Academy of Sciences raising sea stars whose population was devastated during ocean heat wave

ByDan Ashley and Tim Didion KGO logo
Friday, March 22, 2024
Academy of Sciences raising sea stars devastated by heat wave
California Academy of Sciences is raising sea stars, whose population was devastated during an ocean heat wave.

SAN FRANCISCO (KGO) -- If you think raising healthy kids is tough, try sea stars. Researchers at the California Academy of Sciences are taking on the challenge in the face of a dangerous environmental threat along our own coastline.

And their lab looks something like a commercial kitchen.

"So, the spatulas are simulating water currents in the ocean. So we don't want these guys in stagnant water. We want them up in the water column so they can eat," says marine biologist Riah Evin.

Evin keeps a close eye on dozens of jars, swirling with mechanical spatulas, in what's essentially a giant starfish nursery, feeding and raising tiny larvae too small for the eye to see.

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"Yeah we've got several million on both of these tables," she says, surveying the brood.

The nursery at the California Academy of Sciences is part of a multi-site project to rescue a species known as the Sunflower Sea Star from near extinction. To understand the urgency, all you need to do is stroll along our coastline. That's where Evin's colleague, Rebecca Johnson, Ph.D., helped document the Sunflower Stars' disappearance more than a decade ago. An event likely triggered by a severe marine heatwave and a sea star wasting disease.

"They were particularly hard hit, especially here in California, and they really haven't made a recovery. There are a few occurrences in the wild of these animals, but they're really hard to see and really hard to find," Johnson says.

Much easier to see is the environmental chain reaction. The vanishing sea stars normally prey on purple sea urchins, whose population quickly exploded. That was deadly news for local kelp forests, the next rung down on the food chain for the hungry urchins.

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"And so the loss of the urchin predator has released the urchins and allowed their population to grow and for them to eat tons of kelp contributing to a decline of kelp forests along our northern California coast," Johnson said.

The damage to the kelp forests and surrounding ecosystem is so significant, scientists decided to bolster the Sun Flower Star population in captivity, for now.

"Yeah. It's crazy that these guys are going to grow up to be these keystone apex predators," says Evin, pointing to the tiny, translucent larvae. "But they will."

She says, a team of researchers, including The Birch Aquarium at Scripps Institution of Oceanography near San Diego, are working to raise the sea stars. First step is capturing sperm and eggs from a limited number already in captivity. Because the tiny larvae go through dramatic changes before they become sea stars, raising them is a tricky process.

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"And they'll settle down to the bottom of the ocean or the bottom of my tables, and they'll actually start looking like a sea star. At that point, their diet changes completely, and that change in diet is the real sticking point that we we're looking forward to really figuring out what they need and want to eat at that point, Evin explains.

And any decision to reintroduce stars back into the ocean would also be tricky and probably decades away. But the debate is becoming familiar.

There are already proposals to restore native sea otters that vanished from our coast after being hunted nearly to extinction. While labs like the Academy are also working with genetic variations of Coral, that could someday be used to repopulate coral reefs devastated by climate change.

As for the Stars...

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"That's the million dollar question," Johnson said. "There are lots of regulatory hurdles and lots of things that would have to happen for that to be possible. But the hope is to increase the genetic diversity of the things that we're holding in human care and to have as many individuals in as many places to protect the species as we get toward being able to reintroduce them."

So for now, the spatulas continue to swirl and researchers continue to experiment with diets and environment -- preparing for the day their aquarium-raised sea stars could return to become a key link in our coastal ecosystem.

And just to underscore the urgency of the breeding programs, scientists say average ocean temperatures are set to break new records, putting even more pressure on marine life like coral and sea stars.

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