gKey Takeaways:
– Polar bears’ survival in warmer global conditions is increasingly threatened not only by habitat reduction but by a rise in exposure to pathogens and parasites.
– A comparison between past and present data shows increased exposure to pathogens, indicating that these are now persisting in environments previously inhospitable for them.
– Varied diets among the bears directly influence their exposure to pathogens, implying that this threat extends to the entire food chain.
The Climatic Threat to Polar Bears
Polar bear populations, particularly those near Alaska, face burgeoning threats associated with a warming world. Their pristine white habitats are shrinking and now another subtle, yet potentially deadly, change is surfacing: an increased exposure to harmful pathogens.
As the climate warms, it has created conducive conditions for previously absent pathogens to thrive. Karyn Rode, a wildlife biologist at the U.S. Geological Survey’s Alaska Science Center in Anchorage, explains, “With warming, it just allows pathogens to persist in environments they couldn’t persist in before.”
Decoding the Pathogen Puzzle and its Impacts
The extent of these changes remain understudied in the Arctic. But as it undergoes rapid transformation due to climate change, examining polar bear immune systems could unlock essential insights. The focus is specifically on the Chukchi Sea polar bear population, native to waters near Alaska and Russia.
These bears have witnessed drastic shrinkage in sea-ice habitats, forcing them to spend prolonged periods on land, particularly in summers. Unfortunately, this exposes them to humans and garbage, major carriers of pathogens. The Chukchi bears also venture farther south than many other polar bear populations, thereby intensifying their potential exposure to pathogens.
In their research, scientists analyzed blood serum and fecal samples from 232 Chukchi polar bears collected from 2008 to 2017, inspecting for antibodies against a range of bacteria, viruses, and parasites. The presence of these antibodies indicates the bear’s past or present encounters with the respective pathogen. Comparison was also drawn with similar analysis results from 115 bears taken from 1987 to 1994.
A Closer Look at the Findings
The study showed that the exposure rate of polar bears to the parasite Neosporum caninum and to the bacteria behind diseases such as brucellosis and tularemia has at least doubled since the 1990s. Recent data also revealed a higher number of bears with antibodies against canine distemper virus. Additionally, polar bears who’d come into contact with the parasite Toxoplasma gondii increased sevenfold.
Link Between Diet, Pathogens and Increased Threat
Interestingly, diet plays a significant role in determining a polar bear’s pathogen exposure. Varying dietary habits among individual bears affect which animals they primarily eat, therefore altering the bacteria and viruses they encounter.
The wider implication goes beyond polar bears: if they are encountering higher levels of these pathogens, it’s likely that other species within the food chain are also affected. In recent years, ringed seals, one of the polar bears’ primary prey, have suffered significant die-offs from an unidentified disease. This has prompted researchers to investigate pathogens in predatory polar bears.
The pathogens’ progression can influence the entire food chain, with implications for human beings as well. Polar bears sometimes end up in human consumption due to subsistence hunting. However, whether there’s a potential risk of these pathogens infecting people requires further research.
The observations are intriguing, but the matter requires more comprehensive study, as the sampled bear populations were from different geographic locations. Nonetheless, this emerging understanding necessitates a much-needed focus on the impact of critical pathogens on our wildlife amid a changing planet.