The red listed eagle owl (Bubo bubo) population in Norway is exposed to POP levels exceeding threshold values for adverse health effects.

The eagle owl (Bubo bubo) population in Norway is today classified as critically endangered on the red list of endangered species. Because previous studies have detected high concentrations of Persistent Organic Pollutants (POPs) in birds of prey, concerns have been raised whether POPs exposure are a significant factor to the substantial decline of the eagle owl population. The aims of this study were to measure the levels of POPs in eagle owls and to assess whether POPs may represent a potential health risk. POPs were analysed in liver samples from 100 eagle owls collected between 1994 and 2014. The concentrations of POPs were generally very high and individual birds had levels among the highest measured worldwide. The contaminant groups analysed were highly correlated (p < 0.0001). The concentrations of sum of Polychlorinated Biphenyls (∑PCB) exceeded the threshold value from moderate to severe health risk in 90% of the birds. The birds with cachectic or lean body condition had significantly higher levels of contaminants than those with higher body condition scores. No significant temporal or spatial trends were noted. The lack of temporal trends, suggest that the downward trend of POPs, appear to be levelling off. The lack of differences between inland and coastal regions suggest that the risk of exposure may be comparable between predatory birds feeding in marine or terrestrial food webs. The significantly higher POPs levels detected in individuals with poor body condition may be due to reduced fat stores and thereby higher concentration in the remaining fat and/or the weight loss could be induced by toxic effects. The high proportion of birds exceeding the threshold values for severe and high risk of adverse effects, suggest that the high contamination load may reduce the eagle owl's fitness and survival and, thus, contribute to decline of the eagle owl population.

Multiple-stressor effects in an apex predator: combined influence of pollutants and sea ice decline on lipid metabolism in polar bears.

There is growing evidence from experimental and human epidemiological studies that many pollutants can disrupt lipid metabolism. In Arctic wildlife, the occurrence of such compounds could have serious consequences for seasonal feeders. We set out to study whether organohalogenated compounds (OHCs) could cause disruption of energy metabolism in female polar bears (Ursus maritimus) from Svalbard, Norway (n = 112). We analyzed biomarkers of energy metabolism including the abundance profiles of nine lipid-related genes, fatty acid (FA) synthesis and elongation indices in adipose tissue, and concentrations of lipid-related variables in plasma (cholesterol, high-density lipoprotein, triglycerides). Furthermore, the plasma metabolome and lipidome were characterized by low molecular weight metabolites and lipid fingerprinting, respectively. Polychlorinated biphenyls, chlordanes, brominated diphenyl ethers and perfluoroalkyl substances were significantly related to biomarkers involved in lipid accumulation, FA metabolism, insulin utilization, and cholesterol homeostasis. Moreover, the effects of pollutants were measurable at the metabolome and lipidome levels. Our results indicate that several OHCs affect lipid biosynthesis and catabolism in female polar bears. Furthermore, these effects were more pronounced when combined with reduced sea ice extent and thickness, suggesting that climate-driven sea ice decline and OHCs have synergistic negative effects on polar bears.

Diet and metabolic state are the main factors determining concentrations of perfluoroalkyl substances in female polar bears from Svalbard.

Perfluoroalkyl substances (PFASs) have been detected in organisms worldwide, including Polar Regions. The polar bear (Ursus maritimus), the top predator of Arctic marine ecosystems, accumulates high concentrations of PFASs, which may be harmful to their health. The aim of this study was to investigate which factors (habitat quality, season, year, diet, metabolic state [i.e. feeding/fasting], breeding status and age) predict PFAS concentrations in female polar bears captured on Svalbard (Norway). We analysed two perfluoroalkyl sulfonates (PFSAs: PFHxS and PFOS) and C8-C13 perfluoroalkyl carboxylates (PFCAs) in 112 plasma samples obtained in April and September 2012-2013. Nitrogen and carbon stable isotope ratios (δ15N, δ13C) in red blood cells and plasma, and fatty acid profiles in adipose tissue were used as proxies for diet. We determined habitat quality based on movement patterns, capture position and resource selection functions, which are models that predict the probability of use of a resource unit. Plasma urea to creatinine ratios were used as proxies for metabolic state (i.e. feeding or fasting state). Results were obtained from a conditional model averaging of 42 general linear mixed models. Diet was the most important predictor of PFAS concentrations. PFAS concentrations were positively related to trophic level and marine diet input. High PFAS concentrations in females feeding on the eastern part of Svalbard, where the habitat quality was higher than on the western coast, were likely related to diet and possibly to abiotic factors. Concentrations of PFSAs and C8-C10 PFCAs were higher in fasting than in feeding polar bears and PFOS was higher in females with cubs of the year than in solitary females. Our findings suggest that female polar bears that are exposed to the highest levels of PFAS are those 1) feeding on high trophic level sea ice-associated prey, 2) fasting and 3) with small cubs.