February 10, 2014 – ECOLOGY – A puzzling “wasting disease” first observed along the west coast of the United States in June 2013 continues to kill millions of starfish. The gruesome disease causes the creatures to rot–and to rip their own limbs off. As one biology professor told PBS Newshour, two infected starfish he was observing “started ripping themselves apart. The arms just crawl away from the particular body.” Laura James, a diver and videographer from Seattle, Wash., and one of the first to notice starfish with the disease, described a recent dive to Newshour. “There were just bodies everywhere,” James said. “And they were just like splats. To me, it always looked like somebody had taken a laser gun and just zapped them and they just vaporized….We have had now occasional die-offs here and there, but it’s not like this. It’s not a mass mortality event.” Biologists aren’t sure what is causing the mysterious disease, which has now affected 12 starfish species. Pete Raimondi of the University of California, Santa Cruz, said he believes the starfish wasting disease is likely caused by a pathogen in the form of a parasite, virus or bacteria. One theory about the source of such a pathogen is that it came from the ballast water of foreign ships, as the disease has largely appeared along major shipping routes. Other theories for the cause of the starfish die-off include ocean acidification, warming ocean water making starfish more susceptible to infection and even radiation from the 2011 Fukushima power plant disaster.
While the starfish wasting disease cause remains mysterious, one thing is quite clear: the disease is unbelievably deadly. With a mortality rate of 95 percent, the disease has completely killed off entire starfish populations in Puget Sound, off the coast of Washington, and in coastal areas along California. Starfish are a keystone species, eating everything from mussels to clams to crab (and even other starfish). Because they eat so voraciously, starfish have a major impact on ocean ecosystems. Subsequently, when millions of starfish are wiped out, it can have a major effect. “These are ecologically important species,” said Drew Harvell, a marine epidemiologist at Cornell University. “To remove them changes the entire dynamics of the marine ecosystem. When you lose this many sea stars it will certainly change the seascape underneath our waters.” –IST