by SRB. When total sediment respiration rates reach their highest levels during summer, SRB force a decline in the FeRB populations. As sulfate reduction activity slows down after the summer, the FeRB are able to recover.
Koretsky, C.M., Van Cappellen, P., DiChristina, T.J., Kostka, J.E., Lowe, K.L., Moore, C.M., Roychoudhury, A.N. and Viollier, E. 2005. Salt marsh pore water geochemistry does not correlate with microbial community structure. Estuarine, Coastal and Shelf Science. 62:233-251.
Kostka, J.E., Roychoudhury, A. and Van Cappellen, P. 2002. Rates and controls of anaerobic microbial respiration across spatial and temporal gradients in saltmarsh sediments. Biogeochemistry. 60(1):49-76.
Kraeuter, J. 1974. Offshore currents, larval transport, and establishment of southern populations of Littorina littorea Linne along the U.S. Atlantic coast. Thalassia Jugoslavica. 10:159-170.
Kraeuter, J. 1976. Biodeposition by salt-marsh invertebrates. Marine Biology. 35:215-223.
Kraeuter, J. and Setzler, E. 1975. The seasonal cycle of Scyphozoa and Cubozoa in Georgia estuaries. Bulletin of Marine Science. 25:66-74.
Kraeuter, J.N. 1972. Dentaliid taxa referred to the Siphonodentaliidae (Mollusca:Scaphopoda) with a description of a new species. The Veliger. 15:21-28.
Kraeuter, J.N. 1973. Notes on mollusks Ostrea and Siphonaria from Georgia (U.S.A.). The Nautilus. 87:75-77.
Kraeuter, J.N. 1973. Pycnogonida from Georgia. Journal of Natural History. 7:493-498.
Kraeuter, J.N. and Thomas, R.F. 1975. Cephalopod mollusks from the waters off Georgia, U.S.A. Bulletin of Marine Science. 25:301-303.
Krambeck, C., Krambeck, H.J., Schroder, D. and Newell, S.Y. 1990. Sizing bacterioplankton: a juxtaposition of bias due to shrinkage, halos subjectivity in image interpretation and asymmetric distributions. Binary. 2:11-20.
Kreiss, P. and Cormier, M.J. 1967. Inhibition of Renilla reniformis bioluminescence by light: Effects on luciferase and its substrates. Biochimica et Biophysica Acta. 141:181-183.
Krull, K. and Craft, C. 2009. ECOSYSTEM DEVELOPMENT OF A SANDBAR EMERGENT TIDAL MARSH, ALTAMAHA RIVER ESTUARY, GEORGIA, USA. Wetlands. 29(1):314-322.
Abstract
Vegetation structure and soil properties were measured on a sandbar, a three year old sandbar emergent marsh (SEM), and five mature Spartina alterniflora Loisel marshes located near the mouth of the Altamaha River (Georgia, USA) to determine how quickly tidal marsh vegetation and soils develop during primary succession. Those data were compared to published data collected from young (10–16 yr old) natural marshes in Virginia and young (1–28 yr old) constructed marshes in North Carolina to determine if the rate of ecosystem development is similar among tidal marshes of the southeastern US coast. Within three years of emergence, aboveground biomass of SEM was comparable to mature marshes in the area, although stem height and density were distinctly different as the SEM contained more stems that were of shorter height than mature marshes. Following colonization by vegetation, soil properties (0–30 cm) of SEM had begun to differentiate from sediments of the sandbar. Surface (0–10 cm) and subsurface (10–30 cm) soil bulk density was less, and organic carbon (C), nitrogen (N), and percent silt (0–10 cm) were greater in sediments of SEM than in the sandbar. Even so, soils of SEM contained less organic C, N, silt, and clay than mature marshes. However, accumulation rates of organic C (260 6 40 g m22 yr21) and N (11 6 3 g m22 yr21) in soils of SEM was 5 to 7 times greater than in mature marshes (35 6 4 g C m22 yr21, 2 6 0.2 g N m22 yr21). Trajectories of development for soil organic C and N pools were similar for our SEM, young natural S. alterniflora marshes in Virginia, and young constructed S. alterniflora marshes in North Carolina suggesting that soil development proceeds at similar rates for tidal marshes along much of the southeast US coast.
Kudela, R., Covi, M., Robinson, J., Babin, M., Berchok, C.L., Reynolds, K., Gaylor, M.O., Gran, J.E., Griffin, C.A., Hagy, J.D.I., Poteet, M.F., Wagner, S.L. and Rejwan, C. 1991. Abstracts-Research reports presented to The University of Georgia Marine Institute Student Intern Program, 1987-1991. Georgia Journal of Science. 49:162-168.
Kuenzler, E.J. 1961. Phosphorus budget of a mussel population. Limnology and Oceanography. 6:400-415.
Kuenzler, E.J. 1961. Structure and energy flow of a mussel population in a Georgia salt marsh. Limnology and Oceanography. 6:191-204.
Kumar, S., Harrylock, M., Walsh, K.A., Cormier, M.J. and Charbonneau, H. 1990. Amino acid sequence of the Ca2+- triggered luciferin binding protein of Renilla reniformis. FEBS Letters. 268:287-290.
Kunza, A.E. and Pennings, S.C. 2008. Patterns of Plant Diversity in Georgia and Texas Salt Marshes. Estuaries and Coasts. 31(4):673-681.
Abstract
A fundamental question in ecology is how biological interactions and biogeographic processes interact to determine the biodiversity of local sites. We quantified patterns of plant species diversity on transects across elevation at 59 salt marsh sites in Georgia and 49 sites in Texas. Although these regions have similar climates and floras, we anticipated that diversity might differ because of differences in tidal regime. Diversity was measured at global, regional, site, and plot scales to consider processes occurring at all levels. Species pools were similar between regions. Texas had greater diversity at the site and plot scales, suggesting that processes occurring at the site scale differed. The greater diversity of Texas sites and plots was associated with wider distributions of individual species across the marsh landscape and proportionally more middle marsh (a high diversity zone) and less low marsh (a low diversity zone) than in Georgia marshes. Preliminary data suggested that these differences were not due to differences in salinity regime or standing biomass between regions, leaving differences in tidal regime as the most plausible hypothesis accounting for differences in plant diversity. We speculate that the less-predictable tidal regime in Texas leads to temporal variation in abiotic conditions that limit the ability of any one species to competitively exclude others from particular marsh zones.
Kurata, H., Heard, R.W. and Martin, J.W. 1981. Larval development under laboratory conditions of the xanthid mud crab Eurytium limosum (Say, 1818) (Brachyura:Xanthidae) from Georgia. Gulf Research Reports. 7:19-25.
Kuwabara, S., Cormier, M.J., Dure, L.S., Kreiss, P. and Pfuderer, P. 1965. Crystalline bacterial luciferase from Photobacterium fischeri. Proceedings of the National Academy of Science of the USA. 53:822-828.
Laerm, J., Carter, T.C., Menzel, M.A., McCay, T.S., Boone, J.L., Ford, W.M., Lepardo, L.T., Krishon, D.M., Balkcom, G., Van Der Maath, N.L. and Harris, M.J. 1999. Amphibians, reptiles, and mammals of Sapelo Island, Georgia. Journal of the Elisha Mitchell Scientific Society. 115(2):104-126.
Land, L.S. 1964. Eolian cross-bedding in the beach dune environment, Sapelo Island, Georgia. Journal of Sedimentary Petrology. 34:389-394.
Land, L.S. and Hoyt, J.H. 1966. Sedimentation in a meandering estuary. Sedimentology. 6:191-207.
Lee, S.Y. and Kneib, R.T. 1994. Effects of biogenic struture on prey consumption by the xanthid crabs Eurytium limosum and Panopeus herbstii in a salt marsh. Marine Ecology Progress Series. 104:39-47.
Letourneau, M.L. and Medeiros, P.M. 2019. Dissolved organic matter composition in a marsh-dominated estuary: Response to seasonal forcing and to the passage of a hurricane. Journal of Geophysical Research: Biogeosciences.
Letourneau, M.L., Schaefer, S.C., Chen, H., McKenna, A.M., Alber, M. and Medeiros, P.M. 2021. Spatio-temporal changes in dissolved organic matter composition along the salinity gradient of a marsh-influenced estuarine complex. Limnology and Oceanography. 66(8):3040-3054.
Abstract
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.
Letzsch, W.S. 1983. Seven year's measurement of deposition and erosion, Holocene salt marsh, Sapelo Island, Georgia. Senckenbergiana Maritima. 15:157-165.
Letzsch, W.S. and Frey, R.W. 1980. Deposition and erosion in a Holocene salt marsh, Sapelo Island, Georgia. Journal of Sedimentary Petrology. 50:529-542.
Letzsch, W.S. and Frey, R.W. 1980. Erosion of salt marsh tidal creek banks, Sapelo Island, Georgia. Senckenbergiana Maritima. 12:201-212.
Letzsch, W.S. and Frey, R.W. 1980. Organic carbon in a Holocene salt marsh, Sapelo Island, Georgia. Georgia Journal of Science. 39:15-23.
Leuchtmann, A. and Newell, S.Y. 1991. Phaeosphaeria spartinicola, a new species on Spartina. Mycotaxon. XLI:1-7.
Levin, L.A., Boesch, D.F., Covich, A., Dahm, C., Erseus, C., Ewel, K.C., Kneib, R.T., Moldenke, A., Palmer, M., Snelgrove, P., Strayer, D. and Weslawski, J.M. 2001. The function of marine critical transition zones and the importance of sediment biodiversity. Ecosystems. 4(5):430-451.
Li, F. and Pennings, S.C. 2018. Responses of Tidal Freshwater and Brackish Marsh Macrophytes to Pulses of Saline Water Simulating Sea Level Rise and Reduced Discharge. Wetlands. 38(5):885-891.
Abstract
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 (1-31days per month for 3months) 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 16days 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 the hypothesis 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.
Li, F. and Pennings, S.C. 2019. Response and Recovery of Low-Salinity Marsh Plant Communities to Presses and Pulses of Elevated Salinity. Estuaries and Coasts. 42(3):708-718.
Abstract
In estuaries, future variation in sea level and river discharge will lead to saline intrusion into low-salinity tidal marshes. To investigate the processes that control the differential response and recovery of tidal freshwater marsh plant communities to saline pulses, a 3x5 factorial greenhouse experiment was conducted to examine the effects of a range of salinity levels (3, 5, and 10practical salinity units (PSU)) and pulse durations (5, 10, 15, 20, and 30days per month) on community composition of tidal freshwater marsh vegetation. Recovery of perturbed communities was also examined after 10months. The results showed that community composition was increasingly affected by the more-saline and longer-duration treatments. The increasing suppression of salt-sensitive species resulted in species reordering, decreased species richness, and decreased aboveground biomass. Most of the plant species were able to recover from low-salinity, short-duration saline pulses in less than 1year. However, because not all species recovered in the heavily salinized treatments, species richness at the end of the recovery period remained low for treatments that were heavily salinized during the treatment period. In contrast, plant aboveground biomass fully recovered in the heavily salinized treatments. Although the magnitude and duration of pulsed environmental changes had strong effects on community composition, shifts in community composition prevented long-term reductions in productivity. Thus, in this study system, environmental change affected species composition more strongly than it did ecosystem processes.
Abstract
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.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 for vegetation changes over longer time periods.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 indicated that plants typical of higher salinity conditions (e.g. Schoenoplectus sp.) performed well under conditions prevalent in the press plots.In the pulse treatment, only L. repens declined, and there was no effect on community-level above-ground biomass or other community variables.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.
