Developmental effects of urban storm water in medaka (Oryzias latipes) andinland silverside (Menidia beryllina)

Stormwater runoff in a coastal urban area (San Diego County, CA) produced s ignificant toxicity to early life stages of medaka (Oryzias latipes) and Me nidia (M. beryllina). Exposure of embryos to lower concentrations (5 to 25% ) increased the incidence of abnormal swim bladder inflation and other tera togenic responses, whereas higher concentrations resulted in mortality or f ailure to hatch. Comparisons of EC50s for mortality and failure to hatch wi th concentrations of individual chemical pollutants (including Cd, Cr, Cu, Pb, Ni, and Zn) revealed low correlations; however, the correlation with to tal metals was high (-0.84) and corresponded with sample exceedences of Wat er Quality Criteria (WQC) for Cd, Cu, W, and Zn. This strong association be tween developmental toxicity and toxic metal content of storm water compare d favorably with developmental anomalies reported in other studies. Analyti cal chemistry data for pesticides that may have been in these samples were limited to selected pesticides found usually below detection limits. Greate r toxicity of the watershed effluents sampled was generally associated with more developed land surface and less open space. Both medaka and Menidia w ere found to be useful for studying effects of stormwater on embryonic and early larval development.