Think Out Loud

Oregon Coast Aquarium develops treatment plan to save sick and injured sea stars, including one to get federal protection

By Sheraz Sadiq (OPB)
March 20, 2023 2:48 p.m.

Broadcast: Monday, March 20

A sunflower sea star is shown eating a clam inside its habitat at the Oregon Coast Aquarium in Newport. The aquarium recently unveiled a treatment program that proved successful in over 15 sea stars, including sunflower sea stars, that were injured, stressed, or sickened by a wasting syndrome that has decimated populations of the invertebrates along the West Coast.

A sunflower sea star is shown eating a clam inside its habitat at the Oregon Coast Aquarium in Newport. The aquarium recently unveiled a treatment program that proved successful in over 15 sea stars, including sunflower sea stars, that were injured, stressed, or sickened by a wasting syndrome that has decimated populations of the invertebrates along the West Coast.

Courtesy Oregon Coast Aquarium


The sunflower sea star is one of the world’s largest sea stars, growing more than three feet across with two dozen limbs and a territory that once stretched from Baja California, Mexico to the Alaskan Aleutian Islands. But more than 90 percent of these marine invertebrates have been wiped out, and can now mainly be found in the cooler coastal waters of Washington State and British Columbia. Since 2013, sea stars along the West Coast have been decimated by a mysterious wasting disease that may be linked to climate change, and results in loss of limbs, melting tissues and death, often in just a few days.

On Thursday, the National Marine Fisheries Service proposed listing the sunflower sea star as threatened under the Endangered Species Act to aid in its recovery. While there is no cure for sea star wasting syndrome, staff at the Oregon Coast Aquarium in Newport spent two years developing a treatment that has helped save stressed, injured and sick sea stars, including those afflicted with the disease. Evonne Mochon Collura, a sea jelly specialist and assistant curator of fish and invertebrates at the Oregon Coast Aquarium, joins us to share details of the treatment program.

Note: The following transcript was created by a computer and edited by a volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. The sunflower sea star is one of the world’s largest sea stars. They can grow more than three feet across, with two dozen limbs. Their territory once stretched from Baja California, in Mexico, to Alaska’s Aleutian Islands. But more than 90% of these marine invertebrates have been wiped out over the last decade or so. The culprit is a still not fully understood wasting disease. Last week, the National Marine Fisheries Service proposed listing the sunflower sea star as threatened under the Endangered Species Act to aid in their recovery.

Meanwhile, staff of the Oregon Coast Aquarium in Newport recently announced that they’ve developed a way to help save stressed, injured or sick sea stars. Evonne Mochon Collura is the sea jelly specialist and assistant curator of fish and invertebrates at the Oregon Coast Aquarium. She joins us to talk about what they are doing. It’s great to have you on the show.

Evonne Mochon Collura: Thank you for having me.

Miller: I want to start with the reasons for this rehabilitation. Do you remember the first time that you saw a sea star with this wasting disease?

Mochon Collura: I do. It was in 2014. This was a time when we were hearing about sea star wasting occurring south of Oregon, so down in California, [and] north of us, up in Washington. And we had heard descriptions of what an unhealthy sea star would look like. And it finally found its way to Oregon and ultimately to Newport, Oregon, about spring of 2014, around April. And it was very alarming to see this because the descriptions were twisted arms, a deflated appearance, white lesions, and, in some cases, an arm from a sea star would simply walk away from the body. And we saw that beginning to happen here in April of 2014.

Miller: When you say here, do you mean at the aquarium or at tide pools in the wild near you?

Mochon Collura: Good question. So we had seen it here at the aquarium in April. But a few months prior, a visitor had come to the aquarium in January, and she was very concerned. She had just been out at the tide pools and she had seen wasting sea stars all over the tide pool area. So she came to the aquarium, she came in, she happened to walk into the room where I was working and she said, “I need a marine biologist. Something terrible has happened out there.” And she described what she was seeing. And so we contacted a lot of other agencies and support around us to help us figure out, was this a punctuated, local event, or what was the cause? Because at the time, we really didn’t know. It sort of catches you off guard when something of that magnitude happens, all at once.

Miller: And what went through your mind when you realized it was actually inside the aquarium itself?