Li, S.Z. and Pennings, S.C. 2016. Disturbance in Georgia salt marshes: variation across space and time. Ecosphere. 7(10):11.
Abstract
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 similar to 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 similar to 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 similar to 18% in the creekbank zone and similar to 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.
Li, S.Z. and Pennings, S.C. 2017. Timing of disturbance affects biomass and flowering of a saltmarsh plant and attack by stem-boring herbivores. Ecosphere. 8(2):9.
Abstract
In salt marshes, disturbance by wrack (floating mats of dead vegetation) is common and affects 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.
Li, S.Z., Hopkinson, C.S., Schubauer-Berigan, J.P. and Pennings, S.C. 2018. Climate drivers of Zizaniopsis miliacea biomass in a Georgia, USA tidal fresh marsh. Limnology and Oceanography. 63(5):2266-2276.
Abstract
Tidal fresh marshes are at least as productive as nearby salt marshes, but much less is known about controls on primary production in tidal fresh vs. salt marshes. We studied a tidal fresh marsh in Georgia, U.S.A., dominated by the C-3 grass Zizaniopsis miliacea. We documented seasonal variation in Z. miliacea above-ground biomass and below-ground macro-organic matter over 1 yr, and annual variation in end-of-season aboveground biomass over 15 yr in creekbank and midmarsh zones. Aboveground biomass showed a distinct peak in July and October. Belowground macro-organic matter was much greater than aboveground biomass and peaked in October. Overall productivity was similar to that of salt marshes downstream. Z. miliacea end-of-season above-ground biomass showed a classic hump-shaped "subsidy-stress" relationship with plot elevation, but on average the creekbank supported about twofold more above-ground biomass than the midmarsh, and both zones varied in biomass about 1.7-fold among years. Annual variation in above-ground biomass was negatively correlated with maximum and mean temperature in both zones, and positively with river discharge in the creekbank zone. Sea level, precipitation and water column salinity showed biologically plausible trends with respect to biomass. The responses of Z. miliacea to abiotic drivers were muted compared with the responses of nearby salt marshes dominated by Spartina alterniflora. Temperature was more important for Z. miliacea, whereas drivers of porewater 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.
Lim, S.Y. and Forschler, B.T. 2012. Reticulitermes nelsonae, a New Species of Subterranean Termite (Rhinotermitidae) from the Southeastern United States. Insects. 3(1):62-90.
Abstract
Reticulitermes nelsonae, a new species of Rhinotermitidae (Isoptera) is described based on specimens from Sapelo Island, GA, Thomasville, GA, Havelock, NC, and Branford, FL. Adult (alate) and soldier forms are described. Diagnostic characters are provided and incorporated into a supplemental couplet of a dichotomous key to the known species of Reticulitermes found in Georgia, USA.
Lin, W. and Pennings, S.C. 2018. Scale-dependent predator-prey interaction in a ladybug-aphid system. Ecology and Evolution. In review.
Linton, T.L. and Rickards, W.L. 1965. Young common snook on the coast of Georgia. Quarterly Journal of the Florida Academy of Sciences. 28:185-189.
Abstract
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.
Liu, Q., Tolar, B.B., Ross, M.J., Cheek, J.B., Sweeney, C.M., Wallsgrove, N.J., Popp, B.N. and Hollibaugh, J.T. 2018. Light and temperature control the seasonal distribution of thaumarchaeota in the South Atlantic bight. Isme Journal. 12(6):1473-1485.
Abstract
Mid-summer peaks in the abundance of Thaumarchaeota and nitrite concentration observed on the Georgia, USA, coast could result from in situ activity or advection of populations from another source. We collected data on the distribution of Thaumarchaeota, ammonia-oxidizing betaproteobacteria (AOB), Nitrospina, environmental variables and rates of ammonia oxidation during six cruises in the South Atlantic Bight (SAB) from April to November 2014. These data were used to examine seasonality of nitrification in offshore waters and to test the hypothesis that the bloom was localized to inshore waters. The abundance of Thaumarchaeota marker genes (16S rRNA and amoA) increased at inshore and nearshore stations starting in July and peaked in August at>10(7) copies L-1. The bloom did not extend onto the mid-shelf, where Thaumarchaeota genes ranged from 10(3) to 10(5) copies L-1. Ammonia oxidation rates (AO) were highest at inshore stations during summer (to 840 nmol L-1 d(-1)) and were always at the limit of detection at mid-shelf stations. Nitrite concentrations were correlated with AO (R = 0.94) and were never elevated at mid-shelf stations. Gene sequences from samples collected at mid-shelf stations generated using Archaea 16S rRNA primers were dominated by Euryarchaeota; sequences from inshore and nearshore stations were dominated by Thaumarchaeota. Thaumarchaeota were also abundant at depth at the shelf-break; however, this population was phylogenetically distinct from the inshore/nearshore population. Our analysis shows that the bloom is confined to inshore waters during summer and suggests that Thaumarchaeota distributions in the SAB are controlled primarily by photoinhibition and secondarily by water temperature.
Liu, W. and Pennings, S.C. 2019. Self-thinning and size-dependent flowering of the grass Spartina alterniflora across space and time. Functional Ecology.
Loomis, M.J. and Craft, C.B. 2010. Carbon Sequestration and Nutrient (Nitrogen, Phosphorus) Accumulation in River-Dominated Tidal Marshes, Georgia, USA. Soil Science Society of America Journal. 74(3):1028-1036.
Abstract
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 eff ects of salinity on C, N, and P storage and 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 greater in tidal freshwater (4.78 mm yrâ’1) and brackish marshes (4.41 mm yrâ’1) than in salt marshes (1.91 mm yrâ’1). Consequently, organic C and N accumulation was greater in tidal freshwater (124 and 8.2 g mâ’2 yrâ’1) and brackish (93 and 6.5 g mâ’2 yrâ’1) marshes than salt marshes (40 and 2.4 g mâ’2 yrâ’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%). Combining 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. Aft er accounting for N2 fi xation and denitrifi cation, 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 N eutrophication of estuarine ecosystems.
Lorenz, W.W., McCann, R.O., Longiaru, M. and Cormier, M.J. 1991. Isolation and expression of a cDNA encoding Renilla reniformis luciferase. Proceedings of the National Academy of Science of the USA. 88:4438-4442.
Lovell, C.R., Friez, M.J., Longshore, J.W. and Bagwell, C.E. 2001. Recovery and phylogenetic analysis of nifH sequences from diazotrophic bacteria associated with dead aboveground biomass of Spartina alterniflora. Applied and Environmental Microbiology. 67(11):5308-5314.
Lowe, K.L., DiChristina, T.J., Roychoudhury, A.N. and Van Cappellen, P. 2000. Microbiological and geochemical characterization of microbial Fe(III) reduction in salt marsh sediments. Geomicrobiology Journal. 17:163-178.
Lowerre-Barbieri, S.K. and Barbieri, L.R. 1993. A new method of oocyte separation and preservation for fish reproduction studies. Fishery Bulletin. 91(1):165-170.
Lowerre-Barbieri, S.K., Barbieri, L.R., Flanders, J.R., Woodward, A.G., Cotton, C.F. and Knowlton, M.K. 2008. Use of Passive Acoustics to Determine Red Drum Spawning in Georgia Waters. Transactions of the American Fisheries Society. 137(2):562-575.
Abstract
Passive acoustic sampling to locate spawning sites of red drum Sciaenops ocellatus was conducted along the Georgia coast during July–October 1995–1997. Spawning red drum were observed in captivity to determine the level of sound associated with spawning. In 1997, a known red drum spawning site was sampled weekly with a mobile hydrophone and continuously with a remote hydrophone deployed from 23 September to 2 October 1997. Both field and tank observations indicated that red drum males make calls with four or fewer pulses per call without associated spawning. However, calls consisting of at least 8 pulses/ call occurred only prior to spawning. In 1995 and 1996, a total of 372 hydrophone observations were made at regularly sampled stations in Doboy, Altamaha, St. Simon’s, and St. Andrew sounds and at supplemental locations along the Georgia coast. Only one nearshore spawning site was located; it was found in St. Mary’s channel at the mouth of Cumberland Sound. Duration of peak red drum sound production at this site varied from 1 to 4 h but generally occurred from 1600 to 1900 hours. The Cumberland Sound site was characterized by deep water (.13.7 m) and relatively high salinity (.30%). Red drum spawning activity at this site was estimated to occur during August through mid-October based on calls.
Lowerre-Barbieri, S.K., Lowerre, J.M. and Barbieri, L.R. 1998. Multiple spawning and the dynamics of fish populations: Inferences from an individual-based simulation model. Canadian Journal of Fisheries and Aquatic Sciences. 55(10):2244-2254.
Abstract
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 ~ 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 (~ 1 m), although the areas with the highest frequency of wrack as a proportion of available marsh area were at a higher elevation (> 1.3 m) and closer to creeks or shorelines (~ 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.
Lyons, J.I., Newell, S.Y., Buchan, A. and Moran, M.A. 2003. Diversity of ascomycete laccase gene sequences in a southeastern US salt marsh. Microbial Ecology. 45:270-281.
Maccubbin, A.E. and Hodson, R.E. 1980. Mineralization of detrital lignocelluloses by salt marsh sediment microflora. Applied and Environmental Microbiology. 40:735-740.
Maney, D.S., Marland, F.C. and West, C.L. 1968. Conference on the Future of the Marshlands and Sea Islands of Georgia. Published by University of Georgia Marine Institute and Coastal Area Planning and Development Commission. 128 p.
Marcus, E. and Marcus, E. 1967. Some opisthobranchs from Sapelo Island, Georgia, U.S.A. Malacologia. 6:199-222.
Marczak, L.B., Ho, C.K., Wieski, K., Vu, H., Denno, R.F. and Pennings, S.C. 2011. Latitudinal variation in top-down and bottom-up control of a salt marsh food web. Ecology. 92(2):276-281.
Abstract
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.
Marczak, L.B., Wieski, K., Denno, R.F. and Pennings, S.C. 2013. Importance of local vs. geographic variation in salt marsh plant quality for arthropod herbivore communities. Journal of Ecology. 101(5):1169-1182.
Abstract
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.
Marples, T. 1966. A radionuclide tracer study of arthropod food chains in a Spartina salt marsh ecosystem. Ecology. 47:270-277.
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McCall, B.D. and Pennings, S.C. 2012. Disturbance and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill. Plos One. 7(3):7.
Abstract
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. Sampling occurred 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, Littoraria snails 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 are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy.
McCall, B.D. and Pennings, S.C. 2012. Geographic variation in salt marsh structure and function. Oecologia. 170(3):777-787.
Abstract
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.
McFarlin, C.R., Brewer, J.S., Buck, T.L. and Pennings, S.C. 2008. Impact of Fertilization on a Salt Marsh Food Web in Georgia. Estuaries and Coasts. 31(2):313-325.
Abstract
We examined the response of a salt marsh food web to increases in nutrients at 19 coastal sites in Georgia. Fertilization increased the nitrogen content of the two dominant plants, Spartina alterniflora and Juncus roemerianus, indicating that added nutrients were available to and taken up by both species. Fertilization increased Spartina cover, height, and biomass and Juncus height, but led to decreases in Juncus cover and biomass. Fertilization increased abundances of herbivores (grasshoppers) and herbivore damage, but had little effect on decomposers (fungi), and no effect on detritivores (snails). In the laboratory, herbivores and detritivores did not show a feeding preference for fertilized versus control plants of either species, nor did detritivores grow more rapidly on fertilized versus control plants, suggesting that changes in herbivore abundance in the field were driven more by plant size or appearance than by plant nutritional quality.
