Exposure of Pacific herring to weathered crude oil: Assessing effects on ova

In order to determine if exposure to Exxon Valdez oil would adversely affec t progeny, reproductively mature Pacific herring were confined in water con taminated with weathered crude oil. Progeny were generally not affected by a 16-d parental exposure to initial aqueous concentrations of less than or equal to 58 mu g/L total polynuclear aromatic hydrocarbons (PAHs), yielding concentrations of up to 9.7 mu g/g in ova. In contrast, previous research indicated that a 16-d direct exposure of herring eggs to similarly weathere d oil was detrimental to developing embryos at total initial PAH concentrat ions of 9 mu g/L. Progeny of exposed fish could have been insulated from to xic effects for two reasons. First, as an apparent result of partitioning a nd metabolism in parental tissues, lower concentrations and less toxic PAHs were preferentially accumulated by ova (primarily naphthalenes; 84-92%). S econd, peak exposure concentrations occurred before cell differentiation. T he opposite was true for directly exposed eegs; the more toxic multi-ring P AHs (e.g., phenanthrenes and chrysenes) and alkyl-substituted homologues we re accumulated, and internal concentrations increased during cell division, differentiation, and organ development. Thus, Pacific herring embryos are more critically sensitive to oil pollution than are gametes.