Urban land use and future urban expansion pose a serious threat to natural ecosystems. Urban areas rely on outside support from natural ecosystems for resource acquisition and waste disposal. As a consequence, streams in urban systems are affected by multiple disturbances within the watershed, and, in many cases, serve as waste conduits for municipal wastewater discharge. In addition, changes in watershed hydrology due to increased impervious surfaces (i.e. roads, buildings, parking lots) drastically affect stream channel geomorphology by deepening and widening the stream to accommodate new flow patterns. These physical and chemical changes in stream conditions generally result in decreased biological diversity of stream dwelling organisms. An unaddressed question, however, is how reductions in community richness and diversity affect the ecosystem functions and services provided by urban stream communities.
In this study, this question will be addressed by conducting experiments in six streams draining watersheds in which land use varies from 0 to 80% urban cover to determine not only how biological diversity within the stream is impacted by urbanization, but what consequences these losses in biological diversity have in terms of energy flow and nutrient cycling within stream food webs, two processes with profound consequences for in-stream water quality. Dissemination of these results will facilitate the future planning, management, and restoration of urbanized streams by linking commonly observed decreases in stream biological diversity with measureable ecosystem scale functions and services provided by the stream organisms.
