What's Up with Kelp?
Redwoods of the Ocean
Kelp forests are among the most productive and dynamic ecosystems on Earth. Rising from the seafloor toward the sunlit surface, these underwater forests create habitat for a rich diversity of life and support healthy coastal ecosystems throughout the Pacific Coast. Like redwood forests on land, kelp forests provide the architecture for entire communities of life, offering shelter, food, and nursery habitat for fishes, marine mammals, invertebrates, and countless other organisms.
Two canopy-forming kelps dominate these marine forests along the Pacific Coast: bull kelp (Nereocystis luetkeana) and giant kelp (Macrocystis pyrifera). While giant kelp is more common in the waters to the south from Monterey, extending into Mexico, bull kelp thrives from Central California through the Pacific Northwest and Alaska.
Bull kelp is the defining species of the vastly productive kelp forests along California’s North Coast. This majestic kelp can grow up to sixty feet in a single season before reproducing and being carried away by winter storms each year. Known as cʰanamá by the Pomo, it flourishes in the dynamic, wave churned waters of the North Coast, with great heaps of tangled wrack thrown onto the beaches and coves every year when these ocean forests are healthy. For many North Coast residents, this is a familiar sight, and a visible reminder of the vibrant underwater forests just beyond the breakers.
A Forest in Decline
For generations, North Coast kelp forests supported vibrant marine ecosystems and coastal economies along the Mendocino and Sonoma coast. Fisheries for species such as red sea urchin and red abalone depended on healthy kelp forests, while fish, invertebrates, marine mammals, and seabirds relied on kelp habitat for food, shelter, and survival.
And then it went away.
Beginning in 2013, sea star wasting disease devastated sunflower sea star (Pycnopodia helianthoides) populations, once an unassuming but important predator for purple sea urchins. At nearly the same time, a marine heatwave known as The Blob, followed by a strong El Niño event, brought unusually warm ocean conditions to the California Coast.
Together, the loss of sunflower stars and warm ocean conditions reshaped the North Coast ecosystem. Without predators to keep them in check, purple urchin populations exploded. These native hungry urchins consumed vast areas of bull kelp, transforming once lush underwater forests into expanses of urchin barrens. As of 2023, Northern California had lost more than 96% of its bull kelp canopy.
The impacts extend far beyond the ocean; fisheries closed, coastal businesses such as legacy dive shops were negatively impacted, and communities deeply connected to kelp watched a defining part of their ecosystem disappear.
Big River: A Refuge Under Pressure
For many years, the kelp forests at Portuguese Beach near the mouth of Big River (Mendocino County) were among the more resilient kelp patches on California’s North Coast. While kelp forests disappeared across much of the region, Big River remained a productive stronghold and was considered a potential refuge for bull kelp.
Although this kelp bed initially resisted the broader regional decline, substantial losses from urchin barren encroachment were eventually observed here as well. The changes seen at Big River underscored both the vulnerability of North Coast kelp forests and the need for collaborative recovery effort.
This map illustrates changes in kelp canopy extent at Portuguese Beach near the mouth of Big River from 2020-2026. While much of Northern California experienced a dramatic loss of more than 96% of bull kelp canopy since 2015, Big River initially persisted as a stronghold for kelp. In 2023, the sudden collapse of kelp canopy at Big River demonstrated that even this important stronghold was vulnerable to the ecological changes affecting the North Coast, with recovery efforts beginning shortly after. Since then, kelp recovery has been mapped, recorded, and observed by scientific divers, walkers of the Mendocino bluffs, as well as fish, birds, and the biodiversity that has returned to some quadrants of the Big River kelp beds.
Portuguese Beach Kelp Forest Decline
2020
2021
2022
“I’ve been diving Big River since 2018, when it stood out as one of the few places on the North Coast where kelp forests still retained their beauty and abundance despite widespread decline. When we saw a major loss of kelp there in 2023, we knew we had a narrow window to act. An initial investment from the Ocean Protection Council allowed us to launch restoration across five acres and prove what was possible. That early success helped unlock federal support through the Pacific Coast Ocean Restoration Initiative, scaling the effort fivefold to 25 acres and connect with efforts in Sonoma county. Today, we’ve documented more than a 900% increase in kelp abundance and the return of juvenile fish and other species to the restored habitat. Most importantly, that seed funding sparked the partnerships, innovation, and momentum needed to accelerate kelp recovery across California and the region. KelpFest is a testament to the value of these forests to our community and the growing support for kelp recovery efforts. “
– Tristin Anoush McHugh, Associate Director
California Oceans Program, The Nature Conservancy
Kelp Recovery at Big River
Following the sudden collapse of kelp at Big River, Tristin Anoush McHugh with the Nature Conservancy launched and led a collaborative effort focused on kelp recovery at the site in response.
In December 2023, The Nature Conservancy was awarded a 1.6 million dollar grant to advance an integrated approach to kelp recovery, using a combination of techniques used in prior projects through State funding. This project kickstarted recovery efforts at Big River and helped to create a model for recovery at this site that could be scaled to more sites. In 2024, The Nature Conservancy was then awarded an $18 million grant from NOAA to launch the Pacific Coast Ocean Restoration Initiative (PCOR). The PCOR Initiative brings together over 20 partner organizations across California focused on restoring kelp forests, reviving key species such as the sunflower sea star and white abalone, and rebuilding coastal ecosystems and communities. PCOR is also catalyzing efforts to support a skilled marine restoration workforce to advance the implementation of habitat restoration and species recovery projects, touching down first in Mendocino County.
Recovery efforts have brought together a diverse network of partners working on restoration techniques. This work includes purple urchin removals, kelp culturing and outplanting, ecological monitoring, and community engagement. Because lasting recovery depends on both ecological restoration and community stewardship, this work extends beyond the water to include education, outreach, and opportunities for public involvement. Today, this work continues to evolve through partnerships and initiatives such as PCOR, building the knowledge, capacity, and collaborations needed to support long-term kelp recovery.
Kelp forest restoration is a collaborative effort rooted in science, stewardship, and a shared commitment to the future of California’s kelp forests and coastal ecosystems.
In other words, it involves YOU.
The community is highly motivated to facilitate revival through coordinated, grassroots recovery efforts that are holistic in approach. Everyone has a role to play in the recovery of these remarkable underwater forests.
Read a detailed description of the
Kelp Restoration Project at Big River, Mendocino.
North Coast KelpFest!
A Place to Learn and Ask Questions
Every activity of KelpFest! is a place to learn about kelp generally and about the kelp recovery project specifically. We invite you to ask questions and learn how to get involved. Sign up for art workshops to learn about uses of urchin harvested from recovery sites. Eat delicious food made with seaweed, uni, and other wonders of the local ocean that are part of a Blue Economy on the North Coast. Be inspired by artwork that is in turn inspired by the bull kelp itself. Perhaps make some art yourself. In all cases, come enjoy the glories of Mendocino County, the wonders of its coastal waters, and celebrate Kelp!
Dive deep into all things bull kelp with the web-based book The Mysterious World of Bull Kelp by Above/Below:
Review lessons learned from kelp restoration in this digital guidebook created by The Nature Conservancy: