Advisor: Jose Fuentes

Along the Atlantic Coast, the wetlands that remain after the devastating losses in the 1970s are in a continuous threat from human impact. Remaining wetlands are sinking and shrinking, and the replenishing sediments are no longer available as rivers become redirected, thus intensifying their precarious condition. Ironically, wetland loss has been shown to increase the threat to human safety as they protect from coastal hazards such as erosion, flooding and storms. As more wetlands are lost, the carbon that they store is released, thus impacting global temperatures. The proposed project focuses on three parts to understand the carbon cycle in a wetland and how it is affected by local processes, specifically a salt marsh ecosystem. This study targets a salt marsh ecosystem on the Virginia Coast Reserve, which is home to various fishery industries with important ecosystem concerns. First, using continuous measurements on a 7 m tower, properties of the surface layer (e.g., air temperature, soil temperature, photosynthetically active radiation) above the marsh are resolved to determine their influence on the vertical carbon exchange. The project will investigate how tidal influence and environmental drivers affect the carbon dioxide exchange, calculated from the eddy-covariance methodology, by the marsh. A model based on soil temperature will be used to evaluate ecosystem respiration, from which gross primary productivity is quantified as the difference between net carbon dioxide exchange and respiration. Second, utilizing the knowledge of how the climate and environmental drivers affect gross primary productivity, this project will develop a light use efficiency model to estimate the gross primary productivity. The model will then estimate the gross primary productivity for the Virginia Coast Reserve marsh. Finally, the project will also measure the lateral carbon exchange at various tide stages to quantify the export and import of carbon onto the marsh from either the ocean or the upland. This project will provide a new understanding of the carbon cycle of a marsh ecosystem throughout the year to the benefit of future scientific work in regards to wetlands.