California Kelp Forests Decimated by Confluence of Environmental Factors

The California Department of Fish and Wildlife (CDFW) reported last week that kelp forests north of San Francisco Bay have been reduced by over 90% of historical levels this year. The kelp forests, mostly consisting of bull kelp (nereocystis luetkeana), constitute a key ecosystem driving the productivity of California’s coastal waters, and provide food for such commercial species as red abalone and red urchin, as well as shelter and cover for animals as diverse as sea otters and rockfish.

Though experts remain divided on which single factor is most to blame in the reduction of the kelp forests off of Marin, Sonoma, Mendocino, Humboldt and Del Norte Counties, they point to several conditions that have contributed to the historic decline, including a toxic algal bloom in 2011, an epidemic of sea star wasting disease, and unusually warm waters leading up to this year’s El Niño weather patterns.The kelp die-off has already impacted fishermen dependent on the abalone and urchin fisheries in the northern regions of the state, but biologists warn that if the kelp do not recover, this loss of such an ecologically pivotal species may cause economic shockwaves in other fisheries as well.