Stream Erosion and Densities of Etheostoma rubrum (Percidae) and Associated Riffle-Inhabiting Fishes: Biotic Stability in a Variable Habitat

Abstract The Bayou Pierre system in western Mississippi is currently experiencing extensive erosion, with pulses of erosion moving from lower to higher stream reaches (e.g., headcutting). This erosion has caused substantial changes to the system, including channel widening and deepening, general loss of downstream riffle habitats, and the creation of new riffle habitats in more upstream locations. We address the impact of the rapid and ongoing geomorphic changes on Etheostoma rubrum [bayou darter; a federally listed species (Threatened) endemic to Bayou Pierre] and associated, riffle-inhabiting species, including Etheostoma lynceum (brighteye darter), Noturus hildebrandi (least madtom), Cyprinella camura (bluntface shiner), and Etheostoma whipplei (redfin darter). We first characterize stream reaches based on geologic and geomorphic data and then estimate population densities of riffle-inhabiting fishes in each geomorphically homogeneous stream reach. To assess trends in relative abundances of all riffle-...