Habitat and landscape variable associations of freshwater mussel communities in the Susquehanna River sub-basins

The Unionid fauna of the Susquehanna River basin is threatened by impoundments, habitat loss, pollution, and invasive species. The project purpose is to identify mussel community composition and in-stream habitat and landscape characteristics associated with yellow lampmussel (Lampsilis cariosa) and other freshwater mussel occurrences in the Susquehanna River sub-basins.  Snorkel surveys of mussels of the Juniata River sub-basin and Middle Susquehanna River sub-basin were conducted in 2008 and 2009, respectively. Live individuals of ten species were found; shells of one additional species also were encountered. L. cariosa occurred in the largest streams and rivers; eastern Elliptio (Elliptio complanata) was the most abundant in small to medium streams in the Juniata River watershed, but had limited distribution in the Middle Susquehanna River basin. Diversity was positively related to stream width (p < 0.05, R² = 0.36) and watershed area (p <0.05, R² = 0.36) in linear regression models. Richness and diversity were highest at survey sites with intermediate calcium concentrations (10-50 mg/l), but mussel communities are the most diverse and rich at sites with nitrate concentrations below 3 mg/l. Baseline documentation of communities and identification of habitat associations will be used in conservation plans for freshwater mussels.