Is minimally-invasive sampling the future of persistent organic pollutant (POP) research in birds? A meta-analysis on tissue comparisons

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.

Effects of persistent organic pollutants on telomere dynamics are sex and age-specific in a wild long-lived bird

Chemical pollution is a major man-made environmental threat to ecosystems and natural animal populations. Of concern are persistent organic pollutants (POPs), which can persist in the environment for many years. While bioaccumulating throughout the lives of wild animals, POPs can affect their health, reproduction, and survival. However, measuring long-term effects of POPs in wild populations is challenging, and therefore appropriate biomarkers are required in wildlife ecotoxicology. One potential target is telomere length, since telomere preservation has been associated to survival and longevity, and stressors as chemical pollution can disrupt its maintenance. Here, we investigated the effects of different classes of POPs on relative telomere length (RTL) and its rate of change (TROC) in wild long-lived Alpine swifts (Tachymarptis melba). As both RTL and TROC are often reported to differ between sexes and with chronological age, we tested for sex- and age-specific (pre-senescent vs. senescent, ≥ 9 age of years, individuals) effects of POPs. Our results showed that senescent females presented longer RTL and elongated telomeres over time compared to pre-senescent females and males. These sex- and age-related differences in RTL and TROC were influenced by POPs, but differently depending on whether they were organochlorine pesticides (OCPs) or industrial polychlorinated biphenyls (PCBs). OCPs (particularly drins) were negatively associated with RTL, with the strongest negative effects being found in senescent females. Conversely, PCBs led to slower rates of telomere shortening, especially in females. Our study indicates diametrically opposed effects of OCPs on RTL and PCBs on TROC, and these effects were more pronounced in females and senescent individuals. The mechanisms behind these effects (e.g., increased oxidative stress by OCPs; upregulation of telomerase activity by PCBs) remain unknown. Our results highlight the importance in wildlife ecotoxicology to account for sex- and age-related effects when investigating the health effects of pollutants on biomarkers such as telomeres.