The Georgia Coastal Ecosystems (GCE) LTER program, located on the central Georgia coast, was established in 2000. The study domain encompasses three adjacent sounds (Altamaha, Doboy, Sapelo) and includes upland (mainland, barrier islands, marsh hammocks), intertidal (fresh, brackish and salt marsh) and submerged (river, estuary, continental shelf) habitats. Patterns and processes in this complex landscape vary spatially within and between sites, and temporally on multiple scales (tidal, diurnal, seasonal, and interannual). Overlain on this spatial and temporal variation are long-term trends caused by climate change, sea level rise, and human alterations of the landscape. These long-term trends are likely to manifest in many ways, including changes in water quality, river discharge, runoff and tidal inundation patterns throughout the estuarine landscape. The overarching goal of the GCE program is to understand the mechanisms by which variation in the quality, source and amount of both fresh and salt water create temporal and spatial variability in estuarine habitats and processes, in order to predict directional changes that will occur in response to long-term shifts in estuarine salinity patterns.
The objectives of the current project cycle are 1) to continue to document long-term patterns of environmental forcing to the coastal zone, 2) to link environmental forcing to observed spatial and temporal patterns of biogeochemical processes, primary production, community dynamics, decomposition and disturbance, 3) to investigate the underlying mechanisms by which environmental gradients along the longitudinal (freshwater-saltwater) and 4) lateral (upland-subtidal) axes of estuaries drive ecosystem change, and 5) to explore the relative importance of larval transport and the conditions of the adult environment in determining community and genetic structure across both the longitudinal and vertical gradients of the estuary. To meet these objectives, the investigators utilize a suite of approaches including long-term monitoring of abiotic drivers and ecosystem responses; manipulative and natural experiments designed to enable us to examine the importance of key ecosystem drivers; and modeling.
The goal of GCE outreach is to enhance scientific understanding of Georgia coastal ecosystems by teachers and students, coastal managers, and the general public. The GCE schoolyard program is built around long-term contact and mentoring of educators, and has involved 40 teachers to date. At the college level, both undergraduate and graduate students are routinely incorporated into our work, and several investigators have integrated GCE research into the classroom. To reach coastal managers, the scientists partner with the Georgia Coastal Research Council (GCRC) to promote science-based management of Georgia coastal resources by facilitating information transfer between scientists and managers. The GCRC has representation from 9 Universities, 6 Federal agencies, and 4 State and regional agencies. It hosts workshops, assists management agencies with scientific assessments, and distributes information on coastal issues. To reach the general public, GCE scientists routinely participate in public meetings and workshops, and partner with non-profit organizations on the Georgia coast to address questions of public interest. Data collected by the GCE-LTER project can be accessed by other scientists and the general public via the website (http://gce-lter.marsci.uga.edu/lter/), which uses a state-of-the-art information system to manage and display information on study sites, research, taxonomy, data sets, publications, and project administration.
The Georgia Coastal Ecosystems Long-Term Ecological Research program (GCE LTER) started in 2000. GCE scientists study the marshes and estuaries of the Georgia coast to understand how these ecosystems function, track how they change over time, and predict how they might be affected by future variations in climate and human activities. During this funding cycle (GCE-II) we continued a program of research that addresses the five LTER core areas (primary production, populations, organic matter cycling, inorganic nutrients, disturbance) through a combination of long-term observations, field surveys, experimental manipulations and modeling. Signature publications from GCE-II included: 1) Schaefer & Alber (2007) evaluated the relationship between watershed nutrient loading and riverine export for 12 southeastern rivers, and found that their average N export was only 9% of watershed nutrient loading compared to global estimates of 25%. This analysis was featured as a Synthesis and Emerging Ideas paper in Biogeochemistry. 2) Cai (2011) synthesized dissolved inorganic carbon (C) measurements from GCE cruises and other data on C flow to construct a carbon budget for the South Atlantic Bight. He suggested that the marsh is a sink for atmospheric CO2 and that it laterally exports a large quantity of inorganic and organic carbon. This challenges the conventional view that estuarine degassing is supported by riverine C and that lateral export from marshes can be ignored. 3) Hollibaugh et al. (2011) began an evaluation of the temporal dynamics of ammonia-oxidizing Archaea, a group of microbes that convert ammonia to nitrite. Information on these microbes may improve our understanding of nitrogen cycling and controls on nitrogen pollution. 4) Ho et al. (2010) found that high-latitude plants are better food for herbivores. To the extent that superior foods lead to larger body sizes, high-quality plants could be one mechanism behind Bergmann’s rule (animals are larger at high latitudes). This paper was published in the American Naturalist and attracted considerable attention from the press. 5) McKay & Di Iorio (2010) constructed heat and salt budgets for the Duplin River and identified a fortnightly pulse in mixing that causes the salinity gradient to reverse, something that has never been seen before at these time scales, and that could create a barrier for export of material. 6) Radium isotope data from the upper Duplin indicated considerable groundwater discharge, which is often overlooked as a source of water and nutrients to estuaries (Porubsky et al. 2011). 7) Studies of fresh, brackish and salt marsh wetlands show that they provide different levels of ecosystem services and that the loss of services due to sea level rise may be less than that forecast from losses of wetland area alone (Craft et al. 2009). 8) Archaeological studies of Georgia back barrier islands found shell deposits and evidence of Native American occupation going back 4,500 y (Thompson & Turck 2010). 9) Robinson et al. (2010) combined ecological and genetic analyses to reveal how abundance and genetic diversity of larvae vary from inland to offshore, with important implications for populations of snails, barnacles, and other organisms. 10) Guo & Pennings (2011) found that different factors drive the landscape distribution of plants and invertebrates. Their experiments showed that freshwater plants were excluded from saltier sites by physical stress, whereas salt marsh plants were excluded from fresh sites by increased competition. Overall, GCE scientists published 139 journal publications and 62 books, theses, and other one-time publications, and obtained external grants from NSF, DOE and elsewhere to roughly double our efforts. The GCE-LTER also has strong programs in information management, education and outreach. 7 MS theses and 11 PhD dissertations were completed by GCE-LTER graduate students, and we routinely involve undergraduates in our research, many of whom have gone on to graduate school. The GCE Schoolyard program provides in-service training in field ecology for K-12 educators, and we have published a children’s book, "And the Tide Comes In," as part of the LTER schoolyard series. The project provides outreach to coastal managers through the Georgia Coastal Research Council, which promotes science-based management of Georgia coastal resources by facilitating information transfer between scientists and managers. The GCE information management program meets the highest LTER IM standards. At the close of GCE-II there were 480 online data sets in the GCE data catalog, and 455 in the GCE data portal, representing over 6 million data records which are accessed by a diverse user community. Finally, the GCE website (https://gce-lter.marsci.uga.edu/) provides public access to information and data from the project and previous research on the Georgia coast. Between 2001 and 2012 over 615,000 visitors from 227 distinct countries and territories were logged on the GCE website, accounting for over 2.2 million page views.
