Comparative Analysis of Freshwater Mussels on the Effects of Impoundment on the S. Fork Holston River

As ecologically sensitive organisms, freshwater mussels serve as environmental indicators in the rivers and lakes they inhabit. The South Fork of the Holston River has been impounded and channelized, which can result in habitat loss of riffle and shoal areas and negatively impact native species. The aim of this study is to analyze river conditions on a roughly 40 mile stretch of the S. Fork Holston River, encompassing the distance from Eastman Chemical Company in Kingsport to Boone Lake. Information has been gathered using mussel assemblages from two archaeological sites, 40SL34 and 40SL330, and two historic collecting events, SFHSkm25.1 and SFHSkm27.0. The computer program UNIO analyzes the ecological preferences of all input taxa to compile a list of river conditions, including flow velocity and substrate. Compiling the assemblages from all four sites has revealed an increase in unfavorable conditions for many species, leading to a loss in mussel diversity. What were once the most abundant species in the archaeological sites, Ptychobranchus subtentus and Fusconaia subrotanda, both prefer to live in riffle areas with fast current. Currently, P. subtentus is listed as endangered while F. subrotanda is listed as a special concern species. The most abundant species for both historic collecting events is Lampsilis fasciola, a species that is tolerant of conditions that are unfavorable for many species. The substrate of the S. Fork Holston River, a sandy-gravel, has remained the same, but evidence suggests that impoundment has resulted in the loss of fast-moving currents and riffle areas