Divers restore kelp forest off Palos Verdes – one dead sea urchin at a time

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Urchin barren off the coast of Palos Verdes. BY TOM FORD / SMBRF

Off the coast of Palos Verdes, the ocean floor is home to millions of purple urchins… and not much else.

Kelp forests are iconic to the California coastline. Southern California is a world-class destination for divers looking to feel like they’re flying through a redwood forest, immersed in a paradisaical underwater ecosystem.

But the water off the Palos Verdes Peninsula is home to an exploding population of purple sea urchins, surprisingly destructive creatures that are wiping out the kelp forests needed to sustain a vibrant marine ecosystem. The area has become what scientists call an “urchin barren,” a desolate stretch of the seafloor where the urchin population has gone unchecked, trashing kelp forest and reducing biodiversity.

Now, scientists, environmentalists and fishermen are coming together in a massive undertaking. The goal? To kill off 5 million purple sea urchins and thus restore the billowing canopies of kelp forest the area was once known for.

To that end, scientists and volunteers from Santa Monica Bay Restoration Foundation, Los Angeles Waterkeeper, California Sea Urchin Harvesters, and other organizations have begun setting out by boat twice a week to kill urchins – and will continue to do so for the next four to five years.

It’s an ambitious undertaking. The divers are working on an area of 150 acres, killing urchins one by one – with a hammer. It may seem morbid, but for the people involved, it’s all in a day’s work.

“It feels a lot like gardening to me,” explained Heather Coleman, one volunteer diver. “When you have a garden full of weeds, it’s not very productive. It’s not a healthy community. When you weed, when you get rid of all the things that hurt growth, that helps the garden grow. It helps produce food, it helps produce a healthy community. It’s very similar to growing a kelp forest.”

Kelp acts as the base of a healthy coast by providing structure and nourishment for up to 800 marine species. When kelp forest disappears, the animals that live there end up homeless and hungry. To help promote kelp forest re-growth, the divers hope to reduce the density of urchins from 70 per square meter to 2, which means hammering about 20,000 urchins each day they’re at sea.

Many of Southern California’s coastal kelp forests have been lost, due to a number of factors. Sedimentation, urban runoff, and pollution cloud the water and hurt kelp growth by blocking sunlight. Add to that the decline of keystone predators like otters (that normally keep urchins in check by preying on them), and you’ve created ideal conditions for a boom in urchin populations. The purple urchins multiply uncontrollably, all the while feeding on kelp plants and eating their spores, destroying the existing forest and preventing new plants from taking root.

“[Sea urchins] didn’t get the memo to slow it down,” said Tom Ford, the Director of Marine Programs for Santa Monica Bay Restoration Foundation. “Coastal pollution, overfishing and a number of factors have contributed to us having too many sea urchins on our reefs. So what we are doing is trying to reset that balance. We have to get things back moving in the right direction.”

Tom Ford, Director of Marine Programs for Santa Monica Bay Restoration Foundation, with Brian Muchs, Marine Program Manager for LA Waterkeeper. BY MALLORY SMITH.
Tom Ford, Director of Marine Programs for Santa Monica Bay Restoration Foundation, with Brian Meux, Marine Program Manager for LA Waterkeeper. BY MALLORY SMITH. (The original image is no longer available, please contact KCRW if you need access to the original image.)

So now that the area is filled with urchins, urchin fishermen are thrilled, right? Wrong. While it seems like an urchin barren would serve as a veritable gold mine for urchin fishermen, the urchins present in a barren are so starved and skinny that they essentially have zero commercial value. Fishermen are on board with the environmental groups for this project, because thinning an urchin population allows the remaining urchins to grow healthier and more robust, creating the juicy, tasty gonads we love to eat.

Ford says the support for this initiative from the fishing industry is a valuable example of the ways in which economic and environmental interests can in fact go hand in hand.

If successful, the $2 million initiative will cause the resurgence of kelp forest in the area, restoring the peninsula’s coastal ecosystem to a more natural state. “With the success we’ve had with this project in the past, I’m very optimistic when I’m there, because I know that if we do our job well, that kelp forest will be back in the course of a year or so,” said Ford. “It’s hard to ignore that potential when you’re down there.”

Industry, environmental, and government interests are coming together in a strong coalition with a shared goal – to transform the seafloor off Palos Verdes back into the underwater palace it once was, replete with awe-inspiring towers of kelp forest and the hundreds of aquatic species kelp sustains.