Medeiros, P.M., Seidel, M., Dittmar, T., Whitman, W.B. and Moran, M.A. 2015. Drought-induced Variability in Dissolved Organic Matter Composition in a Marsh-dominated Estuary. Geophysical Research Letters. 42. (DOI: 10.1002/2015GL064653) (in press)
Abstract
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 multi-decadal time scales.
Abstract
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, one-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.
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Abstract
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 , 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.
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Newell, S.Y. 1992. Autumn distribution of marine Pythiaceae across a mangrove-saltmarsh boundary. Canadian Journal of Botany. 70:1912-1916.
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Newell, S.Y. and Fallon, R.D. 1982. Bacterial productivity in the water column and sediments of the Georgia (USA) coastal zone: estimates via direct counting and parallel measurement of thymidine incorporation. Microbial Ecology. 8:33-46.
Newell, S.Y. and Fallon, R.D. 1989. Litterbags, leaf tags and decay of non-abscised intertidal leaves. Canadian Journal of Botany. 67:2324-2327.
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Newell, S.Y. and Fell, J.W. 1982. Surface sterilization and the active mycoflora of leaves of a seagrass. Botanica Marina. 25:339-346.
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Newell, S.Y. and Fell, J.W. 1992. Ergosterol content of living and submerged, decaying leaves and twigs of red mangrove. Canadian Journal of Microbiology. 38:979-982.
Newell, S.Y. and Fell, J.W. 1994. Parallel testing of media for measuring frequencies of occurrence for Halophytophthora spp. (Oomycota) from decomposing mangrove leaves. Canadian Journal of Microbiology. 40:250-256.
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Newell, S.Y. and Hicks, R.E. 1982. Direct-count estimates of fungal and bacterial biovolume in dead leaves of smooth cordgrass (Spartina alterniflora Loisel.). Estuaries. 5:246-260.
Newell, S.Y. and Krambeck, C. 1995. Responses of bacterioplankton to tidal inundations of a saltmarsh in a flume and adjacent mussel enclosures. Journal of Experimental Marine Biology and Ecology (760). 190:79-95.
Newell, S.Y. and Palm, L.A. 1998. Responses of bacterial assemblages on standing-decaying blades of smooth cordgrass to additions of water and nitrogen. International Review of Hydrobiology (former: Int. Rev. Ges. Hydrobiol.). 83(2):115-122.
Newell, S.Y. and Statzell-Tallman, A. 1982. Factors for conversion of fungal biovolume values to biomass, carbon, and nitrogen: variation with mycelial ages, growth conditions, and strains of fungi from a salt marsh. Oikos. 39:261-268.
Newell, S.Y. and Wall, V.D. 1998. Response of saltmarsh fungi to the presence of mercury and polychlorinated biphenyls at a Superfund site. Mycologia. 90(5):777-784.
Newell, S.Y. and Wasowski, J. 1995. Sexual productivity and spring intramarsh distriubtion of a key salt-marsh microbial secondary producer. Estuaries. 18(1B):241-249.
Newell, S.Y. and Zakel, K.L. 2000. Measuring summer patterns of ascospore release by saltmarsh fungi. Mycoscience. 41:211-215.
Newell, S.Y., Arsuffi, T.L. and Fallon, R.D. 1988. Fundamental procedures for determining ergosterol content of decaying plant material by liquid chromatography. Applied and Environmental Microbiology. 54:1876-1879.
Newell, S.Y., Arsuffi, T.L. and Palm, L.A. 1996. Misting and nitrogen fertilization of shoots of a saltmarsh grass: effects upon fungal decay of leaf blades. Oecologia. 108(3):495-502.
Newell, S.Y., Arsuffi, T.L. and Palm, L.A. 1998. Seasonal and vertical demography of dead portions of shoots of smooth cordgrass in a south-temperate saltmarsh. Aquatic Botany. 60:325-335.
Newell, S.Y., Arsuffi, T.S., Kemp, P.F. and Scott, L.A. 1991. Water potential of standing-dead shoots of an intertidal grass. Oecologia. 85:321-326.
Newell, S.Y., Blum, L.K., Crawford, R.E., Dai, T. and Dionne, M. 2000. Autumnal biomass and potential productivity of salt marsh fungi from 29o to 43o north latitude along the United States Atlantic coast. Applied and Environmental Microbiology. 66(1):180-185.
Newell, S.Y., Cooksey, K.E., Fell, J.W., Master, I.M., Miller, C. and Walter, M.A. 1981. Acute impact of an organophosphorus insecticide on microbes and small invertebrates of a mangrove estuary. Archives of Environmental Contamination and Toxicology. 10:427-435.
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O'Connell, J.L. and Alber, M. 2016. A smart classifier for extracting environmental data from digital image time-series: Applications for PhenoCam data in a tidal salt marsh. Environmental Modelling & Software. 84:134-139.
Abstract
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. (C) 2016 Elsevier Ltd. All rights reserved.
O'Connell, J.L., Mishra, D.R., Cotten, D.L., Wang, L. and Alber, M. 2017. The Tidal Marsh Inundation Index (TMII): An inundation filter to flag flooded pixels and improve MODIS tidal marsh vegetation time-series analysis. Remote Sensing of Environment. 201:34-46.
Abstract
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 phonology 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, Spardrza 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 phonology, biomass and carbon storage in coastal marshes.
Abstract
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.
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Pennings, S.C. and Bertress, M.D. 1999. Using latitudinal variation to examine effects of climate on coastal salt marsh pattern and process. Current Topics in Wetland Biogeochemistry. 3:100-111.
Pennings, S.C. and Callaway, R.M. 1996. Impact of a parasitic plant on the structure and dynamics of salt marsh vegetation. Ecology. 77(5):1410-1419.
Pennings, S.C. and Callaway, R.M. 2000. The advantages of clonal integration under different ecological conditions: a community-wide test. Ecology. 81(3):709-716.
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Pennings, S.C. and Moore, D.J. 2001. Zonation of shrubs in western Atlantic salt marshes. Oecologia. 126(4):587-594.
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Pennings, S.C., Grant, M.B. and Bertness, M.D. 2005. Plant zonation in low-latitude salt marshes: disentangling the roles of flooding, salinity and competition. Journal of Ecology. 93(1):159-167.
Pennings, S.C., Ho, C.-K., Salgado, C.S., Więski, K., Davé, N., Kunza, A.E. and Wason, E.L. 2009. Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes. Ecology. 90(1):183–195.
Abstract
Despite long-standing interest in latitudinal variation in ecological patterns and processes, there is to date weak and conflicting evidence that herbivore pressure varies with latitude. We used three approaches to examine latitudinal variation in herbivore pressure in Atlantic Coast salt marshes, focusing on five abundant plant taxa: the grass Spartina alterniflora, the congeneric rushes Juncus gerardii and J. roemerianus, the forb Solidago sempervirens, and the shrubs Iva frutescens and Baccharis halimifolia. Herbivore counts indicated that chewing and gall-making herbivores were typically ≥10 times more abundant at low-latitude sites than at high-latitude sites, but sucking herbivores did not show a clear pattern. For two herbivore taxa (snails and tettigoniid grasshoppers), correctly interpreting latitudinal patterns required an understanding of the feeding ecology of the species, because the species common at high latitudes did not feed heavily on plant leaves whereas the related species common at low latitudes did. Damage to plants from chewing herbivores was 2–10 times greater at low-latitude sites than at high-latitude sites. Damage to transplanted “phytometer” plants was 100 times greater for plants transplanted to low- than to high-latitude sites, and two to three times greater for plants originating from high- vs. low-latitude sites. Taken together, these results provide compelling evidence that pressure from chewing and gall-making herbivores is greater at low vs. high latitudes in Atlantic Coast salt marshes. Sucking herbivores do not show this pattern and deserve greater study. Selective pressure due to greater herbivore damage at low latitudes is likely to partially explain documented patterns of low plant palatability to chewing herbivores and greater plant defenses at low latitudes, but other factors may also play a role in mediating these geographic patterns.
Pennings, S.C., Nastisch, S. and Paul, V.J. 2001. Vulnerability of sea hares to fish predators: importance of diet and fish species. Coral Reefs. 20:320-324.
Pennings, S.C., Selig, E.R., Houser, L.T. and Bertness, M.D. 2003. Geographic variation in postive and negative interactions among salt marsh plants. Ecology. 84(6):1527-1538.
Pennings, S.C., Siska, E.L. and Bertness, M.D. 2001. Latitudinal differences in plant palatability in Atlantic Coast salt marshes. Ecology. 82(5):1344-1359.
Pennings, S.C., Stanton, L.E. and Brewer, J.S. 2002. Nutrient effects on the composition of salt marsh plant communities along the southern Atlantic and Gulf coasts of the United States. Estuaries. 25(6A):1164-1173.
Pennings, S.C., Wall, D.V., Moore, D.J., Pattanayek, M., Buck, T.L. and Alberts, J.J. 2002. Assessing salt marsh health: A test of the utility of five potential indicators. Wetlands. 22(2):405-414.
Pennings, S.C., Zengel, S., Oehrig, J., Alber, M., Bishop, T.D., Deis, D.R., Devlin, D., Hughes, A.R., Hutchens, J.J.J., Kiehn, W.M., McFarlin, C.R., Montague, C.L., Powers, S., Proffitt, C.E., Rutherford, N., Stagg, C.L. and Walters, K. 2016. Marine ecoregion and Deepwater Horizon oil spill affect recruitment and population structure of a saltmarsh snail. Ecosphere. 7(12)
Abstract
Marine species with planktonic larvae often have high spatial and temporal variation in recruitment that leads to subsequent variation in the ecology of benthic adults. Using a combination of published and unpublished data, we compared the population structure of the salt marsh snail, Littoraria irrorata, between the South Atlantic Bight and the Gulf Coast of the United States to infer geographic differ- ences in recruitment and to test the hypothesis that the Deepwater Horizon oil spill led to widespread recruitment failure of L. irrorata in Louisiana in 2010. Size-frequency distributions in both ecoregions were bimodal, with troughs in the distributions consistent with a transition from sub-adults to adults at ~13 mm in shell length as reported in the literature; however, adult snails reached larger sizes in the Gulf Coast. The ratio of sub-adults to adults was 1.5–2 times greater in the South Atlantic Bight than the Gulf Coast, consistent with higher recruitment rates in the South Atlantic Bight. Higher recruitment rates in the South Atlantic Bight could contribute to higher snail densities and reduced adult growth in this region. The ratio of sub-adults to adults in Louisiana was lower in 2011 than in previous years, and began to recover in 2012–2014, consistent with widespread recruitment failure in 2010, when large expanses of spilled oil were present in coastal waters. Our results reveal an important difference in the ecology of a key salt marsh invertebrate between the two ecoregions, and also suggest that the Deepwater Horizon oil spill may have caused widespread recruitment failure in this species and perhaps others with similar planktonic larval stages.
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Peterson, R.N., Meile, C., Peterson, L.E., Carter, M. and Miklesh, D. 2019. Groundwater discharge dynamics into a salt marsh tidal river. Estuarine Coastal and Shelf Science. 218:324-333.
Abstract
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 cm(3)/cm(2) marsh/day across all three field campaigns, which are comparable to those to the main channel (averaging 6.0-6.5 cm(3)/cm(2) 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).
