Among the most promising developments in sustainable food production is the rise of seaweed farming. Fast-growing, requiring no freshwater or fertiliser, capable of absorbing carbon dioxide and improving local water quality, and richly nutritious — seaweed is attracting attention from scientists, entrepreneurs, and policymakers around the world as a cornerstone of a future sustainable food system.
What We Mean by Seaweed
The term “seaweed” encompasses thousands of species of macroalgae — red, green, and brown — that range from microscopic filaments to fronds several metres long. Commercially farmed species include Eucheuma and Kappaphycus (used for carrageenan), Sargassum, Gracilaria, Porphyra (nori), and species of kelp including Saccharina and Undaria. Each has distinct growing requirements, market applications, and nutritional profiles.
Environmental Benefits
Seaweed farming requires no land, no freshwater, and no fertiliser inputs. It absorbs dissolved carbon dioxide and nutrients from the surrounding water, potentially helping to buffer local ocean acidification and reduce eutrophication. When grown in proximity to fish or shellfish farms as part of IMTA systems, seaweed effectively recycles nutrients that would otherwise accumulate in the sediment.
Emerging Applications
The applications for farmed seaweed extend well beyond food. Seaweed-derived compounds are used in pharmaceuticals, cosmetics, agricultural biostimulants, and food additives. Research into seaweed-based bioplastics and biofuels is advancing. Asparagopsis, a red alga found in Australian waters, has shown remarkable potential as a feed supplement for livestock, reducing methane emissions from cattle by up to 80 percent in some trials.
Australia’s Opportunity
Australia has significant potential to develop a world-class seaweed industry. With extensive coastlines, diverse native species, clean waters, and growing research capacity, the country is well positioned. However, regulatory frameworks have historically been slow to accommodate seaweed aquaculture, and the industry remains in its early stages compared to counterparts in Asia and Europe. Emerging investment and policy attention suggest this is beginning to change.
Substrate for Seaweed
Seaweed cultivation systems range from open-ocean longlines to land-based tanks. In many systems, particularly those targeting habitat restoration alongside production, the substrate onto which seaweed sporophytes or cuttings are attached is critical. The physical and biological characteristics of the substrate influence attachment success, growth rates, and susceptibility to grazing. Purpose-designed biosubstrates can meaningfully improve outcomes across all of these parameters.
Further reading: csiro.au, fao.org, phyconomy.net.
