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Scientists Uncover Why Sea Stars Are Melting By The Millions

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Scientists say densovirus is the likely culprit behind the death of millions of Pacific sea stars. Also known as starfish, the stars have been dying off over the past year after developing a mysterious wasting illness.

Considering there are 10 million different viruses for each droplet of ocean water, uncovering the viral perpetrator of an oceanic disease is a bit like "looking for a needle in a haystack," study author Ian Hewson, a Cornell University microbiologist, said in a statement.

In laboratory tests, as well as field studies, sea stars who showed wasting symptoms - which included the loss of limbs and melting - were much more likely to have higher amounts of densovirus than their healthy counterparts; the researchers published their findings Monday in the Proceedings of the National Academy of Sciences. It's the first time, Hewson said, that scientists have untangled the genome of a sea star virus.

Catching densovirus is not pretty: Infected sea stars develop skin lesions, "followed by decay of tissue surrounding the lesions, which leads to eventual fragmentation of the body and death," according to the University of California, Santa Cruz. In 2013, such symptoms were seen on sea stars along the Pacific coast from Baja California to Alaska. Similar mysterious starfish plagues had popped up in the '70s and '80s.

When sea stars die, entire ocean ecosystems are imperiled - the spindly critters are important predators whose appetites keep mussel populations in check, for example. "Their disappearance is an experiment in ecological upheaval the likes of which we've never seen," Drew Harvell, an ecologist at Cornell University, said in a statement.

The National Science Foundation applauded the discovery, which it said begins to unravel the way outbreaks start and sheds light on the viral modus operandi. David Garrison, of NSF's Division of Ocean Sciences, called this find a "significant contribution to understanding the disease."