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Kachemak Bay sea stars found stricken with wasting disease

  • Author: Yereth Rosen
    | Arctic
  • Updated: September 28, 2016
  • Published May 12, 2015

The wasting disease that is killing millions of sea stars along the U.S. West Coast has now moved farther north, into Southcentral Alaska's Kachemak Bay, according to scientists who surveyed the area last week.

Brenda Konar, a researcher at the University of Alaska Fairbanks School of Fisheries and Ocean Science, said she and a fellow UAF scientist found a cluster of six to eight sea stars in a relatively small area they regularly survey.

The creatures were stricken by the disease that is bringing lesions, disintegration and, ultimately, death.

"They look like they're falling apart. They're melting," Konar said.

Sea stars afflicted by the disease can lose body parts -- Konar and UAF's Katrin Iken found disembodied sea star arms in tide pools, she said.

Though the wasting disease has been seen in sea stars in past decades, the new epidemic is the largest and most geographically widespread on record, according to a monitoring and research program established at the University of California at Santa Cruz.

The new epidemic was first noticed in 2013 on the Pacific coast, with a smaller outbreak on the Atlantic coast.

The wasting disease is believed to be caused by a virus. Scientists last fall identified the virus they believe is the likely culprit, one that has existed on the Pacific coast for at least 72 years, according to a study published in the Proceedings of the National Academy of Sciences.

The virus is possibly carried by asymptomatic sea stars, Konar said. Symptoms occur when the sea stars are stressed, she said.

Laboratory tests indicate that warmed waters could be the source of stress, though tests have also pointed to increasing acidification as a possible stressor, she said.

While sea star die-offs had been reported as far north as Southeast Alaska, in the past it was believed that most Alaska waters are too cold for the syndrome, Konar said.

There have been some isolated reports of the illness this far north, according to the the UC-Santa Cruz program. Those include the sighting of one stricken sea star in Jakolof Bay, within the Kachemak Bay area, and another among the display animals at the Anchorage Museum, according to the UC-Santa Cruz program.

But what was striking about last week's discovery was the number of affected sea stars -- multiple animals rather than isolated individuals -- and the oceanic location, Konar said.

"These guys were in a totally oceanic environment where there are no salinity issues and no sediment," she said. Past reports from the Kachemak Bay area, she said, have been about animals from more estuarine sites, with fresh water mixing into the salty sea water that sea stars use.

The syndrome is worrisome, scientists say, because sea stars are important predators that maintain balance in the marine ecosystem.

"It's kind of sad to think about it if it does get worse and spread out to other areas, like the Aleutians," she said.

The affected sea stars were in the genus Evasterias, which is common in Kachemak Bay, though one was a Pisaster, more rare in the region, a statement from UAF said.

Konar and Iken were conducting their survey for Gulf Watch Alaska, a long-term ecosystem monitoring program established by the Exxon Valdez Oil Spill Trustee Council.

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