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The long term survival of polar bears is being threatened by man-made pollution that is reaching the Arctic.
This conclusion comes from a major review of research into how industrial chemicals such as mercury and organochlorines affect the bears.
The review suggests that such chemicals have a range of subclinical effects.
When added together, these can have a dramatic and potentially fatal impact on the bears' bones, organs and reproductive and immune systems.
The review, an analysis of more than a decade's research into the effect of pollution on bears, is published in the journal
Dr Christian Sonne Aarhus University
A range of man-made pollutants reach the
These include toxic metals such as mercury, organohalogen contaminants (OHCs) including organochlorines, and polybrominated diphenyl ethers (PBDEs) and perflourinated compounds (PFCs), which are used industrially in insulating fluids, as coolants, in foams and electronics and as pest control agents.
Such chemicals are often fat-soluble and accumulate in the fat of many animals, which are then eaten by top
These top predators are then exposed to increasingly concentrated levels of toxins.
But the impact of these toxins on polar bears has been difficult to measure, with the
That is party because it is logistically difficult to take many and repeated samples of blood or tissue from live polar bears.
Also, only free-ranging healthy animals that are not clinically sick tend to be sampled, making the overall population appear to be healthier than it already is.
So veterinary scientist and polar bear expert Dr Christian Sonne, of the
Previously, Dr Sonne was part of a team of researchers which found that "stress" linked to pollutants and shrinking sea ice appeared to be
His new analysis includes the results of more than 200 organ and skull tissue samples taken from 80 bears in East Greenland between 1999 and 2009, as well as repeated measurements and observations of bears living in the Svalbard archipelago, Norway.
These studies reveal a number of ill-effects associated with industrial pollutants.
However, such studies can only show that contaminant levels are correlated with ill-effects, not that they cause them.
Bears and dogs
So Dr Sonne investigated the direct impacts of Arctic pollutants on two other top predators living in the region, Norwegian
In 2003, researchers started a two-year study in which they fed Arctic foxes clean or contaminated whale blubber. One fox of a pair of brothers was fed clean food as a control, while the other brother ate contaminated food.
Having eliminated all other influences, such as gender and age, the researchers showed that foxes exposed to environmental levels of pollutants do suffer harmful effects.
For example, PCBs trigger decreases in bone density and damage the liver, mercury and organochlorines cause renal lesions, while OHCs alter the amount of vitamins circulating in the blood.
Similar effects were found in comparable studies on Greenland sledgedogs.
"Polar bear studies are correlative, but that is not conclusive as being 'cause and effect'," explains Dr Sonne.
"So including dogs and foxes as model species is important [because] you use species that are much like polar bears, and the species were exposed to similar food items as polar bears."
The impact on the bears is likely to be greater even than those effects which show up in studies.
"It is really important to understand that all organ systems are tied together," says Dr Sonne.
So individual pollutants may only have subtle, non-clinical effects on particular parts of a bear's body.
But in concert, the overall impact can be devastating, reducing an individual bear's ability to hunt, reproduce and resist disease.
"After being very sceptical, I now feel that the impact on bears may be true," says Dr Sonne.
Climatic impact
He also concludes that climate change will exacerbate the impact of pollutants on the bears.
As the level of sea ice declines with warming temperatures, polar bears are fasting for longer.
That may mean they eat fewer seals and therefore less pollutants overall.
But they will have to burn fat to compensate.
That will release greater concentrations of toxins from their fat stores into their blood, says Dr Sonne.
This will cause further illness, weakening bears that will already be in poorer condition and may be exposed to new and more virulent pathogens capable of surviving in a warmer Arctic.
Dr Sonne's research is published a week after another separate study published in the journal
Summary :
Man-made pollution is proven to have caused the lives of polar bears in the arctic. Even the air and water has been polluted by chemicals that have been thrown out by the humans. Also, this has affected the animals to be less reproductive and has damaged the mammal's body. The foxes living the Arctic were also affected by the pollution in the area. With Global warming also around the corner, the bears will fast even longer. This will affect their health as they need to burn out fats to compensate the lack of daily intake. These bears will also have a shorter survival period.
Comments:
This article is written for polar bear lovers and those who wants to know more about what's happening in parts of the world.
The aim of the article is to let people know what global warming has done to the animals living in the arctic and to tall them to stop polluting the earth. They have conducted studies and research to show how some of these waste chemicals that is released to the sea has caused the bears their lives and health. Some examples are "studies reveal a number of ill-effects associated with industrial pollutants" & "This will cause further illness, weakening bears that will already be in poorer condition and may be exposed to new and more virulent pathogens capable of surviving in a warmer Arctic."
The significance of the article is to let other people in the world know that if the situation worsens, the polar bears will maybe go extinct as well as the other animals living in the arctic. It's relevance to the current situation is very important as people are happily living in the modern world, there are some others who are suffering. I think that this a very important time to wake ourselves up to a better thought of how or what can we do to help the situation be better but not worser.
After being very sceptical, I now feel that the impact on bears may be true
Dr Christian Sonne Aarhus University
Even Dr Christan has also felt the impact on the bears are being more real to them and let them be much more aware of the situation now. :)
posted by ALLŸ™ @ 10:00 PM
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