Scientists Identify Bacterial Cause of Sea Star Wasting Disease

Since 2013, sea star populations along the Pacific coast from Mexico to Alaska have suffered massive die-offs due to a mysterious wasting disease. Recent research has identified the bacterium Vibrio pectenicida as the cause of this epidemic.

The disease, known as sea star wasting syndrome, leads to lesions, limb detachment, and eventual disintegration of the sea stars. The sunflower sea star (Pycnopodia helianthoides) has been particularly affected, with over 90% of its population lost within the first five years of the outbreak.

Researchers from the University of Washington, the Hakai Institute, and the University of British Columbia conducted a four-year study to identify the pathogen. They found high levels of V. pectenicida in the coelomic fluid—the internal fluid surrounding sea star organs—of diseased individuals. Laboratory experiments confirmed that introducing this bacterium to healthy sea stars induced the disease, leading to rapid mortality.

The decline of sea stars has had significant ecological consequences. Sunflower sea stars are key predators of sea urchins; their loss has led to unchecked urchin populations, resulting in the destruction of kelp forests that provide habitat for numerous marine species.

Identifying the bacterial cause of sea star wasting disease is a crucial step toward developing conservation strategies. Potential efforts include breeding sea stars in captivity, exploring natural immunity, and developing treatments like probiotics to bolster sea star resilience.