Featured Science Paper
Antarctic Crabs: Invasion or Endurance?
Recent scientific interest following the ‘discovery’ of lithodid or King Crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. The theory surfaced two years ago following the discovery of a major colony of King Crabs (Neolithodes yaldwyni) in the Palmer Deep, off of the Antarctic Peninsula. It was thought this species may have left the continent between 40 and 15 million years ago and was returning as sea-water temperatures rose.
This paper examines the existing lithodid fossil record and the present day distribution and biogeographic patterns from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60°S. All are restricted to waters warmer than 0°C, with their Antarctic distribution limited to the areas of sea floor dominated by warm Circumpolar Deep Water (CDW). Currently, CDW extends further and shallower onto the West Antarctic Shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic Shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day ‘crab invasion’. We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the ‘invasion hypothesis’.
Huw J. Griffiths, Rowan J. Whittle, Stephen J. Roberts, Mark Belchier, Katrin Linse