More than 99% of California’s sunflower sea stars vanished, now scientists have found a mysterious colony that could help revive dying kelp forests
A decade ago, more than 99% of sunflower sea stars vanished from the depths of the ocean. Now, the discovery of a long-lost colony of these organisms is offering new hope for the region’s kelp forests.Sunflower sea stars, known as Pycnopodia helianthoides, may look like an aesthetic and purely decorative feature on the ocean floor, but they are ferocious predators. As adults, they can grow up to 24 arms, span three feet wide, and move three feet per minute. They are superlative, and alien, one of the largest and arguably most ravenous sea stars in the world.They dominated much of the ocean floor until the end of 2013, when a colossal marine heatwave swept over the northeast Pacific just as a mysterious underwater epidemic began causing them to die off en masse. A deadly ailment pocked the starfish bodies with lesions and then dissolved into their flesh. It affected roughly 20 species and killed a whopping 57.5 billion sea stars. Over the past century, these large ribbons of golden-brown seaweed had already dwindled in some stretches of the coast, due to the warming ocean conditions.
A damaged ecosystem
Without the presence of a primary predator, an excess of purple sea urchins insatiably consumed the surrounding kelp forests. By 2017, this sudden explosion of hungry sea urchins and an ongoing marine heat wave, strengthened by an El Niño weather pattern, wiped out more than 90 per cent of kelp forests in some West Coast regions.Kelp forests on the West Coast are critical habitats that support dozens of species including drifting plankton and migrating grey whales. They also form a habitat for lucrative fish species like rockfish, abalone and crabs. More, kelp itself is a sustainable food and helps sequester atmospheric carbon.However, without the presence of sunflower sea stars, kelp forests have been unable to grow back without being devoured by the hungry purple sea urchins. A decade into this devastation, weary coastal communities impacted by the loss of these ecosystems through the state along with the scientists studying this environment wondered whether a population of the sunflower sea stars may have survived somewhere, tucked into a protected coastal inlet or nestled into a forgotten reef.
Sunflower sea stars
Reviving the dead
“The moment I saw my first sunflower star underwater, I was so excited that I literally screamed through my regulator,” Rachael Karm, a research technician at Sonoma State University’s Dr. Brent Hughes ecology and conservation lab, noted in an email to National Geographic. “I came up to the surface before remembering to even take a photo.”A subsequent diving expedition revealed a total of 18 sunflower sea stars, the largest and southernmost population of sunflower sea stars documented since sea star wasting disease spread across the coast. Karm and her peers said this discovery offers a major sign of hope for restoring lost sunflower sea stars and potentially even reviving the coast’s lost kelp forests.Kelp began studying kelp forests in northern California in 2020, after most of the sunflower sea stars had already disappeared. Then, her colleagues found a single adult sunflower sea star at an underwater site they regularly monitored for kelp research projects. When Karm returned about a week later to relocate the star and collect genetic samples she was stunned to stumble across four more sunflower sea stars, juveniles this time, including two silver-dollar-sized individuals on the same rock.Just two months later, Karm convened an event dubbed Pycnopalooza. Once Pycnopalooza was announced, it drew a dream team of 25 scientific divers from eight different institutions: The Nature Conservancy; Greater Farallones National Marine Sanctuary; Moss Landing Marine Labs; University of California, Berkeley; Reef Check California; Sonoma State University; Sunflower Star Laboratory; and the Kashia Band of Pomo Indians, whose scientific dive team oversees kelp restoration on their ancestral lands. Over two days, divers systematically surveyed the humble cove off the coast of Sea Ranch, California using an underwater grid system. Teams entered the frigid water with flashlights, measuring reels, and little red floats to be deployed should a wild “Pycno” be found. They also had access to a new technology that allowed them to find bits of sunflower sea star DNA in environmental samples, also known as eDNA.By the end of the two-day effort, 18 adult sunflower sea stars had been found—each individual marked by its own exuberantly bobbing red buoy.
How the sea star colony could help fight disease
