Yum! Potential new crab fishery if only the Antarctic continental shelf warms a bit

Perhaps I’m a glass half-full kind of guy but I don’t really see a problem with potential new fisheries (I don’t see them as particularly likely, either, so perhaps it’s half-empty after all)

Antarctic king crabs warming up to invade continental shelf, threatening unique marine community – Dangerous and disruptive king crabs lurk in a deep pocket of the Antarctic continental shelf, clamoring to escape their cold-water prison to reach and permanently change the shallower, prehistoric paradise above.

A team led by University of Hawaii oceanographer Craig Smith spotted the meter-long monsters in February 2010. It was the first time researchers have seen king crabs on the continental shelf—a vast undersea platform that surrounds the Antarctic continent. The crabs are disrupting the environment, feasting on myriads of chilled, undersea animals that had thrived without natural predators for millions of years.

Smith and his team were surprised to find the crabs at depths of 980 meters to 1440 meters in Palmer Deep, a basin within the continental shelf off the Western Peninsula of Antarctica. They reported their observations on September 7 in the Proceedings of the Royal Society B.

“We were actually studying it for other reasons and we did an ROV (remote operated vehicle) survey,” Smith told mongabay.com. “We were interested in the bottom fauna, and that’s when we discovered the crabs—this big population of crabs.”

Smith’s team estimates more than 1.5 million king crabs (Neolithodes yaldwyni) are trapped in Palmer Deep. They’re particularly sensitive to temperature: magnesium that’s ubiquitous in the ocean can act as narcotic in cold seawater and can knock sluggish crabs unconscious and kill them, according to marine biologist Richard Aronson of the Florida Institute of Technology in Melbourne.

The Antarctic shelf waters above Palmer Deep are a fraction of a degree colder, a peculiarity of the parts of the ocean near Antarctica. That seems to be the only thing preventing the spindly crabs from lumbering onto the main shelf 250 meters above their stomping grounds. In the colder conditions above 850 meters in the basin, the crabs and their traces vanish, said Smith. (mongabay)

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