A study published in the scientific journal PLOS One reveals that polar bears today face a greater risk of contracting viruses, bacteria and parasites that they were less likely to encounter 30 years ago. This risk arises because the North Pole is warming.
The research provides clues about how Polar Bear disease may be linked to disappearing ice, scientists examined blood samples from bears in the Chukchi Sea, between Alaska and Russia. They analyzed samples that had been collected between 1987 and 1994, and studied samples three decades later, samples between 2008 and 2017.
Researchers found significantly more recent blood samples contained chemical signals indicating Polar Bears had been infected with one of five viruses, bacteria or parasites.
From the blood samples, it’s difficult to know how the bears’ physical health was affected, but wildlife biologist Dr Karyn Rode of the US Geological Survey said this suggests something is changing throughout the Arctic ecosystem.
The researchers tested for six different pathogens in total. Viruses, bacteria, or parasites that are primarily associated with land animals, but have been previously recorded in marine animals, including species hunted by Polar Bears.
“As sea ice disappears on a large scale and there is an increase in land use within (Polar Bear populations), we want to know if exposure has changed. “Especially for some pathogens which we think are land-oriented,” said Dr Rode, quoted by the BBC, Sunday, (3/11).
The five pathogens, as disease-causing agents are known, which have become more common in Polar Bears, are two parasites that cause toxoplasmosis and neosporosis. Two types of bacteria cause rabbit fever and brucellosis, and a virus causes canine distemper.
“Bears are generally quite resistant to disease. “This disease is not normally known to affect bear populations, but I think what it highlights is that things (in the Arctic) are changing,” Dr Rode explained.
In the US, polar bears are classified as an endangered species. Scientists say the biggest threat to their future is the loss of sea ice habitat, which they rely on as a place to pounce on marine prey. Dr Rode explained that Polar Bears are the main predators.
Previous research using lapel cameras on bears showed that, because they spend more time on land, when there is no sea ice available for hunting, the bears are unable to find enough calories.
“Our study shows they gain exposure to several pathogens primarily through their prey species. So, what we see as changes in pathogen exposure in polar bears is indicative of changes that other species are experiencing as well.”(M-3)
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**Interview with Dr. Karyn Rode, Wildlife Biologist at the US Geological Survey**
**Interviewer:** Thank you for joining us today, Dr. Rode. Your recent research reveals alarming trends regarding polar bears’ health as climate change progresses. Can you summarize what your study found?
**Dr. Rode:** Certainly. Our study highlights that polar bears are facing increased risks from a variety of pathogens due to the warming Arctic. By comparing blood samples from bears collected over 30 years, we found significant increases in the presence of viruses, bacteria, and parasites that these bears were less likely to encounter in the past.
**Interviewer:** It sounds concerning. What might be causing this rise in disease risks among polar bears?
**Dr. Rode:** The primary driver is the rapid melting of Arctic sea ice, which significantly alters the polar bear’s habitat. As ice disappears, these animals lose their primary hunting grounds for seals and are forced to spend more time on land. This shift brings them into closer contact with terrestrial pathogens that they normally wouldn’t encounter.
**Interviewer:** Did you focus on any specific diseases or pathogens in your study?
**Dr. Rode:** Yes, we examined samples for six different pathogens. We discovered that more recent samples showed chemical signals indicating infections by at least five viruses or bacteria that tend to be associated with land animals. This suggests a shift in the interactions between animal populations due to changing environments.
**Interviewer:** That shift sounds alarming. What are the potential implications for polar bear populations?
**Dr. Rode:** Increased exposure to these pathogens can weaken bear health, reduce their reproductive success, and ultimately affect population dynamics. We’re already seeing their starvation rates increase due to lack of food, and compromised health from infections can further exacerbate their struggles.
**Interviewer:** What can be done to help protect polar bears and their habitats?
**Dr. Rode:** Immediate action is crucial. Reducing greenhouse gas emissions to limit climate change is essential. Additionally, efforts should be focused on habitat conservation and monitoring the health of polar bear populations to better understand and mitigate the threats they face.
**Interviewer:** Thank you, Dr. Rode, for shedding light on this urgent issue. It’s clear that the changes occurring in the Arctic not only impact polar bears but the entire ecosystem as well.
**Dr. Rode:** Thank you for having me. It’s vital that we continue to raise awareness about these challenges and take action before it’s too late.
