Purple Sea Urchins Are Causing West Coast Nightmare

They've already wiped out 90% of northern California's underwater kelp forests
By Newser Editors and Wire Services
Posted Oct 24, 2019 12:15 AM CDT
Sea Urchins Have Destroyed 90% of Calif.'s Kelp Forests
In this May 20, 2019 photo, a container at the Bodega Marine Lab in Bodega Bay, Calif. holds hundreds of live purple urchins harvested from the Mendocino County coast where they have been decimating kelp forests.   (AP Photo/Terry Chea)

Tens of millions of voracious purple sea urchins that have already chomped their way through towering underwater kelp forests in California are spreading north to Oregon, sending the delicate marine ecosystem off the shore into such disarray that other critical species are starving to death. A recent count found 350 million purple sea urchins on one Oregon reef alone—a more than 10,000% increase since 2014. And in northern California, 90% of the giant bull kelp forests have been devoured by the urchins, perhaps never to return. Vast "urchin barrens"—stretches of denuded seafloor dotted with nothing but hundreds of the spiny orbs—have spread to coastal Oregon, where kelp forests were once so thick it was impossible to navigate some areas by boat.

The underwater annihilation is killing off important fisheries for red abalone and red sea urchins and creating such havoc that scientists in California are partnering with a private business to collect the over-abundant urchins and "ranch" them for sale to a global seafood market, the AP reports. "We're in uncharted territory," says Scott Groth, a shellfish scientist with the Oregon Department of Fish and Wildlife. "You can't just go out and smash them. There's too many. I don't know what we can do." Scientists are not yet sure if climate change is responsible for the sea urchin explosion, but they suspect it plays a role in the cascade of events that allowed the purple urchins to boom. Kelp has been struggling because of warmer-than-usual waters. And, in 2013, a mysterious disease began wiping out tens of millions of starfish, including a species called the sunflower sea star that is the only real predator of the ultra-hardy purple urchin.

(More sea urchins stories.)

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