Biotic responses to low-concentration urban road runoff

Abstract

AbstractA major effect of urbanization on streams is the input of stormwater (SW) runoff from impervious surfaces. This water may contain excess nutrients, heavy metals, and other organic contaminants. These inputs are potential stressors or stimulants for algae, invertebrates, and fish within the aquatic community. We conducted a controlled experiment in mesocosms (∼1300-L tanks) to evaluate the effect of SW quality on different trophic levels. SW runoff was collected before it entered Little Black Creek, which is a tributary draining an urbanized subcatchment in western Michigan. The captured runoff was used to create the following treatments: 0% SW (control, n = 4), 50% SW (n = 4), or 100% SW (n = 4). Nested within each mesocosm were exclosure treatments containing different combinations of algae, snails (Physa sp.), and fish (pumpkinseed: Lepomis gibbosus). SW did not have an overall effect on algal biomass or metabolic activity in the mesocosms. Algal community composition in the 0% SW treatmen...