It's good to be the king … crab, that is. But it's not so good for species that aren't prepared for an onslaught of the voracious predators.
King crabs are expanding their undersea kingdoms into parts of the Antarctic shelf and devouring whole ecosystems in the process.
Sea lilies, brittle stars, sea urchins and other species of echinoderm had thrived for 14 million years in the cold depths of the Antarctic shelf, free of of skeleton-crushing predators. But warmer climes are allowing the king crabs (Neolithodes yaldwyni) to go on a feeding frenzy in new territory.
A recent study of the Palmer Deep basin, off West Antarctica, found that the crabs had spread into the area, forming large breeding populations and wiping out the echinoderms as they went. The research was published in the Proceedings of the Royal Society B.
"This is a very interesting discovery for several reasons," said Craig Smith, of the University of Hawaii, Manoa, in a press release.
"First, it provides evidence that king crabs can now disperse across the Antarctic shelf, and reproduce in at least some Antarctic shelf waters. It also suggests that these predatory king crabs will cause a major reduction in seafloor biodiversity as they invade Antarctic habitats, because they appear to be eating all the echinoderms in the Palmer Deep," said Smith.
The study found that the crabs had moved across 120 kilometers (75 miles) of the continental shelf and established a colony of an estimated 1.5 million individuals in a 146-square-kilometer area, 850 meters (56-square-mile, 930 yards) below the surface.
The researchers estimate that within the next two decades, as polar waters continue to warm rapidly, the crabs may be able to colonize the west Antarctic Peninsula shelf at depths of 400-600 meters (roughly 1,300 to 2,000 feet). They worry that the king crabs may devastate the unprepared wildlife there.
The king crabs prove to be not only the Deadliest Catch, but the deadliest catchers, because they act as “ecosystem engineers” by digging into the soft sediments of the seafloor to prey on animals they find. In this way, they alter the basic habitat structure of the seafloor.
The research was conducted by scientists from the University of Hawaii, Duke University, Ghent University, Lamont-Doherty Earth Observatory and Hamilton College.
Tim Wall reports from Siguatepeque, Honduras, where he teaches journalism to fifth- and sixth-grade public school students.
IMAGE: The southern king crab (Lithodes santolla), a relative of the invasive Antarctic crab. (Wikimedia Commons)
VIDEO: An invasive king crab (Neolithodes yaldwyni) from the Antarctic shelf waters. (Craig Smith, University of Hawaii, Manoa, SOEST)