Mussels of Bear Creek Watershed, Alabama and Mississippi, With a Discussion of the Area Geology

Abstract

Bear Creek, Alabama, is a tributary of the Tennessee River at the lower extremity of Muscle Shoals, Tennessee River mile 225. Study of Bear Creek revealed a significantly changed mussel fauna from that reported by Ortmann in 1925. There was a significant reduction in Cumberlandian species and a significant increase in big-river species of Interior Basin or of unknown origin. Physical and water quality parameters in Bear Creek are thought to be essentially pristine. Only the lowermost 17 miles of Bear Creek have been affected by Pickwick Dam on the Tennessee River. Significant changes in Bear Creek mussel fauna are perhaps due in part to changes in the fish fauna due to impoundment in its lower extremity. The presence of Cumberlandian species in the Bear Creek drainage, which is in the Gulf Coastal Plain, indicates that the Tuscaloosa Group per se is not limiting in the distribution of Cumberlandian mussels, as has been suggested. Disappearance of the siliceous Fort Paype chert, and as a result the Muscle Shoals, limited the downstream distribution of Cumberlandian mussels in the lower Tennessee River.