Freshwater Mussel and Water Quality: a Review of the Effects of Hydrologic and Instream Habitat Alterations

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Proceedings of the First Freshwater Mollusk Conservation Society Symposium, 1999, pages 261-274 © 2000 Ohio Biological Survey Freshwater mussels and water quality: A review of the effects of hydrologic and instream habitat alterations G. Thomas Watters1 Ohio Biological Survey and Aquatic Ecology Laboratory; 1315 Kinnear Road, The Ohio State University, Columbus, OH 43212 ABSTRACT: Hydraulic impacts represent a suite of habitat alterations that, although having different causes, often have similar methods of affecting the mussel fauna. For instance, logging and channelization are very different disturbances, but both generate sediments. These “hydraulic impacts” thus overlap each other to one degree or another. I have attempted to…show more content…
A survey in 1970 of the reservoir found four mussel species. Prior to its impoundment, Ortmann (1918) reported 64 species from the same general area. In addition, the 1970 survey found mussels primarily on flooded preimpoundment land (overbank), not in the original river channel habitat. This probably was due to critically depleted oxygen levels in the channel. Elsewhere, during construction of the Nickajack Dam, the Tennessee River was dewatered at the construction site (Isom 1972). Seventeen species were found. Ortmann (1925) had found 25, for a cumulative total of 33 species reported for this reach. Missing in the latter survey were many endangered and rare species. Whether this was due to the presence of the Hales Bar Dam, 6.4 miles upstream, or other causes was not known. It may be argued that mussel faunal composition changes over time whether dams are built or not. However, Parmalee et al. (1982) documented a fauna that remained essentially unchanged for several millennia until impounded by a dam. The Chickamauga Reservoir of the Tennessee River supported 46 species for perhaps 2,000 years prior to impoundment. After impoundment, 28 species were 262 extirpated, and several are now extinct. Five species, mainly soft-substrate tolerant taxa, have invaded the reservoir. Four original species that survived the impoundment also have increased in abundance. Mussel diversity has declined from 64 species to 30 in the upper Chickamauga

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