Biomarkers of polycyclic aromatic hydrocarbon (PAH) exposure in northwest Gulf of Mexico marine fish and invertebrates: indicators of offshore petroleum contamination

Abstract

Higher molecular weight Polycyclic aromatic hydrocarbons (PAHS) associated with crude oil induce CYPIAI gene expression, and this response has been utilized as a biomarker of exposure to PAHs in aquatic and marine environments. Several benthic marine fish and invertebrates were collected in the vicinity of offshore petroleum platforms in the northwest Gulf of Mexico and subdivided with respect to distance from the platforms (i.e. "near", <100 m or "far", >3000 m). Hepatic tissues were analyzed for CYPIAI MRNA levels using a CDNA probe derived from rainbow trout, and ethoxyresorufin-0-deethylase (EROD) activity (a CYPIAI response) was also determined in the fish species. Invertebrate exposure to PAHs was estimated by determining the dose-dependent induction of EROD activity by invertebrate extracts in rat hepatoma H-4-IIE cells. CYPIAI MRNA levels and EROD activity were detected in all species, though the relative response intensities were low, indicating minimal PAH contamination at these sites. Intensities of the MRNA bands did not correlate with EROD activity in the same fish species. The results indicated that there were no consistent differences between the near and far stations as expected for a contaminant gradient. Interestingly, the CYPIAI MRNA data exhibited some inter-and intraspecies differences, suggesting genetic differences in this gene in various fish species. Bioanalysis of invertebrate extracts in rat hepatoma H-4-IIE cells also indicated low PAH contamination at the study sites. All three assays were sensitive indicators of PAH contamination.