Cutting-Edge Science for Kelp Restoration

Kelps are called “the sequoias of the sea”, and for good reason. These large, canopy-forming macroalgae, including both bull kelp (Nereocystis luetkeana) and giant kelp (Macrocystis pyrifera), can grow more than 100 feet tall, forming vast underwater forests that nourish and support marine life from tiny plankton to gray whales. Many of the more than 300 marine species that are commercially fished in California spend time in these lush algal forests. The diversity and beauty of kelp forests also provide opportunities for a variety of ocean recreation activities, from birdwatching to scuba diving to recreational fishing.

Unfortunately, in 2014 California’s kelp began to decline dramatically, with especially large die-offs along the north coast. One likely catalyst was a record-breaking marine heatwave. Another contributing factor was the proliferation of kelp-eating purple sea urchins after a wasting disease wiped out sunflower sea stars, a key urchin predator. Approximately 95% percent of kelp was lost along a 350-mile stretch of California’s Sonoma and Mendocino County coasts between 2014 and 2019, and has continued to decline. Portions of California’s central and south coasts, such as several Channel Islands and the Monterey Peninsula, have also experienced severe localized declines in kelp. These die-offs have had serious impacts on coastal communities – closing fisheries, shuttering dive shops and affecting tribal members, divers and fishermen across the state. 

In 2021, California Sea Grant, in collaboration with the California Ocean Protection Council (OPC) and the California Department of Fish and Wildlife (CDFW), launched a state-wide Kelp Recovery Research Program that funded six “solutions-oriented” science projects meant to directly inform the efforts of resource managers to protect and restore kelp ecosystems statewide. These projects addressed key issues, such as how to combat the overgrowth of herbivorous urchins, how to grow kelp to restore lost underwater forests, and how to make kelp more resilient in a changing climate. The exciting results of these projects are now publicly available:

Where, When And How? A Guide To Kelp Restoration In California Using Spatio-Temporal Models Of Kelp Dynamics

Researchers at UC Santa Barbara and UC Santa Cruz created a science-informed decision tree with detailed maps to help state agency managers, funders, and other restoration practitioners decide where and when to focus kelp restoration efforts. The framework was developed using cutting-edge modeling, and accounts for factors such as the historic stability of kelp forests as well as the local population size of sea urchins. This information will help guide resource managers on where to focus restoration efforts in areas with the greatest chance of success. Read more here.

Assessment Of Practical Methods For Re-Establishment Of Northern California Bull Kelp Populations At An Ecologically Relevant Scale

Scientists from Moss Landing Marine Labs and San Jose State University developed a novel, low-cost technique for culturing bull kelp year-round. These methods will greatly inform the feasibility and success of future bull kelp outplanting and restoration efforts. Read more here.

A Multi-Pronged Approach To Kelp Recovery Along California’s North Coast

A multi-faceted team at UC Davis, UC San Diego and Sonoma State University investigated aspects of all three factors behind bull kelp loss: kelp’s vulnerability to heat, the recent overabundance of sea urchins, and the loss of sunflower sea stars, a major sea urchin predator. Among other accomplishments, the group refined techniques to rear sunflower sea stars in the laboratory and observed that sea star predation on juvenile sea urchins may be a key factor for controlling urchin populations. These and other results from this project will help to inform future bull kelp restoration and management actions. Read more here. 

Informing Restoration And Recovery Of Central Coast Kelp Forests – Understanding The Dynamics Of Urchin Recruitment, Reproduction, And Density

Researchers from CSU Monterey Bay and Reef Check California surveyed the urchin populations at nine intertidal sites across the Monterey Peninsula and discovered that intertidal areas are a far more important source for urchin populations than previously thought. Resource managers can take this information into account when selecting sites for kelp restoration. Read more here.

Scaling A New Cost-Effective Intervention Tool To Restore And Future-Proof Coastal Kelp Forests

Scientists at UC Irvine adapted a kelp-outplanting technique that originated in Norway for use in California: they grew giant kelp seedlings on gravel in the laboratory and then scattered these individuals on the ocean floor to understand how this tool could be used to restore wild kelp forests. The team also found that some populations of giant kelp can be hardened against heat stress by exposing young algae to warmer water. This could help managers understand how to “future-proof” restoration efforts by selecting kelp populations that appear more resilient against climate change-induced ocean warming. Read more here.

Conservation Genomics and Gametophyte Banking Of Bull Kelp In California

A consortium of researchers from the University of Wisconsin-Milwaukee, UC Santa Cruz and USC developed a “seed bank” of more than 1,700 bull kelp genotypes from 14 sites across the state. A copy of the seed bank has been established at the Aquarium of the Pacific in Long Beach. These collections will help preserve the genetic diversity of imperiled bull kelp for decades to come. Read more here.

These six projects were augmented by funding for paid internships through California Sea Grant’s Undergraduate Research Experience for Underrepresented Students (CA-SURE). The program allowed eight students from underrepresented and minority demographics to work in paid positions alongside the kelp researchers for a year. Many of these students launched new careers as a result of their participation in CA-SURE.

Request for Proposals

The Kelp Recovery Research Program has proven invaluable in filling knowledge gaps, but significant scientific, policy, and management questions remain. To address these needs, in June 2023, California Sea Grant, OPC and CDFW announced another round of $5 million in funding to accelerate and scale up kelp research and restoration across the state. California Sea Grant, OPC and CDFW are now soliciting proposals for projects that will address remaining research needs, support action while a statewide Kelp Restoration and Management Plan is being developed by CDFW and OPC, and promote a “learn by doing” approach to kelp conservation. These projects will help resource managers further develop solutions to the kelp crisis and foster meaningful partnerships with tribes, community-based organizations and impacted stakeholders. California Sea Grant will contribute an additional $300,000 to support the continued participation of undergraduate students from groups that are underrepresented and underserved in marine and coastal science. The agencies are soliciting proposals for projects of up to two years in duration. 

• Letter of Intent due to California Sea Grant: Tuesday, August 15, 2023 by 5:00 p.m.

• Full proposals due to California Sea Grant: Tuesday, October 3, 2023 by 5:00 p.m.

Visit the California Sea Grant website for award and submission details, contact information and more.

While the threats to kelp may appear formidable, California's preeminent kelp researchers, dedicated resource managers, and a united coastal community composed of tribes, fishermen, divers, surfers, artists, and others are committed to protecting the sequoias of the sea and are intensifying their efforts to restore them.