Polar bears in Alaska are encountering a growing number of pathogens due to warming climates, as revealed in a study published in PLOS ONE on October 23. The research indicated that pathogens previously unable to survive in Arctic conditions are now persisting in these environments. This is believed to be a consequence of the rapid changes caused by climate shifts. The findings highlighted a significant increase in exposure among polar bears to viruses, bacteria, and parasites, posing new threats to their already vulnerable populations.

Pathogen Exposure in the Chukchi Sea Region

According to the study, blood samples collected from 232 polar bears in the Chukchi Sea between 2008 and 2017 were compared to samples from 115 bears surveyed between 1987 and 1994. This analysis revealed a marked rise in antibodies for pathogens such as Neospora caninum and bacteria causing brucellosis and tularemia. Exposure to Toxoplasma gondii, a parasite linked to cats, increased from 2 percent to 14 percent, while antibodies for the canine distemper virus were also more frequently detected.

Wildlife biologist Dr Karyn Rode from the U.S. Geological Survey, who contributed to the study, explained in a statement given to Science.org that warming temperatures are enabling pathogens to infiltrate regions previously inhospitable to them. This phenomenon was particularly evident in the Chukchi Sea, where polar bears have been forced to adapt to reduced sea ice by spending prolonged periods on land, often coming into contact with human activities and waste.

Implications for the Arctic Food Chain

The study also examined chemical markers in the hair of polar bears to assess their diets, which revealed a connection between prey consumption and pathogen exposure. The findings suggested that the entire Arctic food chain, including species such as ringed seals, could be impacted.
Concerns were raised about the potential risks to humans who rely on subsistence diets involving polar bears, as per sources. Dr Rode noted that further research is necessary to understand how these pathogens may affect other species and human communities in the region in another statement.

Wildlife disease ecologist Dr Andy Dobson of Princeton University also commented that while the research presents intriguing insights, additional data from across the population range would be required for conclusive results.