Mercury Levels in Arctic Foxes
By Molly Michelson
Arctic foxes on a Russian island called Mednyi in the northern Pacific have seen their population crash tremendously since the 1970s. Among the 100 or so foxes that still live on the island, small and juvenile foxes show high mortality rates, and the entire population exhibits low body weight and poor coat condition.
“When going into this project, we thought that an introduced pathogen would explain the poor condition of the foxes and their high mortality but after extensive screening, we did not find anything," says Alex Greenwood, one of the co-authors of the study. Instead, the researchers began to suspect that something else was at play. “If pathogens were not the cause, we thought perhaps pollutants could be involved.”
Sure enough, high levels of mercury were found in the foxes’ fur. In addition, using museum skin samples from this island population, the researchers also found that the foxes have been suffering from exposure to mercury for a long time.
While mercury levels in the Arctic atmosphere have been increasing recently due to sea ice melt, the researchers confirmed that the source of contamination for the foxes was their food; these foxes feed almost exclusively on sea birds and seal carcasses. Testing the seals and sea birds in the area, the team found equally high mercury levels.
The scientists also compared mercury levels in the Mednyi foxes to arctic foxes that live inland on Iceland. These foxes eat non-marine birds and rodents, and their mercury levels are much lower.
The researchers hope their study has conservation implications and urge the reduction of mercury pollution.