Comparison of gene expression and polycyclic aromatic compound profiles in hepatic tissue of black guillemot (Cepphus grylle) collected from an oil spill site and a non-spill site in the Arctic.

Economic development, marine transportation, and oil exploration are all activities that are increasing in the Arctic region, and there is concern regarding increased oil-related contaminants entering this sensitive environment. Polycyclic aromatic compounds (PACs) are the main chemical constituents in oil-related contaminants and have been detected in wildlife species following both acute and chronic exposure. In 2020, an oil spill occurred in Kaikopok Bay near Postville, NL, Canada. In the present study, we evaluate hepatic PAC burdens and gene expression profiles, using a ToxChip PCR array, to determine key biological pathways most affected by exposure to an oil spill in a seabird species, black guillemot (Cepphus grylle). Black guillemots were also collected from a non-spill site at Nain, NL for chemical and gene expression analyses. We found distinct, diesel-related contaminant profiles in hepatic tissue of seabirds collected from the spill site, characterized by the presence of naphthalene congeners. Conversely, alkylated naphthalene congeners were more prevalent at the non-spill site. Although different chemistry profiles were detected between sites, gene expression profiles at the spill site were not as distinct as expected. However, using a regression modeling approach, the expression of certain target genes were good predictors of actual chemical concentrations. Overall, chemistry and gene expression used together can help support environmental monitoring initiatives in vulnerable species and geographic locations.