Study finds virus likely cause of sea star wasting

[Buster's Uncle]

Study finds virus likely cause of sea star wasting
Associated Press
By JEFF BARNARD  2 hours ago



GRANTS PASS, Ore. (AP) — Scientists have isolated a virus they are pretty sure is causing the mysterious disease that has killed millions of sea stars on the Pacific Coast from Southern California to Alaska by causing them to lose their limbs and eventually disintegrate into slime and piles of tiny bones.

A study published Monday in the journal Proceedings of the National Academy of Sciences says a variety of densovirus is the likely cause of wasting syndrome among sea stars, also known as starfish. Varieties of densovirus are used as a biological control on cockroaches, and include the parvovirus that infects dogs.

Cornell University marine microbiologist Ian Hewson says they found larger amounts of the virus in sick sea stars than healthy ones, and the amount of virus increased as the disease progressed. Also, injecting material from sick sea stars that was filtered to concentrate virus-sized organisms caused healthy sea stars to get the disease.

Hewson said thousands of bacteria and viruses live in and on sea stars, but researchers suspected a virus was responsible for the disease because sea stars got sick in aquariums that drew water from the ocean. The disease did not infect sea stars in museums that exposed the water to ultraviolet light, which kills viruses.

Hewson adds they don't know yet what triggered the outbreak of the virus, which can be found in plankton, sandy ocean bottoms, and sea urchins, and has been found in museum specimens of sea stars dating to 1942. He said It could be related to a population boom in one of the species heavily infected by the disease, a change in the virus, or changes in the environment. Some of the most heavily infected species are members of the same family, suggesting they may share a common vulnerability.

Past outbreaks of sea star wasting have been smaller and more confined in geographic area. The current one started in the summer of 2013 in Southern California and has since spread through Oregon, Washington, British Columbia and southern Alaska. It has infected 20 different species of sea stars, but primarily the five-legged ochre sea stars commonly seen in tide pools, and the sunflower sea stars that have up to 16 legs.

Hewson said the disease was not likely to make any sea stars go extinct, but was likely to affect the mix of species in the intertidal regions of the ocean. Mussels, a favorite food of sea stars, are likely to become more abundant, for example.

Chris Suttle, a marine virus expert at the University of British Columbia, and Bruce Menge, professor of interactive biology at Oregon State University, were not part of the study. Both said the study, though it did not definitively identify a virus as the cause of the disease, was very persuasive.

They 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.

"If (viruses) get in through damaged areas (of the sea star), what causes the damaged area?" Menge asked. "If they don't get in though damaged areas, how do they get in?"

Warming ocean temperature appears to be less of a factor, because outbreaks in Oregon occurred in waters that have been colder than normal lately, Menge said.

Suttle said ocean acidification is affecting other marine invertebrates, such as commercial populations of scallops and oysters.


http://news.yahoo.com/study-finds-virus-likely-cause-sea-star-wasting-201554952.html

[Buster's Uncle]

Virus implicated in massive die-off of North American starfish
Reuters
By Will Dunham  1 hour ago



The leg of a purple ochre sea star is shown disintegrating as it dies from sea star wasting syndrome in Oregon in this undated handout photo provided by Oregon State University November 17, 2014. REUTERS/Elizabeth Cerny-Chipman/Oregon State University/Handout via Reuters



WASHINGTON (Reuters) - Scientists investigating a huge die-off of starfish along North America's Pacific coast have identified a virus they say is responsible for a calamitous wasting disease that has wiped out millions of the creatures since it first appeared last year.

The scientists said on Monday they identified the pathogen as the Sea Star Associated Densovirus, or SSaDV, after ruling out other possible culprits including certain bacteria, protozoans and fungi.

More than 20 species of starfish, also called sea stars, from southern Alaska to Baja California are dying from a wasting disease that causes white lesions to appear before the animal's body sags, ruptures and spills out its internal organs.

"They basically fall apart into a pile of goo on the bottom of the seafloor," said Cornell University biological oceanographer and microbial ecologist Ian Hewson, who led the study in the journal Proceedings of the National Academy of Sciences.

SSaDV is a parvovirus, a tiny form of virus that can cause illness in animals and people.



A starfish, also known as a sea star suffering from a wasting disease epidemic is shown in this handout photo courtesy of Kevin Lafferty of the United States Geological Survey, provided November 17, 2014. REUTERS/Kevin Lafferty/USGA.com/Handout via Reuters


The researchers detected it in older starfish samples, museum specimens from as early as 1942. They said it may have been present at low levels for years and only recently became a large-scale threat due to some kind of viral mutation, environmental trigger, starfish overpopulation or other factor.

"It's probably the largest epidemic in marine wildlife that we know of," Cornell ecologist Drew Harvell said.

"That's the million-dollar question in all this: Why now? What is it that changed that created the conditions for this outbreak? And we don't have the answer to that. But certainly a viral mutation would be one explanation," Harvell added.

The disease was first spotted in June 2013 and has shown no signs of slowing.

"There are 10 million viruses in a drop of seawater, so discovering the virus associated with a marine disease can be like looking for a needle in a haystack," Hewson said.

"Not only is this an important discovery of a virus involved in a mass mortality of marine invertebrates, but this is also the first virus described in a sea star."

Scientists prefer calling them sea stars rather than starfish because they are not fish but rather echinoderms, cousins of sand dollars, sea cucumbers and sea urchins. Most have five arms, although some have more.

The disappearance of so many starfish threatens to disrupt coastal ecosystems because they are important predators in the waters between the shoreline and open sea, the researchers said.

(Reporting by Will Dunham; Editing by Sandra Maler)


http://news.yahoo.com/virus-implicated-massive-die-off-north-american-starfish-225211186.html

[Buster's Uncle]

Virus blamed for starfish deaths along US Pacific Coast
AFP  1 hour ago



Washington (AFP) - A mysterious plague that has killed off millions of starfish along the US Pacific Coast since 2013 is now believed to be a virus that causes the creatures to melt, US researchers said Monday.

Known as densovirus, the microorganism has been found in diseased and dead starfish, and is the likely culprit for the massive upsurge in deaths, said the report in the Proceedings of the National Academy of Sciences.

The virus causes the limbs of starfish, or sea stars, to pull apart and their skin to waste away, and has been wreaking havoc on populations from Baja, California, to southern Alaska.

Ian Hewson of Cornell University led the genomic analysis on sea star associated densovirus (SSaDV), a type of parvovirus commonly found in invertebrates.

"There are 10 million viruses in a drop of seawater, so discovering the virus associated with a marine disease can be like looking for a needle in a haystack," said Hewson, a professor of microbiology.

"Not only is this an important discovery of a virus involved in a mass mortality of marine invertebrates, but this is also the first virus described in a sea star."

Researchers found the virus present at low levels in museum samples of sea stars collected in 1942, 1980, 1987 and 1991.

Overpopulation, pollution or mutations in the virus could have contributed to its sudden surge to epidemic proportions, the study found.

Densovirus has also turned up in water filters from public aquariums, sea urchins and brittle stars.

More research is needed to find out what triggers outbreaks, said co-author Drew Harvell, a professor of ecology and evolutionary biology.

"It's the experiment of the century for marine ecologists," said Harvell.

"It is happening at such a large scale to the most important predators of the tidal and sub-tidal zones. Their disappearance is an experiment in ecological upheaval the likes of which we've never seen."

The study was funded by the National Science Foundation (NSF) and Cornell University's David R. Atkinson Center for a Sustainable Future.


http://news.yahoo.com/virus-blamed-starfish-deaths-along-us-pacific-coast-224656662.html