Polar bear on sea ice near Beaufort Sea,
Alaska. (Image by anim1865 via Flickr CC BY 2.0 )
A drop in mercury levels was discovered among southern Beaufort Sea polar bears, something the researchers say may suggest a changing diet and a shift in foraging habits. Scientists collected hair samples from Beaufort polar bears over a seven-year period, and measured the mercury concentration in these samples. Results showed a 13% drop in mercury levels, which the researchers attributed to a change in diet. Polar bears are at the top of the food chain, which means they also get all the mercury accumulated in the diets of their prey. As the sea ice diminishes, instead of hunting ringed seals and beluga whales, polar bears are now more likely to consume bowhead whale and bearded seals. Bowhead whales, in turn, feed on zooplankton, which has lower mercury concentrations than the fish and invertebrates that make up ringed seals’ and belugas’ diets.
Authors:
Melissa A. McKinney , Todd C. Atwood, Sara Pedro, and Elizabeth Peacock
Corresponding Canadian author:
Melissa A. McKinney, Wildlife and Fisheries Conservation Center, Department of Natural Resources & Center for Environmental Sciences and Engineering, University of Connecticut, CT, Email:
melissa.mckinney@uconn.edu
Original paper published in Environmental Science & Technology on June 14, 2017.
