Cooperative Fish and Wildlife Research Units Program: North Carolina
Education, Research and Technical Assistance for Managing Our Natural Resources

The Southeastern and Mid-Atlantic regions of the United States contain the greatest biodiversity of native freshwater mussels in the world, but they are highly imperiled due to habitat alteration and destruction, pollution and poor water quality, and the introduction of aquatic invasive species. Now they are at even greater risk from the stresses associated with climate change induced sea level rise and its associated changes in salinity, temperature, and stream flow. In this project, a unique opportunity exists to investigate the potential adaptation and vulnerability of a native freshwater mussel, the Tidewater Mucket, in these coastal river systems and offer solutions for its conservation. We have recently discovered a population of these mussels in a reservoir along the North Carolina-Virginia border that have been isolated from their native riverine habitat and associated natural fluctuations in salinity for over 50 years. These mussels have apparently adapted to the relatively high temperatures, low flow, and low salinity of a reservoir environment, whereas their native counterpart populations of Tidewater Mucket in the downstream portions of coastal rivers that have adapted to withstand small but periodic exposures to salinity and altered flows are declining. Our federal and state natural resource management partners, policy makers, and other stakeholders would like to know how these native coastal plain mussel populations will respond to larger and longer durations of salinity incursions like those predicted with sea level rise. In this study, we will use mussels from both the reservoir and riverine populations to understand their vulnerability to salinity by conducting sensitivity tests under controlled laboratory conditions, determine the potential effects of natural riverine salinity gradients by conducting a transplant experiment, and develop risk-based visualization maps of mussel salinity tolerances in existing occupied habitats incorporating predictions in sea level rise and projected salinity ranges. The outcomes of this research will provide actionable management and conservation information for maintaining these highly imperiled, but valuable molluscan resources.