Accumulation of persistent organic pollutants and benzotriazole UV stabilizers in the preen gland oil of Tristram's storm-petrel (Hydrobates tristrami).

Storm-petrels are among the seabird species with the highest frequencies of marine plastic ingestion, owing to their surface pick-up foraging behavior. However, there has been little assessment of plastic-related pollutants in these birds. Tristram's storm-petrels (Hydrobates tristrami), in particular, inhabit the North Pacific Central Gyre, one of the most polluted marine regions in the world. This study aims to measure concentrations of plastic-associated pollutants, i.e., benzotriazole UV stabilizers (BUVSs), and assess their contamination status in Tristram's storm-petrels by comparing them with persistent organic pollutants such as polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethylene (DDE). PCBs, DDE, and BUVSs, one of plastic additives, were analyzed in preen gland oil collected from 13 individuals, including 2 fledglings. The results showed that PCBs and DDE were detected in all individuals at concentrations exceeding 1000 ng/g-lipid, which were higher than those observed in other seabirds in the North Pacific. This is probably owing to their higher trophic level. BUVSs were sporadically detected in four individuals, with concentrations exceeding 100 ng/g-lipid, levels similar to those reported in other seabirds by Yamashita et al. (2021). However, no correlation was found between the concentrations of BUVSs in preen gland oil and those of PCBs or DDE, suggesting that BUVSs were not derived from the birds' natural diet (prey). These findings indicate a high level of contamination in Tristram's storm-petrels and highlight the need for investigating pollutant exposure in storm-petrel species worldwide.