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Arctic Warming Puts Polar Bears at Higher Risk of Disease—Could Our Food Chain Be Next?
As Arctic temperatures rise, polar bears face increasing threats from bacteria, viruses, and parasites at levels not seen since the '90s. Melting ice and rising temperatures may be exposing these majestic animals to dangerous diseases, and experts warn that the impact could ripple up the food chain—potentially affecting humans too. Explore the details of how climate change is reshaping the Arctic and posing unprecedented risks to wildlife and ecosystems alike.
Climate change and rising temperatures are far more impactful than you might think: polar bear habitats are shrinking rapidly!
The warming global climate is making survival increasingly difficult for polar bears. However, the challenges they face don’t stop there. Polar bears—and the Arctic itself—are now confronted with an increasing threat from microorganisms and parasites.
Polar bears in Alaska are currently exposed to five more pathogens than they were just a few decades ago.
Karyn Rode, a wildlife biologist at the Alaska Science Center of the U.S. Geological Survey in Anchorage, explains, “Warming allows pathogens to thrive in environments where they couldn’t survive before.” The extent of warming’s impact on the Arctic isn’t fully understood, which is why Rode and her colleagues are examining the polar bear immune system.
The polar bear population in the Chukchi Sea is a valuable sample for observation.
Studies show that these bears, native to the waters between Alaska and Russia, are spending longer periods on land in the summer due to the dramatic melting of sea ice. This prolonged time on land increases their exposure to pathogens.
Researchers analyzed blood and fecal samples from 232 Chukchi bears collected between 2008 and 2017.
These samples were screened for antibodies against bacteria, viruses, and parasites. The findings indicated “the presence of antibodies aimed at fighting specific pathogens.” This data was then compared to analyses from samples collected from 115 bears between 1987 and 1994. Rising antibody levels signal an increase in diseases!
The illnesses affecting polar bears are on the rise, with some diseases even doubling in frequency.
Since the 1990s, the prevalence of exposure to the parasite Neospora caninum and to bacteria causing diseases like brucellosis and tularemia has at least doubled among polar bears. Additionally, more bears in the current cohort have antibodies against canine distemper virus, and exposure to the parasite Toxoplasma gondii has surged from about 2% to 14%, a sevenfold increase!
Rode believes that polar bears “are likely not the only species experiencing greater exposure to these pathogens”; the entire food chain is impacted.
For example, in recent years, ringed seals—a primary prey species for polar bears—have been observed dying from an unknown disease. Given these concerning trends, scientists have broadened their research efforts.
Andy Dobson from Princeton University notes that while the findings are intriguing, they aren’t conclusive, as the samples come from two different geographic locations.
Rode also highlights that some polar bears are hunted and consumed by humans, underscoring the need for more research to determine whether these pathogens pose a risk of infecting people.
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