In Weeds to Wealth, the Equator Initiative reports on case studies of growing red seaweeds in Brazil. The Equator Initiative is a partnership bringing together the United Nations, civil society, business, governments and communities to help build the capacity and raise the profile of grassroots efforts to reduce poverty through the conservation and sustainable use of biodiversity.
From the report:
In Flecheiras, seaweed cultivators adopt the following method. A rope structure is attached to the sea bed and to buoys near the beach, and seaweed plants are cultivated in the rope. Planting is therefore carried out in shallow waters, and caring for the crop is done through frequent visits by boat. After approximately 3½ months, the plants can be harvested, cleaned and dried for retail. In general, seaweed loses about 80 per cent of its weight after drying. It is possible to cultivate several tonnes of seaweed in each location and studies have been made into the possibility of reducing the growing period. This would have the combined benefit of increasing income and reducing the seasonality of production. In areas such as Flecheiras and Guajiru, harvest periods as low as two months have been achieved.
There has been other research into the non-edible qualities of Brazilian seaweeds – the Brazilian Journal of Biology, vol.63 no.4 São Carlos Nov. 2003, has published research findings by Pereira, da Gama, Teixeira, and Yoneshigue-Valentin. The researchers noted that the Brazilian red seaweed Laurencia obtusa inhibited feeding by herbivores, and conducted research to discover what compounds were present in the plant. From the abstract:
Laboratory and field experiments were performed to assess the ecological roles of natural products produced by the Brazilian red seaweed Laurencia obtusa. Laboratory assays revealed that the natural concentration of the crude organic extract of L. obtusa significantly inhibited feeding by two herbivores: the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. It was verified that this chemically defensive action was due to halogenated sesquiterpenoid elatol, found to be the major natural product of this red seaweed. In addition, it was verified that the antifouling property of the chemicals produced by L. obtusa could make this red alga less attractive for fish grazing. Direct protection against two herbivore species and indirect protection against herbivory by fouling inibition constitute evidence that the major natural product from Brazilian L. obtusa plays multiple environmental roles, thereby increasing the adaptive value of these metabolites. On the other hand, the evidence reinforces the idea that marine natural products may have different functions in the sea.