Forecasting the effects of accelerated sea-level rise on tidal marsh ecosystem services

© The Ecological Society of America www.frontiersinecology.org T wetlands such as salt, brackish, and freshwater marshes provide essential ecosystem services to society. Such services include functions associated with regulation, habitat, and production (Daily et al. 1997; de Groot et al. 2002). Positioned at the interface between land and sea, tidal marshes are uniquely suited to provide ecosystem services associated with waste treatment, biological productivity, and disturbance regulation. These services are especially important to the 53% of the US population that lives in the coastal zone (Boesch et al. 2000). Tidal marshes are susceptible to climate change, especially accelerated sea-level rise (SLR). Sea level is predicted to increase by 30–100 cm by 2100, based on the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES; Meehl et al. 2007). The vulnerability of tidal wetlands to accelerated SLR depends on geologic factors, such as tectonic uplift and glacial isostatic adjustment, which buffer shorelines from SLR, and subsidence, which accelerates it. Tide range also affects marsh vulnerability, as macro(> 4 m) and meso-tidal (2–4 m) marshes are less susceptible to SLR than are micro-tidal (< 2 m) marshes (Stevenson and Kearney in press). In some coastal areas, rising sea level may result in tidal marsh submergence (Moorhead and Brinson 1995) and habitat migration, as salt marshes transgress landward and replace tidal freshwater and brackish marshes (Park et al. 1991). Declining tidal marsh area and habitat conversion may lead to changes in delivery of ecosystem services provided by these wetlands. We used field and laboratory measurements, geographic information systems, and simulation modeling to predict the effects of accelerated SLR on tidal marsh area and delivery of select ecosystem services along the Georgia coast. Our goal was to predict how tidal marsh area and delivery of ecosystem services would respond to different scenarios of sea-level rise during the 21st century.