Stormwater runoff in an urban stream: Impacts on central mudminnows

 Stormwater runoff can be an important factor that affects fish community health in urban areas.  We studied growth and survival of central mudminnows Umbra limi (n = 60) to stormwater runoff into Little Black Creek, Muskegon, Michigan.  We used a 5×2×2 factorial design to investigate the effects of runoff concentration (0, 25, 50, 75, and 100%), location where runoff was collected (US-31 or Seaway Drive), and source of central mudminnows (Little Black Creek or Bark Creek) on fish growth and survival over a 28-d laboratory experiment conducted in individual 2-L aquaria.  Fish growth did not respond significantly to runoff concentration, runoff location, fish source or any of the interactions among the three factors.  Similarly, survival did not respond significantly to runoff concentration or fish source.  However, survival of central mudminnows exposed to US-31 runoff had significantly higher survival (80.5%) than fish exposed to runoff from Seaway Drive (26.9%).  On-going laboratory analyses are underway to ascertain the constituent concentrations of the stormwater runoff, which will be used to identify underlying causes for responses of fish to runoff.  Our preliminary results from one rain event suggest the effects of runoff may differ among road-stream crossings