August 4, 2025
The underside of an grownup sunflower sea star at UW Friday Harbor Laboratories.Dennis Wise/University of Washington
Sunflower sea stars are the most important sea stars on the planet: They have as much as 24 arms and develop to the dimensions of a bicycle tire.
Starting in 2013, these creatures and different sea star species alongside the west coast of North America died in epidemic proportions. The stars had harrowing signs: Their arms contorted earlier than falling off fully. Over the previous decade, sea star losing illness has killed billions of sea stars in as much as 20 species by successfully “melting” their tissues.
The illness has worn out greater than 90% of the once-common sunflower sea stars, most critically within the continental U.S., touchdown them on the International Union for Conservation of Nature’s Red List of critically endangered species. The lack of sunflower sea stars, which help kelp forests by feeding on kelp-eating sea urchins, has had widespread and lasting results on coastal ecosystems.
Until now, nobody knew what precipitated sea star losing illness. But on Aug. 4, a world analysis effort together with scientists from the University of Washington has lastly revealed the trigger: a pressure of the bacterium Vibrio pectenicida. Vibrio is a genus of micro organism that has devastated coral and shellfish in addition to people (for instance, Vibrio cholerae is the pathogen that causes cholera).
The researchers published this finding in Nature Ecology & Evolution.
Drew Harvell holds a sunflower star at UW Friday Harbor Laboratories.David O Brown/Cornell University
“This is the discovery of the decade for me,” mentioned co-author Drew Harvell, a UW affiliate professor within the School of Aquatic and Fishery Sciences and Friday Harbor Laboratories. “We have studied both the cause and the impacts of this disease for the entire epidemic. What’s crazy is that the answer was just sitting right there in front of us. This Vibrio is a sneaky critter because it doesn’t show up on histology like other bacteria do.”
“From initial studies, we thought the culprit was a virus,” Harvell continued. “So it was a surprise to find the pathogen in a more common group of bacteria.”
The long-awaited end result exhibiting V. pectenicida pressure FHCF-3 because the causative agent comes after a four-year analysis course of. Scientists explored many doable pathogens, together with viruses. At first, the researchers regarded in sunflower sea star tissues earlier than they homed in on the excessive ranges of V. pectenicida in sick sea star “blood,” or coelomic fluid.
“When we looked at the coelomic fluid between exposed and healthy sea stars, there was basically one thing different: Vibrio,” mentioned senior writer Alyssa Gehman, a marine illness ecologist on the Hakai Institute and the University of British Columbia. “We all had chills. We thought, ‘That’s it. We have it. That’s what causes wasting.’”
Harvell attributes the staff’s success to:
- Having the fitting amenities on the U.S. Geological Service with correct quarantine and high-quality water movement
- A proficient analysis staff that had pathology, virology and bacteriology expertise
- Having entry to a supply of the fitting check animals, together with sunflower sea stars raised in captivity by co-author Jason Hodin, UW senior analysis scientist at Friday Harbor Laboratories.
Adult sunflower sea stars feeding on mussels at UW Friday Harbor Laboratories. The stars suck out and ingest the delicate tissues of mussels, then discard the shells, which accumulate on the backside of the tank. The sea star on the underside, “Charlotte,” is the mom of the lab’s stars grown in captivity.Dennis Wise/University of Washington
Grace Crandall injects a sea star to reveal it to losing illness firstly of a brand new experiment.Grace Crandall/University of Washington
“I observed and collected health data on nearly every single sea star twice a day for the majority of experiments for all four summers,” mentioned co-author Grace Crandall, a UW doctoral pupil within the School of Aquatic and Fishery Sciences. “I have loved sea stars and have been fascinated by diseases since childhood. To get to participate so actively in research that combines both of these interests has been a dream come true. I’m excited about getting to work on a project with such consequential findings for the conservation of these important sea stars: to find both the cause of sea star wasting disease, and to better understand their immune response.”
To verify that V. pectenicida was the perpetrator, co-author Amy M. Chan, a analysis scientist at UBC, created pure cultures of V. pectenicida from the coelomic fluid of sick sea stars. The staff then injected the classy pathogen into wholesome sea stars, which developed signs of sea star losing illness — the ultimate proof.
“When we lose billions of sea stars, that really shifts the ecological dynamics,” mentioned lead writer Melanie Prentice, an evolutionary ecologist on the Hakai Institute and UBC. “In the absence of sunflower stars, sea urchin populations increase, which means the loss of kelp forests, and that has broad implications for all the other marine species and humans that rely on them. So losing a sea star goes far beyond the loss of that single species.”
The staff poses within the lab on the USGS Marrowstone Marine Field Station. From left to proper: Alyssa Gehman, Grace Crandall, Melanie Prentice and Drew Harvell.Grace Crandall/University of Washington
Now that scientists have recognized the pathogen behind sea star losing illness, they will look into the drivers of illness and potential hallmarks of resilience. Researchers are notably concerned about finding out the hyperlink between sea star losing illness and rising ocean temperatures. The results of the illness appear to be stronger in hotter water, and different species of Vibrio are additionally recognized to proliferate in heat water, Gehman mentioned.
Researchers and venture companions hope the invention will assist information administration and recovery efforts for sea stars and the ecosystems affected by their decline.
“It’s just heartbreaking to watch them die,” Harvell mentioned. “Sunflower sea stars are enchanting creatures and they’re quite interactive. At feeding time, they will come toward you. If you throw clams to the stars, they can catch them. It’s so gratifying to finally have an answer.”
Additional co-authors on this paper are Katherine M. Davis and Jan F. Finke at UBC and the Hakai Institute; Paul Okay. Hershberger on the U.S. Geological Survey; Andrew McCracken on the University of Vermont; Colleen T. E. Kellogg, Rute B. G. Clemente-Carvalho and Carolyn Prentice on the Hakai Institute; and Kevin X. Zhong and Curtis A. Suttle at UBC. The analysis was supported by The Nature Conservancy of California, the Tula Foundation, the Natural Sciences and Engineering Research Council of Canada Discovery Grant, the Canadian Foundation for Innovation and British Columbia Knowledge Development Fund Infrastructure award, the University of British Columbia, the U.S. Geological Survey, Biological Threats Research Program, Ecosystems Mission Area and the Quantitative and Evolutionary STEM Traineeship.
For extra info, contact Harvell at cdh5@cornell.edu.
Adapted from a launch from The Hakai Institute.
Tag(s): College of Arts and Sciences • College of the Environment • Drew Harvell • Friday Harbor Laboratories • Grace Crandall • Jason Hodin • School of Aquatic and Fishery Sciences