Sea urchin population explodes

The purple sea urchin population exploded on the Oregon coast, leading to a rapidly-changing ecosystem on the Oregon’s coastal environment. (Photo courtesy of Jaime of @girlnwaterphotography)

Spiny sea critters decimating state’s marine ecosystems

NEWPORT — Purple sea urchins are decimating stretches of the ecosystem off the Oregon coast, and some scientists worry the spiny creatures could change the future of local marine environments. 

“They’re changing things in a big way,” said Scott Groth, a pink shrimp and south coast shellfish project leader for the Oregon Department of Fish and Wildlife’s (ODFW) Marine Resources Program. “This might be a long-term change.”

A statement released Sept. 12 by ODFW points to a huge jump in the number of purple sea urchins along the Oregon coast, driven in large part by a steep decline in the purple sea urchins’ main predator, the sea star. The entire West Coast’s sea star population dropped off significantly because of sea star wasting syndrome, with Oregon coast populations of the bright orange and purple soft-bodied stars made effectively absent from intertidal zones. 

The phenomenon is the subject of a new study conducted by scientists and researchers at ODFW, which also focuses on the loss of kelp beds off the Oregon coast’s intertidal zones. While the explosion in the purple sea urchin population isn’t the only cause of the loss of kelp forests along this stretch of the coast, scientists maintain the now-overabundant sea urchins might negatively impact the growth of kelp forests here, which provide an important source of support for other sea animals, like rockfish, that feast, on or live in the kelp.

“I don’t know what can be done,” Groth told the News-Times Thursday. “We’re quantifying and identifying what can be done. If kelp become depressed because of purple sea urchins, rockfish recruitment could be affected by that.”

The rockfish, another important fish in Oregon’s coastal marine ecosystem, might not be the only species to be affected by the rapidly changing coastal environment. Habitat and food structures for other species could be impacted, too, Groth added, changing not only the marine ecosystem for species like rockfish and abalone, but also the local economy. 

“The kelp forest provides a backdrop for all of that,” Groth said. 

The research conducted by Groth and his colleagues over the summer found that sea urchins aren’t the only contributor to kelp forest loss. Warmer waters are less conducive to the growth of kelp beds, according to the ODFW statement about the research, and anecdotal accounts referenced in the statement point to warm water conditions for the last four years. The overpopulation of the sea urchin population might magnify the impact of the negative growth conditions of kelp beds by eating what’s left or what grows in the next few years. 

“The most immediate danger we have is the competition with abalone,” Groth said. “The abalone look pretty imperiled by this. We found a lot of dead shells, and the abalone’s future looks like it’s in doubt — competition with the purple sea urchin will kill a lot of abalones.”


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