The Unionid Mollusks of the Upper Kansas Basin of Northwestern Kansas and Southwestern Nebraska

A qualitative survey of the Upper Kansas Basin resulted in the documentation of a unionid fauna consisting of twenty-one native taxa, as well as the introduced bivalve Corbicula fluminea. Biological diversity was greatest in the extreme eastern portion of the basin with the highest concentrations occurring in the habitat-rich eastern-most creeks. Shifting sand substrates and declining or unstable flows, coupled with intensive grazing of livestock, increasingly limit unionid distributions on an east to west continuum