by Brian Merchant, Brooklyn, treehugger.com, March 21, 2011
King crabs haven't historically caroused in Antarctic waters -- it's simply been too cold for the famed crustaceans. But warming waters have allowed crusading crabs to march further south than they have in millions of years. Which is bad news for the diverse sea life currently thriving in the underwater habitats around the Antarctic peninsula: Seeing as how they've been living in a crab-less environment for 40 million years, scientists now fear that Antarctic animals like brittle sea stars, mussels, and sponges will be sitting ducks for the marauding king crabs.
The Washington Post has the story of evolutionary biologist Sven Thatje and his team of researchers, who are trying to figure out how fast the invasion of king crabs is occurring. They dragged a camera underneath an icebreaker as they cruised Antarctic waters, and got footage of the southbound crabs:
"It caught images of bright red king crabs up to 10 inches long, moving into an undersea habitat of creatures that haven't seen sharp teeth or claws for the past 40 million years."
"There were hundreds," Thatje said in an interview on board the Swedish icebreaker Oden, which docked at the main U.S. base in Antarctica, McMurdo Station, after a two-month research cruise. "Along the western Antarctica peninsula, we have found large populations over 30 miles. It was quite impressive."This is a great example of how a seemingly minor shift caused by climate change can have wide-ranging impacts on the natural environment. Water temperatures have risen one degree Fahrenheit since 1950 (air temperatures in the region have risen an in-no-way-minor
11 °F) -- making the waters just warm enough for the crabs to survive.
The scientists explain to the Washington Post that when the "water is too cold -- as it has been along the shallow waters of the Antarctic continental shelf -- crabs can't remove magnesium from their blood. Magnesium is a common mineral in seawater, and if they can't get rid of it, it causes a narcotic effect that stops them from moving enough to survive."
This in turn has scientists worried that the "magnesium barrier" will fall around the world, allowing clawed crustaceans to wreak havoc on pristine environments that have never been exposed to such predators. Chalk up another impact of climate change that will go largely unseen -- but that will nonetheless change the natural world in an irreversible way.