Bay Area scientists work to restore sea star population devastated by pathogen

CBS News

4 days ago

Scientists have determined the cause of an epidemic that has devastated a species of starfish, wiping out billions over the last decade, and a Bay Area team is at the forefront of an effort to restore their population.
At the California Academy of Sciences in San Francisco, inside the Steinhart Aquarium, 7-year-old visitor Dylan Stewart was mesmerized by the Pycnopodia helianthoides, more commonly known as the sunflower sea star.
"I really like it," he exclaimed. "Because they're all going at different directions, kind of like a sunflower petal, and it's big like a sunflower."
The sunflower sea star can grow up to 24 arms, which explains the name. Dr. Rebecca Johnson, director at the Center for Biodiversity and Community Sciences and a scientist for the California Academy of Sciences, said she used to see lots of sunflower starfish at low tide off the California coast. But this is no longer the case.
"We went to places where you'd see hundreds of starfish in a day, but they were just completely gone," Johnson said.
Since 2013, a mysterious "wasting disease" epidemic has killed billions of sea stars, representing 26 species from Alaska to Baja Mexico.
"No one knew at the time what was causing it," Johnson said. "If they would ever recover, like we didn't know anything. It was just, it was just shocking."
The illness turns them to goo, essentially disintegrating them. More than 90% of sunflower sea stars are now wiped out. Now, a team of international scientists has solved the mystery.
After a four-year quest involving 20 experiments, the researchers have finally identified the pathogen. They honed in on the sea star's blood, called coelomic fluid.
"The culprit is a bacterium. It's a species of Vibrio," research scientist Melanie Prentice explained.
Vibrio is a genus of bacteria that can be devastating to coral, shellfish, and human beings. The species of Vibrio that is causing this epidemic in sea stars is known as V. pectenicida strain FHCF-3.
The successful efforts involved the Hakai Institute, the University of British Columbia, and the University of Washington. The scientists collaborated with The Nature Conservancy, The Tula Foundation, the U.S. Geological Survey's Western Fisheries Research Center, and the Washington Department of Fish and Wildlife.
As to what's driving the disease, Prentice pointed to warming waters.
"We have evidence that there is a link between increasing ocean temperatures and this sea star wasting disease epidemic," Prentice said.
The sunflower sea stars are voracious predators that feast on sea urchins. Without these starfish, sea urchins are then free to feast on valuable kelp forests. These forests provide habitat for marine creatures and store planet-warming carbon.
"They grazed or mowed down entire kelp forests," Prentice said. "So now places like Northern California have lost more than 95% of their kelp forest canopies."
The hope is now that scientists know the cause of the epidemic, they can screen for the pathogen. Some marine centers are already breeding sunflower sea stars with the hopes of one day reintroducing them in the wild, including at Cal Academy.
Aquarium curator Kylie Lev brought CBS News Bay Area behind the scenes to see how they are involved in conserving these critically endangered starfish. Along with the Aquarium of the Pacific, the Birch Aquarium, the San Diego Zoo Wildlife Alliance, and the Sunflower Star Laboratory, the scientists have successfully spawned and cross-fertilized sperm and eggs from male and female sea stars, created embryos, and are raising them.
Their efforts are identifying protocols and best practices, so that lab-spawned sunflower starfish may one day return to the wild.
"It is really important just to make sure in order for the population to sustain long-term, to have genetic diversity," Lev explained.
Some of the youngest juveniles are now on display at Steinhart Aquarium, a treat for the curious Dylan and his family.
"It's great that they finally figured out the cause; now it's hopefully figuring out how to get them repopulated," Dylan's father, Kyle Stewart, said.