| Fish community data were used to develop an index of biotic integrity (IBI) to quantify habitat degradation in oxbow lakes of the Delta region of the Yazoo River Basin. Daytime boat electrofishing was used to sample the fish assemblage of 30 oxbow lakes during 2006-2007. We evaluated 70 candidate metrics based on their responses to measures of anthropogenic disturbance. Six metrics were retained for inclusion in the IBI: species richness, Shannon's diversity (H'), average tolerance, and catch rates of buffalo, orangespotted sunfish, and litho-psammophilic spawners. The six IBI metrics showed strong multivariate relationships with measures of habitat degradation in a canonical correlation analysis. Spearman's rank correlation and scatterplot analysis showed that IBI scores changed in a predictable pattern along gradients of habitat degradation. Three additional lakes were sampled in 2008 and were used to successfully validate the IBI. Biotic integrity was found to be impaired in most oxbow lakes of the Mississippi Delta. |
