July 5, 2013
King Crabs In The Antarctic Are Most Likely Native To The Region
Brett Smith for redOrbit.com - Your Universe Online
Citing the recent discovery of a major colony of King crabs near Antarctica, some global warming alarmists theorize that rising temperatures have allowed the crabs to claim territory that was previously uninhabitable.
According to a new review of crab records published in the journal PLOS ONE, the crabs are not newly established settlers; they've been there all along.
The so-called "invasion hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs," the review authors wrote.
Because crabs are susceptible to decay immediately after death, the historical tracking of crab populations can be difficult. The result is an almost complete lack of an Antarctic fossil record for King crabs.
To track the crabs' movements, the British Antarctic Survey team created a database of over 16,000 living and fossil crab records from previously collected data and the extensive fossil collection at the BAS. The researchers also considered records from unpublished fisheries and scientific studies.
From the first record dating back to 1903, 22 species of crab and lobster have been found near Antarctica in the Southern Ocean, including a dozen species of King crabs. The first recording of a King crab spotting is from 1967, when an individual crab was collected close to Scott Island north of the Ross Sea.
With only two species being found only in Antarctica - including one invasive species - researchers said the crabs' distribution pattern indicated an enduring presence in the region, lasting more than a few centuries.
"These findings are important because, for the first time, we were able to piece together all available information to get a clearer understanding of the diversity and distribution of crabs in Antarctica," said lead author Huw Griffiths. "Many of these elusive deep-sea animals, previously thought to be invasive, have turned out to be uniquely Antarctic species."
Other theories surrounding the Antarctic King crabs posit that they pose a severe risk to other fauna in their habitat, specifically mollusks the crabs are thought to prey on. However, the team said they found strong evidence these King crabs scavenge as opposed to hunt.
In their conclusion, the researchers said significant temperature changes in the Antarctic region are more likely to affect other fauna instead of the King crabs.
The team also noted relatively sparse sampling of the region's crabs and suggested their findings be followed up with regular sampling of King crab distributions in Antarctic waters.
King crabs are primarily found in cold seas and are widely hunted for their desirable meat. They are thought to have derived from hermit crabs due to their similar asymmetry found in the King crab abdomen and hermit crab body.
The crabs were thought to have left the Antarctic between 40 and 15 million years ago and returned as regional temperatures rose. Some regions of Antarctica are the fastest warming on the planet, the study said. Previous studies have shown the rate of atmospheric temperature rise on the Antarctic Peninsula is causing the widespread withdrawal of glaciers on the Antarctic Peninsula.