Marine science grad working to restore kelp forests

multiple divers in kelp forest

A group of CSUMB students dive in a Monterey Bay kelp forest.

January 11, 2022

Kelp forests in Monterey Bay and across California have suffered a dramatic decline in recent years, replaced by large areas overrun by purple sea urchins called “urchin barrens.” A CSUMB marine science alumni’s work may help researchers understand why this is happening and restore the kelp forests.

Joshua Smith graduated from CSUMB in 2015 with a bachelor’s degree in marine science. He went on to earn a doctorate degree in ecology and evolutionary biology from UC Santa Cruz in June 2021. 

“I first learned to scuba dive while I was an undergraduate at CSUMB,” Smith told the Santa Cruz Sentinel in March 2021. “My first dive in a kelp forest was a transformative experience. The visibility was about 3 feet, but I was so fascinated by kelp forests that I literally got out of the water and ran into my undergraduate adviser’s office to change my major to marine science.”

Smith’s study of the kelp forest loss phenomenon began in 2017 at UCSC. For three years he worked with a team of sea otter researchers, the U.S. Geological Survey, and the Monterey Bay Aquarium, building on longtime studies of sea otter populations and kelp forest ecosystems along the California coast.

Smith’s findings were published in March 2021 in “Proceedings of the National Academy of Sciences.” He describes a Monterey Bay that used to be dominated by giant kelp forests as “a mosaic of sea urchin barrens interspersed with forests of giant kelp that seem otherwise quite healthy. Our research shows that sea otters are fundamentally responsible for the persistence of the remnant kelp forests here in Monterey Bay.”

The urchin’s main predator, sea otters responded to the urchin outbreak by eating about three times as many of them. This helped maintain patches of healthy kelp forest. To learn more, visit Smith’s research website.