Sucking clams or hunting seals – consequences to walrus health

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The walrus (Odobenus rosmarus) is an ice-associated marine mammal with two recognized subspecies, one distributed in the North Atlantic and the other in the North Pacific. Some walruses feed on high trophic level prey such as seals, while others mainly feed on benthos. Based on previous studies, concentrations of the main chlorinated pollutants, namely polychlorinated biphenyls (PCBs) and chlordanes, in walruses that likely feed on seals are very high - similar to levels observed in polar bears. Although multiple studies have associated contaminant exposure to adverse health effects in polar bears and other marine mammals with similar contaminant exposure, there are, to our knowledge, no studies to date investigating effects of pollutants in walruses. Chronic exposure to environmental pollutants in arctic wildlife has been mainly associated with endocrine disruption and immune suppression. There is a lack of knowledge on how contaminants might affect the health of Atlantic walruses and on pathogens in this species in general. The goal of our study was to investigate contaminant and pathogen exposure and related health effects in walruses feeding at different trophic levels. We will determine concentrations of lipophilic pollutants and perfluoroalkyl substances in 39 adult male walruse collected in 2014-2015. To investigate contaminant-related effects at molecular level, we will examine transcript levels selected genes involved in endocrine disruption and immune suppression in whole blood and blubberFurthermore, the walrus plasma samples will be analysed for thyroid hormones and antibodies against specific seal pathogens.