By Tabor Whitney

Helix

At 4:45 a.m. on a Monday in August of 2024, I join Zechariah Meunier in Yachats, Ore., where shorelines of black basalt border thick forests of Sitka spruce, western hemlock, shore pine, and alder trees. Fully embracing my role as the tag-along marine ecologist, I put on my Wellingtons, grab a clipboard with waterproof paper, wipe my weary eyes and turn on my headlamp. Then Meunier and I traverse through rugged boulders in the moonlight. As the rocky coastline begins to level, we reach exposed tide pools ready to be explored before the tide covers the area once again. “It is us versus the tide,” said Meunier, a coastal ecologist and professor at Willamette University in Salem, Ore.

On the Pacific Northwest’s rocky shorelines, crashing waves and rising and falling tides erode coves, widen crevices and crush bedrock. The ocean meets the land in the rocky intertidal zone, creating a unique habitat that overflows with biodiversity and forms the foundation of marine food webs. Crabs, sea stars, anemones, barnacles, snails, mussels, limpets — to name a few — fill the intertidal pools. Within these pools, sea stars are important predators that eat mussels and barnacles. “Sea stars are like wolves,” said Meunier. So, like wolves, what happens when several sea star species are nearly wiped out?

In November 2013, a sea star wasting disease outbreak was first spotted along the Washington coast and quickly identified from the Gulf of Alaska to Baja California, Mexico. Then, from late 2013 to 2016, a marine heatwave nicknamed “the Blob” hit the West Coast, and in certain regions of the Pacific, temperatures rose 2 to 3 degrees Celsius above average. Within months, ochre sea star populations declined by 85 percent, while other species, like the sunflower sea star, declined by as much as 95 percent. Shortly after, in 2020, the sunflower sea star became the world’s first sea star species ever to be classified as critically endangered by the International Union for Conservation of Nature. When a species disappears, researchers find out exactly what role they play, said Aaron Galloway, a marine ecologist at the Oregon Institute of Marine Biology in Charleston.

Bruce Menge and Sally Hacker, marine ecologists at Oregon State University and Meunier’s former doctoral advisors, have collected data on species composition and abundance along the Pacific Northwest’s rocky intertidal for decades. Meunier mentions Menge started data collection as early as the 1980s at some of the sites we visit along Oregon’s Cape Perpetua. Meunier, Hacker, and Menge found that the decline of the ochre sea star’s population shifted the rocky intertidal’s ecosystem from one anchored by algae to one dominated by mussels and barnacles, at sites in Oregon and California. 

Without ochre and sunflower sea stars, invertebrates, such as mussels and barnacles, flooded in and took up space where algal species typically live. The algae were also struggling to survive after the heatwave. At several sites, Meunier and colleagues documented that species have yet to recover nearly a decade later. This suggests that some rocky intertidal species may have low resilience in the face of other disturbances, such as climate change. To better understand the variability in how climate change impacts ecosystems and why some sites recovered after the ecosystem’s community shift and others didn’t, Meunier, Menge, and Hacker continue to collect data along the Oregon capes today. Long-term data sets could help assess and predict future shifts in coastal ecosystems due to climate change and other stressors, Hacker said.

An hour or so later, I follow Meunier, who is on his hands and knees on a sharp mussel bed, looking for a bolt with a metal detector. Four corner bolts mark square plots each roughly the size of a large pizza box at each site. Menge made these plots decades ago to measure species composition and abundance changes over time. For one specific plot, Meunier searches and searches. Finally, the glorious beep of the metal detector goes off, and Meunier grins like he just struck gold.

In the 1960s, ecologist Robert Paine, of the University of Washington, demonstrated the impact of the ochre sea star on the rocky intertidal. Paine — Menge’s doctoral advisor — discovered that not all species exert the same influence by removing the ochre sea star in some test plots. As a top predator, their removal led to major shifts in the abundance of organisms that make up the rocky shore’s ecological community, and he labeled the ochre sea star as a “keystone species,” a concept that has become a bedrock of ecology. Decades later, Meunier still uses Paine’s experimental methods to understand how important these predators are to a thriving ecosystem.

For our work this morning, there are 20 plots at each site, and we must find and survey them all before the tide comes in. “The tide is burning,” Meunier said as we crunch hurriedly along the mussel and barnacle-covered basalt, careful to avoid the deep crevice that researchers have kindly named the “chasm of death.” In some plots, Meunier’s team removes the mussels, and in others, the sea stars. Every year, Meunier and colleagues come out and re-survey the plots and compare the abundance of all the different organisms between the plots. Today, we are surveying which organisms are in each plot and the percent abundance they make up. “The diameter of a quarter is equivalent to 1 percent cover of the plot,” said Meunier as he draws on his clipboard. “It is like drawing quarters on things with my mind.” With his hands, mentally mapping quarters for me, he showed me that the kelp takes up 25 percent, the mussels take up 15 percent, and so forth.  “It is almost like virtual Tetris,” Meunier said, and I couldn’t agree more. Meunier, Menge and Hacker will continue monitoring these plots, and the long-running data they have collected may contain clues that may someday help these ecosystems recover.

With the ecosystem shift, the decline of sea stars and the Blob, marine biologists also saw a boom in the tiny yet voracious purple sea urchin. Without a predator, purple sea urchins started mowing down kelp forests already stressed by the heat, creating bald patches known as urchin barrens. Kelp populations — largely in California, where the heatwave was more severe — declined by 95 percent between 2016 and 2020. Kelp provides habitats for invertebrates, fish, marine mammals and even birds. “Kelp forests are considered the sequoias of the sea,” said Kalani Ortiz, a seaweed aquaculture researcher at Scripps Institution of Oceanography at the University of California San Diego. Research suggests that kelp forests can support hundreds of species, while urchin barrens and mussel beds are home to just a few dozen. The takeover of mussels and urchins across the Pacific Northwest drastically reduced species diversity.

