|Disease ravaging sea stars|
|Written by Jane Stebbins, Pilot staff writer|
|June 13, 2014 07:15 pm|
The future of the purple ochre sea stars is up in the air — or, more accurately, dissolving into the ocean.
Scientists in April found a starfish with sea star wasting syndrome in Newport, and the epidemic has increased in exponential leaps.
“This is unprecedented,” said Bruce Menge, a professor of marine biology at Oregon State University. “We’ve never seen anything of this magnitude before.”
According to Angela Johnson, a faculty research assistant with the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) collaborative, scientists found 1,000 sea stars at Fogerty Creek near Newport at the beginning of May. Of those, seven showed signs of the wasting disease.
On May 16, researchers found 1,400 sea stars in the intertidal zone, of which 34 were suffering from the disease. And on May 27, they only found 488 starfish, and 235 of them had signs.
Those increases reflect a 30 to 50 percent mortality rate, Menge said.
Worse, scientists have no idea what’s causing it, how severe damage could get, or how long it will last.
Sea stars with this peculiar wasting syndrome were first found off the coast of Canada, shortly after a massive tsunami devastated the Fukushima nuclear reactor plant in Japan just over two years ago. Many believed radioactivity from the leaking plant was to blame, but that was quickly proven not to be the case.
As researchers began investigating viruses or bacterias, dead starfish began showing up along the California, then Washington, coasts.
Oregon looked like it might go unscathed — until April — when one was found in Yaquina Bay in Newport.
“It wasn’t clear why those areas had been hit and Oregon had not,” said Kristen Milligan, program coordinator at OSU for the Partnership for Interdisciplinary Studies of Coastal Oceans, a research collaborative. “We were hoping that Oregon’s coast would be spared. Although it was hit late, we are obviously being hit — and hit hard.”
Researchers are coming to Cape Blanco Sunday to count sea stars at the point where only a handful of starfish were found with the disease last month.
Urchin divers in Port Orford, however, have been reporting much more of it, she said.
And researchers fear the epidemic will intensify and possibly kill all the ochre sea stars in some areas.
Along the entire West Coast, 10 species of sea stars have been affected. Other areas have recovered after such severe losses in sea star populations, but in other locations, the damage has been long-lasting.
Scientists are baffled, and Oregon State University undergrads are taking to the beaches from south of Cape Blanco to north of Depoe Bay to gather information. The research is one of the best documented outbreaks of marine disease ever undertaken in North America.
“We have no clue what’s causing this epidemic, how severe the damage might be or how long that damage might last,” Menge said. “It’s very serious. Some of the sea stars most heavily affected influence the whole diversity of life in the intertidal zone.”
Sea star wasting syndrome is a traumatic process in which, within a week, the popular tide pool creatures begin to lose their legs, disintegrate and ultimately die. They sometimes physically tear their bodies apart, Menge said.
Various epidemics of the syndrome have been observed in the past, but none of this extent — the entire coastline — or severity in the numbers dying. And knowing that an El Nino weather system is gearing up in the Pacific, scientists looked at sea temperatures, but ocean temperatures in Oregon are only at the high end of a normal range, Menge said.
While it’s alarming to see the mass die-off, what’s even more frustrating is not knowing how extensive it will become.
Scientists were hoping the one starfish found with the wasting syndrome in Newport would be the only statistic, but in the past two weeks, starfish are dying by the hundreds.
Menge called it “an epidemic of historic magnitude,” and one that could drive Oregon’s entire population of purple ochre sea stars to extinction.
The ochre sea star is a “keystone” predator, meaning its presence and role within an ecosystem has a disproportionate effect on other organisms within the system. Its removal, or disappearance, allows a population of prey to increase, decreasing overall diversity in the intertidal zone and disrupting the entire ecosystem.
In particular, Menge said, sea stars attack mussels and keep their populations under control. Absent enough sea stars, mussel populations can increase dramatically, covering up algae and other small invertebrates.
Some sea stars also eat sea urchins, and without the starfish, the population of sea urchins — which eat kelp and sea grass — could also increase, eventually decimating habitat for other fish.
More information, including an interactive map of all observations, and opportunities for interested citizens to participate in the observation effort are available online at http://bit.ly/1o5bWNi