Contrasting body burdens of organohalogenated contaminants in two Arctic glaucous gull Larus hyperboreus populations in relation to their dietary ecology

Abstract

This study compared body burdens of organohalogenated contaminants (OHCs) between glaucous gull populations from Bjørnøya and Kongsfjorden, Svalbard and if OHC levels was influenced by their dietary ecology and biological variables (body condition index and sex). To do so, blood from 112 adult glaucous gulls were sampled during the breeding seasons of 2015 until 2019 in Bjørnøya and Kongsfjorden. We measured plasma concentrations of OHCs including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and perfluorinated alkylated substances (PFASs). Feather stable isotopes of nitrogen (δ15N) and carbon (δ13C) were analyzed to indicate trophic level and feeding habitat, respectively. Body burdens of OHCs differed significantly between the two populations for all 5 sampling years. Overall, the population at Bjørnøya had plasma concentrations of OHCs 5.3 times higher than the Kongsfjorden population. The most quantitatively abundant contaminants found in the glaucous gulls were ΣPCBs and ΣPFASs in Bjørnøya and ∑PCBs in Kongsfjorden. No differences in relative trophic position between both breeding populations were reported although Kongsfjorden individuals varied significantly in δ15N across sampling years, while Bjørnøya individuals remained stable over time. In addition, we highlighted no relationship between plasma OHCs and feather δ15N (trophic position) although the lack of association might be due to both tissues (i.e blood and feathers) reflecting different time scales. Only ΣPFSAs and ΣPFCAs showed a positive relationship with δ13C, suggesting that feeding habitat, more than trophic position, might explain variance in contaminant exposure.