There’s hope for sunflower sea stars, with their killer unmasked and reintroductions pending

There’s hope for an iconic ocean predator that has principally disappeared from California’s coastlines: the sunflower sea star (Pycnopodia helianthoides).

The inhabitants started to plummet in 2013, following an outbreak of sea star losing illness, a lethal ailment that pocks starfish our bodies with lesions after which dissolves their flesh. It impacts roughly 20 species, and has killed a staggering 5.75 billion sea stars. But it’s been significantly catastrophic for sunflower sea stars. About 99% of the population alongside its southern vary is gone, from Washington state to Mexico.

It’s the most important epidemic ever to happen within the ocean. Though the illness peaked between 2013 and 2017, localized outbreaks nonetheless happen, and the inhabitants hasn’t recovered.

Now, greater than a decade after the epidemic started, the mysterious killer has lastly been unmasked. Researchers on the University of British Columbia and the Hakai Institute in Canada simply revealed their discovery, figuring out a pressure of the bacterium Vibrio pectenicida as a wrongdoer.

Increasing sea floor temperatures within the Pacific Ocean, pushed by anthropogenic local weather change, are believed to have triggered or exacerbated the illness, in accordance with the IUCN, the worldwide wildlife conservation authority.

Sea stars are voracious predators that feed on sea urchins and different prey. In their absence, urchins have proliferated and laid waste to the kelp forests that traditionally lined the California coast, that are properties and nurseries to innumerable marine species, from fish and seabirds to otters and sea lions.

Now, a coalition of California aquariums, nonprofits, Indigenous teams and authorities specialists is attempting to deliver this starfish again, and together with them, the ecosystem. But even with a groundswell of assist from throughout the state, getting up to now took immense trial and error as a result of little was identified about these echinoderms.

A variety of amenities are actually elevating sunflower sea stars, together with the nonprofit Sunflower Star Laboratory in Monterey, California. It is at the moment elevating  72 juveniles and is gearing as much as start managed releases into the waters of Monterey Bay. It’s a key step within the journey to large-scale reintroductions.

Troubled stars

Sea stars are historic creatures that first appeared on Earth round 480 million years in the past, predateing the age of the dinosaurs by more than 200 million years. Over time, they developed into practically 2,000 distinctive species, forming a bunch referred to as Asteroidea.

Sunflower sea stars are among the many world’s largest, generally rising to the dimensions of a bicycle tire and sprouting as much as 24 arms. Their lifespan within the wild stays unknown, however they’ve survived in aquariums for many years. Most dwell at depths between sea degree and 25 meters (82 toes), however they’ve been found as deep as 455 m (practically 500 ft).

They’re adaptable, residing in eelgrass meadows and kelp forests, in addition to on mud, sand, shell fragments and rocks of all types. What issues most is meals: They prey on clams, mussels, oysters and different bivalves, snails, and, most significantly, sea urchins.

Historically, they have been discovered trawling for prey from Alaska’s Aleutian Islands down the Pacific coast to Baja California in Mexico. When sea star losing illness hit in 2013, it basically eradicated the creature from 2,700 kilometers (about 1,700 miles) of its southern vary.

This ugly affliction begins with splotchy lesions and proceeds to soften tissue. The stars contort and infrequently lose their arms earlier than succumbing inside about two weeks of publicity.

In the laboratory, researchers have seen that hotter water temperatures velocity up the development and the mortality charges of the illness. Out within the sea, higher temperatures have been linked to outbreaks in particular areas.

Climate change might have extra impacts on an animal that’s already in vital situation. In California, the hotter the water, the less the ocean stars, and 14° Celsius (57.2° Fahrenheit) appears to be a powerful cutoff level.

A stellar whodunnit

For years, scientists have tried to determine what induced this large sea star die-off. Initially, poisonous algae blooms have been (wrongly) considered the wrongdoer, then presumably “dead zones” that lacked oxygen. The sea star-associated densovirus was then blamed, and discounted.

Heat was concerned however not considered the trigger: In 2013, simply because the mass die-off of sea stars started, an enormous stretch of heat water dubbed “the Blob” engulfed the Eastern Pacific, extending a whole bunch of toes deep, maxing at 3.9°C (7°F) above regular.

Now, scientists say they imagine they’ve lastly cuffed the sunflower star’s killer. The researchers, led by Melanie Prentice and Alyssa-Lois Gehman on the University of British Columbia and the Hakai Institute, found extraordinarily excessive ranges of V. pectenicida in sick sea stars’ coelomic fluid, which is actually sea star blood.

