Marine ecologists are exploring the potential of cooler waters to protect sunflower sea stars from a devastating illness known as Sea Star Wasting Disease (SSWD). SSWD was first reported in 2013 along the Pacific coast of North America. Since then, it has devastated sea star populations and wiped out about 20 species. The sunflower sea star (Pycnopodia helianthoides) is among the hardest hit species. It has faced a startling decline of around 91 percent, leading to its ranking as critically endangered.
SSWD is famous for producing spectacular physical deformities and consistently killing afflicted sea stars within just a few days of symptom onset. The spread of the disease has raised serious alarm about the impact on our marine environments. As ecological indicators, the health of sunflower sea stars is crucially important. Without these predators, sea urchin populations can explode exponentially. This explosion puts kelp forests in peril, some of the most productive and biodiverse habitats on our planet teeming with life from urchins to otters.
Alyssa Gehman, a marine ecologist at the Hakai Institute in British Columbia, suggests that cooler temperatures may serve as a protective barrier against SSWD for sunflower sea stars. Gehman’s research indicates a strong correlation between catastrophic SSWD outbreaks and atypically hot water temperatures. This relationship serves to underscore the role of temperature in the transmission of this disease.
“Most of the biggest outbreaks are associated with anomalously warm water,” – Alyssa Gehman
Researchers just uncovered a remarkable finding in the fjords of British Columbia. They were surprised to discover a flourishing refuge population of sunflower sea stars. Field biologist Tristan Blaine was key in surveying this newly discovered population. He is the director of the Central Coast Indigenous Resource Alliance. The fjords offer cooler, more stable temperatures and distinct ecological features. They almost appear to produce a refuge for these sea stars.
“The fjords are colder than anywhere else on the coast. It’s super dark and there’s usually blasting current,” – Tristan Blaine
Over the last five years, Gehman and her colleagues have scoured the coasts for sunflower sea stars. Through their research, they paddled the fjords and islands that surrounded their home. They explored by diving down to 14 meters beneath the water’s surface. This initial exploration occurred at seven local sites within the fjords and 26 sites around the close-by islands. The results were shocking! Colorful underwater landscapes within the fjords teem with life, including robust populations of once common sunflower sea stars that have disappeared from many other coastal regions.
SSWD didn’t just generate curiosity in Hewson’s lab — it nudged Hewson himself onto a new path entirely. He suspected that some sort of virus was causing SSWD. But soon after, he began to reverse this conclusion, citing limitations with the data that would ultimately lead him to doubt previous findings.
“We initially thought it was a virus, but went back on that, because the data was either flawed or the results couldn’t be repeated,” – Ian Hewson
The new research underscores the need to identify environmental triggers that lead to disease emergence in marine animals. As scientists learn more about the possible causes of SSWD, they stress the importance of questioning what has already been assumed about its origins.
“[We have] restarted the question from square one on what causes this disease.” – Alyssa Gehman
The potential implications of these findings go well beyond the sunflower sea star. Healthy kelp forests are essential to the well-being of a myriad of marine species. We need to do something to save these amazing ecosystems from rampant sea urchin overgrazing. These cooler waters would likely buffer against the impact of SSWD. This presents a bright opportunity for conservationists interested in restoring sunflower sea stars and their integral role in healthy marine ecosystems.
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