The future of polar bears, one of the Arctic’s most iconic inhabitants, is becoming increasingly precarious as the region continues to warm, research has found, according to a BBC 24 report. While much attention has been paid to melting sea ice and habitat loss, a growing body of research highlights another emerging threat: an increased risk of disease. As temperatures rise, polar bears are facing new health challenges that could further threaten their survival.
Scientists reportedly tested blood samples from polar bears living in the Chukchi Sea within the Arctic Circle to provide clues to the link between polar bear disease and melting glaciers. By comparing polar bear blood samples from 1987-1994 and 2008-2017, the scientists found that there were significantly more chemical elements in the blood of polar bears 30 years later, suggesting that the local polar bears were infected with one of the viruses, bacteria, or parasites that used to be mostly associated with land animals.
The health of the polar bears indicates that the entire Arctic ecosystem is changing,” said Rod, a wildlife biologist with the U.S. Geological Survey (USGS). This study spans 30 years, and as glaciers have declined substantially and the amount of land suitable for polar bear populations has gradually increased, we wondered what changes would result from exposure to terrestrial pathogens. In general, polar bears are highly resistant to disease, and as top predators, they are exposed to pathogens from land primarily through their prey. Although it is not yet clear how much these pathogens are affecting polar bear population numbers, this study nonetheless reflects to some extent the changes in the Arctic ecosystem.
Climate Change and the Risk of New Diseases
The Arctic is warming nearly four times faster than the global average, leading to a massive loss of sea ice, on which polar bears depend for hunting, breeding and travel. These changes are forcing polar bears to spend more time on land, especially in areas where the ice melts earlier in the year. This change not only affects their hunting patterns, but also increases their risk of contracting new diseases. Warmer temperatures and a longer ice-free season create favorable conditions for pathogens and parasites that were previously difficult to survive in the Arctic. For example, several pathogens carried by birds and marine mammals are now finding suitable environments in these new climatic conditions and could potentially enter polar bear populations.
Some Diseases Affecting Arctic Wildlife
Toxoplasmosis: Caused by Toxoplasma gondii, this parasitic infection usually affects cats, but is increasingly being found in marine mammals. As the open water season lengthens, polar bears may encounter these infected species more frequently, increasing their risk of infection.
Avian Influenza and Canine Distemper Virus (PDV): Polar bears often share territory with seals and seabirds, which may carry these viruses. Outbreaks of Avian Influenza and PDV are becoming more common in the Arctic due to the close contact between polar bears and these animals, threatening polar bear populations.
Zoonotic Pathogens: As tourism, oil drilling and fishing activities increase in the Arctic, polar bears may also be exposed to pathogens transmitted by human activities. This human-wildlife interaction poses a risk of zoonotic diseases that may affect polar bear health in unpredictable ways.
Impact of Disease on Polar Bears
For a species already stressed by habitat loss and food scarcity, disease is an additional serious challenge. Malnutrition and prolonged fasting can weaken polar bears and make them more susceptible to infections. If disease further compromises their health, the long-term consequences could be devastating to Arctic ecosystems.
For example, studies have shown that exposure to pathogens reduces reproductive success and overall population growth rates, both of which are critical to polar bear survival. A decline in polar bears would not only affect polar bears as a species, but also disrupt the fragile Arctic food web. The IUCN has listed the polar bear as a vulnerable species on the verge of extinction. While climate change is a key factor in the population’s decline, the biggest threat to polar bears is still the gradual loss of sea ice habitat.
Protecting polar bears in a warming Arctic requires a multifaceted approach, and reducing greenhouse gas emissions is critical to slowing Arctic warming and protecting sea ice habitat. Surveillance and research should also be expanded to better understand disease patterns in Arctic species, enabling scientists to take preventive measures where necessary. In addition, habitat protection can reduce human intrusion and limit the spread of zoonotic diseases among wildlife.
The future of polar bears is complicated by a warming Arctic, with multiple environmental and biological threats in addition to melting ice. By understanding and addressing the increased risk of climate change-related diseases, we can better protect the health and longevity of polar bear populations and the Arctic ecosystem as a whole. For the future of polar bears, global action is needed to reduce greenhouse gas emissions and find solutions to adapt to climate change.
