Structural Community Changes in Freshwater Mussel Populations of Little Mahoning Creek, Pennsylvania

Abstract

As part of a complete biotic survey for Little Mahoning Creek watershed, Western Pennsylvania Conservancy (WPC) used timed searches to survey for freshwater mussels along the entire mainstem of Little Mahoning Creek (56.8 km). The survey captured all historic sites sampled as early as 1905. The 15 sites revealed a high diversity of unionids (10 species) and several rare and endangered taxa, including Pleurobema sintoxia (Rafinesque, 1820), Villosa iris (I. Lea, 1829), and Alasmidonta marginata (Say, 1818). Present survey results indicate an established unionid community with several taxa increasing their distributions compared to historical surveys. Upstream dispersal was halted at the Savan Dam at river kilometer 36.69. No live or dead unionids were found at six sites upstream of the dam. Bray-Curtis similarity indices were calculated between present survey and historical survey accounts. Species composition in the present survey compares favorably (86.14%) with collections by Ortmann (1909) and Bogan and Davis (1992). Several locations have relatively high unionid diversity, despite being located in an area with anthropogenic perturbations.