Antarctic Warming Leads to Crab Migration

A paper co-authored by Geosciences Professor Eugene Domack that demonstrates how rising temperatures in the Antarctic margin have allowed an invasive species to decimate the existing marine life was published on Sept. 7 in the British journal  Proceedings B, the Royal Society's flagship biological research journal. Titled “A large population of king crabs in Palmer Deep on the West Antarctic Peninsula shelf and potential invasive impacts,” the paper resulted from a project for which Domack, the J. W. Johnson Family Professor of Environmental Studies,  served as project  leader.


The discovery began during a 2010 Antarctic cruise led by Domack as part of the  LARISSA campaign, a National Science Foundation funded initiative that has brought an international, interdisciplinary team together to address a significant regional problem with global change implications, the abrupt environmental change in Antarctica's Larsen Ice Shelf System.


In discussing the paper, Domack explained that, “As the Antarctic began to chill 34 million years ago, the cooling ocean temperatures eventually got so cold that crabs could no longer tolerate the temperatures. When the temperature got below about 1.0 degree C, crabs can no longer metabolize Mg ions for blood and circulation, preventing them from reproducing. Hence the Antarctic bottom marine food web evolved in the absence of such predators. For some 20 million years there is absolutely no sign of them in the fossil record.


“We and others have observed that the water temperatures have been warming on and across the Antarctic margin for several decades, and biologists have predicted for some time that this might precipitate the return of crabs. In fact they have been observed approaching the continent but never quite on the shelf---until last year.


“We took some bottom photos of a region (the Palmer Deep) in 1998 and wondered why there was no sign of any organisms in the area. It was as if the bottom had been swept clean of any animals. With a remotely operated underwater vehicle we examined the area and out of the darkness came the red crabs, thousands of them. It is obvious that they have returned and are eating everything in sight. There is no adaptation to prevent them from doing so by the normal benthic communities, which are clearly threatened if they continue to spread, as they surely must be doing,” Domack concluded.

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