Scientists Uncover the Cause of Sea Star Die-Off
For nearly a decade, sea stars along the Pacific coast of North America faced a mysterious and deadly disease. Scientists finally discovered what caused the deaths of over 5 billion sea stars, primarily impacting species like the sunflower sea star.
The problem started in 2013. From Mexico to Alaska, these stunning creatures with their vibrant colors—from orange to purple—began to disappear. By the first five years of the epidemic, the sunflower sea star lost around 90% of its population.
Marine disease ecologist Alyssa Gehman from the Hakai Institute described the effects of this disease. Healthy sea stars typically have firm arms extending outward. However, the disease induces lesions, causing their arms to fall off, leading to slow, painful deaths.
A recent study published in Nature Ecology and Evolution revealed that bacteria, specifically Vibrio pectenicida, is responsible for the disease. This bacteria has also infected shellfish, further complicating the ecosystem. Rebecca Vega Thurber, a marine microbiologist at UC Santa Barbara, emphasized how solving this mystery is essential for ocean health.
The search for the disease’s cause took time. Initially, researchers suspected a virus linked to the problem, only to find it was harmless. Many earlier investigations did not detect the bacteria because they missed the vital coelomic fluid—the fluid surrounding sea star organs.
Blake Ushijima, a microbiologist from the University of North Carolina, praised the research team’s work, noting that pinpointing such environmental diseases is complex, especially underwater.
With this new discovery, scientists are considering how to help remaining sea stars. They may investigate which populations are healthy, relocate them, or breed them in captivity for repopulation efforts in affected areas.
This recovery work is vital. Sea stars play a crucial role in their ecosystems. They keep sea urchin populations in check, which, in turn, protects kelp forests—habitats vital for many marine species. The loss of sea stars has led to a surge in sea urchins, which have devastated kelp forests along the coast.
As researchers delve into this bacteria’s impact, they also hope to explore whether certain sea star populations possess natural immunity or if treatments like probiotics could improve their health.
The ongoing effort to restore sea stars isn’t just about these creatures; it’s about the health of entire Pacific ecosystems, making the work exceptionally important for marine life.
As Gehman aptly stated, sunflower sea stars may appear harmless, but they are fierce eaters that maintain balance in the ocean—a balance that’s crucial for many other species, including fish and sea otters.
By uncovering the disease’s source, scientists have a clear path forward. They aim to rejuvenate sea star populations and, with them, rejuvenate the kelp forests, often regarded as the “rainforests of the ocean.”
For more information on marine ecosystems, visit NOAA’s National Marine Fisheries Service.