Then they grew it within the lab and injected it into wholesome stars. Those animals fell unwell with losing illness signs. Their arms curled and fell off, and so they finally died. The new analysis was published within the journal Nature Ecology & Evolution.

The researchers say they’re satisfied that they’ve solved this macabre thriller. What she noticed occurring within the lab mirrored what she noticed within the sea, Gehman stated. “This is consistent with what I see when I am diving and observing wasting in sunflower sea stars in the field,” she stated. “It is unequivocal that V. pectinicida causes death and SSWD-like presentation.”

One scientist has raised a query, nonetheless. Ian Hewson, a marine ecologist at Cornell University, who has labored on SSWD, famous that the authors didn’t report knowledge on lesions, a telltale signal of the illness.

While the absence of lesions is notable, “disease presentations can vary depending on the pathogen, environmental conditions and host response,” stated Blake Ushijima, a microbiologist and marine illness professional on the University of North Carolina, Wilmington, who wasn’t concerned within the research. Based on the brand new paper, he stated he agrees that this bacterium is a reason for SSWD.

Gehman stated her staff did see lesions in a few of the sunflower stars, however “chose not to use those as metrics because they were less consistent as signs of disease than arm-twisting and arm loss.”

Hewson seemingly has motive to be cautious: In 2014, he led a study incorrectly implicating a densovirus as a possible reason for the illness. He published a mea culpa final 12 months exonerating the virus and reflecting on classes discovered from his expertise.

Responding to the disaster

In response to the sunflower star’s startling demise, the Pycnopodia Recovery Working Group was fashioned in 2019, comprised of members from three international locations and 4 U.S. states. This broad consortium consists of specialists from universities, nonprofit organizations, American Indian Tribes, Indigenous First Nations and authorities companies.

Their objective: to develop a restoration technique. Soon after the group fashioned, they realized the vital want to lift sunflower sea stars in captivity, which had by no means been performed earlier than. It was additionally essential to establish what was killing them within the wild.

In 2021, the IUCN listed the sunflower sea star as critically endangered. Two years later, a review by the U.S. National Marine Fisheries Service proposed itemizing the imperiled star as a threatened species beneath the U.S. Endangered Species Act as a result of it’s more likely to turn into endangered inside the foreseeable future all through a lot or all of its vary. A choice remains to be pending.

The Sunflower Star Laboratory coordinated with the working group to analysis and assist launch a dependable solution to elevate these slow-growing creatures. “We were founded by local members of the Monterey Bay area community who were all watching the kelp disappear from in front of our eyes,” stated Reuven Bank, a diving ranger with the U.S. National Park Service and chair of SSL’s board.

Early on, “nobody knew the sexes of the stars. Nobody knew how frequently they spawned,” stated Ashley Kidd, SSL’s conservation undertaking supervisor.

California aquariums that held them of their collections started shut remark to establish the intercourse of their animals after they subsequent spawned, producing both sperm or eggs. It turned out that Birch Aquarium in San Diego was the one facility with each sexes, dwelling to at least one feminine and 4 males.

Researchers efficiently synchronized the males and feminine to spawn by injecting the hormone 1-methyladenine into the celebs’ arms. The staff — specialists from Birch Aquarium, the Aquarium of the Pacific, California Academy of Sciences, San Diego Zoo Wildlife Alliance, Sunflower Star Laboratory and different companions — managed to efficiently fertilize sea star eggs.

To discover one of the simplest ways to supply sea star offspring sooner or later, they used sperm from the identical male in three separate experiments: recent; frozen at -80°C (-112°F) in a freezer; and cryopreserved at -196°C (-321°F). All have been profitable.

Raising the sunflower sea star ‘cupid cohort’

The fertilized eggs produced at Birch Aquarium — dubbed “the cupid cohort” as a result of the spawning occurred on Feb. 14 — have been shipped to aquariums across the state as a part of the Association of Zoos & Aquariums’ SAFE (Saving Animals From Extinction) program.

Moss Landing Marine Laboratories was among the many locations. There, Andrew Kim was working as an aquaculture analysis technician, and it grew to become his obligation to maintain the larvae alive.

There was restricted infrastructure, he remembers, “but it caused me to get creative.” He housed the larvae in beakers, tubs and different containers, fed them totally different sorts of algae, and examined totally different oxygen ranges.

