Urbanization of a Watershed and Historical Changes in a Stream Fish Assemblage

Abstract

During recent decades, the Tuckahoe Creek (Virginia) watershed has been altered by human activities, including road and bridge construction, commercial and residential development, and riparian losses. We used historical (1958) and recent (1990) data to evaluate the hypothesis that long-term, low-intensity urbanization affects a warmwater stream fish assemblage in ways usually attributed to acute, high-intensity perturbations. In 1990, fish species diversity of Tuckahoe Creek was significantly lower (P < 0.05) than it had been in 1958, and abundance was substantially lower for all species and trophic guilds. Four cyprinids, one ictalurid, and one percid present in 1958 were not collected in 1990. Jaccardˈs community similarity coefficient (species composition by site between 1958 and 1990) was negatively correlated with near-stream development of the watershed at six study sites (r = –0.84; P < 0.05). Some characteristics of the feeding ecology of selected fish species, including consumption of terrestrial prey and diet overlap, exhibited slight differences between 1958 and 1990. Observed changes in the fish assemblage were consistent with our hypothesis. Our findings also suggest that the lack of invasions by exotic fishes may not always indicate undisturbed stream conditions.