Research Starter Grant: Consequences of saltwater intrusion on water quality in coastal plain wetlands

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Human accelerated climate change will alter the functioning of coastal plain wetlands through changes in hydrology and sea level rise. Decreased precipitation and sea level rise will increase the probability of saltwater intrusion into formerly freshwater wetlands. While much work has been conducted on the effects of saltwater intrusion on wetland vegetation, much less is known about the effects on biogeochemical cycling of carbon (C), nitrogen (N), and phosphorus (P). Saltwater intrusion can alter biogeochemical cycling of C, N, and P through both microbial metabolic and physicochemical pathways. Microbial metabolic pathways are due to changes in the availability of electron donors and acceptors. Physicochemical pathways are due to changes in chemical equilibrium, flocculation, and cation exchange with sediments. The main objective is to examine the effects of saltwater intrusion on C, N, and P cycling in coastal plain wetlands. The overarching hypothesis is that saltwater intrusion will increase N and P availability, while decreasing C availability, primarily through physicochemical pathways. The work will be conducted in the Timberlake Observatory for Wetland Restoration (TOWeR) site, a large (440 ha) extensively instrumented wetland restoration project in the coastal plain of North Carolina. The temporal and spatial dynamics of saltwater intrusion into the site provide unique opportunities to test the consequences of saltwater on biogeochemical cycling.The functioning of coastal plain wetlands will change due to alterations in hydrology and sea level rise. Decreased rainfall and sea level rise will increase the probability of saltwater intrusion into formerly freshwater wetlands. While much work has been conducted on the effects of saltwater intrusion on wetland vegetation, much less is known about the effects on biogeochemical cycling of. Saltwater intrusion can alter the cycling of carbon (C), nitrogen (N), and phosphorus (P) in the wetlands. The research proposed will illuminate vital aspects of the coupling of C, N, and P cycles in coastal plain wetlands under saltwater intrusion. The ability to predict how these ecosystems respond to altered precipitation regimes and sea level rise will depend on understanding both the microbial metabolic as well as the physicochemical effects of saltwater on ecosystem function. This work provides a unique opportunity for basic ecosystem ecology research to have a direct impact on the regulations and practice of wetland restoration.