Persistent organic pollutant exposure and associations with gene expression in northern fur seals (Callorhinus ursinus) from St. Paul Island, Alaska

Abstract

Persistent organic pollutants (POPs) are highly lipophilic compounds that accumulate at increased concentrations in high tropic level organisms like marine mammals. Marine mammals’ reliance on blubber makes them susceptible to accumulating POPs at potentially toxic concentrations. In this study, we analyzed POP concentrations, (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and methoxylated-BDE (MeOBDE), in the blubber of 16 subsistence harvested sub-adult, male northern fur seals as well as assessed changes in mRNA gene expression of nine relevant biomarkers including the aryl hydrocarbon receptor, thyroid receptor-α, and adiponectin. PBDE and MeOBDE concentrations were significantly lower than PCB and OCP concentrations. A negative relationship was observed between percent lipid in the blubber and contaminant concentrations, both individual and sum. Expression changes in eight biomarkers were correlated with individual and sum contaminant concentrations. This study shows that contaminant concentrations measured are correlated to changes in expression of genes from different physiological systems, metabolism and endocrine, that are important for the regulation of blubber metabolism. Northern fur seals are reliant on blubber as an energy source during times of low food intake. Potential contaminant induced changes in blubber metabolism pathways could have significant impacts on the health of individuals during critical periods.