Temporal trends in beluga, narwhal and walrus mercury levels: Links to climate change

Abstract

The exposure of Arctic marine mammals to contaminants may change via ecological dynamics in response to climate change. For example, changes to the structure of the food web or shifts in regional foraging could affect dietary exposure. We examined the temporal variation of total mercury (THg) concentrations in Hudson Bay beluga (Delphinapterus leucas) and Foxe Basin walrus (Odobenus rosmarus rosmarus) and narwhal (Monodon monoceros) with δ15N and δ13C signatures (beluga only) and the North Atlantic Oscillation. We found THg concentrations in female Arviat beluga muscle tissue decreased significantly from the early 1980s to 2008. Similarly δ13C signatures in beluga sampled from Arviat declined over the same time period. δ15N and the NAO index did not appear to significantly change over time nor strongly influence THg concentrations. Results suggest beluga summering in Arviat may forage in more offshore areas upon less contaminated prey in response to the increasing ice-free season over the last couple of decades. As sea ice continues to recede, dietary mercury exposure may continually decrease in beluga and other marine mammals. © 2010 Springer Netherlands.