Area 2: Long-term Patterns within the Domain

Long-term Patterns within the Domain

We collect data documenting key ecosystem variables within the GCE domain. Major activities in this area consist of A) field monitoring of water and marsh attributes, B) repeat photography, and C) modeling.

Research Objectives

A) Field Monitoring of Water and Marsh Attributes

• 2A.1 - Continue the GCE core monitoring program in the water column
• 2A.2 - Continue the core monitoring program in the marsh and tidal fresh water
• 2A.3 - Characterize groundwater flow

B) Repeat Photography

• 2B.1 - Continue the GCESapelo Phenocam and add a second site
• 2B.2 - Continue regular aerial photographs of the GCE domain

C) Modeling

• 2C.1 - Upgrade hydrodynamic models (Delft3D)
• 2C.2 - Enhance soil models
• 2C.3 - Enhance Spartina models

Current Progress Report

Below is an update for each of the Area 2 objectives as reported in the most recent annual report. For a list of all reports click here (Annual Reports).

A) Field Monitoring of Water and Marsh Attributes

• 2A.1 - Continue the GCE core monitoring program in the water column

  Activities:  We maintain sondes that collect continuous measurements at 10 sites, and we obtain quarterly or monthly CTD profiles and measurements of nutrients, dissolved organic matter, chlorophyll and suspended sediment at 12 sites (Table 1, Fig. 1).

  Results:  We observed increased salinity in the tidal forest (GCE11) in conjunction with Hurricane Irma, and a more recent increase that corresponded to a combination of high sea surface heights and low river flow (Fig 2). We also observed large changes in DOM composition (analyzed by FT-ICR MS) and high microbial utilization of DOC in association with hurricane Matthew (Letourneau and Medeiros 2019) and are currently processing samples from hurricanes Irma, Michael, and Dorian.

  

  Fig. 2. Salinity measured over the period of record at site GCE11 in the tidal fresh forest. Note large increase due to Hurricane Irma in 2017 as well as increases starting in August 2019, which is likely the result of high sea surface heights (see Fig. 1) in combination with low river flow. Source: Daniela Di Iorio.

• 2A.2 - Continue the core monitoring program in the marsh and tidal fresh water

  Activities:  We monitor plants, invertebrates, and soils in 2 zones at each of our 10 marsh sites (Table 1, Fig. 2). In the tidal forest we measure litterfall, basal area increment, and sediment elevation, and have begun assessing vegetation cover. We are also testing biomimics to evaluate the thermal regimes experienced by macrofauna.

  Results:  Liu and Pennings (2019) used the long-term plant monitoring data to evaluate whether the “self-thinning” law applies to Spartina (see Key Findings). We are also working on a dynamical systems analysis of Spartina biomass in response to external drivers. Preliminary results indicate the spring and preceding fall conditions are causally related to plant production.

• 2A.3 - Characterize groundwater flow

  Activities:  We monitor groundwater levels and salinities at a series of wells associated with the high marsh manipulation (see 3C.2). In 2019 we installed additional wells across the upland marsh transition at Marsh Landing where we have long-term observations of vegetation shifts (Fig. 3).

Table 1. Monitoring program for GCE-IV. LTER core areas are 1: primary production, 2: populations, 3: organic matter cycling, 4: inorganic nutrients, 5: disturbance.

Fig. 3. Groundwater wells were installed in Feb. 2019 in an area of vegetation transition at Marsh Landing. (a) stratigraphy and overall flow patterns, (b) the difference in hydraulic head (top) between well R4 and R3B, which is net positive (landward) and (bottom) between well R3B and R2B, which is net negative (creekward).

Fig. 4. Long-term record of change in A) estimated mean winter soil temperatures and B) green-up day of year (doy). The solid lines are the best fit lines estimating the increase in temperature and change in green-up day with time (P < 0.001). The dashed lines represent the 95% CI for the fit. Modern winter temperatures and green-up dates (open circles) are included for overlapping years; RMSE is the difference between modern and long-term estimates. Source: O’Connell et al. 2019

B) Repeat Photography

• 2B.1 - Continue the GCESapelo Phenocam and add a second site

  Activities:  The GCESapelo Phenocam, which is focused on a Spartina marsh, contributes data to the national phenocam network every 30 min. We are scouting locations for a second camera with both Spartina and Juncus in its field of view.

  Results:  O’Connell et al. (2019) analyzed Phenocam imagery to develop a spring warm-up model for Spartina that suggests long-term changes in the date of green-up onset (Fig. 4, see also Key Findings).

• 2B.2 - Continue regular aerial photographs of the GCE domain

  Activities:  Aerial photography was taken in 2017 and 2018 with funds from a RAPID grant related to Hurricane Irma.

C) Modeling

• 2C.1 - Upgrade hydrodynamic models (Delft3D)

  Activities:  We have recently switched to Delft3D (from FVCOM) because of the added flexibility and additional functions available.

• 2C.2 - Enhance soil models

  Activities:  Our soil model (Miklesh & Meile 2018) predicts porewater salinity based on hydrology and evapotranspiration, and we are working to incorporate soil temperature.

