The fight for California’s other iconic forest

Volunteers, divers and scientists use direct intervention, kelp nurseries to try and save the rapidly disappearing ocean vegetation|

There’s an ancient ecosystem on the Northern California coast. It’s nearly as productive as the Amazon rainforest, scientists say, but in less than a decade it has nearly disappeared.

In the geological blink of an eye, the groves of amber kelp that once filled the blue shorelines of Sonoma and Mendocino counties have gone from full of life to rocky barrens. And no one knows if they’re ever coming back.

Even so, there’s new hope among the fishing families, divers and coastal communities who’ve been hit hardest by the kelp forest collapse. Above and below the sea, a new coalition of researchers and innovators have mounted an ambitious multi-front campaign to rescue, rebalance and perhaps restore hundreds of miles of once-thriving sea life.

Sudden change

The “kelp crash” began in 2013, when divers began to notice that Pacific starfish were dying by the millions from a lethal wasting disease spreading through the ocean. Giant sunflower sea stars, which can grow up to 3 feet wide with two dozen arms, were decimated.

Then an oceanic heat dome struck along the north coast, with exceptionally warm water. And by the summer of 2018, 86% of California’s thick kelp forests were missing, along 200 miles of coastline. The region’s prized $40 million red abalone fishery collapsed, as the mollusks starved in vast numbers without the kelp they depended on. And where kelp forests once reigned, voracious purple urchins massed.

In the coastal ecosystem, sunflower stars love to eat urchins, and the urchins eat kelp. So when 90% of the sunflower global population died, an estimated 5 billion, urchin numbers exploded. And they stripped the kelp beds bare.

On a recent clear September morning, Vienna Saccomanno launched a white drone from a remote beach near Mendocino to scan the sea below for kelp. Saccomanno, an ocean scientist with The Nature Conservancy, leads the group’s kelp mapping and monitoring program.

Flying up to 400 feet high, the drone’s camera can look down and collect dozens of images in a second.

“Knowing where remaining healthy kelp forests are located is the first step to restoration,” she said.

For four years, Saccomanno has been surveying a few remaining kelp strongholds, small patches of survivors along the coast. As much as 10% of the original forests seems to have survived in scattered pockets and struggling groves.

The drone has opened a new way of searching for kelp. While satellites have tracked the kelp canopy since the 1980s, from space it’s only possible to spot patches 100 feet wide and it’s easy to miss kelp close to rocks or shore.

Saccomanno’s drone can measure down to less than an inch. And with new custom software, she has survey results almost immediately on her phone, instead of waiting months for number crunching the old way.

In 2021, her drone flights recorded a small increase in kelp, a promising hint at recovery. But in 2022, the results weren’t as good.

It’s too early, she said, to know whether there’s been any real change or just a blip in the data.

Amber waves of kelp

What everyone’s searching for is bull kelp, the dominant giant algae on the north coast.

Bull kelp forms tall dense forests 60 feet tall or taller in the shallower parts of our ocean. It turns sunlight into food with ribbon-like honey-colored fronds that spread like leaves from a bulbous top. The bulb is filled with gas, which keeps the frond clusters, up to 10 feet long, floating at the surface.

Mats of these floating fronds cover sections of ocean, and that’s how marine scientists know what’s going on in the forest below.

Bull kelp are annuals, which means they sprout, grow and die all in one year, so the forest regrows each spring. Divers compare swimming among kelp to swimming in a cathedral. Kelp is home and shelter to a thousand other ocean species, including crab and many commercially valuable fish we eat.

Like plants ashore, kelp is eaten by grazers, especially urchins, which look like baseballs covered with 2-inch purple spikes. Without their natural predators — sea otters and starfish — urchin can reproduce incredibly fast, overtaking the ecosystem and leveling the kelp forests.

A new normal

Part of the problem with addressing the kelp collapse, scientists explain, is that the habitat has tipped into a new stable state, where urchins dominate.

And even though the kelp is now gone, the purple urchins are still there. Starving urchins can stay alive for years, even decades, kind of a zombie horde, waiting until the kelp reappears.

After the abalone crash in 2018, in coastal communities dependent on the sea for livelihoods, volunteers and local groups scrambled for ideas. What if the urchins could be cleared off?

