Large-scale contaminant exposure in a transhemispheric migratory seabird: POPs and PAHs in Puffinus puffinus

Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) represent a significant threat to marine wildlife, particularly top predators such as seabirds. This study assessed PAH and POP contamination in Puffinus puffinus, a transhemispheric migratory species, using liver samples from 169 stranded individuals collected along the southern and southeastern Brazilian coast through the Santos Basin beaches between 2017 and 2022. PCBs (-1), DDTs (-1), PAHs (-1), mirex, and dieldrin were the main contaminants detected. Highly chlorinated PCB congeners, particularly PCB 153, 138, and 180, predominated, suggesting the influence of persistence and biomagnification processes in marine food webs. No statistically significant differences were observed among biological and environmental factors including sex and age, body condition, location, and year of stranding, indicating relatively homogeneous contamination profiles likely associated with the species' long lifespan, trophic ecology, and broad migratory range. Toxic equivalency (TEQ) values (189.3 pg g^-1) were below the lowest-observed-effect level (LOEL) for CYP1A induction in birds and within the range reported for other Procellariiformes. These findings demonstrate the widespread exposure of P. puffinus to organic contaminants across oceanic regions and reinforce the value of migratory seabirds as bioindicators of large-scale marine contamination, contributing to environmental monitoring and conservation initiatives along the Brazilian coast.