Some researchers attribute fewer grey whales in Oregon and a change in their foraging to the indirect effects of the major heatwave, the disease epidemic and the loss of kelp. When kelp quantity and quality declined, there were fewer mysid shrimp and zooplankton — a significant portion of the gray whale’s diet. That may have prompted gray whales to visit their offshore feeding spots less often and spend less time foraging overall.

Marine ecologists are just starting to understand how the disappearance of sea star species coupled with a marine heatwave ripple through the food chain and continues to impact it a decade later.  “Everything is connected in nature,” Meunier said. “If you pull on one lever, it will change many different species in the community.”

Researchers, environmental non-profits and companies are teaming up to tackle the problem of faltering kelp forests. But scientists suggest that it could take 20 years or more to remove all the purple sea urchins off just one large reef in Oregon, where scientists found that population sizes grew 100-fold from 2014 to 2019. To restore the kelp, purple sea urchin removal is needed, and the jury is out on what the best approach is to winnow the urchin population, said Galloway of the Oregon Institute of Marine Biology who studies the dynamics of sunflower sea stars and purple sea urchins in kelp forests. Research teams and companies are testing a range of strategies to cut the impact of urchins. These include plucking urchins out by hand for commercial harvesting and installing flexible barriers that keep urchins from encroaching on recovering kelp areas. Divers are also using tools like crowbars to remove or crush urchins in place. Meanwhile, other scientists are trying to nudge ecosystems back to health by bringing back their top predators, sea stars.

In 2019, larval biologist Jason Hodin at the University of Washington’s Friday Harbor Laboratories started the first captive rearing program for the sunflower sea star. Hodin realized that there was a lack of research on sea star species in general, especially about their life cycle or how to rear them in captivity. Aware of the urgency to re-populate this species in the wild, Hodin’s lab collected 30 wild adult sunflower sea stars at Friday Harbor in the San Juan Islands and observed them closely. Hodin slowly started rearing some in the lab, and five years later — eleven years after the sea star wasting disease outbreak —the first group of lab-raised sea stars was released into the wild in early August of 2024 off of the Washington coast.

A single sea star can produce millions of larvae, Galloway said. “They are broadcast spawners. That’s how they roll.” Scientists and collaborators hope these efforts could someday produce millions of new sea stars in the wild. In early January of 2026, 48 reared sunflower sea stars were placed into the ocean off California for the first time. After a month of monitoring, the sea stars were retrieved, and 98 percent survived their initial exposure to ocean conditions. While an encouraging result, more fundamental research is needed to guide informed decisions for the next phase of restoration.

Further down the coast, Rafael Cuevas Uribe, an aquaculture researcher at Cal Poly Humboldt, along with Karen Gray from GreenWave, a non-profit supporting regenerative ocean farms, established ProvidenSea, California’s first commercially licensed, open-water seaweed farm , in 2019 in Humboldt Bay. This farm now cultivates commercially and ecologically important types of seaweed, including kelp species, many of which have drastically declined due to the Blob and recurring heat waves since 2016. Among these, bull kelp — a critical but understudied species — has experienced dramatic losses. Recognizing the urgency of restoring this species, Kalani Ortiz, Cuevas Uribe’s former graduate student, has been pioneering efforts to understand its life cycle. Ortiz takes wild bull kelp species and waits for them to spawn in her controlled lab setting. Once the spores are released, she monitors and feeds them until they turn into tiny blades that can be planted on tweed, wrapped around PVC pipes and placed on the long lines that make up the seaweed farm. While many seaweed farms use tanks held at offshore facilities, an open-water approach allows researchers to explore how kelp and other seaweed species can thrive in natural conditions, a critical step toward ecological restoration, Ortiz said.

Seaweed farms have a number of benefits. They can turn a profit while cleaning up the waters through carbon sequestration and providing habitats for various marine animals, Cuevas Uribe said. Over 90 percent of seaweed is imported from Asia, so expanding seaweed farming in California could provide a sustainable alternative to bolster local economies and help grow the next generation of California’s kelp to replant kelp forests. 

All these actions — from removing purple sea urchins to seeding kelp and reintroducing sunflower sea stars — could bolster kelp forests. But no single approach is likely to return the ecosystem to what it was like before the disturbance, Galloway said.

Restoring kelp forests and rebalancing the Pacific Northwest’s coastal ecosystem may seem insurmountable.  Still, these ecosystems — and the many creatures they host — are worth fighting for.  That will take sustained research and long-term monitoring, especially as the pace of climate change quickens. Meunier, Galloway, Hodin, Ortiz and Cuevas Uribe all highlighted the need for monetary, federal and public support to conduct basic research on the marine organisms that make up these dynamic coastal ecosystems. Understanding each organism’s role in its ecosystem and the details of how it lives will be crucial for predicting and blunting the effects of future disease outbreaks and marine heatwaves. Ultimately, the future of these ecosystems depends not only on local restoration interventions but also on widespread efforts to curb climate change.

Tabor Whitney is a recent graduate from the Department of Anthropology’s Ph.D. Program at Northwestern University. She is currently a postdoctoral scholar in Northwestern’s Paula M. Treinens Institute for Sustainability and Energy.

Correction: An earlier version of this story stated that Hodin and colleagues collected 10 sunflower sea stars; they collected 30.

Editor’s note: This story was written in 2024.  After the story was written, in August of 2025, a team of researchers, including Jason Hodin from the University of Washington, found the causative agent of sea star wasting disease. Knowledge about the strain of the disease-causing bacterium can now help to guide management and recovery efforts for sea stars.