Assessing the impacts of trace element contamination on the physiology and health of seabirds breeding along the western and southern coasts of Portugal

• Published in: Environmental pollution (1987) 2024-10, Vol.358, p.124528, Article 124528
• Main Authors: dos Santos, Ivo, Paiva, Vitor H., Norte, Ana C., Churlaud, Carine, Ceia, Filipe R., Pais de Faria, Joana, Pereira, Jorge M., Cerveira, Lara R., Laranjeiro, Maria I., Veríssimo, Sara N., Ramos, Jaime A., Bustamante, Paco
• Format: Article
• Language: English
• Subjects: Animal biology; Animal haematology; Ecotoxicology; Heavy metals; Laridae; Life Sciences; Procellariidae; Risk; Stable isotopes; Toxicology; Vertebrate Zoology
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2024.124528

Coastal seabirds serve as sentinels of ecosystem health due to their vulnerability to contamination from human activities. However, our understanding on how contaminant burdens affect the physiological and health condition of seabirds is still scarce, raising the uncertainty on the species' vulnerability vs tolerance to environmental contamination. Here, we quantified 15 Trace Elements (TE) in the blood of gull (yellow-legged gull Larus michahellis and Audouin's gull Ichthyaetus audouinii) and shearwater (Cory's shearwater Calonectris borealis) adults, breeding in five colonies along the Portuguese coastline. Additionally, stable isotopes of carbon (δ13C) and nitrogen (δ15N) were quantified to elucidate foraging habitat and trophic ecology of adults, to identify potential patterns of TE contamination among colonies. We used immuno-haematological parameters as response variables to assess the influence of TE concentrations, stable isotope values, and breeding colony on adults' physiological and health condition. Remarkably, we found blood mercury (Hg) and lead (Pb) concentrations to exceed reported toxicity thresholds in 25% and 13% of individuals, respectively, raising ecotoxicological concerns for these populations. The breeding colony was the primary factor explaining variation in five out of six models, underlining the influence of inherent species needs on immuno-haematological parameters. Model selection indicated a negative relationship between erythrocyte sedimentation rate and both Hg and selenium (Se) concentrations, but a positive relationship with δ13C. The number of immature erythrocyte counts was positively related to Hg and Se, particularly in yellow-legged gulls from one colony, highlighting the colony-site context's influence on haematological parameters. Further research is needed to determine whether essential TE concentrations, particularly copper (Cu) and Se, are falling outside the normal range for seabirds or meet species-specific requirements. Continuous monitoring of non-essential TE concentrations like aluminium (Al), Hg, and Pb, is crucial due to their potential hazardous concentrations, as observed in our study colonies. [Display omitted] •Some individuals exceeded toxicity thresholds for blood Hg and Pb concentrations.•Se:Hg molar ratios suggest that these species might be protected from Hg toxicity.•Colony emerged as a primary factor of variation in seabird health parameters.•ESR and IE counts related to δ13C values, and Hg and