October 21, 2022
Devastating wasting illness of influential, iconic sea stars still a mystery
Rena Kingery

Community science is adding to research on an illness that has decimated sea star populations on the West Coast since 2013. One of those efforts, the Cherry Point Aquatic Reserve Citizen Stewardship Committee, samples sea stars at Point Whitehorn Marine Reserve. (Photo courtesy of Melissa Miner)

October 21, 2022
Devastating wasting illness of influential, iconic sea stars still a mystery
Rena Kingery

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Nearly a decade ago, a devastating illness ravaged sea star populations up and down the West Coast. The illness, called sea star wasting syndrome, plagued more than 20 species of stars in the Salish Sea and beyond, causing a swift decline in sea star populations from the Gulf of Alaska to northern Mexico.

Diseased stars quickly lost rigidity in their bodies and began to peel away from the rocks to which they clung. Usually within days, white lesions appeared, and the animals essentially disintegrated as their arms detached from their bodies. 

Today, the disease remains a mystery to scientists, and its presence still threatens the region’s sea star populations. But with the help of community science efforts, local experts have gained better understanding and are working to ensure that sea stars will be around for generations to come.

Community-led science

Sea stars are known as a keystone species because of their significant influence on life in intertidal ecosystems. But they’re also a beloved symbol of the sea for humans.

“Everybody knows what sea stars are. They’re just an iconic species,” said Eleanor Hines, the Northsound Baykeeper and lead scientist at Bellingham’s RE Sources. “So when they all started melting from sea star wasting syndrome a lot of people got freaked out.”

Hines leads community science efforts throughout the year to monitor sea star wasting in the area. Each summer and winter, she and 5 to 20 volunteers scour the rocks of Neptune Beach and Clayton Beach at low tide for signs of sea stars. When they find a star, they identify the species, look for signs of disease and measure its size from the central radial disk to the end of one arm.

In addition to organized surveys, anyone with a smartphone or a watchful eye on the beach can record sea star sightings and wasting signs with the iNaturalist app or in the observation log of the Multi-Agency Rocky Intertidal Network (MARINe), a project that monitors intertidal life at more than 200 sites from Alaska to Mexico.

Melissa Miner, a Bellingham-based MARINe scientist and research associate for the University of California, Santa Cruz, said that community science has been essential for keeping tabs on the recovery of area sea stars.

Before 2013, Miner and her team at MARINe regularly monitored intertidal life at 10 sites in the Salish Sea, but she knew those wouldn’t be enough to identify trends in sea star wasting throughout the region’s extensive coastline. So, she applied for emergency funds to initiate community science projects and received an overwhelming response.

“It was really heartening to just see how much the community cares,” Miner said. “It was sad because we lost so many stars, but it also was really amazing how much community response we got.”

Thanks to community volunteers, scientists now have years of data from hundreds of sites, allowing them to track the disease’s progress.

Then: a thick cluster of ochre sea stars flourishes around a tidepool, in a pre-2013 photo.

“What we’re seeing locally is it’s not as bad as it was when [sea star wasting] was full bloom … we are seeing that it seems like it’s persisting at lower levels in certain areas.” Hines said.

Miner agreed that some regions have been more heavily impacted than others, and flare-ups are still impeding the road to recovery for many sea star species

Some sites have shown only minimal signs of a resurgence. “We are seeing fewer diseased stars but almost always find a handful that are sick,” she said. “Sea star wasting has never fully gone away.”

Locally, in some sites such as Larrabee State Park and Point Whitehorn, counts of ochre sea stars (Pisaster ochraceous) are reaching their 2013 levels, but their sizes are still comparatively small. At Post Point, a site south of Bellingham that MARINe has monitored since 2009, numbers spiked in 2019 when a large batch of juvenile stars were reported, but most were lost in the following years. 

Bringing back sunflowers

One species especially hard-hit in 2013 and 2014 was the massive sunflower sea star (Pycnopodia helianthoides). Sunflower sea stars can grow to 3 feet in diameter and have as many as 24 arms. Their population declined by more than 90 percent, and they have essentially vanished from waters south of Oregon, where they used to be abundant. The International Union for Conservation of Nature recently listed the sunflower star as critically endangered.

That’s why Jason Hodin, a senior research scientist at the University of Washington’s Friday Harbor Laboratories, is attempting to do something never done before: breed and raise sunflower stars in captivity. He and his colleagues began rearing sunflower stars in 2019, and they hope that someday their stock of healthy stars can help rebuild the sunflower star population along the West Coast.

“In the first year, it was a very, very steep learning curve,” Hodin said. “This year we’ve got 110 baby stars, so now we can raise hundreds of stars, and we’re getting to the point where we’re pretty much limited by our staff and our space. That’s pretty exciting.” 

But there is still a lot of work to be done before they can safely reintroduce sunflower stars into wild waters. On the Olympic Peninsula, they’ve partnered with Harvell Lab of Cornell University and the University of California, Merced, to answer some pressing questions about sea star wasting and how it might affect captive-bred sea stars in the wild.

Drew Harvell, a marine disease ecologist and principal investigator for the Cornell lab, hopes to use some of Hodin’s juvenile sea stars next year, to test whether they are susceptible to sea star wasting in early life stages. Another question Hodin wants to answer is why certain sunflower stars survived the wasting event of 2013.

“We’re basically doing this kind of 23andMe for sunflower stars right now with [a] lab in California,” said Hodin, adding that UC Merced scientists are looking for clues to disease resistance in the genomes of his brood of healthy sunflower stars. The UW is conducting a fundraising campaign (Stars for the Sea) to support Hodin’s research.

Hodin said that all these experiments are truly seeking to answer the most basic question about sea star wasting syndrome: What is it?

A bewildering illness

Sea star wasting syndrome has been documented around the world for more than a century, but previous flare-ups had been isolated to specific geographical regions and affected only a few species at a time. The outbreak that began in 2013, however, is the most widespread ever reported, stretching along more than 2,000 miles of coastline.

In 2014, researchers linked the syndrome to a virus, but a later study revealed that the virus did not consistently cause sea star wasting across species. The origin of the disease, and why this outbreak affected so many stars, still puzzles scientists.

“It might be one of those things where there are multiple factors that cause sea star wasting syndrome,” Hines said, adding that it could be connected to a bacteria or virus or to environmental conditions like warmer waters.

Whatever the cause, Hodin hopes that the knowledge gained in the past nine years through research and community science will better prepare them for the next outbreak.

“It’ll be a bad thing if we see a big uptick in it, but at least we’ll be more ready for being able to make some headway into trying to understand this disease and the effect it has,” said Hodin.

— Reported by Rena Kingery

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