An ecosystem is highly dependent on all of its parts, and removing even a single species can result in serious consequences. Polar bears are at the top of the predators(食肉动物) where they live. They play an important part in the ecosystems. They feed on seal, fish and deer. Several other carnivores depend on the kills of polar bears. The failure to save polar bears might result in loss of these predators.
In addition, all large predators perform a very important function in their habitat: helping to control the populations of other species. When an animal group loses its natural predators, its population will rise rapidly, having a direct result in underpopulating other groups. A huge boom in population of Arctic seals would have a direct effect on the prey of seals, and could reduce numbers of certain types of fish.
This could also have a direct effect on humans, who might have to compete with Arctic seals for food supplies from fish. Lack of polar bears could eventually affect human food supply. Human beings shall save Polar bears to ensure the food supply.
There is no doubt that we should save polar bears. However, there is still another question: can they be saved? This is a matter that scientists debate because of rapid degradation(恶化) of the polar bears' environment in recent years due to warming temperatures. It is estimated that if the bears cannot adapt to changing climates, they might die out before the end of the 21st century, with about 50% of the animals disappearing by 2050. So time is running out!
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