Helping Kelp in Greater Farallones National Marine Sanctuary
December 10, 2024
In response to catastrophic loss of kelp, Greater Farallones and Cordell Bank National Marine Sanctuaries and Greater Farallones Association are leading collaborative efforts with experts to research the best methods to restore this vital ecosystem. The project includes understanding conditions at sites where kelp has persisted, working with commercial urchin divers to remove urchins within restoration sites, and outplanting kelp.
Julieta Gomez, kelp restoration specialist, and Rachael Karm, a research technician at Sonoma State University, are leading the effort to culture bull kelp at the UC Davis Bodega Marine Laboratory so that there is a readily available supply for outplanting. Bull kelp is an annual species and produces patches of spores on its blades when it's ready to reproduce. These spores are collected from adult reproductive kelp and tended carefully to grow to adult size. They tumble in an outdoor tank with the proper seawater and sunlight conditions to support their growth. The team trims the kelp and cleans the tanks to maintain the healthiest conditions for the kelp, which in turn produces more spores. The spores are then cultivated where they can settle on twine for outplanting into the restoration sites. The intent of outplanting sori is to help increase the spore stock at the site.
This past summer bull kelp grown on the twine at Bodega Marine Lab was outplanted in Greater Farallones National Marine Sanctuary by scientific divers who then conducted surveys to monitor the growth of the bull kelp on the twine and on the seafloor nearby. Divers observed hundreds of small bull kelps growing on the lines in September. We will continue to tend to bull kelp cultures over the winter to prepare for outplanting in the sanctuary in spring 2025. We are also working with fishers to reduce purple urchin densities to reduce grazing pressure on outplanted bull kelp at restoration sites.