CONTAMINANT EFFECTS ON REPRODUCTIVE SUCCESS IN SELECTED BENTHIC FISH

Field studies on ovarian development in English sole from urban and non-urban sites in Puget Sound, Washington, USA, demonstrated that animals with elevated levels of fluorescent aromatic compounds (FACs) in bile were less likely to enter vitellogenesis and had lower plasma concentrations of estradiol than female sole with low levels of contaminant exposure. Biliary FACs were positively correlated with hepatic P450 activity, which was also elevated in sole showing inhibited ovarian development. These findings suggest that contaminant exposure may disrupt vitellogenesis in female fish. Results of the field study were supported by laboratory experiments showing that pretreatment of gravid female English sole with extracts of contaminated sediment decreased levels of endogenous estradiol. A similar response was observed in rock sole and flathead sole treated with Prudhoe Bay crude oil. However, exposure of English sole to sediment extracts had little effect on the activity of hepatic-steroid-metabolizing enzymes, indicating that some mechanism other ther enhanced steroid metabolism may be responsible for reductions in endogenous circulating-steroid levels. Our recent studies suggest that reductions in endogenous estradiol levels may result from depressed ovarian steroidogenesis, as contaminant-associated reductions in in-vitro ovarian estradiol production were observed in English sole, rock sole, and flathead sole. Preliminary studies on winter flounder and white croaker indicate that they may also experience reproductive impairment as a result of exposure to contaminants, but the phase of the reproductive impairment as a result of severely impacted varies from species to species.