Mochon Collura: Basically your heart breaks when you see this happening. We go to work every day to take care of animals and to meet their needs and give them the best care possible. And so when you see that something has now breached your perimeter, so to speak, and come in, it’s a sense of urgency and it is a sense of . . . pull all the resources you can think of to start addressing this issue because we need to resolve this issue to save the animals that are under our care.

Miller: What’s the theory for how it would have come inside the aquarium?

Mochon Collura: Our location is right here at the Yaquina Bay where the river meets the ocean. So we’re in an estuary and we are basically right at the ocean. We draw in natural seawater at high tide. And if this is occurring, if something is occurring in the natural environment, there’s a pretty good chance that it could come in through our sea water, which is then pumped to all the various exhibits and holding tanks.

Miller: Can you remind us how sea stars fit into the larger marine ecosystem? I mean, you were saying earlier that it broke your heart because you’re taking care of these individual animals as representatives of their species. But there are also the bigger ecosystem questions. So where do sea stars fit into this? It’s been a little while since we’ve talked about this on our show.

Mochon Collura: Oh, they have a very important role in the ecosystem. So they are great predators which might surprise some people because when they go to a tide pool, it seems to be this motionless animal that is just clinging to the rock. But there is a lot going on under the water, when things get moving. So these animals will go around in the… whether it’s in the tide pool or a kelp forest, an offshore reef and they graze upon various animals that fall into the category of shellfish. So mussels and clams and sea urchins even. So expanding outside of shellfish into sea urchins. So you have this predator that is doing a job to basically keep populations in check. Not with intention, it just happens. That’s the basic biology.

So if you remove that animal from that ecosystem, everything else changes once that predator has been removed, and so certain populations can actually increase. So we see an explosion of sea urchin populations. The sea urchins actually graze on kelp forests and they eat kelp algae. So if you’ve taken away their predator they are able to just graze without check. And so then that will start to decimate the kelp forests. And then, as we all know, there are so many animals, so many different species that depend on a healthy kelp system for survival. Everything from juvenile rockfish to little wolf eels. A number of species, fish and invertebrates, are relying upon a healthy ecosystem.

Miller: I gotta say every time the really intricate relationships between all these different species are described to me in a way that that makes up a functioning, longstanding ecosystem. I feel such a sense of humility and smallness as a human just to be reminded again of just how interconnected things are and how tenuous these connections can be when one thing goes awry.

Mochon Collura: True. It really is true that balance is everything and that everything is connected. So when one part is affected or impacted negatively, it really does have a ripple effect throughout the entire system.

Miller: So let’s turn to the attempts at answers here for what caused this. In a second, we’re going to turn to what you’ve been doing there and staff to rehabilitate or bring back to a healthy state, some of these sick sea stars. But in order to do that, I imagine you had to have some theories as to what was causing the wasting disease to begin with. What are the reigning theories right now?

Mochon Collura: As you say, it really is an unknown cause at this point. The scientific community still has not been able to pinpoint the actual culprit for this situation. But what we do know is that whatever it is that’s happening or whatever that causative agent might be, it’s impacting the animal’s immune system. As with any animal, if you can boost that immune system and give the animals a fighting chance to stave off… whether it’s a little parasite or bacteria or a virus or fungus, any of those things… you give that animal a chance. And so we shifted our focus from trying to identify a specific bacteria or isolate a specific virus or fungus or anything like that. And we just stepped back in our view and said, “How do we support this animal’s immune system to give it the upper hand?” Because everything has an immune system and they can fight illness and heal injury if they are well equipped to do so.

Miller: It almost sounds like the decision seemed like a kind of triage. One, that the situation was so dire that you didn’t have the luxury to, in a kind of academic way, learn the mechanism of this disease. You had instead switch to a kind of an emergency response to just help it fight this thing that’s still a mystery.

Mochon Collura: Absolutely, well said. That’s exactly how it felt. It was like a triage situation. And we knew that there were university labs, research labs all around the country working 28 hours a day trying to isolate the causative agent. Trying to find out what this was so that we could come up with a solution. If it’s bacterial, we could find the right antibiotic, that sort of approach.

In academia other groups were really trying hard to work on that element. Whereas we were standing here with an animal in a tank of water and its arms were walking away from its body. So we did have to hold on all of our knowledge and work with our veterinary staff as well and work with collaborators and other aquariums to share information. Quickly keep the communication open and look into options that could treat whether it was going to be a bacteria, virus, fungal or something that we weren’t even thinking of at the time. And it was like a triage.

