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Neves, R. J. and J. D. Williams (1994). Status of the freshwater mussel fauna in the United States. Journal of Shellfish Research. 13:345-346.

A comprehensive review of the conservation status of the 297 species and subspecies of native freshwater mussels in the U.S. was completed to assess present and future trends for the fauna. Distributional data, historic and recent collection records of biologists, and literature reviews provided sufficient information to categorize the status of each species. Twenty-one taxa (7%) are listed as endangered but presumed extinct; 77 (21%) are endangered but extant; 43 (14%) are threatened; 72 (24%) are of special concern, 14 (5%) are of undetermined status; and only 70 (24%) are considered stable at this time. The primary reasons for the decline of freshwater mussels are habitat destruction from dams, channel modification, siltation, contaminants, and the introduction of exotic mollusks. Construction of dams within the Tennessee River system by the Tennessee Valley Authority, and dams and navigation projects in large rivers by the U.S. Army Corps of Engineers created impoundments and tailwaters that were unsuitable for many indigenous species. Nonpoint source pollution from agriculture and urban runoff, and point source discharges have contributed pollutants and contaminants to degrade water quality. Competition from non- native mollusks such as the Asian clam (Corbicula fluminea) has seemingly affected some mussel populations in streams, and the zebra mussel (Dreissena polymorpha) appears poised to decimate commercially important mussel populations occurring in large rivers. The high numbers of imperiled freshwater mussels in the U.S., which harbors the most diverse mussel faunal globally, indicate an impending extinction crisis that will severely reduce an important component of aquatic biodiversity. The harvest and export of mussel shells for the cultured pearl industry in Asia will be affected by the decline in mussel populations in the U.S.