Antarctic invasion by crabs and sharks might endanger native marine life

Washington, Feb 16 : A new research has indicated that as a result of global warming, predatory animals such as crabs and sharks are all set to invade the Antarctic waters, thus endangering the native marine life.

According to a report in Discovery News, back in the late Eocene epoch, predatory animals such as sharks and crabs were driven away from Antarctic depths when the continent and its surrounding waters freezed up.

The result was a virtually predator-free zone on the seafloor and a paradise for worms, sea lilies, clams, brittle stars and other bottom-dwelling animals.

But now, researchers from the University of Rhode Island have determined that due to global warming, water temperatures in the Antarctic waters are rising to the point where, very soon, the long-exiled predators could return and wreak havoc on the ocean floor.

Along the Antarctic Peninsula, the northernmost, warmest part of the continent, global warming is raising air temperatures quickly.

"Water temperatures have been warming as well, at a rate of about 0.04 degrees Celsius per year," said researcher Cheryl Wilga of the University of Rhode Island. "That comes to about one degree per 25 years," she added.

Compared to the relative stability seen for tens of millions of years, that's incredibly fast. As a result of this extraordinary warming, king crabs have already started to show up in the region.

The crustaceans have been found way down on the deep slopes off the Antarctic continental shelf - where the water is slightly warmer than elsewhere.

"As the upper waters continue to warm, nothing will stop the king crabs from moving up onto the continental shelf and feasting. That will "hammer" the old seafloor communities," said marine scientist Richard Aronson of Dauphin Island Sea Lab and the University of South Alabama.

"We expect the populations of seafloor invertebrates to take a dive," he added.

"The species in the Antarctic (seafloor) have no defense for shell-crushing predators," said extreme species researcher Brad Seibel, also of the University of Rhode Island. "I don't think that anyone was really aware of this issue," he added.

Sharks are also set to return to the sea floor around Antarctica, with the most likely candidate being the spiny dogfish, which are already abundant off the coast of South America, poised for invasion as soon as the water gets a tad warmer.

According to Wilga, if there's any shark that can eke out a living first in the warming waters, it is the diminutive and virtually global spiny dogfish.

Though the predator invasion of Antarctica may be unavoidable, it could be moderated if something is done immediately to reduce emissions of global warming greenhouse gases into the atmosphere.

"As global warming proceeds, the deeper water around Antarctica will only get warmer," said Aronson.

"The momentum of global warming is, indeed, huge and cannot be stopped, but it can be slowed," he added.

ANI