By Stephen Beech via SWNS
Polar bears are at greater risk from disease due to global warming, warns new research.
The threatened species are being increasingly exposed to germs and viruses as the Arctic warms, say scientists.
Three decades of blood samples suggest an increased exposure within their food web.
And the disease could spread to humans living in the region, warn scientists.
The findings of the new study, published by the journal PLOS One, show that polar bears now face a greater risk of contracting several bacteria or viruses- known as pathogens – than bears did 30 years ago.
Study co-author Dr. Karyn Rode, of the U.S. Geological Survey, said: “The environmental changes associated with global warming are creating new opportunities for viruses, bacteria and parasites to infect Arctic wildlife.”
As a top predator with a large range, scientists suspected polar bears may be affected by changes in disease transmission.
Researchers examined blood samples from polar bears in the Chukchi Sea from 1987 to 1994 and then three decades later, from 2008 to 2017, looking for antibodies to six pathogens.
Five of the pathogens had become more common in the later samples: the parasites that cause toxoplasmosis and neosporosis, the bacteria that cause rabbit fever and brucellosis, and the canine distemper virus.
Dr. Rode said: “The increases in the prevalence of these pathogens represent some of the most rapid changes in exposure ever reported among polar bears.
“The proportion of bears testing for antibodies more than doubled for three of these pathogens and was higher than levels reported for other polar bear populations.
“Despite this change, however, the body condition, reproduction and cub survival of polar bears in the Chukchi Sea has been stable suggesting that this increased exposure has not impacted population dynamics.
“These results suggest that pathogen transmission pathways have changed in this Arctic ecosystem.
Researchers also looked at factors that increased the bears’ risk of exposure to disease.
They found that exposure varied with diet and was higher in females than males, potentially as a result of pregnant females staying on land to raise cubs.
Dr. Rode said: “In the Arctic, where warming is occurring at nearly four times the global rate and polar bears are experiencing a rapid loss of their sea ice habitat, infectious diseases present a growing concern to both wildlife managers and human communities.
“Concurrent to sea ice loss are other environmental changes in Arctic ecosystems.
“Where sea ice loss has occurred, increases in land use during the summer has been one of the most common responses.
“This change in habitat use alters feeding behavior and energetics, interactions and potential conflict with humans, and exposure to novel pathogens.”
She added: “People living in the Arctic sometimes hunt polar bears for food, and many of the pathogens whose presence was detected in this study can also be transmitted to humans.
“Our findings highlight that there are a myriad of changes occurring in Arctic ecosystems that have the potential to affect animal and human health.”
