Streamer Resistivity Surveys In Delmarva Coastal Bays

This paper reports on streaming resistivity ("DC resistivity") surveys conducted in Maryland and Virginia Atlantic coastal bays in the spring of 2001. Surveys in Assawoman, Isle of Wight, and Chincoteague Bays, MD and VA, were used to study profiles of electrical resistivity of submarine strata to delineate submarine freshwater discharge and submarine saltwater interfaces and salinity distributions in submarine groundwater. The studies follow similar resistivity surveys in Rehoboth and Indian River Bays in spring of 2000 (Krantz and others, 2000; Madsen and others, 2001; and Manheim and others, 2001).

The Delmarva Peninsula coastal studies are part of larger cooperative programs between the U.S. Geological Survey, regional federal and state organizations, and academic institutions. They address the problem of excess nutrient discharge into Delmarva coastal bays. Like the Delaware coastal bays, Maryland and Virginia coastal bays receive excess nutrients due to human activities. The excess nutrients enhance growth of phytoplankton and fouling macroalgae, which impedes boat operation, coats beaches, and lays down organic-rich mats. This organic matter fosters anoxic conditions in the bottom sediments. Growing stagnation alters the habitat for benthic organisms and reduces biological diversity. Recent studies suggest that excessive organic growth inhibits natural mechanisms (like denitrification) that help transform and remove nutrients from the bay systems.