A wasting disease that exploded during a severe Pacific marine heatwave between 2013 and 2016 — known as “the Blob” — wiped out vast numbers of sea star species and caused the collapse of enormous stretches of coastal kelp forests stretching from the Aleutian Islands all the way down to the Baja Peninsula. Among the hardest-hit species was the sunflower sea star, a top-of-the-food-chain predator that keeps kelp forest ecosystems in check by feeding on sea urchins and other kelp grazers.
Now, as captive breeding efforts and the discovery of new sea star refuges — including one found in Greater Farallones National Marine Sanctuary in August 2025 — offer renewed hope for the species, researchers at NOAA’s Pacific Marine Environmental Laboratory (PMEL) have created a fast environmental DNA, or eDNA, detection method that gives scientists a powerful new way to track the sunflower sea star’s health and potential comeback.
“By analyzing tiny amounts of genetic material they shed into the water, we can now identify these large but elusively rare sea stars without ever seeing them,” said Zachary Gold, a scientist who leads PMEL’s Ocean Molecular Ecology program. “This opens the door to efficiently monitoring the recovery of this species, especially at deeper depths and sites that are difficult for divers to survey.”
The eDNA technique is capable of detecting just a small handful of DNA copies in a single liter of seawater. Compared to traditional dive surveys, it is cheaper, more sensitive, and better suited for quick assessments. Results can come back within one to two days and can then be followed up with visual confirmation in the water. In one recent example, after an eDNA signal was detected in Northern California’s Noyo Bay, divers were able to locate a juvenile sunflower sea star roughly the size of a teacup.
Why the Sunflower Sea Star Matters to Kelp Forests
The sunflower sea star — once plentiful along the Pacific Coast and now proposed for listing under the Endangered Species Act — plays a role similar to that of the sea otter. Both are aggressive hunters of bottom-dwelling sea urchins. When sunflower stars, sea otters, and other healthy predator communities are present and thriving, they help keep sea urchin populations in check, which in turn protects vital kelp forest ecosystems.
Kelp forests rank among the most biologically productive and economically valuable ecosystems on the planet. They serve as nurseries and high-quality habitat for hundreds of marine species, filter nutrient pollution, and support fish populations and commercial fishing industries worldwide.
Under normal conditions in healthy kelp forests off California, sea urchins play a natural role — grazing on algae and helping cycle nutrients along the ocean floor. But when that balance breaks down, urchin populations can explode, turning once-vibrant kelp forests into barren underwater wastelands. Even after the Blob’s warmth faded, starving sea urchins continued to prevent kelp from bouncing back by constantly eating off new growth across hundreds of miles of coastline.
Captive Breeding Programs Offer a Lifeline
When the sea star wasting disease outbreak struck, scientists moved quickly to bring surviving sunflower stars into captivity to protect the species and study the illness. That intervention led to two major breakthroughs: researchers learned how to successfully breed sunflower stars in a captive setting, and they identified a previously unknown bacterium called Vibrio pectenicida as the main cause of the disease.
The captive breeding program also gave scientists a way to test and validate their new eDNA detection tool. The research team put the method through its paces in labs, in aquarium settings, and out in the ocean, comparing results alongside traditional dive surveys. The findings were clear — the test accurately identified whether the species was present or absent, and the more sunflower stars divers spotted, the higher the concentration of DNA the method picked up.
Signs of Recovery Being Tracked Along the Pacific Coast
In recent years, scattered sightings in Olympic Coast National Marine Sanctuary and in Northern California tidepools have sparked cautious optimism that sunflower stars may be slowly returning to parts of their historic range. In 2026, a team that included NOAA scientists surveyed 39 sites across California — covering former population hotspots, locations with recent informal sightings, and areas within and near marine protected areas.
Using the eDNA method, the researchers confirmed the presence of sunflower stars at six separate sites across Mendocino, Sonoma, and San Mateo counties. Notably, one of those detections marked the first confirmed presence of the species south of San Francisco in ten years.
PMEL’s Ocean Molecular Ecology program has since been deploying the tool to assist conservation partners. In Olympic Coast National Marine Sanctuary, researchers are now pairing eDNA detections with visual surveys to modernize how they track the species.
“The development of a targeted, validated detection method for the sunflower sea star adds to NOAA’s growing inventory of tools to monitor and evaluate species of concern or importance,” said Krista Nichols, a genetics program manager with NOAA’s National Marine Fisheries Service. “For sea stars in particular, the use of eDNA could be a game changer for this struggling apex predator.”
