California Academy of Sciences researchers breed sea stars to help protect coastal ecosystem

BySpencer Christian and Tim Didion KGO logo
Thursday, January 26, 2023
Academy of Sciences researchers breed sea stars to save ecosystem
California Academy of Sciences researchers breed sea stars to help protect the coastal ecosystem.

SAN FRANCISCO (KGO) -- Keeping track of sea stars along our coastline has been an urgent mission for Rebecca Johnson, Ph.D., of the California Academy of Sciences. She and her teams of volunteers watched as several species, including the giant Sunflower Star, were decimated by a wasting disease possibly triggered by a marine heatwave roughly a decade ago -- which unleashed a chain effect on the ecosystem.

"The loss of this huge starfish allowed for one of its prey items -- the purple sea urchin -- its population to explode. And so with an exploding population of these sea urchins came a decline in kelp, because sea urchins are voracious predators are herbivores of kelp," Johnson said.

She says the explosion of hungry purple urchins has evolved into a long-term threat to the kelp forests, which provide major benefits from sequestering carbon, to providing critical habitat for marine life. They've been particularly destructive to the Bull kelp, prevalent along the Northern California coast.

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"Kelp forests are amazing. I mean, they're nurseries and habitat for tons of different species of fish, for many, many different invertebrates, for otters on the more southern coast. But they also protect the coast from storm surge. They, you know, they buffer the waves," adds Johnson.

While many species have recovered along the coast, Johnson says the Sunflower Star is still largely missing. And with the pressures from climate change, there is ongoing concern about what the future might hold.

Enter senior biologist Riah Evin, with the Academy's captive breeding program. Like an expecting parent, she's currently watching over the tiny specks that will grow into adult "bat stars." And while bats aren't endangered themselves, Evin says the secrets they're unlocking could one day help other species like the Sunflower Stars.

"Using what we've learned raising bat stars, to help that species, those are critically endangered species. And just learning more about their background, what their life cycle's like, what their nutritional needs are, and that is a great gateway to actually do some sort of release program," Evin said.

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She explains that plans to release any species would likely be far off in the future. But there is increasing interest worldwide in learning about the biodiversity of Star populations -- the research geared in part to learning which genetic traits might allow a species to survive pressures like warming ocean waters or marine diseases.

"So this was kind of our catalyst to make sure we can do it here in-house and use it as a jumping-off point to hopefully work with other sea star species," she says.

Academy researchers are doing similar work with coral, which is also facing pressure from climate change and fluctuation in the marine environment. They're hoping that the work on both species will help scientists better understand the changes along our coast and, perhaps, better manage the fragile ecosystems and the predators like sea stars that help keep it in balance.

There are now calls by some experts to reintroduce sea otter populations to the north coast, which also prey on sea urchins. The hope is that, like the sea stars, the otters would help the kelp forests by keeping the hungry urchins in check.

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