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As the polar seas are heated, mammals will find less sluggish, prey



Global warming will make life for mammals and birds in the polar seas difficult by harvesting fish that are slow, stupid and easy to catch in icy water, scientists said on Thursday.

Seals, whales, penguins, and other warm bodies have polar seas partly because their constant internal temperatures allow them to descend quickly and remain more vigilant than cold-blooded prey, they write in the journal Science.

But rising temperatures in the Arctic Ocean and the seas around Antarctica slowly revive fish, from small mothers to big sharks whose bodies and brains slowly move into cold waters.

"Generally, warm predators are preferred when the prey is slow, stupid and cold," wrote the scientists led by John Grady of Michigan State University.

"Being faster than your prey or your enemies … is an important asset to surviving and getting food," Grady told Reuters by emailing the results of scientists in the United States, Germany, Canada and England.

Deadly Sharks

– Faster sharks are deadly sharks. The most vulnerable mammals and birds are fast-moving fish and need to worry about shark predators: it includes many penguins, owls and sea lions, "he writes.

The great variety of marine mammals and seabirds in the polar regions is biologically strange, because the species are more diverse closer to the equator. The advantage of the warm body in the icy waters helps to explain the paradox.

Scientists have calculated that increasing degrees of sea surface temperature would lead to a 12% decrease in the abundance of marine mammals at each degree of Celsius (1.8 Fahrenheit).

Almost 200 governments have committed themselves in the Paris Climate Agreement for 2015 to limit the rise of temperatures to "well below" two degrees Celsius over pre-industrial times by removing fossil fuels. But governments are lagging behind and temperatures are expected to rise by 3C (5.4F) or by 2100, according to U.N.

The polar struggle for power between warmth and cold-blooded beings is one aspect of warming, which also causes many species of fish and other marine life to the poles or to the depths.

And scientists have discovered that in recent years thick layers of fat, a sign of health for Arctic mammals, have settled on seals of harps and whales. This may be a signal that they are losing their competition from cod when catching smaller fish.

"Codes have invaded some of the areas where harp seals and mink whales have been fed without competition," said Torre Hug, a Norwegian marine research scientist. He did not participate in the study on Thursday.

Posted in Daily Times, January 26father 2019,


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