THE IMPACT OF HYDROPOWER DAMS ON THE SHELL MORPHOLOGY OF THE UNIONID ELLIPTIO COMPLANATA (RAQUETTE RIVER, ST. LAWRENCE COUNTY, NY)

The Raquette River in northern New York State is one of the main New York tributaries to the St. Lawrence River. Twenty-seven dams built to harness hydroelectric power disrupt the flow of the river today. This river is home to an ecosystem that, although occupying only a small area of the world, is home to a rich diverse community of invertebrates. The damming strongly influences the connectivity of the riverine system and leads to isolation of habitats and a major decline in the diversity of these fresh water communities. In this study we examine the shell morphology of Elliptio complanata, a common unionid species. These bivalves disperse by attaching their larvae to certain fish species, whose migration routes are disrupted due to damming of the river and, thus, create completely isolated bivalve populations. We hypothesizes that this isolation is reflected in shape differences between these unionid groups.

Samples were collected from twenty localities between three dams around Potsdam, NY, along the Raquette River. We collected, cleaned, photographed and landmarked over nine hundred right valves of this taxon and analyzed their shell shapes using morphometric methods. Preliminary results suggest that although these unionid populations have been isolated by dams, there seems to be no significant shape differences between these groups. Dams have been reported to simplify the river ways, which leads to a more uniform habitat and, thus, might lead to homogenous habitats, reflected by the similarity of unionid shape.