Posted on | September 9, 2011 | Comments Off
King crabs and other crushing predators are thought to have been absent from cold Antarctic shelf waters for millions of years. Scientists speculate that the long absence of crushing predators has allowed the evolution of a unique Antarctic seafloor fauna with little resistance to predatory crabs. A recent study by researchers from several universities including UH Mānoa Professor Craig Smith indicates that one species of king crab has moved across the continental shelf in West Antarctica and established a large, reproductive population in the Palmer Deep along the west Antarctic Peninsula.
“This is a very interesting discovery for several reasons,” says Smith. “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 on seafloor biodiversity as they invade Antarctic habitats because they appear to be eating all the echinoderms in the Palmer Deep.”
The researchers evaluated the abundance and foraging behavior of king crabs in the Palmer Deep. They found that the king crab, a species known as Neolithodes yaldwyni, is acting as a major “ecosystem engineer,” digging in soft sediments, preying on seafloor animals and altering basic habitat structure at the ocean bottom. Echinoderms, such as sea lilies, brittle stars, asteroids and sea urchin, which generally are common and diverse in Antarctic waters, were wholly absent in the crab zone in Palmer Deep. The crab population in Palmer Deep was also both reproducing and surprisingly large.
In the future, Smith and his colleagues hope to conduct population genetic studies of the Palmer Deep king crab to reconstruct its colonization history, and to see whether this population is connected to populations of the same species in deep-water on the other side of Antarctica.