Restoring Sunflower Sea Stars to Revive California Kelp Forests

Kelp forests off Monterey, California, once towering like “redwoods of the sea,” have collapsed dramatically. Over the past decade, a marine heatwave that began around 2013 raised Pacific coastal temperatures, accelerating sea-star wasting syndrome. The disease eliminated more than 90 % of the sunflower sea star (*Pycnopodia helianthoides*) population, a predator that once helped control purple sea urchins. With the stars gone, urchin numbers exploded, grazing kelp holdfasts and converting lush forests into barren “urchin barrens.”

The Guardian

Researchers from the nonprofit Sunflower Star Laboratory are conducting the first field trials of lab-raised sunflower sea stars in Monterey Bay. Divers release the animals from plastic bags into open-cage enclosures on the seafloor, allowing them to roam freely while scientists monitor movement and urchin behavior. The goal is to re-establish the “halo of fear” that deters urchins, thereby giving young kelp a chance to re-anchor and grow. If successful, the team aims to scale up re-introductions over the next few years.

The Guardian

• Current local abundance: “The known number of sunflower stars in Monterey Bay is zero.”

The Guardian

• Kelp loss: 95 % of kelp forests have disappeared in the last 10–12 years.

The Guardian

• Predation rate: a single sunflower star can consume three to four urchins per day.

The Guardian

Co-founder Reuven Bank described the stars as a critical deterrent, explaining that urchins and other grazers flee when they detect the predator’s scent. Bank argued that restoring the sunflower star is “the single most important step” for saving California’s kelp forests, given the current absence of the species in Monterey Bay.

The Guardian

• “We have a star that decided to go for a walk today,” — Ashley Kidd, co-founder, Sunflower Star Laboratory

The Guardian

• “They are a sea star, but the cool thing with these guys is they have more than five arms,” — Ashley Kidd, co-founder, Sunflower Star Laboratory

The Guardian

• “There were 6bn sunflower stars from Alaska down to Baja California,” — Reuven Bank, co-founder, Sunflower Star Laboratory

The Guardian

• “Urchins and other grazers smell a sunflower star coming and they take off in fear,” — Reuven Bank, co-founder, Sunflower Star Laboratory

The Guardian

• “So this ridiculous alien monster here is Titan,” — Reuven Bank, co-founder, Sunflower Star Laboratory

The Guardian

• “The known number of sunflower stars in Monterey Bay is zero,” — Reuven Bank, co-founder, Sunflower Star Laboratory

The Guardian