A trip to the coast usually means you’re going to see sea stars. But a mysterious disease has been wiping out sea star populations up and down the West Coast. Researchers had hoped Alaska might be spared the epidemic — until scientists working with the Sitka Sound Science Center detected the first mass die-off in the state.
Local researchers are tracking the spread of the disease — and they’ve reported some disturbing findings.
Patty Dick lives on a boat in Thompson Harbor. 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,” said Dick. “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,” she said. “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 starfish that is not affected, and they were all dead. They were all dead.”
They had sea star wasting disease. All along the West Coast, sea stars, commonly known as starfish, have been dying of this disease. The first case was discovered in the summer of 2013 on the Olympic Peninsula in Washington State, 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 you have to go just from the top left corner and go through the entire plot, counting as many starfish as you see,” she said.
She takes me for a walk along the beach to see for myself. We’re looking at six-legged sea stars called leptasterias on Sage Beach, next to the Science Center.
“This one looks fine,” she said, pointing at one. “This is a healthy one. It’s the largest of the three. There’s another one over here, it seems like a leptasterias, and it only has three arms, and yeah, a very much lesioned body.”
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 longterm 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 longterm MARINe sites in the state. 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, and I feel like a lot of people are paying a lot of attention,” said White.
Once sea star wasting hits an area, it can quickly spread through the population. Research divers from the University of Alaska Southeast 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.
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.”
The aquarium uses an open system, so sea stars live in water straight from the ocean. White 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 much bacteria in the water. They just kind of break down after that point.”
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, until sometimes only a central disk is left. The aquarium has had 35 sea stars die within just three weeks.
Scientists know there will be substantial impacts from these mass deaths, but they aren’t sure yet what to expect. Marnie Chapman, a biology professor at the University of Alaska, Southeast, has been working with White in the long-term 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 as those predators that we’re more familiar with.”
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, however, there’s not much that can be done. If it’s a pathogen, there won’t be a sea star vaccine. If it’s a change in pH levels or water temperature, 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,’” said Chapman. “There were a lot of really healthy, unaffected ones on the side they were looking on, 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 be making a comeback. In time, we’ll know better.
For now, however, Chapman encourages everyone to go out and appreciate Alaska’s sea stars.
Researchers are asking the public to report sightings of either sick or healthy sea stars, to seastarwasting.