Levels and Effects of Organohalogens on Corticosterone Hormones in glaucous gulls (Larus hyperboreus) from Kongsfjorden, Svalbard
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- Institutt for biologi 
Long-range atmospheric transport, ocean currents, sea ice and rivers are transporting environmental contaminants into the Arctic. Some of these contaminants can reach high concentrations in the upper trophic levels in the Arctic food web due to processes of bioaccumulation and biomagnification. The present study indicates a sex-specific pattern of levels and effects of selected organohalogenated contaminants (OHCs) in the avian top predator, glaucous gull (Larus hyperboreus), breeding in Kongsfjorden, Svalbard. The aim of this present study was to report levels of OHCs and investigate whether the high levels detected in glaucous gulls can induce stress and thereby influence the stress response (measured by corticosterone concentration). No statistical differences were recorded for stress-induced or baseline corticosterone concentrations for males and female glaucous gulls. In females, a significant negative association was reported for lipid weight in blood plasma and baseline corticosterone. In male glaucous gulls, positive associations were found between levels of twenty-two OHCs and elevated baseline levels of corticosterone; indicating for the first time a cocktail effect of specific OHCs in blood plasma associated with high baseline levels of corticosterone in male glaucous gulls. It is suggested that the high levels of OHCs may act as a chronic stressor. The OHCs may interfere with the Arctic seabirds ability to respond to environmental stressors, such as climate change and food availability, by disrupting the baseline levels of corticosterone and weakening the feedback mechanisms of the stress axis. Elevated baseline levels may lead to suppression of immune parameters and reduced survival rate. Due to a small sample size assessed in the present study, more research is needed to confirm a possible relationship between the disrupted stress axis and environmental contaminants in the Arctic seabirds.