Climate Change Linked with Higher Chemical Load in Polar Bear Diet

Polar bears are changing their diets to adapt to climate change, a new study has found. Researchers also found that a change in the diet has led to increase in toxic chemicals in the bears' bodies.

The study was conducted by researchers from the Greenland Institute of Natural Resources, Aarhus University (Denmark) and their colleagues. The team found that the diet of polar bears has changed over the past few decades and their tissue samples are showing high levels of contaminants.

 Polar bears primarily feed on three species of seals; the high Arctic ringed seal and the two sub-Arctic species harp seal and hooded seal. The number of ringed seal in the wild declined dramatically in past 30 years, leading to the bears switching over to the sub-Arctic seals.

At first glance, it may look like polar bears are doing better now. But, their tissue samples show that they are accumulating unhealthy levels of contaminants.

"The problem is that the sub-Arctic seals that the polar bear has switched to, have a higher content of contaminants because they live closer to the industrialised world and are higher up in the food chain. Therefore, climate change undermines the improvements that you would otherwise have obtained owing to international regulations in the use of environmental use of persisten organic pollutants (POPs). We can see that the content of the POPs after year 2000 decreases slower in the polar bear than in, the ringed seal," Professor Rune Dietz, Aarhus University explained in a news release.

The study was based on adipose tissue taken from 310 polar bears hunted by East Greenland Inuits from the Scoresbysund area between the year 1984 and 2011. 

Previous study by researchers at the Carleton University and Aarhus University had found that at least eight brain regions of polar bears had significant amount of several PFASs including perfluorooctane sulfonate (PFOS) as well as several compounds of perfluorinated carboxylate (PFCAs).