Stream fish community structure across an urban gradient in a northeastern US watershed

Anthropogenic land cover change in watersheds has the potential to degrade stream habitat quality and alter fish assemblage structure. The objective of this study was to examine the relative importance of urbanization at different spatial scales and local habitat conditions on both the fish taxonomic assemblage and trait assemblage. Fish assemblages were sampled in 22 wadeable streams within a single sub-basin in the northeastern USA. Urbanized land cover at the watershed and riparian scales was associated with increases in specific conductivity and pH, but was not a major determinant of taxonomic or trait assemblage structure. Instead, taxonomic and trait assemblages were associated with a gradient of decreasing elevation and increasing temperature, and some of the most urbanized sites supported diverse and unique fish assemblages. These results contribute to a greater understanding of the variation in the effects of urbanization on stream health.