Scientists at the Hakai Institute are finding hope in the fjords of British Columbia’s Central Coast. New research shows that endangered sunflower sea stars (Pycnopodia helianthoides) are surviving disease outbreaks in these cold-water ecosystems—but not due to temperature alone.
The sunflower sea star—which can grow 20 arms and measure a meter across—was once a common fixture of the Pacific Northwest intertidal zone. Despite its large size, Pycnopodia is a fast and voracious predator of bottom-dwelling species, such as sea urchins, making it important for the health of kelp forests. But in 2013, a marine malady known as sea star wasting disease (SSWD) took hold, wiping out more than 90 percent of all sunflower sea stars between Alaska and Mexico in a handful of years.
Disease outbreaks have been linked to marine heatwaves—which are becoming more frequent with climate change—suggesting that waters with consistently cold temperatures could act as marine refuges for Pycnopodia. The new study, conducted in partnership with the Central Coast Indigenous Resource Alliance (CCIRA) and Fisheries and Oceans Canada (DFO), finds that Central Coast fjords may hold keys to sea star survival.
It was collaborators from CCIRA and member First Nations who first reported sightings of large Pycnopodia in the Central Coast fjords—a sign of remnant populations that had dodged SSWD.
“We got to see what the subtidal zone used to look like before the wasting disease outbreak,” said Alyssa Gehman, the lead researcher on the study, who visited Burke Channel for a dive after getting the tip from CCIRA. “It was like looking into the past. It was magical.”
It’s not that SSWD hadn’t yet reached the fjords; it had, Gehman says. But compared with offshore islands, the sunflower sea stars in the fjords were much larger and more abundant, suggesting a refuge.
“Fjords have all sorts of weird oceanographic things happening,” Gehman said. “Arctic storms come in the winter to churn up the ocean and create an infusion of high-oxygen cold water. But then in the summer, there’s melting snow and glacial runoff, and you get this surface layer a couple of meters thick that is low-salinity—basically a river.”
Gehman and her colleagues knew that both temperature and salinity were important for sea star health. But to Gehman’s surprise, Pycnopodia responded differently in the fjords than they did around the islands: they ventured a bit deeper to escape the snowmelt, bringing them into colder seawater that inadvertently helped them stave off SSWD.
“It’s like a cooler where the freshwater runoff is a lid of low salinity that’s holding them down,” Gehman said. “It’s interesting because it’s a different way for the environment to be protecting an animal.”
Gehman notes that these fjords are not safe from climate change, however. In 2024, the Central Coast received much less snow than usual, which could be devastating for the sea stars. This study underscores the interconnectedness of environmental conditions—from winter storms to melting snow—that work together to support species like Pycnopodia, which itself assists kelp forests that are crucial for maintaining biodiversity and fighting climate change.
“We now realize that no species is safe,” said Mike Reid, fisheries manager for Heiltsuk First Nation, in whose territory some of the research took place. But the study’s findings align with Indigenous knowledge about coastal fjords nurturing various species, including kelp, Reid says, lending additional support for conservation measures in these regions.
“Our nation transplanted seaweed, shellfish, salmon, crab, and other species throughout our territory, including inland fjords,” Reid said. “To this day, the seaweed thrives in the deepest fjords, which are potentially a lifesaver for the species.”
Climate change requires us to look backward as well as forward and identify microclimates that might help threatened species, Reid added. “This research is a step in understanding microclimates and how they may be a refuge against climate impacts.”
