Short Wave - The Fight To Save Sunflower Sea Stars

Episode Date: August 26, 2021

Sunflower sea stars play a key role in ocean ecosystems on the West Coast - and they are disappearing in record numbers. Science correspondent Nell Greenfieldboyce tells us about the plight of the Sunflower sea star and one biologist's unique fight to save them. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey everybody. Emily Kwong here. Okay, so my notes say we're going to be talking about a voracious sea creature that can have up to 24 arms. And the person we'll be talking to is NPR science correspondent Nell Greenfield Boyce. Hey, Nell. Hey there, Emily. I have only two arms. But I am nonetheless here to tell you about these things.

I want all your arms around this story. Tell us about this many-armed briny beast. Well, it's a sea star. It's one of the biggest in the world. It can be the size of a trash can lid or a, you know, manhole cover or something like that. It's called the sunflower sea star. Ah, yeah, yeah, yeah. So these things used to be common all along the West Coast from Alaska all the way down to Baja, California, in northern Mexico.

Yeah, I've heard of these. I've seen pictures. They're beautiful, though used to be. I mean, those are som ominous words. It is a grim, grim situation. The species is critically. endangered. It seems to be dying off. It's just disappearing from lots of places. Some people think it's completely extinct in California. And this is a big deal because the sunflower sea star is a top predator.

It eats animals like mussels and sea urchins and keeps their numbers in check. I didn't realize that the sunflower sea star is a top predator. I know that sea stars, though, have for years been plagued by a disease off the West Coast. Is that what's killing sunflower sea stars too? Yes. So this is a wasting syndrome, and scientists can't agree on what's causing it. It's hit more than 20 C-Star species since a big die-off in 2013 on both the East and the West Coast. But a researcher named Jason Hoden told me that sunflower C-stars seem to be particularly susceptible. They really do kind of like dissolve into a pile of goo. It's why he agreed to try raising them in captivity. Wow. So becoming in effect like a C-star foster parent? That is exactly how he sees himself. He is

deeply attached to these sea stars. He started out by collecting about 30 sunflower sea stars from the wild. One of the things that's been really fascinating in that I didn't really anticipate with the juveniles or the adults really is how exuberant their behaviors are. You get to know them, and you get to know them individually. We noticed early on that we could tell them apart by their color patterns. And so we gave them names. A lot of them are named after their colors like Prince. Prince has purple-tipped arms. They can be bright orange, pink, green. Now, I have a thousand and one follow-up questions. I mean, starting with how do you raise a C-star in captivity? And does this story have a sad ending? I swear this is a hopeful story. This is not a depressing story. This is a hopeful one of

people actually trying to make things better. All right. Well, today, the plight of the sunflower sea star. What might be killing them and how scientists are figuring out how to breed them in captivity with the goal of maybe boosting the sunflower sea star population in the wild. You're listening to Shortwave, the Daily Science podcast from NPR. Okay, no. So where is this lab where they're trying to breed this enormous sunflower sea star? It's at the University of Washington's Friday Harbor Labs, which is on an island, San Juan Island, off the coast of Washington State. You have to take a ferry to get there.

It's like kind of a tourist place. I can kind of picture it. It's probably got like whale watching and kayaking options. That is exactly the type of place. So Hoden's Lab is in a little building right by the water. There's this boat dock there. And we walked out onto it and he hauls up a rope that was hanging off into the water. At the end of the rope was this kind of square Tupperware container. Like the ones for sandwiches? Those are the ones. So this one had holes cut into the sides that were covered with this fine mesh to let water flow through. So he pulls off the lid, water runs out, we peer inside. You can see some crushed shells, and there's some tiny reddish-arange dots. Like that guy right there.

See that? A little dot right there in front of my finger. That's a juvenile sea star is about a month old. It was the size of a poppy seed. Aw, cute baby sunflower sea star. How long does it take for them to get from that size to their massive manhole cover size in adulthood? That was a major question that Hoden and his colleagues had at the start. The Nature Conservancy approached him in 2019 about maybe trying to breed these sunflower sea stars,

but no one had the most basic information, like how fast do they grow. Nobody knows how to age a sea star, so you see something in the wild that's, you don't have no idea how old it is. It could be two years old. It could be 50. It could be 100. Can they really live that long? Nobody knew, but Hoden told me that related species can be really long lived. he took on this project, even though it was no sure thing. And his lab is now just kind of full of containers filled with burbling water. There's glass pickle jars that have little larvae floating around in there.

You can barely see them. And then he's got these sort of Tupperware food type containers with, you know, these little poppy seed-sized ones that have sort of settled out from floating and are now growing on the bottom and sides of the little containers. And you said they have some big ones too from the wild? Those were caught so that scientists could get sperm and eggs from them. Got it. And they are outside the lab in these sort of big outdoor tanks.