Miller: You’ve mentioned this phrase twice, arms literally walking away from their bodies, meaning they’re coming off, but they’re still a little bit of enervation. The nerves are still making them walk, but then they stop. What happens when, when these limbs come off?


Mochon Collura: It’s actually referred to as self-amputation. The animal has a system of tube feet: little water filled tubes that are like little plungers. So anybody who’s ever looked at the underside of a sea star has seen this vast number of tube feet that allow the animal to walk away or to hold onto a rock or to hold onto a clamshell and pry it open. So the animal is very mobile. And what we’ve seen is that it can actually start to disconnect where an arm is joining to that central part of the body. And whether it’s the arm walking away from the animal or the animal walking away from an arm, hard to say, but they will drop an arm and just move.

You see the animal, itself sort of deflating, twisting a little bit, withering a little bit and moving in a different direction. And then you see just an isolated arm with some exposed open tissue trailing as the animal moves off. So it creates an open wound at the central part of the body. The arm itself would not be able to recover, survive and generate a new star. It would need a major part of that central body in order to do so. So when we see a separated arm, there really isn’t anything we can do about that, but we can turn our efforts towards the animal that has the central part of the body intact, and try to heal that wound and give the animal the ability to regenerate a new arm where that injury or open wound is vulnerable.

Miller: So let’s turn to that work. How do you help boost the immune systems of sea stars?

Mochon Collura: This was a very clever idea that came about in discussions with the staff here, and in particular [from] Tiffany Rudek, [who] is managing our medical and quarantine area. She came with a background that was looking at immune health and she knew that probiotics were being used in some facets of aquaculture to help animals maintain good health. And so she started investigating if that could play a role here because probiotics can boost the immune system. She found some supplements that also contained not just the probiotics, but they had the ability to provide a protective slime coat. They also had a disinfection agent that could actually stave off any sort of parasites or pathogens that might continue to feast on the tissue of an injured or an ill sea star. And so we started these trials.

Because at the time, all you know is… as you say, you’ve got this urgent situation, you’re in a triage moment. You need to address an open wound and an unhealthy animal. And we don’t know really what’s going on inside the animal since their water chemistry inside is so heavily impacted by the water chemistry outside the body. So we took this overarching approach to think about how we could better manage the water within the animal, the water surrounding the animal and how we could provide the supplements and meet needs right down to trace micronutrients and things that could help protect that animal from an infection.

Miller: And at this point, I imagine after some trial and error, what does success look like? How do you know things are working?

Mochon Collura: The exciting part is that in some cases, it was within minutes. So we would have an animal submerged in a therapeutic bath, containing some of these agents that I’ve just described. And you would see the animal change from a tightened coiled posture into a more relaxed posture and start to move about the tank freely. And if it was deflated, you would see it start to re-inflate a little bit more, to swell up and take a more natural appearance. So sometimes this was happening very quickly, right before our eyes.

Miller: That almost sounds like magic. I’ve come to think of any treatments… it’s just taking time, especially if this is a disease. That’s so hard to understand. It’s really surprising that it could happen almost instantly.

Mochon Collura: And it really speaks to the fact that the chemistry is so important. We even experience this as humans too. If you are in some sort of a chemical environment that isn’t suited to what you need to be healthy, you’re going to start to feel terrible. And as soon as you remove yourself from that environment and get yourself into a healthier situation, you start to feel better, almost instantly.

Miller: Get a power bath that gets your slime coat ready again.

Mochon Collura: Exactly, yeah. [Laughing]

Miller: How many sea stars have been rehabilitated using this technique?

Mochon Collura: Within the last year, we have used this technique on 17 of our sea stars. We’ve had 15 that successfully recovered. We currently, right now, have five sea stars in the medical warehouse that are under treatment right now and it’s not always for wasting. It could be something like a simple little injury, a nick or a cut. As we know if you don’t take care of, even sometimes the smallest injury, things can get out of control pretty quickly. So we monitor the animals, we watch and we look at them every day and we know any sort of differences. They can’t tell us when something is wrong, so we have to be watching for it.