• 2C.3 - Enhance Spartina models

  Activities:  We are gathering data on soil temperature, above- and below-ground biomass, and NPP that can be used to enhance Spartina models.

Area 2 Publications from GCE-IV

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. 124:1545-1559. (DOI: 10.1029/2018JG004982)

Liu, W. and Pennings, S.C. 2019. Self-thinning and size-dependent flowering of the grass Spartina alterniflora across space and time. Functional Ecology. 33:1830-1841. (DOI: 10.1111/1365-2435.13384)

Miklesh, D.M. and Meile, C. 2018. Controls on porewater salinity in a Southeastern salt marsh. PeerJ. 6:e5911. (DOI: 10.7717/peerj.5911)

Area 2 Publications from GCE-III

Journal Articles

Liu, W. and Pennings, S.C. 2019. Self-thinning and size-dependent flowering of the grass Spartina alterniflora across space and time. Functional Ecology. 33:1830-1841. (DOI: 10.1111/1365-2435.13384)

Peterson, R.N., Meile, C., Peterson, L., Carter, M. and Miklesh, D.M. 2019. Groundwater discharge dynamics into a salt marsh tidal river. Estuarine, Coastal and Shelf Science. 218:324-333.

Damashek, J., Tolar, B., Liu, Q., Okotie-Oyekan, A., Wallsgrove, N.J., Popp, B.N. and Hollibaugh, J.T. 2018. Microbial oxidation of nitrogen supplied as selected organic nitrogen compounds in the South Atlantic Bight. Limnology and Oceanography. 64:982-995. (DOI: 10.1002/lno.11089)

Li, S., Hopkinson, C.S., Schubauer-Berigan, J.P. and Pennings, S.C. 2018. Climate drivers of Zizaniopsis miliacea biomass in a Georgia, U.S.A. tidal fresh marsh. Limnology and Oceanography. 63:2266-2276. (DOI: 10.1002/lno.10937)

Liu, Q., Tolar, B., Ross, M., Cheek, J., Sweeney, C., 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. 12:1473-1485. (DOI: 10.1038/s41396-018-0066-4)

Takagi, K., Hunter, K.S., Cai, W.-J. and Joye, S.B. 2017. Agents of change and temporal nutrient dynamics in the Altamaha River Watershed. Ecosphere. 8(1):33. (DOI: 10.1002/ecs2.1519)

Wang, Y., Castelao, R. and Di Iorio, D. 2017. Salinity Variability and Water Exchange in Interconnected Estuaries. Estuaries and Coasts. (DOI: 10.1007/s12237-016-0195-9)

Whitby, H., Hollibaugh, J.T. and van den Berg, C.M. 2017. Chemical speciation of copper in a salt marsh estuary and bioavailability to Thaumarchaeota. Special Issue: Organic ligands - A key control on trace metal biogeochemistry in the ocean. Frontiers in Marine Sciences. 4. (DOI: 10.3389/fmars.2017.00178)

Caffrey, J.M., Hollibaugh, J.T. and Mortazavi, B. 2016. Living oysters and their shells as sites of nitrification and denitrification. Marine Pollution Bulletin. (DOI: 10.1016/j.marpolbul.2016.08.038.)

Li, S. and Pennings, S.C. 2016. Disturbance in Georgia salt marshes: variation across space and time. Ecosphere. 7(10):e01487. (DOI: 10.1002/ecs2.1487)

Tolar, B., Wallsgrove, N.J., Popp, B.N. and Hollibaugh, J.T. 2016. Oxidation of urea nitrogen in marine nitrifying communities dominated by Thaumarchaeota. Environmental Microbiology. (DOI: 10.1111/1462-2920.13457)

Conference Papers (Peer Reviewed)

Weston, N.B., Hollibaugh, J.T., Sandow, J.T. Jr. and Joye, S.B. 2003. Nutrients and dissolved organic matter in the Altamaha river and loading to the coastal zone. In: Hatcher, K.J. (editor). Proceedings of the 2003 Georgia Water Resources Conference. Institute of Ecology, University of Georgia, Athens, Georgia.

Conference Posters and Presentations

Craft, C.B., Stahl, M. and Widney, S. 2017. Presentation: Tidal freshwater forests: sentinels for climate change. 10th International Workshop on Nutrient Cycling and Retention in Natural and Constructed Wetlands, September 21-24, Trebon, Czech Republic.

Hollibaugh, J.T., Bratcher, A., Cheek, J., Liu, Q., Malagon, E., Popp, B.N., Ross, M., Schaefer, S.C., Sweeney, C., Tolar, B., van den Berg, C.M., Wallsgrove, N.J. and Whitby, H. 2017. Poster: LIGHT AND TEMPERATURE CONTROL THE SEASONAL DISTRIBUTION OF THAUMARCHAEOTA IN THE SOUTH ATLANTIC BIGHT. Fifth International Conference on Nitrification and Related Processes (ICoN5)23-27 July, 2017, 23-27 July, 2017, Vienna, Austria.

