MONITORING IMPACTS OF SEA-LEVEL RISE AND ANTHROPOGENIC IMPACTS ON A MID-ATLANTIC MAINLAND SALT MARSH IN GREENBACKVILLE, CHINCOTEAGUE BAY, VIRGINIA

A new multi-university initiative is being implemented to: 1) monitor the lasting impacts of 15 decades of human impacts on a salt marsh located on Chincoteague Bay, Virginia, 2) evaluate the geologic origin and assess the future of the marsh, and 3) provide an easily accessible location to study coastal change. The salt marsh is a bay-promontory salt marsh located just SE of the village of Greenbackville. Thirty acres of the marsh located between the village and Chincoteague Bay are owned by the Chincoteague Bay Field Station. Built on stilts, the historic hamlet of Franklin City was located on the marsh. In its day it had oyster shucking houses, wharves, a canning factory, a rail depot, hotels, restaurants, and dozens of homes. Overharvesting, disease, and storms, including the 1962 Ash Wednesday storm resulted in its downfall after nearly 80 years focused on seafood and tourism. Our efforts are currently focused on both surface and subsurface processes in order to evaluate changes in salt marsh hydrology as a result of dredging and ditching activities, marsh fill for roads and railroad beds, and from shucked oysters that have blocked tidal creeks. A network of piezometers and water-level loggers have been installed to evaluate the roles of tides, rainfall, groundwater flow, and storm surge on the distribution of native and invasive vegetation. Vibracoring has focused on evaluating the subsurface geology responsible for forming the marsh. Soil analyses are being carried out to evaluate changing hydric soil characteristics as a result. In addition mapping with aerial imagery and GPS has focused on measuring rates of shoreline erosion. Although GIS analyses are ongoing, average shoreline erosion rates in the last six years have ranged from a low of 3.2 m to at least 21.3 m. For a 4.5 km stretch the average has been about 9.9 m or about 1.6 m/year. Given that the eroding marsh edge is underlain by soft, unconsolidated silts and muds, deterioration of the marsh by human activities including nutrient enrichment and continued hydrologic impairments will undoubtedly contribute to continued rapid loss the salt marsh and its critical ecosystem services which include protecting the village of Greenbackville. Our efforts will be focused on developing and implementing a comprehensive restoration plan to help slow the loss of the marsh.