Previous studies had already shown that mercury in the environment accumulates in the hair and skin of polar bears that live in the Beaufort Sea, in the waters south of the Arctic, damaging their health. Now, ironically, the same effect that bears have had to change their eating habits , climate change, is the one that has given them an advantage: bears ingest less mercury , which translates into bears in better conditions of health and greater span . This is pointed out by a study published by the journal Environmental Science & Technology.
For the preparation of the study, the concentration of mercury, a mineral that can affect the nervous system of the polar bear, was analyzed in the tissue and hair of specimens from the southern area of Beaufort, between 2004 and 2011. During that stage , mercury concentrations decreased 13% per year. Lower mercury concentrations were associated with higher body mass index (BMI) and higher proportions of lower trophic position .
Scientists suggest that this decrease in mercury in bears is due to a change in their feeding routines: polar bears no longer feed on animals that accumulate mercury , such as seals, but have been forced to hunt new prey due to to thaw.
Good news for bears? Relatively. “Sometimes things like this happen in ecology. What you hope will have a negative effect, have a positive effect. They are ecological traps “, in the words of Ana Payo, a graduate in oceanography and environmental sciences and a doctor in biodiversity.
The polar bear is a predator found high up the food chain in the Arctic ecosystem. Now he is forced to hunt other types of prey , such as boreal whales and bearded seals. Both species accumulate a lower concentration of mercury than ringed seals , on which the predator would normally feed.
The mercury that accumulates in animal tissues, however, comes largely from emissions from human industrial activities.
References:
Melissa A. McKinney. (2017). Ecological Change Drives a Decline in Mercury Concentrations in Southern Beaufort Sea Polar Bears. Environmental Science & Technology. DOI: 10.1021 / acs.est.7b00812
