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

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