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Scientists think they finally know what mysterious illness has been causing mass die-offs of Pacific starfish. New evidence suggests a mysterious wasting disease killing sea stars by the millions may be the result of a virus that has been found in starfish since at least the 1940s, according to research published Monday, November 17, 2014 in Proceedings of the National Academy of Sciences.
Cornell University microbiologist Ian Hewson and colleagues identify the Sea Star Associated Densovirus (SSaDV) virus as the microbe responsible for Sea Star Wasting Disease (SSWD). NHM Curator of Echinoderms Gordon Hendler and Collections Manager Cathy Groves, along with scientists from universities and aquariums along the coast (including NHM neighbor, the California Science Center), joined forces for this study.
Since June 2013, the largest die-off of sea stars ever recorded has swept the Pacific Coast. At least 20 different species of sea stars have been affected, including iconic species like the “ochre star” and the multi-armed “sunflower star.” Moreover many populations of sea stars from Southern Alaska to Baja California have already disappeared.
“I was diving off the UCSB campus in January and came across hundreds of sea stars that were contorted and disintegrating,” said co-author Lafferty, a specialist in marine diseases. “It looked like a battlefield. I’ve seen no sea stars since.
There’s not much researchers can do to stop the virus, though. “We can’t quarantine, we can’t effectively cull, and we can’t vaccinate,” said Drew Harvell, a marine ecologist at Cornell University in Ithaca, New York, in an interview earlier this year. The best they can hope for is that populations can recover once the epidemic winds down.
The virus, dubbed the sea star-associated densovirus, is also quite common. “It’s been around for 70 years,” said Hewson, and “it’s probably present all over the world.” Museum specimens from the 1940s have tested positive for the virus, and it lurks in ocean sediments and in seawater.Scientists involved in the study agreed that the increasing acidity of ocean waters associated with climate change could be a factor in triggering the outbreak, perhaps by making the sea stars more vulnerable to attack.
In the meantime, scientists like Marine microbiologist Dr. Ian Hewson will have to rely on public sightings of sea star wasting disease to track how far the epidemic is spreading and which species of starfish are affected. Bottom line he explained: “No virus wipes out its host population entirely. There’s never been an extinction as a result of a virus.”