| Polynuclear aromatic hydrocarbons (PAHs) have become significant contaminants of the marine environment. Classical chemical analysis is often used to assess such contamination in both the biotic and abiotic components of the marine ecosystem. However, such techniques do not incorporate the toxicological impacts of complex mixtures on the exposed organisms. The aim of this research is to develop and validate biomarkers of PAH contamination in marine fish and invertebrates. Specifically, the research assesses environmental contamination with established P450-mediated biomarkers (ethoxyresorufin-O-deethylase activity, CYP1A mRNA, and immunoreactive CYP1A protein) in PAH-treated fish and in fish collected from Galveston Bay and near platforms in the Gulf of Mexico. Significant site differences were found in CYP1A-mediated responses in Galveston Bay, and this correlated with site-specific contaminant concentrations. Moreover, in fish collected near to and far from production platforms in the Gulf minimal chemical contamination was detected with chemical and bioassay techniques. Also, the sensitivity of a suite of biomarkers was compared using both controlled dosing experiments of killifish and hardhead catfish and field collected samples. Killifish proved to be highly aryl hydrocarbon responsive, whereas hardhead catfish were relatively insensitive. For risk assessment of abiotic substrates or invertebrates, induction of enzyme activity by extracts of these samples was determined in the H4IIE rat hepatoma cell line. The presence and contribution of specific carcinogenic PAHs (such as benzo(k)fluoranthene, benzo(b)fluoranthene, indeno(1,2,3-c,d)pyrene, and dibenzanthracene) to the induction potency of environmental extracts was determined. Oysters exposed to a reconstituted PAH mixture proved to be a good model for comparing bioassay- and calculated-induction equivalencies. Both the in vitro and in vivo bioassays used in this research provided means to assess sub-lethal PAH exposures to marine organisms. |
