The fragile future of the North Coast's beleaguered bull kelp forests is perhaps best captured in a single photograph taken off the Mendocino County coast last summer.
The image is at once hopeful and ominous: A tiny bull kelp stem with a single blade sways in the currents, reclaiming a spot on a once barren reef. But, looming large in the background, the shadowy figure of an urchin readies to seal the new start's fate.
For marine ecologist Tristin McHugh, who took the picture while diving a Noyo Harbor site that had recently been scoured of as many urchins as possible, the moment was emotional.
The rapid decline of the North Coast's once thriving underwater forests has been well-documented in recent years, with the coasts of Mendocino and Sonoma counties bearing the brunt of what scientists describe as a "perfect storm" of changing oceanic conditions that ultimately decimated red abalone populations.
While ebbs and flows in the undersea ecosystem occur naturally, McHugh says the devastation wrought in those areas has been intense, with more than 95 percent of the waxy bull kelp canopies gone in less than a decade.
"It happened very quickly," she says.
The stage for the bull kelp's disappearance was being set back in 2013 when a still mysterious wasting disease began decimating starfish populations up and down the Western coast. Especially hard hit was the sunflower star — a voracious, 24-armed predator that can swallow a sea urchin whole — which has yet to rebound.
"The Warm Water Blob" — essentially a marine heat wave — entered the scene next, stressing bull kelp forests that are dependent on nutrient-rich cold waters to thrive, only to be followed by another round of high ocean temperatures with the "Godzilla" El Niño in 2015.
In the wake of these climate change-driven anomalies, a "negative feedback loop happened," McHugh says. Bull kelp forests were left in a weakened state and fewer new stocks settled onto the region's rocky reefs, removing vital food sources from the ecosystem.
That, she says, drove sea urchins — normally content to settle into nooks while feeding on drifting algae — to noticeably shift their behavior.
"They went from passive grazers to active grazers," McHugh says.
At the same, with no sunflower stars to keep their numbers in check, the purple urchin population exploded and set its sights on the surviving bull kelp forests. In some places, they reduced once thriving marine ecosystems that boasted an array of sea life to wastelands known as "urchin barrens."
Unable to compete against the seemingly unstoppable urchin force, red abalone starved, their numbers plummeting across a wide swath of coastline stretching from Sonoma to Southern Humboldt. The commercial red sea urchin fishery neared collapse, creating economic reverberations for the surrounding communities amid the ecological disaster.
After shuttering the recreational season in 2017 in a bid to save the prized shellfish — the California Fish and Game Commission recently extended the closure to at least 2026.
But cooperative efforts are underway to learn more about the workings of the complex bull kelp ecosystem while also bringing together a network of stakeholders, from scientists and government agencies to commercial urchin divers and nonprofits, to create a restoration framework.
The Noyo project — which saw six teams of commercial divers working in conjunction with scientists cull more than 26,000 pounds of the spiky urchins over the course of last summer — is one part of the puzzle.
Mike Esgo, the marine ecosystems program manager and tribal liaison for the state's Ocean Protection Council — which funded the removal project — described it as a pivotal component of a restoration toolkit the agency is putting together with the California Department of Fish and Wildlife as part of a statewide kelp restoration and protection plan.
The basic idea was to see whether bull kelp would return if enough of the urchin were taken.
And more ideas are on the table.
For McHugh, who recently transitioned to become Nature Conservancy's kelp project director, that includes looking at the potential of trapping urchin and leveraging the private sector to find pathways for using the catches — whether its fatting the urchins up on a farm to sell to market or using them as compost.
The hope, she says, is to find ways to "reset the ecosystem," with a focus on "scalable solutions that benefit both humans and the environment."
And Humboldt County may play an important role in those efforts, with preliminary plans underway to develop an experimental bull kelp nursery in Humboldt Bay.
Still early in the works, the idea is for the environmental nonprofit GreenWave and Humboldt State University — which are already working together to launch and scale regenerative ocean farms on a separate project — to partner on the endeavor with the Nature Conservancy to create a "stock of kelp" that could possibly be used in restoration efforts.
Unlike its southern cousin the giant kelp, bull kelp grows as a single stalk and dies off each year — basically an annual marine plant rather than a perennial — making it more vulnerable to hungry urchin mobs that can hinder its ability to reestablish new growth.
So for McHugh, the bull kelp's return to a barren space in Noyo Harbor raised a number of questions. Primarily, how old are the kelp seen there, where did they come from and where are their parents?
There's evidence, she says, that bull kelp spores can live for a very long time, decades in some cases. But how long is still one of those knowledge gaps the Humboldt Bay project might help answer.
For the most part, the bull kelp here has fared better than other areas to the south.
According to Brian Tissot, director of the Humboldt State Marine Lab in Trinidad, the local coast has never really had the urchin barrens seen in other areas, like Mendocino, noting the situation along the state "really varies from site to site."
"It still is a serious problem but we've been spared that; why, I'm not really sure," says Tissot, who surveyed stretches of the local coastline over the summer as part of a state Marine Protection Areas monitoring project. "We're a little bit colder. ... If anything, we're seeing more of a recovery of bull kelp and that's good news. Hopefully, that will continue."
But even amid that bit of good news, Tissot and other marine experts, including McHugh, are still concerned. Overall, 2020 was a good year for ocean temperature, but the question is more when, not if, another marine heatwave will return.
Tissot notes that it was the warm water blob that really took a toll on the bull kelp by creating low-nutrient conditions.
"What we are seeing is a slow recovery," he says. "It's good to see those kinds of things coming back. ... The long-term prognosis is what I worry about."
McHugh agrees, saying projects like the bull kelp farm and efforts to minimize the grazing pressure from urchins may help put safety nets in place.
"We're thinking ahead, so when the next marine heatwave hits, we're prepared and have tools," she says, noting another big question is what the magnitude and frequency of the next warming event will be. "Some situations might need a wrench and, in other cases, a really big mallet."
Kimberly Wear (she/her) is the Journal's digital editor. Reach her at 442-1400, extension 323, or firstname.lastname@example.org. Follow her on Twitter @kimberly_wear.