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Abstract
Landscape ecology concepts developed from terrestrial systems have recently emerged as theoretical and analytical frameworks that are equally useful for evaluating the ecological consequences of spatial patterns and structural changes in the submerged landscapes of coastal ecosystems. The benefits of applying a spatially-explicit perspective to resource management and restoration planning in the coastal zone are rapidly becoming apparent. This Theme Section on the application of landscape ecology to the estuarine and coastal environment emerged from a special symposium at the Coastal and Estuarine Research Federation (CERF) 20th Biennial Conference (Estuaries and Coasts in a Changing World) held in Portland, Oregon, USA, in November 2009. The 7 contributions in this Theme Section collectively provide substantial insights into the current status and application of the landscape approach in shallow marine environments, and identify significant knowledge gaps, as well as potential directions for the future advancement of ''seascape ecology''.
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Pomeroy, L.R. 1960. Residence time of dissolved phosphate in natural waters. Science. 131:1731-1732.
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Abstract
Benthic foraminifera have long served as indicators of environmental conditions - both natural and anthropogenically impacted. To better understand the responses of benthic foraminifera to specific heavy metal contaminants (Cd, Pb, Zn), assemblages of coastal benthic foraminifera were grown from propagules (tiny juveniles) in the lab with exposure to a single heavy metal over a range of concentrations, based on the US Environmental Protection Agency''s Critical Maximum Concentration (CMC) values. Foraminiferal propagule banks were collected from relatively pristine mudflats, located on the southern end of Sapelo Island, Georgia (USA). Consistent with the findings of numerous field-based studies, foraminifera were found to respond negatively to Cd, Pb, and Zn. Overall, assemblages grown with exposure to higher concentrations of these metals are characterized by decreased abundances, species richness, and evenness. All of the acute responses observed in these metrics occur at concentrations equal to or somewhat higher than the USEPA''s CMC values. Foraminiferal responses vary by metal, though the four most common species (two monothalamids: Ovammina opaca Dahlgren, Psatrunophaga sapela Altin Ballero, Habura, Goldstein; and two rotaliids: Haynesina germanica (Ehrenberg), Ammonia tepida (Cushman)) responded in a broadly similar fashion. The monothalamid species however may be more sensitive to high concentrations of each metal. Of the metals examined, exposure to Pb had the most deleterious effect, followed by Zn, then Cd. These four most abundant species appear to be more tolerant of Cd than the other metals. Zn was the only metal in the study that produced abundant aberrant test morphologies. Ammonia tepida grew abnormally more frequently than any other species encountered and exhibited a distinctive enlarged aperture as well as aberrant patterns of calcification, chamber arrangement, and enlarged pores. Abnormal tests were also found in H. germanica and a miliolid. The monothalamid species did not produce aberrant test morphologies. Results support the application of foraminifera as bio-indicators in polluted environments.
Ragotzkie, R.A. 1956. Mortality of loggerhead turtle eggs from excessive rainfall. Ecology. 40:303-305.
Ragotzkie, R.A. 1959. Plankton productivity in estuarine waters of Georgia. Institute of Marine Science, University of Texas. 6:146-158.
Ragotzkie, R.A. and Bryson, R.A. 1955. Hydrography of the Duplin River, Sapelo Island, Georgia. Bulletin of Marine Science of the Gulf and Caribbean. 297-314.
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Abstract
Evolutionary ecologists have long been intrigued by the fact that many plant species can inhabit a broad range of environmental conditions and that plants often exhibit dramatic differences in phenotype across environmental gradients. We investigated responses to salinity treatments in the salt marsh plant Borrichia frutescens to determine if the species is responding to variation in edaphic salt content through phenotypic plasticity or specialized trait response. We grew seedlings from fruits collected in high- and low-salt microhabitats, assigned seedlings to high- and low-salt treatments in a greenhouse, and measured traits related to salt tolerance. All traits were highly plastic in response to salinity. Plants from the two microhabitats did not differ in trait means or respond differently to the treatments. These results suggest that environmental differences between the two microhabitats are not creating genotypes adapted to high and low salt levels. In addition, despite evidence for variation in allozyme markers in this population, there was no significant genotypic variation (family effect) in any of the trait means measured across microhabitats. There was variation in plasticity for only leaf Na and leaf B concentration. The high degree of plasticity for all traits and the lack of differences among microhabitats across the salinity gradient suggest plasticity in many traits may be fixed for this species.
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Abstract
Factors that maintain genetic and species diversity may act in concert in natural ecosystems. Here, we investigate correlations between genetic diversity (in eight salt marsh species) and community species diversity. A significant positive correlation existed between genetic diversity and species richness, although the relationship was not significant for any species individually. Nonetheless, four of the eight comparisons showed strong positive relationships between genetic and species diversity. Additionally, several abiotic variables were used in a model selection procedure to determine what site-level characteristics might drive differences in genetic diversity in this system. The rate of larval influx, as measured by barnacle abundance on Spartina alterniflora, was the strongest predictor of site-level genetic diversity in our samples. Our results suggest that estuarine management efforts should consider recruitment rates when selecting areas for protection.
Roden, A.E., Champagne, D.E. and Forschler, B.T. 2011. Biogeography of Triatoma sanguisuga (Hemiptera: Reduviidae) on Two Barrier Islands off the Coast of Georgia, United States. Journal of Medical Entomology. 48(4):806-812.
Abstract
Thirty-three Triatoma sanguisuga (LeConte) adults and nymphs were collected during June and July 2009, at five sites on Cumberland Island and two sites on Sapelo Island, Georgia, to assess genetic diversity within and between sites. All but three specimens were found in a peridomestic habitat. The entire length (699 bp) of the cytochrome oxidase II mitochondrial gene was sequenced for each specimen. Twelve haplotypes were identified, nine from Cumberland Island and three from Sapelo Island. No haplotypes were shared between the two islands, indicating there is limited or no movement of gene flow between the islands. Phylogenetic relationships among the haplotypes were determined using both neighbor-joining and maximum parsimony analyses. The phylogenetic trees from both analyses were similar, with no distinct clades on either tree devoted to haplotypes from a single island. A haplotype network structure was determined using nested clade analysis, which produced two haplotype networks, one containing only specimens found on Cumberland Island. The second network included specimens from both islands, with the ancestral haplotype from Sapelo Island. This pilot study is the first to highlight triatomine populations in the southeastern United States using the cytochrome oxidase II mitochondrial gene, and indicates strong population structuring along the Georgia Coast.
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Abstract
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 mu g/L-3 (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. Data from an additional 53 inland lake, reservoir, and river stations were included for comparison in algorithm testing. 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 a transect capturing transitions between the Nueces River and Corpus Christi Bay in Texas. These analyses were useful in addressing issues important to coastal management.
Schalles, J.F., Hladik, C.M., Lynes, A.A. and Pennings, S.C. 2013. Landscape Estimates of Habitat Types, Plant Biomass, and Invertebrate Densities in a Georgia Salt Marsh. Oceanography. 26(3):88-97.
Abstract
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.
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Seer, F.K., Putze, G., Pennings, S.C. and Zimmer, M. 2021. Drivers of litter mass loss and faunal composition of detritus patches change over time. Ecology and Evolution. 11(14):9642-9651.
Abstract
Decomposition of vegetal detritus is one of the most fundamental ecosystem processes. In complex landscapes, the fate of litter of terrestrial plants may depend on whether it ends up decomposing in terrestrial or aquatic conditions. However, (1) to what extent decomposition rates are controlled by environmental conditions or by detritus type, and (2) how important the composition of the detritivorous fauna is in mediating decomposition in different habitats, remain as unanswered questions. We incubated two contrasting detritus types in three distinct habitat types in Coastal Georgia, USA, to test the hypotheses that (1) the litter fauna composition depends on the habitat and the litter type available, and (2) litter mass loss (as a proxy for decomposition) depends on environmental conditions (habitat) and the litter type. We found that the abundance of most taxa of the litter fauna depends primarily on habitat. Litter type became a stronger driver for some taxa over time, but the overall faunal composition was only weakly affected by litter type. Decomposition also depends strongly on habitat, with up to ca. 80% of the initial detrital mass lost over 25 months in the marsh and forest habitats, but less than 50% lost in the creek bank habitat. Mass loss rates of oak versus pine litter differed initially but converged within habitat types within 12 months. We conclude that, although the habitat type is the principle driver of the community composition of the litter fauna, litter type is a significant 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 becomes the dominating factor in determining decomposition of older litter. Thus, the major driver of litter mass loss changes over time from being the litter type in the early stages to the habitat (environmental conditions) in later stages.
Seliskar, D.M., Gallagher, J.L., Burdick, D.M. and Mutz, L.A. 2002. The regulation of ecosystem functions by ecotypic variation in the dominant plant: a Spartina alterniflora salt-marsh case study. Journal of Ecology. 90:1-11.
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Abstract
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 ~ 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 > 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.
Sinclair, N.R. 1971. A reviewal of Odhneria odhneri Travassos, 1921 (Trematoda:Microphallidae). Journal of Parasitology. 57:980-982.
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Sinclair, N.R. 1972. Studies on the heterophyid trematode Apophallus brevis, the "sand-grain grub" of yellow perch (Perca flavescens). I. Redescription and resolution of synonymic conflict with Apophallus imperator Lyster, 1940 and other designations. Canadian Journal of Zoology. 50:357-364.
Sinclair, N.R. 1972. Studies on the heterophyid trematode Apophallus brevis, the "sand-grain grub" of yellow perch (Perca flavescens). II. The metacercaria: position, structure, and composition of the cyst; hosts; geographical distribution and variation. Canadian Journal of Zoology. 50:577-584.
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Smith, C.W. and Goldstein, S.T. 2019. The effects of selected heavy metals (As, Cd, Ni, Zn) on experimentally grown foraminiferal assemblages from Sapelo Island, Georgia and Little Duck Key, Florida, U.S.A. Journal of Foraminiferal Research.
Smith, C.W. and Goldstein, S.T. 2021. EFFECTS OF VARIED TEMPERATURE AND SALINITY ON ASSEMBLAGES OF FORAMINIFERA GROWN WITH EXPOSURE TO HEAVY-METAL POLLUTANTS (NICKEL AND ZINC). Journal of Foraminiferal Research. 51(3):99-114.
Abstract
Benthic foraminifera are important environmental indicators of heavy-metal contaminants in marine environments because of their unique sensitivity to environmental change. However, this sensitivity can make parsing the effect of contaminants from other factors such as salinity and temperature difficult. To address this problem, this study individually compares the effects of heavy metals nickel and zinc on temperate rotalids and subtropical miliolids under different temperature and salinity regimes, including intermediate (22 degrees C, 32 psu), elevated temperature (30 degrees C, 32 psu), reduced temperature (18 degrees C, 32 psu), elevated salinity (22 degrees C, 40 psu), and reduced salinity (22 degrees C, 12 psu). Assemblages of foraminifera were grown experimentally from propagules (small juveniles) collected from two shallow marine sites: Sapelo Island, Georgia, and Little Duck Key, Florida. Surface sediment was collected from both locations and sieved immediately after collection. Using the propagule method, assemblages of foraminifera were grown in a controlled setting from propagules in these sediment samples. Either nickel or zinc was added to each assemblage. Experimental conditions were held constant with only metal concentration, salinity, and temperature varying. Exposure to elevated concentrations of nickel and zinc led to limited foraminiferal abundances compared to the controls under all temperatures and salinity conditions examined. In addition, high concentrations of nickel and especially zinc resulted in an increase of deformed tests of Sapelo Island foraminifera under intermediate (22 degrees C, 32 psu) and high salinity (22 degrees C, 40 psu) conditions. Far fewer deformities occurred in Sapelo Island assemblages in higher or lower salinities and temperatures. These results support the usefulness of foraminiferal abundance and species abundance as tools for environmental analysis. Consistent with previous work, results also identify the problems associated with using test deformities alone as a bioindicator tool.
