Spatiotemporal patterns in the distribution and abundance of the introduced Redbreast Sunfish (Lepomis auritus) and native Longear Sunfish (L. megalotis; Centrarchidae) in reservoirs of the Tennessee River drainage

摘要

The Redbreast Sunfish (Lepomis auritus) was introduced in the Tennessee River drainage (TRD) in the 1940s, and contemporary anecdotal evidence suggests that L. auritus is possibly displacing the native Longear Sunfish (Lepomis megalotis). This study aimed to characterize temporal patterns in regional abundances of L. auritus and L. megalotis populations in the TRD based on a multiyear analysis of historical and contemporary fish assemblage datasets (percent abundance, density, biomass). Results indicate that L. megalotis abundance declined in reservoirs where L. auritus was found in high or increasing abundances. Also, L. auritus surpassed L. megalotis in mean percent abundance in Nickajack-Chickamauga River section and has consequently shifted Lepomis species composition. Although it is difficult to isolate causal variables, the interaction of both biotic (i.e., L. auritus competition) and abiotic (i.e., geographic variables, land use, and water quality) factors likely explain the changes in L. megalotis abundance and variability within river sections.