A massive kelp forest once anchored the North Bay’s marine ecosystem. Here’s how scientists are trying to bring it back

Sometime in the next couple of weeks, scientists will wrap specially infused twine around clay bricks and toss them into Drakes Bay.

The twine will be saturated with the reproductive cells of baby kelp, and the experiment, researchers hope, will help ensure the survival of a critical cornerstone of the entire North Coast marine ecosystem.

More than 90% of a once-abundant bull kelp forest, which towered from ocean floor to the surface, has disappeared from the Sonoma and Mendocino coasts over the last decade, thanks to environmental stressors and shifting ocean ecology.

But researchers hope their experiment may hold the key to is survival, with the potential to begin regrowing a few lost kelp beds off the Sonoma Coast as early as this fall.

The “baby” kelp being raised in tanks at the UC Davis Bodega Marine Lab are invisible to the naked eye at the moment and are barely enough to discolor a water drop on a clear microscope slide.

The experiment is being conducted through the Greater Farallones National Marine Sanctuary and the nonprofit Greater Farallones Association. The goal is to find the best way to culture and capture kelp reproductive material for introduction to select offshore sites.

After the “inoculated” twine is dropped into Drakes Bay next week or the week after, observers will see if kelp will sprout and how long it might take to spread. Scientists call this process “outplanting.”

The work is part of a larger project aimed at restoring about 27 acres of kelp forest habitat across four strategic coastal sites: Fort Ross Cove and Timber Cove initially, and eventually Ocean Cove and Stillwater Cove.

The plan also includes hiring commercial divers to remove masses of purple urchin from the outplanting sites to reduce grazing pressure on the newly introduced kelp. Divers will also map the kelp canopy to monitor natural growth and help gauge success in the weeks and months to follow.

“We’re learning and doing at the same time,” said Jennifer Stock, media liaison for the Greater Farallones and Cordell Bank National Marine Sanctuaries. “If we didn’t do anything, we could be looking at extinction.”

The North Coast’s kelp forest has been decimated by an extended marine heat wave and suppression of the area’s nutrient-filled cold upwelling. In addition, a boom of purple urchins, which feed on kelp, has raised populations to more than 60 times their historical number as their predators have been wiped out by disease.

While scientists saw a slight resurgence of kelp growth the year before last, 2022 “was definitely really, really low,” said Rietta Hohman, Kelp Restoration Project Manager for the marine sanctuary and the Greater Farallones Association, and a National Oceanic and Atmopheric Administration affiliate.

In addition to urchin culling at strategic sites by commercial and recreational divers that has been underway for the past six years, some scientists are working on captive breeding of sunflower sea stars, the urchins’ natural predators, hoping they can be reintroduced to the coastal waters some day.

Others, like those at the Bodega Bay, are working out strategies for regrowing kelp beds, using spores or successive stages of young kelp settled onto different materials, including gravel, bricks, pavers and twine.

While the overall effort involves multiple government agencies, nonprofits and academic labs, there is a high degree or collaboration and networking.

But Stock said it was important for the National Oceanic and Atmospheric Administration and the Greater Farallones Marine Sanctuary to assume some leadership in the effort in recognition of the critical importance of the kelp forest ecosystem, which provides food and shelter to a vast array of fin fish, invertebrates and other aquatic organisms, as well as buffering storm surge and sequestering carbon.

“It is one of our most valued habitats on the planet,” Stock said.

The nonprofit Greater Farallones Association received $2 million toward the work from Congress last year and is in line for another $4.9 million in federal funding through the Bipartisan Infrastructure Law and the Inflation Reduction Act. About $9 million total has been funded through those and other sources, Hohman said.

At the Bodega Marine Lab, two young scientists who studied together at UC Santa Cruz and Sonoma State University, Rachael Karm and Julieta Gomez, have worked out a process using kelp blades provided by San Jose State University’s Moss Landing Marine Labs to provide the genetic material for their experiment.

Kelp blades tossed around in two outdoor tanks provide the spores that start the process, released from dark patches calls sori that develop on the blades as they mature.

The sori are washed in iodine and then rinsed in cold seawater to shock them into releasing their spores, once dried, according to Karm, a laboratory technician for the Hughes Lab at Sonoma State University, and Gomez, a kelp restoration specialist with the Greater Farallones Association and a NOAA affiliate.

Then the spores are put in tanks with twine spooled around PVC pipes, where the spores settle in the glow of indoor grow lights and eventually form young, new plants that may eventually grow to towering kelp that reach from the ocean floor to the surface.

Gomez and Karm expect to be out on the water soon to “outplant” the inoculated twine in Drakes Bay, in partnership with the Hughes Lab.

That test will then inform the pilot deployment of young kelp later this year at Fort Ross and Timber Cove, sites chosen in part for persistent kelp growth in the past and their accessibility. Protected waters mean researchers have more opportunity to get out, Hohman said.

The pilot project, being conducted in partnership with Sonoma State University and the Moss Landing Marine Lab, will scale up next year, Hohman said.

Karm, who, like her research partner, has spent three years working on kelp loss, said she’s heard it likened to underwater deforestation, having the impact of a devastating wildfire that few ever observe themselves.

“It’s really tragic it’s not getting the attention it deserves,” she said. “It’s devastating to see this catastrophe and see people who are dependent on it not realize what’s going on.”

You can reach Staff Writer Mary Callahan (she/her) at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.

Editor’s Note: Twine infused with microscopic baby kelp will be introduced into Drakes Bay this month after it is wrapped around clay bricks, not PVC pipe as indicated in an earlier version of this story.