Smith, C.W., Fehrenbacher, J.S. and Goldstein, S.T. 2020. Incorporation of heavy metals in experimentally grown foraminifera from Sapelo Island, Georgia and Little Duck Key, Florida, USA. Marine Micropaleontology. 156:13.
Abstract
Benthic foraminifera are valuable indicators in environmental studies, including those on marine pollution monitoring. While a great deal of foraminiferal biomonitoring research utilizes abundance and distributional data, further value resides in better understanding the incorporation of heavy metal pollutants in foraminiferal calcite. By experimentally growing assemblages of foraminifera from propagules (small juveniles) gathered from Sapelo Island, Georgia and Little Duck Key, Florida, this study examines foraminiferal incorporation of the heavy metals arsenic, cadmium, nickel, and zinc over a range of concentrations. Surface sediment was collected and sieved to concentrate the propagules. The propagules were then used to experimentally grow assemblages with each exposed to a different heavy metal. After one month, the experimentally grown foraminifera were harvested and samples of the two most common species from each location, Ammonia tepida (Cushman) and Haynesina germanica (Ehrenberg) from Sapelo Island and Quinqueloculina sabulosa (Cushman) and Triloculina oblonga (Montagu) from Little Duck Key, were selected for trace element analysis. Calcite of the tests was analyzed using LA-ICP-MS to quantify the heavy metal incorporation. Rotalid species A. tepida and H. germanica incorporated more cadmium as its concentration in the surrounding water increased, whereas miliolid species Q. sabulosa and T. oblonga incorporated more of the metals zinc and nickel. This study shows that while foraminiferal incorporation of heavy metals has great potential as a biomonitoring tool, multiple factors (especially inter-clade variation) must be considered carefully. In future marine environmental research, these factors may help to create a more targeted assessment of environmental pollution.
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Abstract
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.
Stallins, J.A. 2001. Soil and vegetation patterns in barrier island dune environments. Physical Geography. 22(1):79-98.
Starr, T.J. 1956. Relative amounts of vitamin B12 in detritus from oceanic and estuarine environments near Sapelo Island, Georgia. Ecology. 37:658-664.
Stewart, R.A. and Pilkey, O.H. 1966. Sediments of the northern Arabian Sea. U. S. Naval Oceanogr. Office Tech. Rept. 186. 28 p.
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Tackett, N.W. and Craft, C.B. 2010. Ecosystem Development on a Coastal Barrier Island Dune Chronosequence. Journal of Coastal Research. 26(4):736-742.
Abstract
Soil and litter organic carbon, nitrogen, and phosphorus were measured across a dune chronosequence on Sapelo Island, Georgia, U.S.A., to characterize ecosystem development and nutrient cycling during primary succession. As successional theory predicts, litter biomass and soil organic matter increased with dune age. The proportion of nutrients contained in the litter also increased with dune age. No litter was present in the grass-dominated foredunes, whereas in the forested dunes litter accounted for 37%, 17%, and 0.11% of the ecosystem (soil plus litter) C, N, and P, respectively. Soil C and N pools increased from the foredunes to older dune classes. Surface soil (0-10 cm) plant-available N (NH(4)(+), NO(3)(-)) increased from the foredunes to middunes, whereas soil P showed little change with dune age. Nitrogen was highly limiting across the chronosequence. Total soil N ranged from 0.006% (per gram of dry soil) in the foredunes to 0.087% in the middune. Soil N : P was less than 1.3 across all sites, also suggesting N limitation of plant productivity. Plant-available NO(3)(-) and total N concentrations in soil and ecosystem (litter plus soil) pools were greater in the middunes, where the N-fixing shrub Morella cerifera was present, than in either the foredunes or forested dunes. Our results suggest that the development of dune nutrient cycles is controlled by both successional age and colonization by N-fixing species.
Takacs, M., Egeberg, P.K. and Alberts, J.J. 1999. Characterization of natural organic matter from eight Norwegian surface waters: Proton and copper binding. Environment International. 25(2/3):315-323.
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Teal, J.M. 1956. The cattle egret in Georgia. The Oriole. 21:33.
Teal, J.M. 1957. Community metabolism in a temperate cold spring. Ecological Monographs. 27:283-302.
Teal, J.M. 1958. Distribution of fiddler crabs in Georgia salt marshes. Ecology. 39:185-193.
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Teal, J.M. 1962. Energy flow in the salt marsh ecosystem of Georgia. Ecology. 43:614-624.
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Abstract
Also: Paper presented at the 59th Annual Meeting of the Southeastern Archaeological Conference
Tolar, B.B., Bratcher, A., Liu, Q., Ross, M.J., Hagan, P. and Hollibaugh, J.T. 2015. Short-term variability of ammonia oxidizer populations in a SE USA salt marsh environment. ISME Journal.
Abstract
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 – â€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.
Abstract
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 Lâ’1 dâ’1, Mann-Whitney U-test p < 0.0001), and the South Atlantic Bight (20 ± 8.8 versus 2.2 ± 1.7 nmol Lâ’1 dâ’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 Lâ’1 dâ’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.
Treplin, M., Pennings, S.C. and Zimmer, M. 2013. Decomposition of Leaf Litter in a U.S. Saltmarsh is Driven by Dominant Species, Not Species Complementarity. Wetlands. 33(1):83-89.
Abstract
To add to our understanding of species richness-effects on ecosystem processes, we studied the importance of species complementarity in driving decomposition in a saltmarsh in Georgia, USA. We studied pair-wise interactions of both detritivores and plant litter species and how they affect decomposition rates in an experiment located on the mid-marsh platform. Needle rush, Juncus roemerianus, had 2-3 times higher decomposition rates than cordgrass, Spartina alterniflora, or live oak, Quercus virginiana. Mixing litter types did not promote decomposition rates. Cordgrass decomposition was 1.5-times higher when periwinkles, Littoraria irrorata, were present than in detritivore-free controls. In contrast, neither coffee-bean snails, Melampus bidentatus, nor wharf crabs, Armases cinereum, increased cordgrass decomposition rates. Mixing detritivore species did not increase cordgrass mass loss beyond expected rates from an additive model. We conclude that in this system, species do not act complementarily with each other, but that decomposition rates are controlled by the dominant species of angiosperms and invertebrate detritivores.
Trott, T.J. and Robertson, J.R. 1984. Chemical stimulants of cheliped flexion behavior by the Western Atlantic ghost crab Ocypode quadrata (Fabricius). Journal Experimental Marine Biology and Ecology. 78:237-252.
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Vorobev, A., Sharma, S., Yu, M.Y., Lee, J., Washington, B.J., Whitman, W.B., Ballantyne, F., Medeiros, P.M. and Moran, M.A. 2018. Identifying labile DOM components in a coastal ocean through depleted bacterial transcripts and chemical signals. Environmental Microbiology. 20(8):3012-3030.
Abstract
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- and metabolism-related genes whose relative expression decreased implicated osmolytes, carboxylic acids, fatty acids, sugars and organic sulfur compounds as candidate bioreactive molecules. FT-ICR MS analysis of depleted molecular formulae implicated functional groups similar to 30-40 Da in size cleaved from semi-polar components of DOM as bioreactive components. Both gene expression and FT-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.
Vu, H.D. and Pennings, S.C. 2018. Predators mediate above- vs. belowground herbivory in a salt marsh crab. Ecosphere. 9(2):10.
Abstract
Predators can significantly affect prey by removing prey individuals and by changing prey behavior. 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 below-ground, 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.
Vu, H.D. and Pennings, S.C. 2021. Directional movement of consumer fronts associated with creek heads in salt marshes. Ecology. 102(9):11.
Abstract
Consumers often deplete local resources and aggregate along edges of remaining resources, forming "consumer fronts." We examined the factors that promote Sesarma reticulatum crab aggregations at saltmarsh creek heads to explain the directional but slow movement of these fronts. We also created artificial creek heads to test the hypothesis that hydrological conditions at creek heads create superior habitat for crabs. Soil temperatures were similar to 11-12% cooler, hydrogen sulfide concentrations lower (0.0 vs. similar to 0.58 mg/L), and dissolved oxygen concentrations twofold higher at the creek head versus the marsh platform. In the artificial creek-head experiment, altering hydrological conditions led to lower dissolved sulfide levels, higher dissolved 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, suggesting that crabs were increasing erosion. Our results suggest that abiotic conditions for crabs are better at the leading edge of the creek head than the trailing edge, explaining the directional movement of the front. Moreover, the speed at which the front propagates appears to be limited by the rate at which the creekhead erodes, rather than by crab mobility. The directional and slow movement of Sesarma fronts compared to consumer fronts of other invertebrates appears to result from the inextricable link between Sesarma and marsh geomorphology, whereas other consumer fronts are associated mostly with food resources.
Abstract
Ecosystem engineers affect different organisms and processes in multiple ways at different spatial scales. Moreover, similar species may differ in their engineering effects for reasons 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 tidal creek networks in salt marshes experiencing sea level rise. In the field, crab burrows were associated with heads of eroding creeks and the loss of plant (Spartina alterniflora) stems. S. reticulatum was closely associated with creek heads, but densities of the other crab species did not vary across marsh zones. In mesocosm experiments, S. reticulatum excavated the most soil and strongly reduced S. alterniflora biomass. The other three species excavated less and did not affect S. alterniflora. Creek heads with vegetation removed to simulate crab herbivory grew significantly faster than controls. Percolation rates of water into marsh sediments were 10 times faster at creek heads than on the marsh platform. Biomass decomposed two times faster at creek heads than on the marsh platform. Our results indicate that S. reticulatum increases creek growth by excavating sediments and by consuming plants, thereby increasing water flow and erosion at creek heads. Moreover, it is possible that S. reticulatum burrows also increase creek growth by increasing surface and subsurface erosion, and by increasing decomposition of organic matter at creek heads. Our results show that the interaction between crab and plant ecosystem engineers can have both positive and negative effects. At a small scale, in contrast to other marsh crabs, S. reticulatum harms rather than benefits plants, and increases erosion rather than marsh growth. At a large scale, however, S. reticulatum facilitates the drainage efficiency of the marsh through the expansion of tidal creek networks, and promotes marsh health.
Wall, V.D., Alberts, J.J., Moore, D.J., Newell, S.Y., Pattanayek, M. and Pennings, S.C. 2001. Effect of mercury and PCBs on organisms from lower trophic levels of a Georgia salt marsh. Archives of Environmental Contamination and Toxicology. 40:10-17.
Wall, V.D., London, J., Warren, J.E., Gossett, R., Wenholz, M.D. and Klaine, S.J. 1998. Development of a continuous-flow renewal system for sediment toxicity testing. Environmental Toxicology and Chemistry. 17(6):1159-1164.
Walters, K. and Bell, S.S. 1994. The significance of copepod emergance to benthic, pelagic, and physical linkages in a subtidal seagrass bed. Marine Ecology Progress Series. 108:237-249.
