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Bull Kelp
Over the last decade, northern California kelp forests have experienced a 95% loss in historic kelp coverage. This is due to multiple stressors, such as El Niño events, marine heatwaves, and loss of keystone predators. The loss of kelp forests has led to a decrease in marine mammal and fish species that rely on kelp forest habitat. These losses directly impact local communities that are reliant on kelp forest species for commercial, recreational, and cultural uses, including Tribal and local communities around Trinidad Bay in Humboldt County.
Purple urchins, which feed on kelp, are a part of this 'perfect storm' of related factors contributing to kelp decline. Purple urchin numbers in Northern California have increased dramatically in recent years, with large urchin barrens appearing after intense marine heat wave and seastar die-off events in the mid-2010s. While the overpopulation of purple sea urchins has not been attributed to any one factor specifically, it is clear that their high numbers have negative effects on kelp populations, and that innovative restoration actions and solutions are needed to solve this ecosystem imbalance.
Desmarestia species seaweed (also known as acidweed or mermaid's hair) store sulfuric acid in their tissues. Species of Desmarestia can be found in urchin barrens, suggesting some form of chemical or physical protection from urchin predation. In partnership with the Trinidad Rancheria, Brayden Wiley (Bourdeau Lab) has completed a lab and field investigation of how Desmarestia proximity to Bull Kelp plots impacts kelp recruitment and survival. His results suggest that presence of acidweed may provide protective advantage for bull kelp in urchin-dominated areas and point to the advantages of looking beyond a single-species approach for kelp restoration.
