Mercury in organs of Pacific walruses ( Odobenus rosmarus divergens ) from the Bering Sea

Abstract

The Pacific walrus (Odobenus rosmarus divergens) is still used as an important source of protein-rich food by indigenous peoples of Chukotka, Alaska, and other Arctic regions. Total mercury (THg) concentration was measured in eight internal organs of walruses. Samples were taken from 22 individuals (11 males and 11 females). Age of the animals ranged from 1 to 30 years. All the walruses were harvested by local hunters from the coastal waters off the Chukchi Peninsula (Russia) during the autumn of 2011. Total mercury concentration in the samples was determined by atomic absorption method. No statistically significant difference in the level of mercury was found between males and females. Mercury was detected in all the organs of the studied walruses. The highest total mercury concentration was recorded from excretory organs: liver and kidneys. The level of mercury in liver (mean = 1.87 μg/g, range = 0.05–5.87) was by an order of magnitude higher than in kidneys (mean = 0.54 μg/g, range = 0.09–1.64.); in kidneys, it was by an order of magnitude higher than in the rest of the organs. The analyzed organs can be arranged in the order of decreasing Hg concentration as follows: liver >> kidney >> muscle > spleen ≥ heart ≥ intestine > lung ≥ testis. The mercury concentration values in walruses from the coastal waters off the Chukchi Peninsula are lower than those obtained from walruses in Alaska and the Canadian Arctic. Our findings may provide a basis for the further long-term monitoring of the condition of the Pacific walrus population and pollution of the Arctic ecosystem.

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