Background/Question/Methods  Urban population growth and expansion can drastically alter stream ecosystem structure and function. Many studies have documented reduced macroinvertebrate richness and biotic integrity with increased urbanization.  However, the effect of urbanization on stream macroinvertebrate secondary production is still largely unknown.  In this study, we estimated macroinvertebrate production in six streams along an urban development gradient (UDG), and linked changes in production to in-stream environmental characteristics and catchment land use/cover (LUC) patterns along the UDG.
Results/Conclusions Total production was highest on the urban fringe in a stream dominated by pastureland and developed-open green spaces and lowest in the most highly urbanized stream (75% Urban). Forested streams exhibited intermediate production levels. Regression analysis indicated nutrient enrichment, leaf litter availability, and chloride concentrations were the in-stream variables most related to production along the UDG. In-stream environmental variables were also strongly related to catchment-scale LUC. Our results suggest that total production first increases along the UDG due to increased nutrient enrichment. However, once development has reached a threshold, other stressors associated with the UDG ultimately cause decreases in total production to levels below forested stream production. These changes in macroinvertebrate production along the UDG could greatly alter food webs, energy flow, and the cycling of matter in these human-dominated ecosystems.