Without predators like starfish to keep them in check, urchin populations can explode and begin eating their way through kelp forests, turning them into urchin barrens [Photo credit: Katie Davis]
After more than a decade of mystery, scientists have identified the bacterium responsible for the devastating sea star wasting disease that has wiped out billions of starfish along the West Coast — including those off Mendocino County’s rocky shoreline.
The culprit, Vibrio pectenicida, was pinpointed after researchers induced the disease in controlled experiments using tissue, fluid, and water from infected sunflower sea stars. These tests, along with deep genetic sequencing, confirmed the bacterium as a causative agent.
The findings are particularly significant for Northern California’s coastal ecosystems. The collapse of sunflower sea star populations removed a key predator of purple sea urchins, whose numbers have since exploded. On the Mendocino Coast, these urchins have grazed vast stretches of kelp forest down to barren “urchin barrens,” disrupting marine habitats and fisheries.
By identifying the cause of the epidemic, scientists can now develop recovery strategies — from culturing healthy sea stars in labs to monitoring and managing bacterial presence in the wild — offering a path toward restoring the region’s kelp forests and the biodiversity they support.