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Walters, K. and Shanks, A.L. 1996. Complex trophic and nontrophic interactions between meiobenthic copepods and marine snow. Journal of Experimental Marine Biology and Ecology. 198:131-145.
Walters, K., Jones, E. and Etherington, L. 1996. Experimental studies of predation on metazoans inhabiting Spartina alterniflora stems. Journal of Experimental Marine Biology and Ecology. 195:251-265.
Wampler, J.E., Hori, K., Lee, J.W. and Cormier, M.J. 1971. Structured bioluminescence. Two emitters during both the in vitro and the in vivo bioluminescence of the sea pansy, Renilla. Biochemistry. 10:2903-2909.
Wampler, J.E., Karkhanis, Y.D., Morin, J.G. and Cormier, M.J. 1973. Similarities in the bioluminescence from the Pennatulacea. Biochimica et Biophysica Acta. 314:104-109.
Wang, S.R., Di Iorio, D., Cai, W.J. and Hopkinson, C.S. 2018. Inorganic carbon and oxygen dynamics in a marsh-dominated estuary. Limnology and Oceanography. 63(1):47-71.
Abstract
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 O-2 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 O-2. Rates of metabolism were extremely high, with respiration (43 mol m(-2) yr(-1)) greatly exceeding gross primary production (28 mol m(-2) yr(-1)), such that the overall system was net heterotrophic. Metabolism measured with DIC were higher than with O-2, 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 O-2 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 O-2 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.
Ward, W.W. and Cormier, M.J. 1975. Extraction of Renilla-type luciferin from the calcium-activated photoproteins aequorin, mnemiopsin, and berovin. Proceedings of the National Academy of Science of the USA. 72:2530-2534.
Ward, W.W. and Cormier, M.J. 1976. In vitro energy transfer in Renilla bioluminescence. Journal of Physical Chemistry. 80:2289-2291.
Ward, W.W. and Cormier, M.J. 1978. Energy transfer via protein-protein interaction in Renilla bioluminescence. Photochemistry and Photobiology. 27:389-396.
Ward, W.W. and Cormier, M.J. 1979. An energy transfer protein in coelenterate bioluminescence. Characterization of the Renilla green-fluorescent protein. Journal of Biological Chemistry. 254:781-788.
Wason, E. and Pennings, S.C. 2008. Grasshopper (Orthoptera: Tettigoniidae) species composition and size across latitude in Atlantic Coast salt marshes. Estuaries and Coasts. 31:335-343.
Abstract
Although grasshoppers are common salt marsh herbivores, we know little about geographic variation in their species composition. We documented latitudinal variation in species composition of the tettigoniid grasshopper fauna of Atlantic Coast salt marshes. Tettigoniids (N=740 adults) were collected from the Spartina alterniflora zone of 31 salt marsh sites across a latitudinal range of 13.19° (Florida to Maine), with an additional 52 individuals collected from the Juncus roemerianus zone of low-latitude marshes for comparative purposes. Eight species were collected, but some were common only at a few sites or rare throughout the entire collection range. The tettigoniid community was dominated by Orchelimum fidicinium at low latitudes and Conocephalus spartinae at high latitudes. Several factors might explain this shift, including changes in climate, plant phenology, and plant zonation patterns. O. fidicinium and C. spartinae increased in body size toward low latitudes. In laboratory feeding assays, O. fidicinium readily ate S. alterniflora and J. roemerianus leaves, Orchelimum concinnum, which is largely restricted to the J. roemerianus zone, ate only J. roemerianus leaves, and Conocephalus spp. ate neither, consistent with literature suggestions that they mainly consume seeds and flowers. Geographic variation in species composition and body size of grasshoppers may help explain documented patterns of geographic variation in plant palatability and plant–herbivore interactions in Atlantic Coast salt marshes. Because it can be difficult to identify tettigoniids to species, we present a guide to aid future workers in identifying the tettigoniid species common in these marshes. Keywords Biogeography . Latitude . Plant–herbivore interactions . Bergmann’s rule . Orthoptera . Spartina alterniflora . Salt marsh
Webb, K.L. 1966. NaCl effects on growth and transpiration in Salicornia bigelovii, a salt marsh halophyte. Plant and Soil. 24:261-268.
Webb, K.L. and Burley, J.W.A. 1964. Stachyose translocation in plants. Plant Physiology. 39:973-977.
Webb, K.L. and Burley, J.W.A. 1965. Dark fixation of 14CO2 by obligate and facultative salt marsh halophytes. Canadian Journal of Botany. 43:281-285.
Webb, K.L. and Johannes, R.E. 1967. Studies of the release of dissolved free amino acids by marine zooplankton. Limnology and Oceanography. 12:376-382.
Webb, S. and Kneib, R.T. 2004. Individual growth rates and movement of juvenile white shrimp (Litopenaeus setiferus) in a tidal marsh nursery. Fishery Bulletin. 102:376-388.
Webb, S.C. and Kneib, R.T. 2002. Abundance and distribution of juvenile white shrimp Litopenaeus setiferus within a tidal marsh landscape. Marine Ecology Progress Series. 232:213-223.
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Welch, R., Remillard, M. and Alberts, J.J. 1991. Integrated resource databases for coastal management. GIS World. 4:86-89.
Welch, R., Remillard, M. and Alberts, J.J. 1992. Integration of GPS, Remote sensing & GIS techniques for coastal resource management. Photogrammetric Engineering and Remote Sensing. 58:1571-1578.
Wheeler, J.R. 1976. Fractionation by molecular weight of organic substances in Georgia coastal water. Limnology and Oceanography. 21:846-852.
Wheeler, J.R. 1977. Dissolved organic carbon: Spectral relationships in coastal waters. Limnology and Oceanography. 22:573-575.
Wheeler, P.A. and Kirchman, D.L. 1986. Utilization of inorganic and organic nitrogen by bacteria in marine systems. Limnology and Oceanography. 31:998-1009.
Whicker, F.W., Pinder, J.E., Bowling, J.W., Alberts, J.J. and Brisbin, I.L. 1990. Distribution of long-lived radionuclides in an abandoned reactor cooling reservoir. Ecological Monographs. 60:471-496.
Whitby, H., Hollibaugh, J.T. and van den Berg, C.M.G. 2015. Identity of marine copper-binding ligands resolved: L1 and L2 are thiols and humic substances. PENDING.
Abstract
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 Oxidising 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′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.
Whitney, D.E. and Darley, W.M. 1979. A method for the determination of chlorophyll a in samples containing degradation products. Limnology and Oceanography. 24:183-186.
Whitney, D.E. and Darley, W.M. 1983. Effect of light intensity upon salt marsh benthic microalgal photosynthesis. Marine Biology. 75:249-252.
Wicks, R.J., Moran, M.A., Pittman, L.J. and Hodson, R.E. 1991. Carbohydrate signatures of aquatic macrophytes and their dissolved degradation products as determined by a sensitive high-performance ion chromatography. Applied and Environmental Microbiology. 57:3135-3143.
Abstract
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 2.5x2.5m 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.
Wiebe, W. and Bancroft, K. 1975. Use of the adenylate energy charge ratio to measure growth state of natural microbial communities. Proceedings of the National Academy of Science of the USA. 72:2112-2115.
Wiedemann, H. 1971. Shell deposits and shell preservation in Quaternary and Tertiary estuarine sediments in Georgia, U.S.A. Sedimentary Geology. 7:103-125.
Wiegert, R.G., Chalmers, A.G. and Randerson, P.F. 1983. Productivity gradients in salt marshes: the response of Spartina alterniflora to experimentally manipulated soil water movement. Oikos. 41:1-6.
Wieski, K. and Pennings, S. 2014. Latitudinal variation in resistance and tolerance to herbivory of a salt marsh shrub. Ecography. 37(8):763-769.
Abstract
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.
Wieski, K. and Pennings, S.C. 2014. Climate Drivers of Spartina alterniflora Saltmarsh Production in Georgia, USA. Ecosystems. 17(3):473-484.
Abstract
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 creekbank and midmarsh zones to estimate annual net primary production (ANPP). River discharge was the most important driver of S. alterniflora ANPP, especially in creekbank 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.
Wieski, K., Guo, H.Y., Craft, C.B. and Pennings, S.C. 2010. Ecosystem Functions of Tidal Fresh, Brackish, and Salt Marshes on the Georgia Coast. Estuaries and Coasts. 33(1):161-169.
Abstract
We examined patterns of habitat function (plant species richness), productivity (plant aboveground biomass and total C), and nutrient stocks (N and P in aboveground plant biomass and soil) in tidal marshes of the Satilla, Altamaha, and Ogeechee Estuaries in Georgia, USA. We worked at two sites within each salinity zone (fresh, brackish, and saline) in each estuary, sampling a transect from the creekbank to the marsh platform. In total, 110 plant species were found. Site-scale and plot-scale species richness decreased from fresh to saline sites. Standing crop biomass and total carbon stocks were greatest at brackish sites, followed by freshwater then saline sites. Nitrogen stocks in plants and soil decreased across sites as salinity increased, while phosphorus stocks did not differ between fresh and brackish sites but were lowest at salty sites. These results generally support past speculation about ecosystem change across the estuarine gradient, emphasizing that ecosystem function in tidal wetlands changes sharply across the relatively short horizontal distance of the estuary. Changes in plant distribution patterns driven by global changes such as sea level rise, changing climates, or fresh water withdrawal are likely to have strong impacts on a variety of wetland functions and services.
Williams, A.K. and Eagon, R.G. 1962. Studies on the alginase of Agarbacterium alginicum. Canadian Journal of Microbiology. 8:649-654.
Williams, R.B. 1963. Use of netting to collect motile benthic algae. Limnology and Oceanography. 8:360-361.
Williams, R.B. 1964. Division rates of salt marsh diatoms in relation to salinity and cell size. Ecology. 45:877-880.
Williams, R.B. 1966. Unusual motility of tube-dwelling pennate diatoms. Journal of Phycology. 1:145-156.
Winker, C.D. and Howard, J.D. 1977. Plio-Pleistocene paleogeography of the Florida Gulf coast interpreted from relict shorelines. Transactions-Gulf Coast Association of Geological Societies. 27:409-420.
Wolf, P.L., Shanholtzer, S.A. and Reimold, R.J. 1972. First occurrence of the violet goby in Georgia. Quarterly Journal of the Florida Academy of Sciences. 35:81-84.
Wolf, P.L., Shanholtzer, S.F. and Reimold, R.J. 1975. Population estimates for Uca pugnax (Smith, 1870) on the Duplin estuary marsh, Georgia, U.S.A. (Decapoda Brachyura, Ocypodidae). Crustaceana. 29:79-91.
Wolfe, G.V. and Kiene, R.P. 1993. Effects of methylated, organic, and inorganic substrates on microbial consumption of dimethyl sulfide in estuarine waters. Applied and Environmental Microbiology. 59:2723-2726.
Wolfe, G.V. and Kiene, R.P. 1993. Radioisotope and chemical inhibitor measurements of dimethyl sulfide consumption rates and kinetics in estuarine waters. Marine Ecology Progress Series. 99:261-269.
Woolsey, R., Henry, V.J. and Hunt, J. 1975. Backshore heavy-mineral concentration on Sapelo Island, Georgia. Journal of Sedimentary Petrology. 45:280-284.
Wu, F.R., Pennings, S.C., Ortals, C., Ruiz, J., Farrell, W.R., McNichol, S.M., Angelini, C., Spivak, A.C., Alber, M. and Tong, C.F. 2021. Disturbance is complicated: Headward-eroding saltmarsh creeks produce multiple responses and recovery trajectories. Limnology and Oceanography.:15.
