It's more probable for polar bears to contract pathogens.
Beyond the dwindling Arctic habitat, climate change poses another predicament for polar bears: an American team of researchers has concluded that the animals are encountering disease-causing pathogens more frequently.
For this study published in the journal "PLOS One", researchers led by Karyn Rode from the U.S. Geological Survey in Anchorage (Alaska, USA) examined blood samples from polar bears and looked for antibodies against six different pathogens - such as the parasite Toxoplasma gondii and the canine distemper virus (CDV). The samples came from two time periods: 1987 to 1994 and 2008 to 2017, collected from the polar bear population in the Chukchi Sea, which is part of the Arctic Ocean between Alaska and Siberia.
Infection rates have doubled for three pathogens
In comparison to the earlier period, five of the six pathogens were detected more frequently in the blood samples from after 2008. The infection rates for three of the pathogens had even more than doubled. Females, on average, were more frequently infected than males. This could potentially be due to many of them spending their pregnancy on land in this region, a theory the researchers propose. Alternatively, the preferred prey could also influence their exposure to individual pathogens.
Researchers estimate that the Arctic is warming at a rate almost four times faster than the global average. The polar bears' habitat, the sea ice, is disappearing rapidly. Meanwhile, climate change is enhancing the conditions for viruses, bacteria, and parasites in the Arctic. Through this study, the researchers aimed to determine how the spread of such pathogens has evolved. "As a top predator that roams large, remote areas, changes in pathogens and parasites in polar bears are a good indicator of changing transmission dynamics in Arctic ecosystems," they write.
More pathogens does not necessarily mean more sick polar bears
The results indicate that polar bears are encountering various pathogens more frequently today than in the past, but the exact impact on their health is unclear. "All the pathogens we detected can cause diseases in wild animals, but understanding the exact impacts on free-ranging animals is not straightforward," the authors write.
For example, a comparison with brown bear populations in Alaska suggests that pathogen contact has not yet significantly affected polar bear health. Further monitoring is necessary to evaluate the situation further.
The Commission has acknowledged the findings of the study published in "PLOS One," where researchers found an increase in infection rates for three pathogens in polar bears from the Chukchi Sea. The Commission is now considering the implications of this increase on the overall health and survival of polar bears in the Arctic.
