Sources of persistent organic pollutants and their physiological effects on opportunistic urban gulls
David Nos, Tomás Montalvo, Núria Cortés-Francisco, Jordi Figuerola, Raül Aymí, Joan Giménez, Montserrat Solé, Joan Navarro
Abstract
Urbanization is associated with drastic shifts in biodiversity. While some species thrive in urban areas, the impact of inhabiting these human-altered environments on organism physiology remains understudied. We investigated how exposure to polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) affects the physiology of yellow-legged gulls (Larus michahellis) inhabiting a densely populated, industrialized city. We analyzed blood samples from 50 gulls (20 immatures and 30 adults) and assessed 27 physiological parameters and biomarkers related to xenobiotic protection, health, and feeding habits in these same individuals. We also tracked the movements of 25 gulls (15 immatures and 10 adults) to identify potential sources of persistent organic pollutants (POPs). Both adult and immature gulls primarily inhabited urban areas, followed by marine habitats. Immature gulls spent more time in freshwater, landfills, and agricultural areas. Bioaccumulated ΣPCB median = 92.7 ng g-1 ww (1.86–592) and ΣPBDE median = 1.44 ng g-1 ww (0.022–9.58) showed no significant differences between age and sex groups. Notably, immature males exhibited the highest correlations with POP concentrations, particularly with the activity of carboxylesterases (CEs), suggesting a higher sensitivity than adults. These findings highlight the potential of plasmatic CEs in immature yellow-legged gulls as effective tracers of POPs exposure and effects, offering insights into the anthropogenic impacts on urban biodiversity. This manuscript addresses the study of environmentally relevant pollutants, specifically polychlorinated biphenyls (PCBs, 7 congeners) and polybrominated diphenyl ethers (PBDEs, 10 congeners), in blood and their impact on gulls’ physiology. These pollutants are well-known for their persistence in the environment, posing a significant threat to long-lived predators due to their capacity to bioaccumulate. Furthermore, this study is also relevant as it was conducted in a densely populated urban area, where both humans and wildlife co-exist. Therefore, in accordance with the One Health approach, gulls could serve as sentinel species for assessing pollutant exposure in cities.