A trip to the coast usually means you’re going to see sea stars, but a mysterious disease is killing them along the West Coast. There had been a few reports of sick sea stars in Alaska, but recently in Sitka, the first mass die offs in the state were detected. Scientists in Sitka are tracking the progress.
Patty Dick lives on a boat in Thompson Harbor in Sitka. In the morning, when it’s low tide and she has an extra moment, she goes out and checks on the sea stars living in the area.
“I just sit there in awe of the beauty of that animal,” she said. “Everybody loves sea stars.”
Dick teaches 6th grade biology at Blatchley Middle School. She often takes her students on field trips to learn about marine animals, and they usually find dozens of sea stars.
But one morning last month, Dick noticed something was wrong with the sea stars. “I just looked over and I just stopped. There were these big, huge, white spots all over them and they were just wasting away. My heart just sank.”
She’d heard about this happening, but she hadn’t seen it with her own eyes. “I’m trying to find one star fish that is not affected,” she said, “and they were all dead. They were all dead.”
They had sea star wasting disease. All along the West Coast, sea stars have been dying of this disease. The first case was discovered in the summer of 2013 on the Olympic Peninsula and scientists still don’t know what’s causing it.
Taylor White is the aquarium manager at the Sitka Sound Science Center. For the past year, she’s been working with a team that is monitoring sea stars and other marine life in Sitka and along the West Coast.
“It’s a lot of just crouching down and going from the top left corner and going through the entire plot, moving this rockweed around, and counting as any starfish as you see,” White said.
She takes me for a walk along the beach to see for myself. She pulls up a rock and is looking at some six-legged sea stars called leptasterias. We’re looking at sea stars on Sage Beach, next to the science center.
The Sitka Sound Science Center is part of a project called MARINe, which stands for Multi-Agency Rocky Intertidal Network. MARINe is made up of agencies that use the same marine monitoring methods. They’ve set up about 120 sites along the coast in the U.S., from Southern California to Alaska. There are three sites in Sitka – the only long-term MARINe sites in Alaska. White helps monitor the Sitka sites as part of her job at the science center.
“You really do look a lot harder at sea stars now that sea star wasting disease is occurring,” she said. “I feel like a lot of people are paying a lot more attention now.”
Once sea star wasting hits an area, it can quickly spread through the population. Research divers from the University of Alaska, Sitka, have surveyed different areas in Sitka Sound and have seen evidence of wasting in most locations. At Sage Beach, divers found that in the past few weeks, sunflower stars have disappeared, leaving behind white ‘ghost piles’ of tissue.
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When a sea star has the wasting disease, its legs can walk away from its body, sometimes leaving behind only a central disk.[/caption]
While there have been minor wasting events in the past, this event is by far the longest and most widespread.
White says she’s seeing the same thing happen in the touch tanks at the Sitka Sound Science Center. “A lot of those guys have been in there for a very long time. It was hard to see it suddenly hit.”
They use an open system, so sea stars live in water straight from the ocean. She describes what she saw when the disease hit. “They just started crawling away from their bodies,” she said. “They contort themselves. Then they just started to decay since there are so many bacteria in the water. They just kind of break down after that point.”
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The Sitka Sound Science Center is part of a project called MARINe, which is a consortium of agencies on the West Coast that use the same longterm monitoring methods. Sage Beach is one of Sitka's three MARINe sites.[/caption]
When sea stars are sick, they can lose a leg and then regrow a healthy one. But with the wasting disease, they just keep losing legs, sometimes until only a central disk is left. The aquarium has had 35 sea stars die within three weeks, and now, only two remain in the touch tanks.
Scientists know there will be substantial impacts from these mass deaths, but they aren’t sure what yet.
Marnie Chapman, a biology professor at the University of Alaska, Sitka, has been working with White in the longterm monitoring project. She says sea stars play a big role in the ecosystem.
“They are major predators in the intertidal,” she said. “They’re definitely the lions and tigers of the intertidal environment.”
And they’re diverse. There are about 1900 species of sea stars in the world, and at least 18 in Sitka alone. “Sea stars are as unique and as individual than those predators that we’re more familiar with,” said Chapman.
There are several groups trying to figure out what’s causing this mass die off. It could be a bacterium, a virus, or environmental change, like lower pH levels in the ocean or warmer water. Most scientists think it’s a combination of things.
When scientists do figure it out, there’s not much that can be done. If it’s a pathogen, there won’t be a sea star vaccine. If it’s warmer water, that’s irreversible.
Chapman worries about the future of the species. She recalls a day when she was out counting dying sea stars and a boy was looking at healthy ones nearby. “This young kiddo was saying, ‘mom, look at all the sea stars,’ and there were a lot of really healthy, unaffected on the side they were looking on,” she said, “and I thought, ‘boy, I hope that still happens. I hope that still happens next summer.’”
But there is some hope. At some of the MARINe sites along the coast, they’re seeing some juvenile sea stars. So, they could make a comeback. In time, we’ll know better.
And there is something that everyone can do to help track the disease. If you see sick or healthy sea stars, report it to seastarwasting.org. Reports from the public help scientists better understand the disease and could help solve this mystery.
