Polar bears and pollution is a subject that has not been written about as widely as the effects of global climate change but added together they represent a potentially fatal blow to the Polar bear population.
Most of the pollution in the Arctic is transported Northward by the large rivers draining into the Arctic and on wind and ocean currents that bring pollutants from southern latitudes. Polar bears feed on other Arctic marine animals such as seals which easily store fat in their blubber. As a result, a Polar bear carries a concentration of pollutants many times greater than that in the rest of the Arctic Ocean.
PBDEs (Polybrominated diphenyl ethers), a flame retardant found in hard plastic and polyurethane foam, have been detected in every Arctic species tested including fish, seals, Polar bears, beluga whales, pilot whales and birds. Many of these species are on the menu of Polar bears which are at the top of the Arctic food chain.
From water to algae to shrimp to cod to ringed seals to Polar bears — at each step up in the food chain, PBDEs increase five- to tenfold in a process called bio-magnification.
continued...Based on studies in other species, it is reasonable to believe that the concentration of pollutants in Polar bears in some areas are negatively affecting the immune system, hormone regulation, growth patterns, reproduction, and survival rates of Polar bears. Because cubs are being nursed on the fat rich milk of their mothers, they are being exposed to very high pollution levels.
Recent studies in Norway and Canada show that Polar bears' immune cells and antibodies, needed to fight off disease, have been suppressed, and that their levels of testosterone, progesterone, vitamin A and thyroid hormones are altered by PBDEs. The most polluted Polar bears live in NE Greenland, the Barents Sea and the Kara Sea.
A mother Polar bear stores chemicals from a lifetime of exposure in her fat cells. The bodies of Polar bears are very efficient at metabolizing (breaking down) some pollutants but the problem is that many of these metabolites (by products of the break down process) are very active in their bodies before they are excreted. Furthermore, because female Polar bears fast during gestation the amount of pollution that is active in their bodies increases because they are using their fat stores for energy. This is where the pollutants they ingest from other marine animals is naturally stored. Because Polar bear cubs are nursed on fat rich milk, the cubs are exposed to very high pollution levels from their mothers and this is what makes the future of Polar bears questionable. That's borne out by the fact that most Polar bears die before their first birthday. This can be due to natural causes of course but pollution has increased their mortality rate significantly.
Aother major concern with Polar bears as a result of pollution pertains to their reproductive and immune systems. There is evidence that suggests that the hormone system of Polar bears is affected by pollution and this may interfere with reproduction and growth and a weakened immune system may mean that these Polar bears are more susceptible to succumbing to disease or parasites.
Given that no Polar bear in the world is free from pollution, there is a great cause for concern. Although some pollutants such as PCBs have had their levels dramtically reduced, there is still a lot of work to be done by governments to totally erase the negative impact that human pollution has on Polar bears.
2 comments:
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ANYAWY THANKA
What an extremely concerning issue!
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What I mean is that if Polar Bears are being affected somehow, then all human beings will be too.
It is about time for us to realized it and do something about it!
C'mon! Let's awake!
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