Mean SE, range in parenthesis species richness, catch per unit effort CPUE, and Shannon Diversity Index SDI for mussel surveys in the Meramec River basin, Missouri, by year. Community metrics including the relative abundance of Missouri Species of Conservation Concern SOCC, species in the tribes Amblemini, Pleurobemini, and Quadrulini APQ taxa, Lampsilini, and common species A. plicata, A. ligamentina are also presented. Values for a parameter within each row followed by the same letter were not significantly different among sites P 0.05, KruskalWallis test. For each river, 1997 values followed by an asterisk were significantly different from 1978 values for individual parameters P 0.05, KruskalWallis test.