Kim discovered that sunflower star larvae thrive beneath many various circumstances so long as they’re well-fed. When he left Moss Landing to turn into lab supervisor at Sunflower Star Laboratory, his subsequent problem was overseeing the younger stars’ journey to maturity.

Starfish start life as free-floating, gelatinous larvae, and solely settle onto the seafloor, the place they mature, in the event that they detect that circumstances are good.

Kim added an alga, Calliarthron tuberculosum, into the water and located that it glad larvae, and so they settled down. The lab is now dwelling to 72 younger sunflower stars. The largest, named Titan, measures 20 centimeters (8 inches) throughout.

As the celebs have grown up, their distinctive personalities have began to emerge. “I have a couple of stars that every single time I feed them, they engulf the food,” stated laboratory technician Mariana Jimenez, whereas others are “little babies, and they want love and attention.”

One star, Bigby, has a repute as an escape artist, utilizing its tiny tube toes to crawl up and out of its container. “We’ve seen Bigby literally three-fourths of the way into another star’s tub,” Jimenez stated.

But if all goes nicely, Bigby might sometime be capable of discover a wider world. SSL is working towards a small-scale launch of stars to check what circumstances they should thrive. To that finish, the lab has been in contact with California state regulators from the very starting, Reuven Bank stated.

“We’re addressing the path towards reintroduction from an interdisciplinary and holistic approach,” Bank added. “It’s a comprehensive plan with the ability to monitor them and the ability to produce them at scale.”

Sunflower stars have already been raised and released by researchers on the University of Washington’s Friday Harbor Laboratories. In August 2024, divers launched 20 younger stars off San Juan Island, ranging in age from 1 to three years outdated..

Looking in direction of restoration

It will take additional analysis to know all of the elements that created and unfold the ocean star losing epidemic, however for now, it happens at a lot decrease ranges.

Looking to the long run, the SAFE program revealed a 2024-2027 conservation plan for sunflower star restoration alongside North America’s west coast. It encompasses the Pycnopodia Recovery Working Group’s analysis and highlights seven important targets: establishing restoration targets and pinpointing threats; monitoring remaining wild populations; increasing illness analysis and discovering methods to battle it; increasing captive breeding and determining tips on how to launch stars; understanding the federal government allowing course of and any potential biosecurity points; and bettering communication with the general public.

There’s widespread assist for sea star restoration. Even fishers who compete with sunflower stars for urchins need the many-armed giants again, Bank stated.

“Purple and red urchin fisheries need healthy kelp forest to have healthy, fat urchins for them to harvest,” he stated. “So many disparate groups within the community, who may even have been at odds on other conservation issues, are generally supportive of sunflower star recovery.”

Banner picture: A sunflower sea star clings to life in Knight Inlet, British Columbia, in 2025. Image courtesy of Grant Callegari/Hakai Institute.

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Citations:

Selgrath, J. C., Carlton, J. T., Pearse, J., Thomas, T., & Micheli, F. (2024). Setting deeper baselines: Kelp forest dynamics in California over a number of centuries. Regional Environmental Change, 24(3), 104. doi:10.1007/s10113-024-02260-1

Hodin, J., Pearson-Lund, A., Anteau, F. P., Kitaeff, P., & Cefalu, S. (2021). Progress towards full life-cycle culturing of the endangered sunflower star, Pycnopodia helianthoides. The Biological Bulletin, 241(3), 243-258. doi:10.1086/716552

Prentice, M.B., Crandall, G.A., Chan, A.M., Davis, Okay. M., Hershberger, P. Okay., Finke, J. F., … Gehman, A. M. (2025). Vibrio pectenicida pressure FHCF-3 is a causative agent of sea star losing illness. Nature Ecology & Evolution. doi:10.1038/s41559-025-02797-2

Hewson, I., Button, J. B., Gudenkauf, B. M., Miner, B., Newton, A. L., Gaydos, J. Okay., … Harvell, C. D. (2014). Densovirus related to sea-star losing illness and mass mortality. Proceedings of the National Academy of Sciences, 111(48), 17278-17283. doi:10.1073/pnas.1416625111

Hewson, I., Johnson, M. R., & Reyes-Chavez, B. (2024). Lessons discovered from the ocean star losing illness investigation. Annual Review of Marine Science, 17. doi:10.1146/annurev-marine-040623-082617