Impacts of sea level rise and associated salinity changes on at-risk native freshwater mussels and their habitats in Atlantic coastal rivers

Project Information

Greg Cope, NC State University
Tom Kwak, USGS NC Cooperative Fish and Wildlife Research Unit

Proposed Project Completion: September 2021

Implements Science Plan Theme: Impacts and Adaptation

Project Cooperators: Sarah McRae (US FWS), Todd Ewing (NC Wildlife Resources Commission), Brian Watson (VA Dept of Game and Inland Fisheries), Robert Bringolf (U. Georgia)

Overview

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.

This project investigates the potential vulnerability and adaptation of a native freshwater mussel, the Tidewater Mucket, in coastal river systems and offer solutions for its conservation. Scientists 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 located in the downstream portions of coastal rivers that have adapted to withstand exposures to salinity and altered flows, are declining. Federal and state resource managers 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.

This study 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.