A devastating bout of wasting syndrome has been demolishing sea star populations throughout the North Pacific Ocean from Alaska to Mexico.
“It has been recognized as one of the largest mass mortality events ever recorded,” Ucluelet Aquarium curator Laura Griffith-Cochrane told the Westerly News. “It’s unbelievable. It’s a massive, massive, die off.”
She pointed to monitoring efforts conducted by Simon Fraser University (SFU) that show sea star wasting syndrome has been wiping out sea star species around Oregon at a staggering rate since 2013.
“Almost all surveyed sites lost between 80-84 per cent of their stars in both the Howe Sound and the Oregon coast surveys,” she said adding other sites lost as much as 90 per cent.
A widely reported population boom late last year raised hopes that the syndrome’s effects might be dwindling but Griffith-Cochrane cautioned the boom was recorded during cold winter months and the disease strikes the hardest when temperatures rise.
“I believe that there’s still traces of the virus in our ecosystem and that a lot of stars are developing and growing while the water is cold but could easily become affected by sea star wasting syndrome when the water is warm again,” she said.
“Depending on how warm our summer is and how the health of our ecosystem is, we’ll be able to see whether we’re starting to move out of this really nasty trend of mortality and into recovery. But, I believe that it’s too early to tell.”
She added sea stars get stressed out in warm waters and this stress weakens their immune systems.
“Because we live in the North Pacific, our waters are typically cold and most species are used to cold water so when it warms they become stressed out,” she said.
“When we start to get the warm summer temperatures of 14-15 C, that’s when we’re going to start to see stress and disease and that’s when we’ll know whether or not that virus is still present in the ecosystem.”
She noted citizen science efforts have been launched to get a handle on what’s happening, including local sea star monitoring by the West Coast’s Strawberry Isle. Research Society.
“People are just trying to share and gather data and figure out what’s going on,” she said. “There really isn’t anything we can do to help the stars other than leave them be and allow them to keep mating and reproducing to try to rebuild those populations.”
She said even if the virus is disappearing, some sea star species may never recover.
“Because of that unbelievable volume of loss, it’s really difficult to say whether we’re coming back from that. I think it will take a number of years before we get a clear trend,” she said.
Sea stars are keystone species vital to the West Coast’s marine ecosystems because they eat urchins and mussels that would otherwise destroy the kelp forests that local ocean animals need to survive.
“That term keystone species means an animal that has a disproportionate effect on its environment. Sea stars are basically a controlling agent of the ecology out here,” Griffith-Cochrane said noting ochre and sunflower stars are specifically important locally.
“Without ochre stars, you just get mussels everywhere and there’s really nowhere for anything else to move in. Things can’t lay their eggs there; it’s just one species.”
She added the Oregon study done by SFU proved the significance of sunflower stars.
“The study showed 90 per cent of sunflower stars died in 2013 and the populations of green sea urchins, over the course of their study, quadrupled and 80 per cent of the kelp specimens were lost,” she said.
“Urchins are big predators of kelp so, in areas where there are lots of sunflower stars, there are less urchins and more kelp.”
She added any change to the West Coast’s biodiversity could have unforeseen negative effects.
“We might have a decrease in kelp populations and then we go to a state where a lot of fish don’t have refuge zones to grow so our fisheries might be negatively affected,” she said.
“We can predict that mussels and urchin populations will go up without stars, but sometimes we can’t predict the outcomes and we never know which thing is going to survive when we create change...The further we get from a state of balance, the harder it is to return to a state of balance.”
As sea star populations vanish, more attention is being given to the curio trade—selling and buying shells and dried out sea stars as mementos—and Cochrane urges locals and visitors to refrain from participating in that industry.
“We can not only protect our own ecosystems, but we can protect ecosystems around the world by not buying into that trade,” she said.
She said a 2013 study done in Mexico showed roughly 880,000 sea stars are lost to the curio trade each year.
“Their populations are in such dire straits that some of them might be endangered,” she said. “If we continue to collect them as little mementos, we’re doing even more damage.”
She added West Coast tourists might be taking sea stars from the beach without knowing the damage they’re doing.
“We’ve heard a lot of stories from different hotels and resorts about a lot of people taking stuff off the beach and into their rooms,” she said. “It’s not only that that’s bad for the ecosystem, that’s a living organism that is now going to die a very slow death.”
She suggested raising awareness of sea stars is difficult but important and education must be delivered in a non-divisive way.
“It’s hard for us to recognize stress levels in an animal that doesn’t have facial features,” she said.
“People just don’t really realize that they’re doing harm and we want to educate but we don’t want to attack people. If you attack people, it puts them on the defensive and they’re not going to be able to hear your message.”
More than just leaving them on the beach, Griffith-Cochrane said sea stars should be left alone entirely.
“One way that we can protect stars is by watching where we’re going, not pulling them off rocks and leaving them where they are,” she said adding picking the creatures up can damage the chemoreceptors that help them survive.
“It’s how they get a sense of their world; how they find prey and how they latch onto things. If we’re damaging them by ripping them off the rocks, we’re not doing them any favours.”
She encourages locals to bring visitors up to speed on the sea star situation.
“It’s up to us as West Coast people to ask people not to take them and to say, ‘These populations are in jeopardy and you can really support the ecosystem and keep it healthy by leaving them be,’” she said.