Peterson, R.N., Meile, C., Carter, M., Peterson, L., Waldorf, A. and Miklesh, D.M. 2017. Poster: Groundwater inputs to a back-barrier salt marsh tidal river. 2017 Chemical Oceanography Gordon Research Conference, July 2017, Holderness, NH.

Stahl, M., Widney, S. and Craft, C.B. 2017. Presentation: Tidal freshwater forests: a sentinel for climate change. SPEA Ph.D. Students' 17th Annual Conference, February 24, 2017, Bloomington, IN.

Widney, S., Stahl, M. and Craft, C.B. 2017. Presentation: Tidal forests: sentinels for climate change. Society of Wetland Scientists Annual Meeting, June 8, 2017, San Juan, Puerto Rico.

Hollibaugh, J.T., Liu, Q., Ross, M., Cheek, J., Sweeney, C., Tolar, B., Hagan, P., Whitby, H., Bratcher, A., Malagon, E., Lynn-Bell, N., Shalack, J., Reddy, C.M. and Walker, J.T. 2016. Poster: Coupling between Sediment and Water Column Populations of Ammonia Oxidizing Thaumarchaeota in a Salt Marsh Estuary.

Alber, M., Schaefer, S.C., Pomeroy, L.R., Sheldon, J.E. and Joye, S.B. 2008. Presentation: Nitrogen inputs to the Altamaha River estuary (Georgia, USA): a historic analysis. American Society of Limnology and Oceanography, 3/08, Orlando, FL.

Alber, M., Schaefer, S.C., Pomeroy, L.R., Sheldon, J.E. and Joye, S.B. 2008. Presentation: Nitrogen inputs to the Altamaha River estuary (Georgia, USA): a historic analysis. American Society of Limnology and Oceanography, 3/08, Orlando, FL.

Seay, J.E., Bishop, T.D. and Tilburg, C.E. 2006. Poster: Spatial and temporal variations of Porcelain Crab larval abundance in a Georgia Estuary. Southeastern Estuarine Research Society Fall 2006 Meeting, 19 October - 21 October 2006, Savannah, Georgia.

Pennings, S.C. 2005. Presentation: Physical forcing and variation in salt marsh plant productivity at multiple time scales. Ecological Society of America 2005 Meeting - Ecology at multiple scales, August 7-12, 2005, Montreal, Canada.

Shalack, J. and Bishop, T.D. 2004. Poster: Spatial and temporal variability in recruitment of decapod megalopae in the Duplin River, Georgia. Semiannual Meeting of the Southeastern Estuarine Research Society. Invertebrates - Poster Session. Southeastern Estuarine Research Society, 15-17 April 2004, Ft. Pierce, FL.

Bishop, T.D. 2003. Presentation: Invasive biology and status of the green porcelain crab (Petrolisthes armatus) in Georgia waters. South Georgia Invasive Species Workshop, sponsored by The Nature Conservancy and Sapelo Island National Estuarine Research Reserve. October 2003, Brunswick, GA.

Bishop, T.D. and Hurley, D. 2003. Poster: The non-indigenous porcelain crab, Petrolisthes armatus: population trends in the Sapelo Island National Estuarine Research Reserve. 2003 Estuarine Research Federation meeting. September 2003, Seattle, WA.

Bishop, T.D. and Hurley, D. 2003. Poster: The non-indigenous porcelain crab, Petrolisthes armatus: population trends in the Sapelo Island National Estuarine Research Reserve. National Estuarine Research Reserve System / National Estuarine Research Reserve Association Annual Meeting. October 2003, Charleston, S.C.

Bishop, T.D., Hurley, D. and Alber, M. 2003. Presentation: An inventory of the macroinvertebrate fauna of oyster reefs in the Duplin River, Georgia, with emphasis on non-indigenous species occurrence. 2003 Estuarine Research Federation meeting. Sept. 14-18, 2003, Seattle, WA.

Ogburn, M.B., Bishop, T.D. and Alber, M. 2003. Poster: Population dynamics of two salt marsh snails in three Georgia estuaries. Southeastern Estuarine Research Society meeting. March 2003, Atlantic Beach, NC.

Bishop, T.D., Alber, M. and Wiegert, R.G. 2001. Poster: Macrofaunal population shifts and changing coastal salinity regimes. ERF 2001: An Estuarine Odyssey. Estuarine Research Federation, Nov. 4-8, 2001, St. Pete Beach, Florida.

Goodbody, G., Bishop, T.D. and Alber, M. 2001. Presentation: Distribution of snails in the Satilla and Altamaha River Estuaries. Southeastern Estuarine Research Society Meeting. Southeastern Estuarine Research Society, Mar 01, 2001, Charleston, South Carolina.

Pennings, S.C., Bertness, M.D., Donnelly, J.P., Ewanchuk, P.J., Silliman, B.R. and Callaway, R.M. 2001. Presentation: Impacts of global change on coastal salt marshes. Keynote address to the German Limnological Association, September 17-21, 2001, Kiel, Germany.