What happened to sunflower sea star? This lab is working to find out

FRIDAY HARBOR — Meet the sunflower sea star.

Here, in the burbling tanks at the University of Washington’s Friday Harbor Laboratories, these charismatic orange and maroon sea stars are snacking on mussels and dog-piling their siblings.

The sunflower star was once a ubiquitous delight of the Salish Sea, but a disease, called sea star wasting syndrome, wiped out an estimated 99% of the species in Washington after a series of marine heat waves. Today, the National Oceanic and Atmospheric Administration proposed to list the animal as threatened under the federal Endangered Species Act, indicating the species’ dire outlook.

But Jason Hodin’s humble sunflower star lab on San Juan Island may hold one piece of a blueprint for recovery. He’s raised hundreds of young sea stars in the nation’s first captive breeding program, and his team is gearing up to dunk them in the Salish Sea, with hopes of eventually releasing them into the wild to rebuild the population.

The wasting disease causes the stars to fall apart. Pieces of their arms fall off and walk away. Their bodies disintegrate on pilings, beaches, rocks and the seafloor. There’s still much to learn about the cause of the disease, but it’s clear sunflower stars have been suffering the worst of it.

Scientists don’t yet know much about the life cycle of sunflower stars. They’ve studied crabs, mussels and urchins at greater length — because they’re also food, said Hodin, a senior research scientist at Friday Harbor Labs. But sunflower stars for years didn’t warrant the same attention. That’s changing rapidly.

From an oblong microscopic blob of larva with nothing more than a stomach, esophagus and mouth floating around in canning jars, the baby stars grow sticky “landing pads” for their eventual descent to the bottom. They grow into eight-legged silver-dollar-size stars in a year, and can be almost as big as a trash can lid with more than a dozen arms as 3-year-olds. 

Separate tanks hold sea stars at each phase of their early life in the lab.

Deep Blue has beautiful indigo-dipped arms and Fanta is bright-orange, like the beverage. The dozens of aptly named sea stars in tanks on San Juan Island receive five-star care from Hodin and the research team.

With a laptop in hand, researchers check on them twice a day, documenting whether they’re eating, or showing any worrisome signs. If the stars start curling up their arms, or flattening out their bodies, they go into quarantine in a separate tank as a precaution.

The team hopes this work could lead to a restoration strategy that could be replicated elsewhere.

“When they disappeared and all kinds of other ecological consequences started to pop up, like kelp forests’ disappearance and massive overpopulation of sea urchins, then all of a sudden people were like, hey, maybe we need to know more about that,” Hodin said. “We’ve been sort of taking them for granted.”

Cascading effect

When full grown, sunflower stars are dotted with tiny suction cups that allow them to navigate rocks and sand on the ocean floor. They use the outer ends of their arms to hunt and “see” light, chemical and mechanical changes in their surroundings.

“They’re just cool,” said Joe Gaydos, science director at the SeaDoc Society. “They’re the largest sea star in the world, they can be 3 feet across and they’re the fastest sea star, they’re just like these little mini cheetahs underwater.”

They also play a critical role in marine ecosystems, Gaydos said, dining on spiny sea urchins to protect the Salish Sea’s lush kelp forests from overgrazing.

A recent study found the sunflower star consumes kelp-eating urchins at rates sufficient to recover kelp forests. The discovery comes at a time when overabundant purple urchins have decimated entire forests along the Pacific Coast.

For thousands of years, the region has relied on abundant kelp forests, with olive and purple strands swaying with the currents. They suck up carbon, provide shelter and food for salmon, herring and rockfish and sustain Indigenous ways of life.

But as sunflower sea star populations waned from disease, sea urchins boomed — with populations seeing an estimated 10,000% increase in a reef surveyed off the coast of Oregon — consuming more and more kelp along the way. The absence of bull kelp would likely cause other marine species to disappear.

“We could see this kind of cascading effect,” Gaydos said.

The National Oceanic and Atmospheric Administration has also been petitioned to list bull kelp under the Endangered Species Act.

The agency on Thursday will begin taking public comments on its proposal to list the sunflower star.

Once a species is listed, NOAA monitors their population and reviews their status on a five-year basis. The agency develops recovery plans to reduce or eliminate threats and reestablish sustainable wild populations. A listing under the Endangered Species Act also adds protections from human activity that could harass or harm the species.

On a recent winter day, baby green urchins, red bumpy “Turkish towel” seaweed and chunky white-frilled anemones hung out under the docks outside Friday Harbor Labs. A Troschel sea star clung to a piling nearby, but no sunflower stars were in sight.

“I think the possibility that you could lose a species like the sunflower star that was as common as a robin before this disease is kind of staggering to everybody,” said marine ecologist Drew Harvell, author of “Ocean Outbreak, Confronting the Rising Tide of Marine Disease.”

What’s to come

Scientists are beginning to unravel the mystery around what caused the disease, and why it hit the sunflowers harder than other sea stars.

Studies are underway to examine what makes sea stars more resilient to the disease — some researchers are breaking down the genes activated by exposure and what can help them survive. It’s exciting work that could help breed disease-resistant stars in the future, Harvell said.

In a separate study, researchers at the Hakai Institute have exposed visibly healthy sunflower stars to infected ones in various ways. They’ve injected them with coelomic fluid, or “blood” from a sick star, and exposed them to water from a sick star’s tank. “In the experiments that we’ve done,” said Alyssa-Lois Gehman, a Hakai Institute scientist, “every single individual that we have exposed to disease has wasted and died — every single one.”

The ongoing research suggests it began with a pathogen, Gehman said. 

Meanwhile, researchers at the Oregon Coast Aquarium say they have successfully saved 17 stars using cool water, probiotics and medicated baths to treat the disease.

Unlike vertebrate species, invertebrates like sea stars can’t be vaccinated. They won’t develop any immunity because they don’t have an adaptive immune system, Harvell said. The only way to help them build resistance to disease is selective breeding.

Massive marine species recovery efforts like this are rare.

More recently, scientists have been working to recover pinto abalone, colorful sea snails with a shell and one foot. Their population plunged 97% from 1992 to 2017, mostly the result of overfishing and ocean acidification. Thousands have since been raised in tanks and released near the San Juan Islands.

Eventually, mounting research to understand how sea star wasting disease spreads will intersect with Hodin’s efforts and widespread reintroduction could begin.

“I can’t say enough about the value of the success of the captive breeding program,” Harvell said. “I think it not only gives hope, but it just shows very clearly other avenues that are possible.”

Next month, research technicians from Friday Harbor Labs will begin testing an “outplanting” project — dropping stars into the wild in little plastic cages. They’ll start with fake sea stars to test the flow, temperatures and other factors inside and outside of the cages.

If all goes well, they’ll deploy dozens of 1- and 2-year-old stars in cages, testing for growth and survival. Meanwhile, geneticists from the University of California, Merced, will “fingerprint” each star to see if there are some traits that might make them better suited for reintroduction into the wild.