THE FRESHWATER MUSSELS (MOLLUSCA: BIVALVIA: UNIONIDAE) OF THE LITTLE BLUE RIVER DRAINAGE OF NORTHEASTERN KANSAS AND SOUTHEASTERN NEBRASKA

A survey in the Little Blue Basin documented the presence of 22 extant or extirpated unionid mollusk species. Bivalve habitat is severely impaired by surface and subsurface water withdrawals, erosion, siltation, and grazing. Chemical contaminants and other pollutants washed into area streams from agricultural fields probably exert a further deleterious impact upon the fauna of the region. Half of the species recovered were represented only by chalky or badly weathered shells, suggesting their possible elimination from the basin. The generally poor condition of shells of many of the remaining species suggests they are also in severe decline in the region