The fight for California’s other iconic forest
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?
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