Abstract
Disturbances are one of the most important processes affecting natural systems, but there is a gap between simple conceptual models of disturbance and complex empirical studies. We studied the perturbation caused by headward-eroding creeks in southeastern USA salt marshes. We measured disturbance responses (magnitude and recovery trajectory) of 19 variables. Some variables (shoot density, root biomass, snail density, soil pH, soil strength, soil temperature, elevation) declined sharply, while other variables (crab burrow density, soil organic matter, soil redox) increased sharply, in response to the burrowed and grazed conditions at the creek head. These variables recovered over subsequent years or decades. Other variables (shoot height, aboveground biomass, rhizome biomass, 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 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, and in some cases variables never converged with control values, indicating a persistent state change. Reducing the dimensionality of the data set into 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.
Yacobi, Y.Z., Alberts, J.J., Takacs, M. and McElvaine, M. 2003. Absorption spectroscopy of colored dissolved organic carbon in Georgia (USA) rivers: the impact of molecular size distribution. Journal of Limnology. 62(1):41-46.
Yetka, J. and Wiebe, W.J. 1974. Ecological application of antibiotics as respiratory inhibitors of bacterial populations. Applied Microbiology. 28:1033-1039.
Zhang, C.Y., Mishra, D.R. and Pennings, S.C. 2019. Mapping salt marsh soil properties using imaging spectroscopy. Isprs Journal of Photogrammetry and Remote Sensing. 148:221-234.
Abstract
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.
Zhang, Y., Li, B., Wu, J., Pennings, S.C. and Lambrinos, J. 2020. Contrasting latitudinal clines of nematode diversity in Spartina alterniflora salt marshes between native and introduced ranges. Diversity and Distributions.
Abstract
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.
Ziegler, A., Grospietsch, T., Carefoot, T.H., Danko, J.P., Zimmer, M., Zerbst-Boroffka, I. and Pennings, S.C. 2000. Hemolymph ion composition and volume changes in the supralittoral isopod Ligia pallasii Brandt, during molt. Journal of Comparative Physiology, A. 170:329-336.
Zimmer, M., Danko, J.P., Pennings, S.C., Danford, A.R., Carefoot, T.H., Ziegler, A. and Uglow, R.F. 2002. Cellulose digestion and phenol oxidation in coastal isopods (Crustacea: Isopoda). Marine Biology. 140:1207-1213.
Zimmer, M., Danko, J.P., Pennings, S.C., Danford, A.R., Ziegler, A., Uglow, R.F. and Carefoot, T.H. 2001. Hepatopancreatic endosymbionts in coastal isopods (Crustacea: Isopoda), and their contribution to digestion. Marine Biology. 138:955-963.
Zimmer, M., Pennings, S.C., Buck, T.L. and Carefoot, T.H. 2002. Species-specific patterns of litter processing by terrestrial isopods (Isopoda: Oniscidea) in high intertidal salt marshes and coastal forests. Functional Ecology. 16:596-607.
Zimmer, M., Pennings, S.C., Buck, T.L. and Carefoot, T.H. 2004. Salt marsh litter and detritivores: a closer look at redundancy. Estuaries. 27(5):753-769.
Books and Book Sections
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Alberts, J.J., Takacs, M. and Pattanayek, M. 2000. Natural organic matter from a Norwegian Lake: Possible structural changes resulting from lake acidification. Pages 261-275 in: Ghabbour, E.A. and Davies, G., eds. Humic Substances: Versatile Components of Plants, Soil and Water. Proceedings of the 4th Humic Substances Seminar , March 22-24, 2000, Northeastern University, Boston, Massachusetts. Royal Society of Chemistry, Cambridge, UK.
Alberts, J.J., Takacs, M., McElvaine, M. and Judge, K. 2001. Apparent size distribution and spectral properties of natural organic matter isolated from six rivers in Southeastern Georgia, USA. Pages 179-190 in: Ghabbour, E.A. and Davies, G., eds. Humic Substances: Structures, Models and Functions. Royal Chemical Society, Cambridge, England.
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Abstract
We measured soil properties, vertical accretion, and nutrient (organic C, N, and P) accumulation across a range of habitats to evaluate spatial variability of soil properties and processes of alluvial floodplain wetlands of the Altamaha River, Georgia, USA. The habitats vary in elevation and distance from the river channel, creating differences in the depth and duration of inundation. Habitats closer to the river had lower bulk density and higher total P than habitats further removed. 137Cs and 210Pb accretion rates were also greater at sites closer to the channel. Mineral sediment deposition and nutrient accumulation were greater in sloughs closer to the channel and lower in elevation relative to other habitats. We found distance to be a significant predictor of mineral soil properties across the floodplain. Bulk density increased whereas TP and silt content decreased with distance from the river channel. 137Cs accretion, P accumulation, and mineral sediment deposition also decreased with distance from the main channel. Elevation was not a significant predictor of soil properties or processes measured. Long-term (100 year) sediment accumulation rates based on 210Pb were significantly higher than 50-year rate of sedimentation based on 137Cs, perhaps as the result of greater land clearing for agriculture and lack of best management practices in the southeastern USA prior to 1950. Distance from the main channel is the driving force behind the spatial variability of soil properties and processes measured; however, slough habitats closest to the channel and lowest in elevation relative to other habitats maintain distinct vegetation patterns and are hotspots for N, P, and sediment accumulation. Characterization of soil properties and processes of alluvial floodplain forests and other wetlands should take into consideration microtopographic and spatial variation across the wetland.
Basan, P.B. and Frey, R.W. 1977. Actual-palaeontology and neoichnology of salt marshes near Sapelo Island, Georgia. Pages 41-70 in: Crimes, T.P. and Harper, J.C., eds. Trace Fossils II. Geological Journal, Special Issue 9.
Basan, P.B., Chamberlain, C.K., Frey, R.W., Howard, J.D., Seilacher, A. and Warme, J.E. 1978. Sedimentology and trace fossils. Pages 13-47 in: Basan, P.B., ed. Trace Fossil Concept. SEOM Short Course No. 5.
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Berman, T., J., W.W. and Hanson, R.B. 1983. Effects of organic substrate additions on size partitioning of heterotrophic activity in estuarine and nearshore bacteria. Pages 367-375 in: Shuval, H., ed. Developments in Ecology and Environmental Quality. Balaban Int. Sci. Serv. Rehovot, Philadelphia.
Bertness, M.D. and Pennings, S.C. 2000. Spatial variation in process and pattern in salt marsh plant communities in eastern North America. Pages 39-57 in: Weinstein, M.P. and Kreeger, D.A., eds. Concepts and Controversies in Tidal Marsh Ecology. Academic Publishers, Dordrecht, The Netherlands.
Chalmers, A.G. 1982. Soil dynamics and productivity of Spartina alterniflora. Pages 231-242 in: Kennedy, V.S., ed. Estuarine Comparisons. Academic Press, New York.
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Howard, J.D. and Frey, R.W. 1980. Physical and biogenic processes in Georgia estuaries. III. Vertical sequences. Pages 221-232 in: McCann, S.B., ed. Sedimentary Processes and Animal-Sediment Relationships in Tidal Environments. Geological Association of Canada, Short Course.
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Hoyt, J.H. and Henry, V.J.J. 1965. Significance of inlet sedimentation in the recognition of ancient barrier islands. Pages 190-194 in: Symposium on Sedimentation of Late Cretaceous and Tertiary Outcrops, Rock Spring Uplift, Wyoming. Wyoming Geological Assoc. Guidebook, Casper, Wyoming.
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Abstract
Tidal freshwater wetlands (TFW) have developed in a gradually yet constantly changing environment, but current and predicted future rates of environmental change, driven in large part by human activities, are often faster than those in the recent geological past. Global warming and increases in atmospheric CO2, sea level rise and salt water intrusion, and eutrophication-related changes in water quality are likely to affect the distribution, floral/faunal composition, biogeochemical functioning, and persistence of TFW. The current distribution of TFW indicates that these wetlands can persist across broad gradients of climate, hydrology, and nutrient loading. Comparisons across these gradients provide insight into the changes that may occur as individual wetlands are subjected to a changing environment. Because salt water intrusion is going to change one of the defining features of TFW (i.e., the presence of fresh water), this stressor is likely to have the largest long-term impact. In systems where river discharge is insufficient to offset salt water intrusion, TFW are likely to migrate upstream if space is not limited by topography or human development. Community changes are likely in current TFW as saltintolerant species are replaced by brackish species. Salt water can also affect nutrient sorption and availability, and may alter rates of vertical accretion and carbon/nutrient sequestration. It is likely that TFW will be impacted by multiple, simultaneous environmental changes. Understanding feedbacks between these stressors and TFW responses is necessary to accurately forecast how global changes will impact these ecologically unique ecosystems in a future climate. Plant nomenclature follows USDA Plants Database (http://plants.usda.gov). Zoological nomenclature follows Integrated Taxonomic Information System (http://www.itis.gov/)
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Theses and Dissertations
Abstract
Phenotypic trait variation is ubiquitous among plant populations. Multiple evolutionary and ecological processes may produce trait variation, including divergent selection due to heterogeneous environmental conditions driving local adaptation, phenotypic plasticity, historical genetic structure, genetic drift, and barriers to gene flow. Consequently, disentangling the principal cause driving trait variation is challenging, since multiple processes may result in similar outcomes. Understanding the underlying source of phenotypic trait variation is particularly critical for informing restoration and conservation decisions. Uniola paniculata is a perennial grass that occurs on southeastern U.S. coastal dunes and is federally protected due to its role in stabilizing dune habitats. Across a single dune system, U. paniculata’s range spans a localized environmental gradient from the dynamic dunes closest to the shoreline to the more stabilized dunes farther inland. We characterize the shoreline-to-landward environmental gradient and determine that variation in morphological and physiological traits in U. paniculata mirrors variation in the underlying abiotic conditions in a mensurative field study. We find no evidence that populations are locally adapted to microhabitats along the environmental gradient using reciprocal transplants of individuals from each habitat. We employ a comparative approach using a greenhouse common garden to examine variation in quantitative traits and genetic analyses (allozymes) to examine neutral genetic variation. This study includes populations from four Georgia barrier islands. We find evidence of divergent selection on both aboveground and total biomass which appears to be driven primarily by inter-island differences rather than intraisland differences from habitats along the shoreline-to-landward environmental gradient. Lastly, we explore the genetic structure of a widely dispersed beach annual, Cakile edentula, which is comprised of three subspecies associated with particular geographic distributions. This study has three key findings to contribute to our understanding of C. edentula: genetic diversity (Hep) is fairly low; taxonomic subspecies designations are supported by UPGMA-dendrogram clusters and AMOVA analysis indicating that variation among regions explains 42% of total variation; and pairwise FST estimates suggest that there are significant rates of migration between populations.
Conference Papers (Peer Reviewed)
Hardy, D., Bailey, M. and Heynen, N. 2021. "We''re Still Here": An Abolition Ecology Blockade of Double Dispossession of Gullah/Geechee Land. Annals of the American Association of Geographers.
Hopkinson, C.S. and Weston, N.B. 2021. Comparative Metabolism and Blue Carbon Sequestration of Two Wetland-Dominated Estuaries.
Hughes, Z.J., Farron, S.J. and FitzGerald, D.M. 2021. Impacts of crab bioturbation on marsh sediment properties and tidal creek incision.