Over the next year, commercial divers dove into two coves near Albion and Noyo Harbor, both in Mendocino County, to gather as many of the purple critters as possible. Mendocino’s Waterman’s Alliance raised $100,000 in donations from sport agencies and recreational divers to pay for nine commercial urchin boats to haul them in. The California Ocean Protection Council provided $617,000 in funding, and Reef Check California monitored the catch, collecting data on its effectiveness.

“We wanted to know, if you take urchins away from an area where there’s a persistent little kelp bed, could we spread that spore source over in the new restoration zone?” said Sheila Semans, the Noyo Center’s executive director.

About 48,000 pounds of urchins later, studies confirmed that clearing by hand could work, if the number of urchins could be kept below a certain critical level, less than two per square meter.

Where urchins were harvested, kelp went from completely absent to around 20% of its pre-crash density. Outside the site, the kelp was still gone.

New partnerships for kelp

Norah Eddy, associate director of The Nature Conservancy’s California Oceans Program, now spends her days focused on kelp recovery and restoration. It’s a daunting task, but Eddy is hopeful.

The Nature Conservancy is engaged in a wide-ranging partnership to try and rescue California’s kelp habitat, if possible. They’re working with university laboratories, international kelp and coral experts, the California Department of Fish and Wildlife, the California Ocean Protection Council, Greater Farallones Association and the Reef Check Foundation.

“We’re developing new science,” Eddy said. “It’s a ‘learn a thing while doing a thing’ approach.”

The project has four main areas, Eddy explained: mapping and monitoring kelp, resetting the ecosystem, restoring the ecosystem and developing tools to, eventually, manage a healthy ocean habitat.

They’re already seeing progress, she said. This year, marine scientists at University of Washington’s Friday Harbor Laboratories announced they’d successfully raised baby sunflower sea stars for the first time, opening the possibility of reintroducing them to their native habitat.

New nurseries have started growing bull kelp, too. One project at Moss Landing in Monterey County reported raising first crops of kelplings from wild spores this past spring. Now various ways of transplanting them are being investigated.

Uncharted territory

Tristin McHugh, kelp project director with the California Oceans Program at The Nature Conservancy, noted that while other kelp beds around the world have suffered similar challenges, this is a first-of-its-kind effort.

“We know from the past, the kelp here was robust and stable,” McHugh said.

For the first native people, the food-rich kelp beds were an ice-free highway down into North America and a sustaining habitat for more than 10,000 years.

“Kelp loss isn’t ‘one size fits all,’” she said. “Each local place has a unique set of features that affect what’s happening. Each stretch of coast is different. One patch may be overwhelmed, while another may be protected in some way.”

That’s why Saccomanno’s drone flights are essential — to discover where remaining kelp may be.

“These aerial surveys are like gold to divers,” McHugh said, because they can precisely pinpoint, along hundreds of miles of coast, promising spots for further investigation.

“To be effective, we need to develop a strategic understanding of persistent patches and barren patches,” she said.

McHugh noted that it’s not clear the kelp forests may ever return to what they once were. The challenges facing kelp are growing worse over time, she said. What’s possible remains to be seen. But kelp beds have been recovered elsewhere, in Japan, for example.

Eddy explained, “We’re at a point now where we’re seeing some early signs of success. We now know urchins need to be kept below a certain threshold for kelp to recover, and that may be possible in select locations within years, not decades.”

The first step may be to establish kelp refuges, from which they can reseed nearby areas over time, Eddy said.

The key message, Eddy said, is that people should know how important these kelp forest systems are to the entire western United States.

The forests support commercial fisheries worth hundreds of millions in commerce per year. They anchor and protect an entire web of species, take in carbon and reduce ocean acidification. By breaking the brunt of heavy surf, they protect shorelines from erosion.

Above the turquoise water of a Pacific cove near Caspar in Mondocino County, Saccomanno piloted her drone, mapping signs of an ancient living forest. She’s part of a new generation who’ve set out to find whether humans can protect and restore the sea.

Stephen Nett is a Bodega Bay-based Certified California Naturalist, writer and speaker, with local nature stories at Contact him at

This article has been updated to correct information about the urchin-gathering project in Albion and Noyo Harbor.

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