And if we notice anything is out of alignment, perhaps it’s even just the appearance of the top of the animal we’ll move them into a medicated bath, where we can start to help them with this immune support. In some cases, we’ve had sea stars that had dropped arms for a reason that was not related to sea star wasting and they have regenerated, they healed their wounds, they regenerated their arms. And right now you’d be hard pressed to find which arms were new in which arms were the original in some cases.

Miller: What have you heard from other aquariums or other marine scientists since you’ve shared this technique widely?

Mochon Collura: Oh, it’s, it’s been a really positive reception, honestly. So we worked to get all of this put into print and we published in the journal Drum and Croaker, which is basically a journal for the aquarium industry. And so this was the best way for us to get that message out to our colleagues quickly and to provide some sort of written recipe for lack of a better description, so that other places could potentially use this to, to treat their own animals if they saw any signs of illness or injury. And within probably a day or two of that publication’s release, we were hearing from colleagues at other aquariums and we were hearing great feedback from a sea star working group that basically thanked us for sharing this information.

And now they had follow up questions, and they wanted to work with us to be able to find a way to tailor these methods to their systems and to their animals. So it’s been a really great experience because we could share what we’ve seen,

what we’ve done and how it’s worked here. And now we can help other facilities tailor it, because they might have a different setup. For instance, they might be located somewhere where they’re not pulling in natural seawater. Perhaps they make their own seawater at an inland aquarium. They might have different species of sea stars that they would like to try to use this [on]. So it’s been a really wonderful, collaborative experience with universities, with other aquariums and with academia.

Miller: I can see how, as other institutions start to employ these methods, maybe with slight tweaks, based on their own setups that dozens or hundreds, maybe even in the thousands of sea stars in these facilities could be helped. But what about the wild where there are hundreds of millions out there? We’re talking about a still mysterious disease that went up and down the entire Pacific coast of North America. You can’t make the Pacific Ocean a medicated bath. So what are the implications for animals in the wild?

Mochon Collura: And that is a great question that has been addressed by a sunflower star working group, a Pycnopodia working group. They are working with many agencies from state fish and wildlife agencies to universities, to aquariums and zoos, marine science centers to try and gather data to try and set up some sort of a sea star rearing situation to… their long term vision is to perhaps provide more animals back out to the wild, to restock, in some cases, something like the sunflower sea star that is currently being proposed to be listed as threatened. Perhaps [this will] help boost their population in the future.

So it’s a really big question. It’s a very big project. And as you say, there’s not a way that we could actually apply this out to the Pacific Ocean and make that work. But it does give us the ability to share the information with people that our impacts could affect things like the pH and the salinity and the temperature. Maybe not salinity, but the pH and the temperature of the ocean and then the impact that we could see in the natural populations. And then you take that knowledge and you expand it into agencies such as, I believe Nature Conservancy is working with this working group, to look for ways to help reboot certain populations.

Miller: What did it mean to you when you heard that the National Marine Fishery Service is asking for the sunflower sea star to be listed as threatened under the Endangered Species Act?

Mochon Collura: Well, that was a step forward. Certainly, that was good news to hear because for several years now, let’s see, 2014-2020… it’s been over eight years now, we’ve been dealing with this. So part of our job, we come to work every day, we take care of our animals, we’re watching our sea stars, and it’s always been on our mind, maintaining the health for these animals. So this isn’t new to us. This is something we’ve been dealing with for quite awhile, but it could be new to other people. And this could be the first time that they’re learning about it.

And it’s exciting that we have gotten to a point where this information can be shared so widely now and perhaps engage other people at other levels and get more people on board to include more brains in the troubleshooting really. So this is a great step forward. Of course, it’s a shame that the species would have to be in this situation. But I think part of the progress is broadening that acknowledgement or that recognition that there is a situation that really should be addressed.

Miller: Evonne Mochon Collura, thanks very much.

Mochon Collura:  Thank you.

Miller: Evonne Mochon Collura is a sea jelly specialist and assistant curator of fish and invertebrates at the Oregon Coast Aquarium in Newport. She joined us to talk about the Aquarium’s newly announced techniques to help ailing sea stars.

Contact “Think Out Loud®”

If you’d like to comment on any of the topics in this show, or suggest a topic of your own, please get in touch with us on Facebook or Twitter, send an email to, or you can leave a voicemail for us at 503-293-1983. The call-in phone number during the noon hour is 888-665-5865.