CULTIVATION OF NOVEL SEAWEED SPECIES FOR CLIMATE CHANGE RESILIENT ABALONE FORAGE IN SOUTHERN CALIFORNIA

Wild harvesting of giant kelp, Macrocystis pyrifera, currently supplies most of the biomass of forage for land-based cultivation of abalone. Climate change, specifically warming ocean temperature, is causing a poleward shift of kelp forest distributions worldwide. Ocean heat wave events have caused episodic die backs of giant kelp on the coast of California, destabilizing the supply of forage for abalone farms. Aquaculture of more thermally tolerant species can replace or supplement wild harvesting of kelp. The goals of our work are to identify and domesticate novel seaweed species that will provide an alternative to wild harvested giant kelp and can be cultivated on long lines in Southern California coastal waters.

Our criteria for choosing potential species were both biological and economic. Potential species must be native to Southern California, suitable for abalone forage, of known life history, with large size (minimum length 30 cm) and annual biomass yield. Resilience to marine heat waves was predicted from literature on thermal biology and/or biogeographic distribution. In addition to abalone forage, potential species must also have one or more additional markets or economic uses  including human consumption, terrestrial animal feed supplement or high-value, extractable, biochemicals, for economic sustainability.

We identified 2 novel species for cultivation, the kelp, Laminaria farlowii, commonly called Golden Kombu (Figure 1) and the large red seaweed, Chondracanthus exasperatus, commonly called Turkish Towel.  We are currently cultivating these two species in the laboratory, in raceways and on test lines in the field. Here, we present results for growth rates, yields and thermal tolerances of isolates of Golden Kombu and Turkish Towel in Southern California, and recommended cultivation conditions for these novel species.