Conference Posters and Presentations
Alberts, J.J., Filip, Z. and Hertkron, N. 1997. Interaction of light with estuarine fulvic and humic acids. Proceedings of the 8th Meeting of the International Humic Substances Society. The Role of Humic Substances in the Ecosystems and in Environmental Protection. The Polish Society of Humic Substances, September 9-14, 1996, Wroclaw, Poland.
Alberts, J.J., Newell, S.Y. and Price, M.T. 1987. Translocation and physiological state of controlling mechanisms for Al, As, Cu, Mn, and Sn in salt marsh cordgrass. Proceedings of International Conference on Heavy Metals in the Environment, Sept. 15-18, 1987, New Orleans, La. New Orleans.
Alberts, J.J., Takacs, M. and Andersen, D.O. 2000. Spectroscopic analysis of natural organic matter (NOM) in aquatic systems. Proceedings' 98, 2nd National Symposium on Agricultural Instrumentation (II SIAGRO). Anais do II Siagro (Simposio Nacional de Instrumentacao Agropecuaria). EMBRAPA, San Carlos, Brazil.
Claus, H., Filip, Z.K. and Alberts, J.J. 1997. Microbial utilization and transformation of riverine humic substances. Proceedings of the 8th Meeting of the Internatinal Humic Substances Society. The Role of Humic Substances in the Ecosystems and in Environmental Protection. The Polish Society of Humic Substances, September 9-14, 1996, Wroclaw, Poland.
Eddy, J., Henry, V.J.J., Hoyt, J.H. and Bradley, E. 1967. Description and use of an underwater television system on the Atlantic Continental Shelf. U. S. Geological Survey Prof. Paper 575C.
Ertel, J.R., Alberts, J.J. and Price, M.T. 1991. Transformation of riverine organic mattter in estuaries. Proceedings of the 1991 Georgia Water Resources Conference. Institute of Natural Resources, The University of Georgia, Athens, GA.
Fallon, R.D., Newell, S.Y., Sherr, B.F. and Sherr, E.B. 1986. Factors affecting bacterial biomass and growth in the Duplin River estuary and coastal Atlantic Ocean. Deuxieme Colloque International De Bacteriologie Marine CNRS, Brest, 1-5 Oct. 1985, Actes De Colloques, 3, 1986.
Filip, Z.K., Trubetskoj, O.A. and Alberts, J.J. 1997. Electrophoretic comparison of humic substances derived from natural and anthropogenic environments. Proceedings of the 8th Meeting of the International Humic Substances Society. The Role of Humic Substances in the Ecosystems and in Environmental Protection. September 9-14, 1996, Wroclaw, Poland.
Fornes, A.O. and Reimold, R.J. 1973. The estuarine environment: Location of mean high water--Its engineering, economic and ecological potential. Proceedings of the American Society of Photogrammetry Fall Convention, Lake Buena Vista, Florida, October 2-5, 1973.
Gallagher, J.L. and Reimold, R.J. 1973. Tidal marsh plant distribution and productivity patterns from the sea to fresh water--a challenge in resolution and discrimination. Proceedings of the 4th Biennial Workshop on Color Aerial Photography.
Gallagher, J.L., Reimold, R.J. and Thompson, D.E. 1971. Remote sensing and salt marsh productivity. Proceedings of the 38th Annual Meeting, American Society of Photogrammetry, Washington, D.C.
Hoyt, J.H. 1967. Theory of barrier island facies association. Preprint, 7th International Sedimentological Congress.
Hoyt, J.H. 1968. Genesis of sedimentary deposits along coasts of submergence. XXIII International Geological Congress, Vol. 8.
Johannes, R.E. and Webb, K.L. 1969. Release of dissolved organic compound by marine and freshwater invertebrates. Symposium on Organic Matter in Natural Waters, Univ. of Alaska. Pergamon Press, Virginia Institute of Marine Science, Gloucester Point, Virginia.
Kinsey, D.W. 1981. The Pacific/Atlantic reef growth controversy. Proceedings of the Fourth International Coral Reef Symposium, Manila.
Newell, S.Y. 1984. Bacterial and fungal productivity in the marine environment: a contrastive overview. International Colloquium for Marine Bacteriology, Marseille, France, May 1982.
Newell, S.Y. and Fallon, R.D. 1983. Study of fungal biomass dynamics within dead leaves of cordgrass: Progress and potential. Proceedings of the International Symposium on Aquatic Macrophytes, Nijmegen, The Netherlands.
Odum, E.P. 1961. The role of tidal marshes in estuarine production. Information Leaflet, June-July 1961, N. Y. State Conservation Dept.
Pfeiffer, W.J., Linthurst, R.A. and Gallagher, J.L. 1973. Photographic imagery and spectral properties of salt marsh vegetation as indicators of canopy characteristics. Proceedings of the American Society of Photogrammetry Fall Convention, Lake Buena Vista, Fla., October 2-5, 1973.
Pomeroy, L.R. 1963. Isotopic and other techniques for measuring benthic primary production. Proceedings of the Conference on Primary Productivity Measurement, Marine and Freshwater. U.S. Atomic Energy Commission, Division of Technical Information, Washington, D.C. (TID-7633).
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Reports
Hodson, R.E., Benner, R. and Maccubbin, A.E. 1982. Microbial degradation of natural and pollutionally-derived lignocellulosic detritus in wetland ecosystems. In: Interior, U.S.D.o.t., ed. Office Water Resour. Technol. Proj. Tech. Rept. A-082-Ga. 58.
Government Documents
Kneib, R., Simenstad, C., Nobriga, M. and Talley, D. 2008. Tidal marsh conceptual model. Sacramento (CA): Delta Regional Ecosystem Restoration Implementation Plan., Sacramento, CA.
Abstract
Tidal marshes are a subset of estuarine wetlands defined by the presence of emergent vegetation types uniquely adapted to sheltered intertidal zones of temperate and subtropical coastal plains (Chapman 1960, 1976, Mitsch & Gosselink 1993). They are found across a full range of salinity conditions from seawater on the immediate coast to freshwater tidal reaches of estuarine river systems. Marshes are transitional ecosystems that provide critical connections between adjacent subtidal and terrestrial ecosystems within the estuarine landscape (Simenstad et al. 2000; Levin et al. 2001). These “critical transition zones” often function as conduits for substantial fluxes of materials and energy (Ewel et al. 2001), and provide a variety of valuable ecosystems functions, goods and services related to the maintenance of biodiversity, fish and wildlife habitat, water quality, flood abatement and carbon sequestration (Rabenhorst 1995, Costanza et al. 1997, Weslawski et al. 2004, Zedler & Kercher 2005). However, estuarine marshes and the biotic communities that depend on them are vulnerable to both direct and indirect anthropogenic impacts (Holland et al. 2004, Snelgrove et al. 2004), and the functionality of these systems can be difficult to restore once severely impacted (Zedler & Kercher 2005). The San Francisco Bay and Sacramento-San Joaquin River Delta estuary is perhaps the most hydrologically-engineered estuarine wetland system in the United States, and an estimated 95% of the marsh area that existed there in 1850 has been altered or converted to other land uses (Josselyn 1983). The principal source of freshwater input to the estuary enters through the Sacramento and San Joaquin rivers; their inland delta (the Delta) is the terminus of a watershed that drains about 40% of California’s land area. Anthropogenic alterations of the estuary’s hydrologic characteristics have profoundly affected the extent and functioning of the tidal wetlands, particularly in the brackish and tidal fresh portions of the upper estuary associated with the Delta. Although the conceptual model presented in Figure 1 is intended to capture the features and dynamics of tidal marshes in the Delta (e.g., Suisun Bay to the upriver extent of the tides in the Delta), oligohaline and tidal freshwater marshes generally remain poorly understood. Recent texts (e.g., Sharitz & Pennings 2006) still consider the review by Odum (1988) as the best treatment of these low salinity tidal ecosystems. Consequently, development of the current conceptual biological model often required us to judiciously borrow from the more extensive literature on temperate salt marshes in diverse regions. Although one of our principal objectives in developing this model involves identifying the dominant processes and interactions that characterize restoring marshes at various stages of development, the model is intended to characterize the dynamics of “equilibrium” marshes at their mature state of geomorphic and ecological functioning (Pestrong 1972, Reed 2002, Williams et al. 2002). Our rationale is that restoring marshes are considerably variable and that trying to capture intermediate stages of development (e.g., positions along a development “trajectory”; Simenstad & Thom 1996 [however, see Zedler & Callaway 1999]) would introduce too much variability for a single model, and because the ultimate objective of restoration is the self-sustaining, equilibrium condition. However, we have sought were appropriate to describe important processes that influence restoration trajectories and affect the ecosystem functions, goods and services that marshes provide in various landscape settings that are found in the Sacramento-San Joaquin Delta. This broad-view model explicitly acknowledges the importance of interactions among structural components of tidal marsh ecosystems and the hydrologic characteristics that are modulated by both extrinsic and intrinsic factors (e.g., Zeff 1999, Kirwan & Murray 2007). The interaction of these factors control biological/ecological processes that support two of the more important ecosystem services of tidal marshes: provision of essential habitats for biota (e.g., Visintainer et al. 2006) and the net export of high-quality organic production (e.g., Kneib 2004). It also highlights the transitional position of tidal marshes between adjacent ecosystems, including terrestrial and aquatic interfaces that represent the dynamic and permeable boundaries of the tidal marsh; these interfaces may function as membranes through which the exchange of materials (organisms, surface/groundwater, etc.) and energy between upland and open water estuarine environments via the intervening marsh ecosystem may be modified or blocked, i.e., permeable to varying degrees (Lawrence et al. 2004, Kneib 1997, Levin et al. 2001). A variety of distinct landscape elements such as channels, sloughs, ponds and pannes are common features that are embedded in intertidal marsh mosaics and are prominent in many of the interactions across the marsh interfaces. These elements contribute spatial heterogeneity, and may serve important functions as sources/sinks in metapopulation dynamics involving marshes (e.g., Dean et al. 2005), conduits for the transport or retention of water and waterborne materials (e.g., sediments, nutrients, pollutants), as well as corridors for the active movement of animals through the ecosystem (e.g., Rozas et al. 1988). While implicitly acknowledging the importance of these landscape features in connecting marshes with adjacent ecosystems, we focus the present version of this conceptual model on the vegetated marsh proper (or marsh plain) that is depicted as the Marsh Structure and Processes box, explicitly recognizing variation in the types of emergent marsh vegetation (i.e., plant architecture) and associated sub-system contributions, as well as the in situ production of plants that leads to the support of a regionally characteristic animal biodiversity and food web. This box can be expanded to include more details of both physicochemical (e.g., sediment accretion, light attenuation) and ecological interactions (including trophic dynamics) that result in different marsh physical and biotic assemblage structures and/or enhance the production of specific plant or animal components. However, it is not the intention of the present broad-view model to provide that level of detail, although we have attempted to identify important feedback loops between biological and physical processes (e.g., plant growth and sedimentation) that affect intermediate outcomes and drivers (e.g., inundation regime affected by changes in elevation) of ecosystem functioning. Thus, the details of these physical, biological and ecological processes operating within the marsh are not included in this conceptual model, but can be added as a module if that level of understanding is required.
Electronic Book Sections
Pittman, S.J., Kneib, R.T., Simenstad, C.A. and Nagelkerken, I. 2011. Seascape ecology: application of landscape ecology to the marine environment. Marine Ecology Progress Series. Inter-Research 187-302.
