Image courtesy of denn via flickr
Don't look now, but an army of crabs is silently massing up along the borders of the Antarctic Peninsula, waiting for just the auspicious moment to launch a large-scale invasion. Notch another one up for global warming: though once limited by the Antarctic Ocean's frigid waters, rising sea temperatures in the region have made it possible for a wave of new species - crabs and other fast-moving predators - to make a return. This return, millions of years in the making, could fundamentally alter the region's species distribution - and cause many to simply disappear. The Independent's Steve Connor, reporting from the AAAS meeting in Boston, quoted Southampton University's Sven Thatje, who explained that crab populations, which have already become established in slighly warm, deeper waters, will soon be able to move on to the Antarctic Peninsula's shallower habitats.
Up until recently, crabs hadn't been able to make inroads into the Antarctic's cold waters because of their inability to eliminate magnesium from their system; a build-up of the element in their blood caused them to pass out and die. Species immune to this effect, which have come to dominate the seabed, include slow-moving predators like sea stars and ribbon worms. The arrival of the crabs could change all that.
As the Dauphin Island Sea Laboratory's Rich Aronson lamented, the disruptions caused by the crabs' invasion could irrevocably change one of nature's last pristine areas: "Antarctic marine communities look like primeval communities from hundreds of millions of years ago because modern predators such as crabs and fish are missing . . . that would be a tragic loss for biodiversity in one of the last truly wild places on earth."