A Survey of Freshwater Mussels in the West Pearl River, Mississippi and Louisiana, 1995

Authors: Andrew C. Miller; Barry S. Payne; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS ENVIRONMENTAL LAB

Abstract:

A survey to assess community characteristics, density, population demography of dominant species, and the presence of endangered species of mussels (Family: Unionidae) was conducted in selected reaches of the West Pearl River and lateral canal, near Slidell, LA, August-October 1995. The study was conducted to assess the environmental effects of maintenance dredging required for resumption of commercial navigation traffic. Twenty-two species of bivalves, including the nonindigenous C.. fluminea, were collected in the project area using quantitative and qualitative methods. The nonindigenous zebra mussel, Dreissena polymorpha, introduced into the Great Lakes in the late 1980s, and the threatened mussel, Potamilus inflatus, listed as endangered, were not found although they have been collected in the Pearl River upriver of the lateral canal. The bivalve community area can be characterized as species rich and diverse; typically, no single species dominated. Based on qualitative collections, the most abundant species were Quadrula refulgens and Polamilus purpuratus, which comprised 25 and 16.7 percent of the fauna. Eleven species each made up 1 to 10 percent of the fauna, and nine species were less than 1 percent of the collection. Mean density of Unionidae at three sites in the Bogue Chitto River near the lateral canal ranged from 5.2 to 30.8 with an overall mean of 19.5 (Standard error = 18.5). Overall, 4.8 percent of the individuals and 14 percent of the species had at least one species less than 30-mm total shell length. It is likely that some mussels will be lost by the effects of dredging and disposal of dredged material. It is difficult to predict just how much time will be required for dredged or disposal areas to recolonize. If the substratum is stable with moderate to low velocities, the area could colonize in leshd3^3I- )^)^)^)^)^)^)^)^)^)^)^)^)^)

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APPROVED FOR PUBLIC RELEASE