A CHANGE IN PERSPECTIVE: UCSB researchers say sea urchins a key for kelp forests

Research at UCSB casts a different view of sea urchins who have commonly been made out to be villains.

A research paper published in the Proceedings of the Royal Society B finds that, rather than being responsible for the destruction of kelp forests, they may help keep kelp forests healthy, according to a UCSB news release.

The research team was led by Christie Yorke, a postdoctoral student at UCSB’s Marine Science Institute. The other members were Bob Miller and Mark Page, research biologists at the MSI.

The team “studied how urchins might function to break up tough kelp into more manageable pieces that can feed other scavengers, also known as detritivores, living on the kelp forest floor.”

Ms. Yorke said that it was one of the “first experiments” to look at how sea urchins function in the marine ecosystem.

“It’s one of the first experiments. Animals that shred food that’s not palpable is not new, but this was one of the first experiments that were done in a marine ecosystem,” Ms. Yorke told the News-Press.

The process of research and experimentation took about two years.

“It was about a year of method development and a month to run the experiments, another year to process the samples and run the models because we had to dissect everything and run isotope analysis,” Ms. Yorke said, adding that the whole process was “fun.”

Ms. Yorke said that she was the primary researcher as it was part of her dissertation, but she credited her co-authors with securing funding and helping her with research and writing.

“They helped with thinking through the experiment and making sure I was choosing the best path. They also helped with the writing and interpretation of the experimental results,” she said.

Ms. Yorke is pleased that her work was published in a non-marine specific journal.

“I’m really excited to see my research published in the Proceedings of the Royal Society. It’s the first time that my work has been published that’s not marine specific and it will hopefully attract a broader readership,” she said.

That allows the paper to be cited more often, which is a boon for Ms. Yorke’s academic career.

The researchers found that urchins may be “crucial” for the health of kelp forest ecoystems

They conducted experiments, comparing detritivores in tanks, with half of the tanks containing sea urchins, and found “that a whole host of detritivores can take advantage of kelp as long as urchins are there to process it for them, whereas otherwise they can’t.”

The researchers also looked at long-term data to put their findings in context. Using data from the Santa Barbara Coastal Long Term Ecological Research project, they found that urchins could be responsible for a “significant portion” for the resources available to these detritivores.

“The scientists looked at 11 years of relevant data, including the amount of kelp litter over time, as well as sea urchin abundance and biomass. Their analysis suggested that the amount of kelp that urchins shred and process could be a significant portion of the resources available to the creatures that live on the seafloor,” the news release stated.

They compared sea urchins to grasshoppers, explaining that both are a “healthy part of the ecosystem” but can be a danger and a nuisance if out of control.

Sea urchins need to be studied more and should not be destroyed by anyone until scientists have a better understanding of their role in the ecosystem, according to Dr. Miller.

“We should not go around and vilify or smash sea urchins before we understand their role in the ecosystem better,” Dr. Miller said. “They’re not necessarily always the bad guy they’re made out to be.”

Ms. Yorke is no longer working with sea urchins, but is working on a kelp farming project centered around genome association for giant kelp, she said.

“We’re farming giant kelp and we’re trying to trace phenotypic traits back to its genotype,” she said.