Rare Sunflower Sea Star Colony Discovered, Offering Hope for Kelp Forest Recovery

More than 99 % of sunflower sea stars disappeared after a 2013 marine heatwave sparked a lethal wasting disease, allowing purple sea urchins to overgraze and eliminate over 90 % of kelp forests in several West Coast regions. In June 2025, divers from a coalition of universities, NGOs and Indigenous groups, coordinated by Rachael Karm of Sonoma State University, uncovered 18 sea stars in a remote cove off Sea Ranch, the largest surviving population recorded since the epidemic.

Researchers are analyzing genetic samples at the University of California, Merced to pinpoint traits that may have conferred resistance to the disease. The culprit bacterium Vibrio pectenicida has been identified, with rising Pacific sea temperatures linked to its spread. The team hopes the colony will supply disease-resistant stock for captive-breeding and eventual re-introduction, helping to restore the keystone predator and enable kelp forests to recover, benefiting biodiversity and carbon sequestration.