One of the lab workers there, Flora Anto, she took me out there so I could watch her feed them. This here is Deep Blue, and she's our biggest. So she took muscles and basically was just gently tucking them under the starfish arms. So some of them, when, you know, I opened the cage, will basically really start moving their arms to the surface like Olga here. And some of them are a little shyer. That's cute. Though I don't really

think of a C-star as having a personality. They are amazing to watch. I mean, for one thing, their colors seem to almost glow, almost like they're lit from the inside. They're really bright. And also, they move surprisingly fast. And when they get prey, they sort of hunch over it so they can swallow

it whole. When food comes, then you really see, like, the predator come out. Sunflower C-stars are predators and really voracious ones. And you don't think of a sea star as being something like a tiger or a shark, but they really are a top predator in the ocean. I mean, something like a scallop would be totally terrified of this thing. So now, okay, what is happening in places where this predator has disappeared? People have been seeing changes in the kelp forests, which are home to lots of marine creatures. Kelp is like the rainforest of the sea. And the thing is, if a

A predator like a sunflower sea star is gone. That means certain prey species like sea urchins are just left completely unchecked. They can go wild and they start mowing down kelp in these big carpets of purple sea urchins just sort of like eating everything in sight. It's a big problem. And I assume this lab, if they're successful, their ultimate goal is to build back the sea star population, this predator population in the wild. So how long is that going to take? So the initial tests in local waters could happen relatively soon, like maybe potentially as soon as next year. The oldest sea stars produced by this lab are now nearly a year and a half.

So those are about three inches across. To me, something that, you know, that starts out that you could barely see it. And then a year later, it's already the size of the palm of your hand. I mean, that is super fast growth. Hoden says he thinks they could be fully grown adults capable of reproducing by next year. And that's just based on what they've seen in the wild, the smallest ones out there that they know are reproductively mature. And how many sea stars do they have that are that old? Only about a dozen.

But Hoden thinks they were lucky to get that many, given that almost nothing was known about how to do this. And plus, they were having to do it all during a global pandemic that I'm sure you can imagine interrupted their lab operations. But now that they've figured out all the tricks, the lab is working to produce hundreds of young sunflower sea stars that would be about that size. And Hoden says the ideas you might want to first put them in the local area where their parents came from and you would just sort of assess how well a lab-grown starfish could do out in the wild. All right. So we've got this sunflower sea star nursery over here. But the ocean, it doesn't seem safe enough for them. Like wouldn't C-star wasting disease?

I hate to say it. But wouldn't it just kill all the lab-grown ones once they're put into the wild? That really depends on what is causing the disease, right? And, you know, I asked this kind of question when I spoke to Drew Harvel. And she's a research scientist at Friday Harbor Labs and also a professor emeritus at Cornell University. I would say at the outset that it's critical to understand more about what's killing them before trying to put them back. Yeah. She thinks the disease is caused by an infectious agent, something like a virus.

But other scientists don't think it's a contagious disease. They think C-Stars could be killed by just things like warming oceans. or maybe other environmental changes that lead to C-stars getting less oxygen. It is extremely controversial. There is not agreement. She told me that reputable scientists have looked at this and have just gotten different results depending on the experimental conditions. So like if you bring C-stars in from the wild and expose them to something like high temperatures or low oxygen in the lab, you know, you can see them waste away and it can be tempting to say that's what's killing them

these environmental conditions. Her view is that, maybe they were already carrying some infection that made them weaker and more likely to die if conditions are poor. She says one of the reasons she's excited about the captive breeding program is that, you know, researchers would love to raise sunflower sea stars in completely clean conditions and then use them as test animals in the future to try to figure out some of this stuff. Right now, any sea star that's taken from the wild, you know, you don't know what it's been exposed to. I see. But how isolated are these lab-grown sea stars? Like, I'm assuming. they pump in the seawater that's right outside, do they filter it or anything? It's filtered, but not completely sterilized, so Hoden doesn't know if his beloved animals are

susceptible or not. We hope they don't get it, obviously. And we actually hope even more so that because we're, you know, filtering water, but not that intensely, that they've been exposed and the fact that they've survived it maybe suggests that they're resistant. That's the hope anyway. But we would love to be able to know for sure. And so knowing the nature of the disease in particular, you know, would really help. He's constantly on the lookout for any signs that they're falling ill. He's completely devoted to these animals. I mean, I watched him use a pair of tweezers to sort of tenderly feed this tiny muscle to one of the young ones.

You know, it was like curling its arm around the treat. He told me he even dreams about them. Yeah, I can hear it in his voice that obviously these sea stars are personally very important to him. He's deeply attached to them. This is a very personal project for him. But, you know, it's important to other people, too, just because kelp forests are so essential for life in the oceans on the West Coast. And they are in trouble. And so sea stars are interesting and beautiful just in and of themselves.

But they're also part of this bigger thing that's happening out there in the ocean that has people worried. Well, we're just going to have to stay tuned. Let us know what comes of this. Thank you for this update on Sunflower Sea Stars. Thanks for having me on the show. This story was edited by Giselle Grayson. Produced by Indy Kara with help from Rebecca Ramirez and fact-checked by Burley McCoy. The audio engineer for this episode was Quasi Lee.

I'm Emily Kwong. Thanks for listening to Shortwave, the Daily Science podcast from NPR.