Climate change is threatening Polar Bears deeper than feared

Due to human activity, the climate crisis and global warming, the polar bear is losing its habitat and is endangered by the action of pathogens, always a consequence of climate change

by Lorenzo Ciotti
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Climate change is threatening Polar Bears deeper than feared

Polar bear lives in the Arctic and its habitat is included in 6 countries: Canada, especially in Manitoba, Newfoundland, Northwest Territories, Nunavut, Ontario, Québec, Yukon, Alaska, Russia, Greenland, Norway to Svalbard and Iceland.

The current polar bear population is estimated at 20-25,000, 60% of which are in Canada. As evidence of this, a polar bear is depicted on the Canadian 2 dollar coin. Polar bear is (an alpha predator, being at the top of the food chain it therefore has few enemies.

Only the young can be attacked by wolves and other bears such as browns, blacks and even other polar bears. Of course, man remains the real danger for this species. Due to human activity, the climate crisis and global warming, the polar bear is losing its habitat and is endangered by the action of pathogens, always a consequence of climate change.

Long-term increases in pathogen seroprevalence in polar bears (Ursus maritimus) influenced by climate change, published on the Global change biology, makes an interesting retrospective on the subject. The researchers said: "The influence of climate change on wildlife disease dynamics is a burgeoning conservation and human health issue, but few long-term studies empirically link climate to pathogen prevalence.

Polar bears (Ursus maritimus) are vulnerable to the negative impacts of sea ice loss as a result of accelerated Arctic warming. While studies have associated changes in polar bear body condition, reproductive output, survival, and abundance to reductions in sea ice, no long-term studies have documented the impact of climate change on pathogen exposure.

We examined 425 serum samples from 381 adult polar bears, collected in western Hudson Bay (WH), Canada, for antibodies to selected pathogens across three time periods: 1986-1989 (n = 157), 1995-1998 (n = 159) and 2015-2017 (n = 109).

We ran serological assays for antibodies to seven pathogens: Toxoplasma gondii, Neospora caninum, Trichinella spp., Francisella tularensis, Bordetella bronchiseptica, canine morbillivirus (CDV) and can ine parvovirus (CPV).

Seroprevalence of zoonotic parasites (T. gondii, Trichinella spp.) And bacterial pathogens (F. tularensis, B. bronchiseptica) increased significantly between 1986-1989 and 1995-1998, ranging from + 6.2% to + 20.8%, with T. gondii continuing to increase into 2015-2017 (+ 25.8% overall).

Seroprevalence of viral pathogens (CDV, CPV) and N. caninum did not change with time. Toxoplasma gondii seroprevalence was higher following wetter summers, while seroprevalences of Trichinella spp. and B. bronchiseptica were positively correlated with hotter summers.

Seroprevalence of antibodies to F. tularensis increased following years polar bears spent more days on land, and polar bears previously captured in human settlements were more likely to be seropositive for Trichinella spp.

As the Arctic has warmed due to climate change, zoonotic pathogen exposure in WH polar bears has increased, driven by numerous altered ecosystem pathways."