Threatened Sea Stars Are Finding Refuge in BC Fjords
A new study suggests that cold-water fjords on British Columbia’s Central Coast could be a marine refuge for threatened sunflower sea stars, which have been hit hard by sea star wasting disease. But recovery may require more than just cold seawater.
Sunflower sea stars are clinging to life in the cold-water fjords of British Columbia’s Central Coast, such as Burke Channel shown here. Photo courtesy of Grant Callegari/Hakai Institute
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,” says 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.”
Researcher Alyssa Gehman from the Hakai Institute counts and measures sunflower sea stars in Burke Channel on the Central Coast of British Columbia. Photo courtesy of Bennett Whitnell/Hakai Institute
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 says. “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 says. “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,” says 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 says. “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 to identify microclimates that might help threatened species, Reid adds. “This research is a step in understanding microclimates and how they may be a refuge against climate impacts.”
Refuge colonies of sunflower sea stars found in the fjords of British Columbia’s Central Coast, such as in Knight Inlet shown here, are like windows into the past before outbreaks of sea star wasting disease. Photo courtesy of Grant Callegari/Hakai Institute
About the study
The study results are based on oceanographic data collected by the Hakai Institute between June 2012 and August 2023 combined with subtidal surveys by Hakai between 2013 and 2023 and dive surveys conducted by the Central Coast Indigenous Resource Alliance from 2018 through 2023.
“Fjord oceanographic dynamics provide refuge for critically endangered Pycnopodia helianthoides” was published in Proceedings of the Royal Society B: Biological Sciences in April 2025.
Gehman A-LM et al. 2025 Fjord oceanographic dynamics provide refuge for critically endangered Pycnopodia helianthoides. Proc. R. Soc. B 292: 20242770. https://doi.org/10.1098/rspb.2024.2770
Download the media kit that includes this press release and available photos.
Contact
Alyssa Gehman Hakai Institute research scientist (206) 251-9115 alyssa.gehman@hakai.org
About the Partners
Hakai Institute
The Hakai Institute, part of the Tula Foundation, is a British Columbia–based scientific institution dedicated to advancing science on the coastal margin. Hakai pursues its mission from ice fields to oceans, leveraging its ecological observatories and other strategic locations on the province’s coast. The Hakai Institute partners with universities, NGOs, First Nations, government agencies, businesses, and local communities to move the needle on advancing long-term coastal research. Learn more at www.hakai.org
Tula Foundation
The Tula Foundation is a British Columbia–based organization that harnesses science and technology to tackle urgent global issues. Tula takes a comprehensive approach to these challenges, from coastal biodiversity and public health to data management and mobilization. Along with rural healthcare in Guatemala, Tula’s work drives pivotal action for coastal conservation and ocean research in British Columbia and beyond. Learn more at www.tula.org.
Central Coast Indigenous Resource Alliance (CCIRA)
First Nations culture and well-being are intricately linked to the health of our environment. For over 10,000 years, First Nations sustainably managed territorial resources, ensuring that the trees, fish, and water provided for today’s needs without compromising the future. CCIRA is working to return us to the healthy communities of our past by supporting First Nations governance and management of our waters and marine resources through effectively linking Indigenous knowledge and Western ecological science. Learn more at www.ccira.ca. Fisheries and Oceans Canada (DFO) Fisheries and Oceans Canada (DFO) is the federal institution responsible for safeguarding Canadian waters and managing the country’s fisheries and ocean resources. DFO helps to ensure healthy and sustainable aquatic ecosystems through habitat protection and sound science. We support economic growth in the marine and fisheries sectors, and innovation in areas such as aquaculture and biotechnology. Learn more at www.dfo-mpo.gc.ca.
