A Roadmap for the Restoration of the Freshwater Mussel Fauna of Abrams Creek

Freshwater mussels are among the most imperiled faunal groups in North America and can be a vital component of a healthy aquatic ecosystem. Abrams Creek, a tributary of the Little Tennessee River in Great Smoky Mountains National Park, was historically one of the most biodiverse rivers in the park, until 1957 when a rotenone treatment and subsequent impoundment of its lower 3.2 km eliminated much of its native ichthyofauna. This study characterizes the Abrams Creek mussel assemblage, evaluates landscape scale environmental factors influencing species richness and abundance, and identifies candidate species for translocation to guide future restoration efforts. Using timed searches, five extant species were documented, including Cambarunio iris, Leaunio vanuxemensis, Lampsilis fasciola, Medionidus conradicus, and Pleurobema oviforme; species accumulation analyses indicated that this survey effort captured the full assemblage. Multiple models were created to evaluate environmental factors that may influence both the species richness and abundance of the mussel fauna of this system; model selection identified catchment area and available water supply as the strongest predictors of mussel abundance and species richness, highlighting the importance of watershed scale management and maintaining adequate baseflow in supporting viable mussel populations. Using a tiered framework based on habitat associations, host fish availability, proximity to source populations, and restoration feasibility, fourteen candidate species were prioritized for reintroduction. Eurynia dilatata and Pressodonta viridis were selected from this list and tested with an in-situ experiment to evaluate translocation potential. Although vandalism reduced experimental sample sizes, surviving individuals remained healthy after one year, supporting the viability of translocation as a tool for future restoration efforts. Together these results provide a roadmap for restoring mussel biodiversity in Abrams Creek.