New status could help save giant sea stars
The demise of sunflower sea stars has been linked to the loss of kelp forests, a crucial marine habitat
The brightly colored creatures grow as big a trashcan lid, with as many as two dozen arms to help their slithering scamper after prey along the sea floor.
The sunflower sea star is like no other sea star you’ve seen — and, in California, there have been no recorded sunflower sea star sightings since 2018.
But on Thursday, Dec. 10, in what biologists are calling a key step toward preserving and restoring the species, an influential international conservation monitoring group designated the creatures “critically endangered.”
“These sea stars used to be easy to find, and they were a hit with students and scuba divers because they are unforgettable,” said Oregon State University’s Sarah Gravem, a marine ecologist and lead author of the study that led to the new designation by the International Union for Conservation of Nature.
“Unfortunately, your chance of finding one now are next to nothing in most of the contiguous U. S.,” she said. “I don’t think they’re coming back without our help.”
Recent trends back that up. A mysterious wasting syndrome began killing some 20 species of sea stars in 2013, but the sunflower sea star has been hit hardest. An estimated 90% of the population has disappeared from an offshore habitat that stretches from Alaska to Baja California.
And what’s bad for sunflower sea stars is bad for the ecosystem overall.
The giant sea stars’ diet includes urchins — and a recent population boom of urchins is one reason for a corresponding loss of kelp forests, which provide crucial habitat for a variety of marine life. Additionally, the mere presence of sunflower sea stars can scare urchins from venturing out of crevices and into the kelp.
Kelp forests have been shrinking worldwide due to a number of factors, including warming seas, pollution, and invasive species. The loss of sunflower sea stars is a factor particular to the northeast Pacific, according to the study led by Oregon State University and The Nature Conservancy, and aided by marine data gathered by more than 60 partner institutions over the past 50 years.
“These sea stars used to be easy to find, and they were a hit with students and scuba divers because they are unforgettable.” — Sarah Gravem, marine ecologist
While sunflower sea stars are no longer found in California or Mexico, they are still present in the Washington’s Puget Sound, British Columbia and Alaska, as well as in more limited numbers in the outer coastal waters of Oregon and Washington.
Captive breeding
There are no signs that their population is recovering, but the “critically endangered’ designation could help turn the tide.
“This brings international recognition to the dramatic loss of this species
and provides a scientific basis to work toward its recovery,” said Walter Heady, a senior scientist at The Nature Conservancy. The designating organization, the International Union for Conservation of Nature, works with governments and the United Nations.
“It’s internationally recognized as the global authority on the status of the natural world and the actions needed to preserve it,” Heady said. “The designation creates momentum for this effort.”
Because there is little chance of natural recovery
in parts of its range, The Nature Conservancy is partnering with the University of Washington to explore captive breeding of the sunflower sea star. Now in the second year of this work, the researchers have successfully raised them from larvae to juveniles, Heady said.
“We think it’s very unlikely that the population will recover on its own in California and Mexico without conservation action,” he said. “Without adults there, it’s likely they would have to be reintroduced into the environment.”
Much remains unknown
about the sunflower sea star, including the cause of the wasting disease and whether it will be possible to reintroduce them to wild after captive breeding, as has been done with the California condor and the island foxes of the Channel Islands.
Heady would not predict how soon efforts might be made to try releasing captivebred sunf lower sea stars into the wild.
“There are many potential steps along the way,” he said. “But we’re exploring those steps and developing a road map for recovery.”