Polar Bear Population Is Threatened And It Is Not Because Of Climate Change

Aside from threats of losing the polar bears' habitat due to climate change, there is another reason why they need more attention when it comes to wildlife conservation.

Smithsonian.com reported that a certain chemical has been proven to greatly affect the polar bear population. While these top Arctic predators are considered to have one of the slowest reproductive rates among mammals, a chemical called PCB (polychlorinated biphenyls), which has already been banned in the 1970s, was discovered to have poisoned their fertility.

According to the study conducted by researchers at Academy of Sciences in the Czech Republic, PCBs have impacted polar bear's fertility by disrupting their hormonal functions. Although the production of chemicals has already been banned, particles have already contaminated the air and ocean where fish, which make up a seal's diet, feed on.

Seals are polar bears' prey, so it means that these top predators ingest the highest amount of PCBs than any other species in the food chain. Furthermore, it is the males that retain more contamination since they do not have the chance to actually excrete it.

"The cub gets contaminated, but on the other hand, the female gets rid of some of its burden (when she breast feeds)," explained study's lead author Viola Pavlova. "The males can't get rid of the contamination that easily."

Polar bears are currently on vulnerable status in conservation. One of the possible major reasons can be a female's ignorance of a male's infertility, which already denies one of her only five chances of breeding in her lifetime. This means that any threat to a polar bear's fertility can be a huge factor to hinder the species' population growth.

"The biggest danger of such a secret infertility is that the males are actually taking up the chance for a female to conceive," Pavlova added. "So it is very important for the females to have enough males available to breed with."

This study was published in the journal Proceedings of the Royal Society B.