Some areas on Vashon may hold clues to the wasting disease that has caused a mass die-off of sea stars beginning in 2013.

Now, researchers say their chances for continued recovery depend on stemming the effects of climate change before more marine life is lost.

Islander Rayna Holtz has walked the beaches on the west side of the island for nearly 15 years, scanning the shore for dead birds hammered by weather patterns and conditions out at sea. She is part of the University of Washington’s citizen scientist program that monitors for debris washed up on the coast such as plastics, metals or objects animals could mistake for food. Those findings are used to consider the growing impact that human activities have on native wildlife, and the data volunteers gather can serve as a basis for further research of the environment.

Holtz said she never found any birds to report, but there were always plenty of sea stars.

“You saw more when the tide was farther out, and it was not unusual to see 100 sea stars in a single walk,” she said, adding that the rocky beaches, boulders and eelgrass scattered along the edge of Colvos Passage made for an ideal habitat. ”They were ubiquitous. That was the fun of seeing them.”

But by 2014, the number of sea stars began to drop rapidly. That was when Holtz said Jeff Adams, an islander and marine ecologist who works for Washington Sea Grant, encouraged her and those concerned about what was happening to form a field team of citizen scientists and monitor the wasting disease as it took hold in island waters.

Holtz staked out two plots in Docton Park to monitor the numerous sea stars that were known to climb the underside of the dock and pilings.

What she discovered, Holtz said, was surprising. There was a massive decline of various sea stars on the pilings that finally bottomed out last year when there were none left to count. But they are faring better under some sections of the floating dock.

“It’s a real puzzle,” said Holtz. “If I was just going by that, I would say maybe those surviving stars are a strong indication that they are developing resistance.”

Warming temperatures in the ocean have long been suspected of hastening the disease by activating a virus later identified in all sea stars exhibiting symptoms. Holtz surmised that the dock may provide the right amount of shade or other latent benefits to protect the sea stars from the same fate as those dying in open waters nearby.

But she is concerned about the next generation of sea stars. Holtz has not observed many juveniles in the years since she started keeping a record of her sightings, and today, she believes the outlook for the island’s remaining population of sea stars is bleak.

“Most of Vashon is not recovering, because on the last beach walk I didn’t see a single sea star of any species,” she said.

Drew Harvell, professor of ecology at Cornell University, is the lead author of a research paper published in January tracing the startling decline of more than 20 species of sea stars. For the paper, Harvell and her colleagues focused on the sunflower star — once numerous in shallow nearshore waters, they have suffered an 80-100 percent wipeout from Washington to British Columbia across a distance of more than 1,800 miles.

Harvell said the sunflower stars can grow to the size of a manhole cover, but research suggests they were no match against exposure to temperature anomalies that are thought to have mechanized the initial outbreak.

“A lot of our work and a lot of other people’s show they are really not coming back,” she said.

The wasting disease starts as lesions in the skin of the sea stars. As it progresses, Harvell said it essentially atomizes the animals, slowly pulling them apart until they melt.

“That’s what makes the disease so ghoulish and awful,” she said. “You’d see a sea star walking away from an arm that was just ripped off.”

Similar to the sunflower stars, the common intertidal purple sea star, formally known as ochre, displayed a higher risk of infection and mortality as temperatures fluctuated. But according to Harvell, their downturn has tapered off some, and now there is renewed hope they are developing resistance to the disease.

Nevertheless, she emphasized that there is a reason to worry.

“People are still finding both species with signs of wasting, so it’s not actually like this has gone away,” she said.

Harvell said that ochre sea stars play a smaller role in the ecosystems of the Pacific Northwest than the pivotal sunflower star, which is a voracious predator of sea urchins. With the sunflower stars almost gone, populations of sea urchins exploded everywhere, notably in California, where they have since mowed down kelp beds. That poses major consequences to abalone shellfish and a variety of other species which depend on the kelp beds.

Harvell spoke at Town Hall in Seattle on Saturday to discuss the emerging threats facing coral, salmon, crabs and even dolphins today in the world’s oceans. She said one theme of her new book, “Ocean Outbreak: Confronting the Rising Tide of Marine Disease,” is that an increasingly warmer world is a sicker world. That trend, she added, makes it a priority to train students who will contribute to the understanding of climate change as the ramifications continue to mount.

“We don’t really know what’s going to happen next,” she said.

Vashon High School students in grades nine and ten are assessing data collected last month from several monitoring sites across the island where they watched for sea stars as part of the Vashon Nature Center’s Scientists in the Schools program.

“Even just in our small area, there are different microclimates that affect how the sea stars are responding,” said Nature Center Director Bianca Perla. She noted that there has been a stronger comeback in certain parts of the San Juan Islands than farther south, but around Vashon, ochre sea stars are returning, albeit at a snail’s pace.

Despite their relative success, Perla said the ochre sea stars are nowhere near as abundant as they were in 2014. For all species, the Nature Center estimates the island-wide fallout is between 76 percent and 90 percent across the board. Mottled stars experienced a 98 percent decline overall, and the last sunflower star seen on Vashon was tallied in 2017.

Student data from previous surveys of sea stars across the island (Vashon Nature Center Photo).

But it’s a different story at Raab’s Lagoon near Portage on Maury Island.

“The end of 2014 was when the sea star wasting disease started here on Vashon,” said Perla. “[Yet] our numbers from 2014 at Raab’s were incredible.”

Like most places, sea stars have succumbed to the wasting disease around the beach of the saltwater lagoon that flows through a rocky, cascading channel into Quartermaster Harbor at high tide. However, Perla said that the outflow is a sea star sanctuary, mere steps away from where most others have perished since that site was first evaluated.

In 2014, students counted 176 sea stars in the Raab’s Lagoon outflow. This year, there were 76, with none on the beach. Meanwhile, sea stars continue to dwindle at Maury Marine Park and Point Robinson according to the survey results, with only a handful counted at KVI Beach.

Using funds awarded to the Nature Center by the Vashon Partners in Education, Perla said that the students next set out to test the water quality of Raab’s Lagoon, yielding interesting results. They documented the temperature being cooler in Raab’s Lagoon than the shallow pools around the beach where the sea stars congregated in the past. Moreover, water tested in the lagoon measured higher on the pH scale, meaning that it was less acidic in contrast to the pools.

“That’s telling us maybe some of the water quality differences are affecting the survival rates of sea stars. And most of our sites don’t have that cooler moving water that Raab’s does, and so maybe this didn’t hit as hard [there],” said Perla.

But while the early results are promising, she cautioned that the origin of the epidemic remains largely unknown to the scientific community.

“Nobody really knows exactly why these sea stars are wasting and whether it really is a virus or not, a combination of a virus or bacteria, or whether it’s just changing ocean conditions that are creating these limb diseases or responses,” she said.

Adams of the Washington Sea Grant co-coordinates the Kitsap Beach Naturalist program and monitors the progression of the wasting disease for the Multi-Agency Rocky Intertidal Network, a consortium of agencies, universities and private groups. He said that some progress has already been made on behalf of sea stars at the policy level.

“It wasn’t too long ago when Fish and Wildlife regulation allowed you to collect a few of them. Of course, that’s illegal now,” he said.

But without examining how modern society has remade the oceans, he said, mankind runs the risk of unknowingly facilitating the demise of all marine life on earth.

“Otherwise, oceans are kind of silent. [Without looking], all you see is the surface of the water.”