California’s Kelp Forests in Climate Peril

Kelp in CA’s Monterey Bay. Image: Chad King/NOAA

Kelp forests are some of California’s most iconic ecosystems and a new satellite study show they’re almost gone. As the Ocean Conservancy explained, kelp forests are the anchor of nearshore ocean wildlife communities, sustaining marine biodiversity by providing shelter, habitat, and even food for an array of fish and invertebrates. They’re also important to coastal economies and fisheries.

Northern California’s kelp forests declined by as much as 95% since 2013 due in part to an intense ocean warming period between 2014 and 2017 which stressed kelp and likely supercharged a mass die-off of starfish. Starfish prey on native purple urchins, keeping their numbers in check and without these predators, the urchins proliferated, devouring kelp forests at a staggering pace.

As a result of this ecosystem depletion, regulators have also forced the closure of the $44 million recreational abalone fishery in 2018 and the commercial red sea urchin fishery has also nearly shuttered.

Why This Matters: As global efforts focus on protecting and replanting forests, we can’t forget about the world’s underwater forests. Ecosystems like kelp and seagrass have immense ability to sequester carbon–kelp especially, a process that cleantech companies are looking to supercharge. It’s unclear if kelp restoration programs and urchin culling can overcome the stresses posed to California’s kelp forests, though scientists and volunteers aren’t giving up.

What’s Next: As Smithsonian Magazine explained, “At this point, getting kelp forests to come back to the Northern California coast means the purple urchins carpeting the bottom have got to go. But getting rid of the urchins is no easy feat. Despite having eaten all their favorite foods, the simple, hardy spiked invertebrates somehow manage to persist.”

Meredith McPherson, a graduate student at UC Santa Cruz’s Ocean Sciences department and coauthor of the study told the San Francisco Chronicle that, the urchins “can actually survive under starvation conditions” adding that, “The impact has been that basically there is no kelp forest at all left, really.”

While individual ocean warming events cannot necessarily be attributed to climate change, these heatwaves are being made worse and more frequent by a rapidly warming planet. Climate change also stresses entire ecosystems, making them far less resilient to sudden natural events–which is the case with California’s kelp forests. There are serious efforts underway by researchers to help replant kelp forests and protect the keystone species that keep them healthy, but this work is racing the clock of a rapidly warming planet.

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