| Summary: | Recent evidence shows that temporal changes of persistent organic pollutants (POPs) in Arctic ecosystems are not only due to emission patterns and regulations; environment-related changes in prey availability and long-range transport may also influence concentrations of these compounds in tissues of Arctic predators. Arctic foxes (Vulpes lagopus) in Svalbard, Norway, scavenge and hunt opportunistically for variable prey items throughout the year. In this study, temporal trends of POPs in arctic foxes from Svalbard were updated. Organochlorinated pesticides (OCPs), polychlorinated byphenyls (PCBs) and brominated flame retardants (polybrominated diphenyl ethers [PDBEs] and hexabromocyclododecane [HBCDD]) were analysed in total of 209 liver samples from 1997 to 2019. Stable isotope values (13C, 15N) in muscle tissue were used as proxies for feeding habits on marine versus terrestrial food and trophic position respectively. Reindeer carcasses, size of geese population and sea ice extent were used as proxies for food availability. Non-linear additive models were used to analyze temporal changes of POPs in relation to variation in feeding habits, food availability, body condition and concentrations of POPs in air from Svalbard. Measured POP changes were compared to changes corrected for temporal variation in diet and food availability, to investigate the potential effect of direct or indirect environment-related changes on POPs. All contaminants increased with higher trophic position and marine diet. All contaminants were lower in fat than lean individuals apart from BDE-47. HCB concentrations decreased when reindeer carcasses were abundant and increased with increasing sea ice extent. Changes in concentrations for contaminants showed a general decline through the whole study period, which is in accordance with the decrease of PCBs and organochlorine pesticides in Arctic biota during the last 20 to 30 years. All our estimated changes per year for adjusted and measured concentrations were similar among contaminants, with the exception for BDE-47 which showed a higher rate of decline compared to other contaminants when adjusted for covariates. HCB changes per year were lower when adjusted for covariates, with overlapping confidence intervals, meaning that changes in diet and food availability in arctic foxes could non-significantly affect the temporal changes of contaminants.
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