There aren't supposed to be crabs in Antarctica. It's been too cold for the beclawed crustaceans to congregate round the southern pole for some 30-40 millions years. But now, thanks to some inexplicable phenomenon that nobody can quite put their finger on (come on scientists, get on this), ocean waters have been warming up. And the crabs are invading.
And "invading" is the right word. The crabs are like marauding pillagers, wiping out unsuspecting antarctic wildlife as they march southward.
A recent piece in the science journal Nature offers an extended look at the alarming trend. Scientists had been watching the feed from a remote-operated vehicle (ROV) in the deep Antarctic, when they came across (another) zone that had been altogether empty of brittle stars and sea pigs, the region's typical fauna. They'd been wiped out, and they soon saw the culprit: crabs.
It probed the mud methodically — right claw, left claw, right claw — looking for worms or shellfish. Another crab soon appeared, followed by another and another “They're natural invaders,” murmured Craig Smith, a marine ecologist from the University of Hawaii at Manoa. “They're coming in with the warmer water.”
... warm water from the ocean depths is now intruding onto the continental shelf, and seems to be changing the delicate ecological balance. An analysis 1 by Smith and his colleagues suggests that 1.5 million crabs already inhabit Palmer Deep, the sea-floor valley that the ROV was exploring that night. And native organisms have few ways of defending themselves. “There are no hard-shell-crushing predators in Antarctica,” says Smith. “When these come in they're going to wipe out a whole bunch of endemic species.”
Researchers are worried that rising crab populations and other effects of the warming waters could irrevocably change a sea-floor ecosystem that resembles no other on Earth.
The whole situation, in other words, is like this.
OK, actually more like this.
Still freaky though. Scientists have been aware that crabs have been storming the Antarctic for a couple years now, but the latest research reveals the extent of the invasion–a million and a half crab-vikings–and that it may have began decades ago, when the waters first grew warm enough.
And obviously, climate change is the presumed culprit here; the crab-monitoring scientists express little doubt that global warming has driven this shift.
Richard Aronson, another marine biologist at the Florida Institute of Technology in Melbourne, who was part of a team that found crabs on another part of Antarctica's continental shelf in December 2010. “It's a fascinating thing,” he says. “A little scary, because it's a very obvious footprint of climate change.”
Of course. Global warming is changing the game for crustaceans everywhere; not just the Antarctic. It's turning lobsters into cannibals in the Atlantic, and it's rendering others more prone to disease. But perhaps nowhere else is it giving a particular crustacean such a potentially devastating advantage–which is why scientists are doubling their efforts to study these particular areas of Antarctic biosphere, before the crabs steamroll it, leaving a path of brittle star legs and plundered sea mud in their path.