Seaweed aquaculture is a growing industry in the United States and worldwide. The most commonly farmed seaweed in the US is sugar kelp, but this industry could be challenged by future climate change, since wild kelp populations are sensitive to rising temperature and marine heatwaves. As-yet-uncultivated seaweed species may prove more resilient to climate change.
The seaweed Laminaria farlowii, or golden kombu, is native to southern California and has uses as both feed for abalone aquaculture and human food. This project will assess the climate change resilience of the species, as well as the potential economic value of Laminaria farlowii cultivation for abalone forage.
The researchers have determined an optimal temperature for hatchery conditions (13°C for gamephytes and 15°C for juvenile sporophytes). The team also measured growth rates of sporophyte fronts as a function of temperature and determined that in 75% of historical conditions between 2007 and 2021, golden kombu would be capable of frond growth. The species also appeared to continue to grow after simulated marine heat waves lasting three and five days, though with lowered photosynthesis rates, a result that warrants further study.
The project also supported the first California Seaweed Fair, which brought together the nascent California seaweed industry in a celebration of all things seaweed. Roughly 450 people attended the festival in person, with a similar number of viewers joining online. During a no-cost extension of the original award, the team plans to produce a cultivation guide for industry, resource managers and other stakeholders. The guide will incorporate data from tests of sporophyte ropes.