The King crab species Neolithodes yaldwyni is large, scarlet red, aggressive - and expanding its range to swarm the Antarctic ocean floor. Warming ocean temperatures have encouraged this invader to creep ever southward, much faster than researchers had initially forseen. Three years ago researchers predicted that N. yaldwyni would invade Antarctica within the next 100 years. But submersible videos show that "more than a million Neolithodes yaldwyini have already colonized Palmer Deep, a basin that forms a hollow in the Antarctic Peninsula continental shelf."
This particular type of King crab (there are many, including those that end up on our dinner tables) is particularly damaging to its environment. In addition to having a voracious appetite for just about every animal it encounters, N. yaldwyni also spends a lot of time probing the sediment with the tips of its long, sharp legs. This disturbs the sediment layers, kicks up silt that clouds the water, and disrupts the critical population of microscopic organisms that make the Antarctic ocean floor sediment their home.
And then there is the matter of their appetites. In territory occupied by N. yaldwyni forces, the number of species is only a fourth that of untouched areas. The crabs eat anything they can catch, cleaning out the populations of "sea urchins, sea lilies, sea cucumbers, starfish, and brittle stars."
The crabs are pulled into Palmer Deep in their young, larval forms. Until recently, the water was too cold for them to survive, just above freezing at 1.2 degrees Celsius. But it turns out that only a tiny change can make the difference for these king crabs, because now that the water has warmed to an average 1.47 degrees Celsius, the crabs are thriving. They creep slowly along at depths of 4,500-3,000 feet below the sea's surface, probing and eating everything in their path.
These kinds of unprecedented animal migrations are becoming commonplace as the world's oceans temperature profiles shift. Ironically, rising water temperatures are being blamed for the recent decline in the numbers of the King crab fishery in Alaska. At the same time, rising ocean temperatures are encouraging the spread of the Alaskan king crab (Paralithodes camtschaticus ) as an invasive pest species in the Barents Sea along the coast of Norway.
Which raises the obvious question… why not fish our way out of this problem? Maybe next year Discovery Channel will host a new series, "Deadliest Catch: Antarctica"!