Antarctic invaded by giant crabs


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A large, reproductive population of giant king crabs have been discovered in deep waters off Antarctica, prompting fears for the biodiversity of ecosystems there.

The crabs, Neolithodes yaldwyni are considered to be major predators of sea floor fauna and could cause local extinctions of some species.

They were spotted by researchers from the University of Gent, Belgium who were exploring an under sea basin known as the Palmer Deep with their remotely operated vehicle, (ROV) Genesis.

The colossal crustaceans were previously unreported in the region as the water is too cold, however it's now thought rising sea temperatures brought about by global warming have meant that larvae swept into the Palmer Deep by occasional influxes of warmer water across the cold continental shelf are now able to survive as the water in the deep basin is above the critical 1.4°C they require.

Sea temperatures in the area get warmer the deeper you go, and the crabs were only resident at depths of below 850m so the team suspect they have been present for between 30 and 40 years, as before that the Palmer Deep was too cold.

The density of tracks and numbers of crabs seen could indicate a population of as many as 1.5million.

The ROV recorded a total absence of typical marine fauna such as brittlestars, sea lilies and sea cucumbers where the crabs were found and more worryingly it appeared that the crabs are venturing upward into colder water for feeding forays as the populations of echinoderms were poor at up to 100m above the 'crab zone'.

Scientists believe that if sea temperatures continue to rise as expected, the water on the continental shelf could be warm enough for the crabs within 20 years, fundamentally changing the ecology of the area.

For more information, see the paper: C.R. Smith, L.J. Grange, D.L. Honig, L. Naudts, B. Huber, L. Guidi, E. Domack (Sept. 2011); A large population of king crabs in Palmer Deep on the west Antarctic Peninsula shelf and potential invasive impacts. Proceedings B doi:10.1098/rspb.2011.1496

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