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Is Alaska Safe For Sea Stars?

Taylor White
/
Earthfix

A deadly disease has been wiping out West Coast starfish for more than a year. One place that has held off the disease the longest is Alaska. Researchers recently traveled there to search for new clues.

It's early morning in Sitka, Alaska. The stars have yet to fade from the night sky.  A group of scientists is setting out in search of a different kind of star. Sea stars, commonly known as starfish, have been vanishing from North America’s Pacific Shoreline. Rete Raimondi is one of the lead scientists studying the alarming epidemic that’s been killing starfish by the millions.
Scientists believe that warming water or an infectious pathogen are to blame, but no one knows for certain.
Raimondi’s team has been conducting intensive surveys of Pacific coastal areas.

Rete Raimondi: "Almost everywhere we’ve looked in the last year we’ve seen catastrophic losses of sea stars."

They noticed signs of the disease in Sitka last year, but there hasn’t been a die-off until now.  The researchers can’t stop an outbreak. But they can count and measure the creatures that live here in an effort to help track the spread of the disease.
Raimondi pounds bolts into the rocks. His team uses measuring tape to rope off a patch of shoreline. They’ll study this area over time to see how the starfish are doing.
Raimondi crouches on the rocks. He aims his flashlight into the cracks and crevices.  He’s hunting for a tiny six-armed star called a leptasterias, or lepta, for short.

Raimondi: “These cracks ... in the previous years would be full of guys, you guys didn’t see any last time either did, you? No. back in June?”

Their data has provided a critical point of comparison for what normal starfish populations have been in the past.

Raimondi: "If you don’t know what’s there, you don’t know what’s lost. I’ve got one mildly sick lepto”

Raimondi inspects a lepta up close. Even at full-size, the star fits in the palm of his hand. Symptoms of the wasting syndrome vary depending on the species of starfish -- but Raimondi says it usually starts the same way.

Raimondi: "They get white lesions. They become necrotic, that means the tissue dies. And as the tissue dies, they often times will lose arms and then waste away. We call wasting away -- they disintegrate."

Nearby researcher Melissa Miner finds an ochre star that looks even sicker. Two of its arms look ghostly white, like they’ve been dipped in candle wax.

Miner: “So this animal here is probably the worst one that we’ve seen here today. You can see it’s diseased pretty heavily along this arm and then it’s also spreading onto this arm.”

Sea Star Wasting Syndrome now affects almost every species of west coast starfish. The plague has hit so hard over the past year that biologists fear some species could even go extinct.
Researchers believe that a virus or bacteria may be the root of the problem. Raimondi and Miner will ship some samples to other researchers who are trying to figure out which virus or bacteria is causing this.

Drew Harvell is a Marine Epidemiologist working at the University of Washington’s Friday Harbor labs.
She’s been coordinating nation-wide research on the wasting syndrome. And she says the team is close to identifying a pathogen.

Harvell: "This is what we call a wide host range pathogen. It means that it affects many different species. And those are the most dangerous in wildlife disease in terms of a potential risk of extinction."

Scientists think warm water could play role in triggering the outbreaks.
Starfish are stressed by higher temperatures, which make them more vulnerable to infection. As die-offs continue in Puget Sound and along the coast of Oregon, scientists are looking north for a sign of hope.

Harvell: "The hope is that the waters are cold enough in Alaska, the northern part of their range for many of these species, that they’ll persist there."

Scientists hope that Sitka will mark the northern edge of the wasting syndrome.  As long as there are still pockets of healthy stars, Pete Raimondi says recovery is possible. That’s because baby starfish float in the water for up to 45 days. And ocean currents can carry them hundreds of miles from where they were born.

Raimondi “So that allows there to be replenishment downstream from populations upstream that are not affected. That’s why it’s critical to go north to find whether there are still extant populations that are healthy."

Starfish farther north in Juneau seem to be holding strong. If that continues, parts of Alaska could still serve as a refuge from the disease.
 

Copyright 2014 Earthfix

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