Seaweed farming

The seven most cultivated taxa are Eucheuma spp., Kappaphycus alvarezii, Gracilaria spp., Saccharina japonica, Undaria pinnatifida, Pyropia spp., and Sargassum fusiforme.

Eucheuma and K. alvarezii are attractive for carrageenan (a gelling agent); Gracilaria is farmed for agar; the rest are eaten after limited processing.

[8][9] The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate recommends "further research attention" as a mitigation tactic.

[10] World Wildlife Fund, Oceans 2050, and The Nature Conservancy publicly support expanded seaweed cultivation.

Attempts to introduce technology to cultivate detached plant growth in tanks on land to reduce labor have yet to attain commercial viability.

[24] Evidence suggests that seaweed farming can have positive impacts which include supplementing human diets, feeding livestock, creating biofuels, slowing climate change and providing crucial habitat for a marine life, but must scale sustainably in order to have these effects.

[21][22] Seaweed farms have been proposed to protect coral reefs[28] by increasing diversity, providing habitat for local marine species.

[5] Pollinac reported an increase in Siginid population after the start of farming of Eucheuma seaweed in villages in North Sulawesi.

A study conducted by the Philippines reported that plots of approximately one hectare could produce net income from Eucheuma farming was 5 to 6 times the average wage of an agriculture worker.

[30] In Indonesia, seaweed farms account for 40 percent of the national fisheries output and employ about one million people.

[6] Seaweed farming has had widespread socio-economic impacts in Tanzania, has become a very important source of resources for women, and is the third biggest contributor of foreign currency to the country.

In 1982 Adelaida K. Semesi began a programme of research into seaweed cultivation in Zanzibar and its application resulted in greater investment in the industry.

[33] Farmed seaweed is used in industrial products, as food, as an ingredient in animal feed, and as source material for biofuels.

Seaweed cultivation in the open ocean can act as a form of carbon sequestration to mitigate climate change.

[57] According to one study, covering 9% of the world's oceans with kelp forests could produce "sufficient biomethane to replace all of today's needs in fossil fuel energy, while removing 53 billion tons of CO2 per year from the atmosphere, restoring pre-industrial levels".

Carbon dioxide intake would raise pH locally, benefitting calcifiers (e.g. crustaceans) or in reducing coral bleaching.

Seaweed is largely transported from coastal areas to the open and deep ocean, acting as a permanent storage of carbon biomass within marine sediments.

[66][67][68][69][70] The concept envisions using artificial upwelling and floating, submerged platforms as substrate to replicate natural seaweed ecosystems that provide habitat and the basis of a trophic pyramid for marine life.

[72][73] The idea featured as a solution covered by the documentary 2040 and in the book Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming.

[76] In autumn of each year, farmers would throw bamboo branches into shallow, muddy water, where the spores of the seaweed would collect.

[84][85][86][87] Seaweed farming spread beyond Japan and the Philippines to southeast Asia, Canada, Great Britain, Spain, and the United States.

[88] In the 2000s, seaweed farming has been getting increasing attention due to its potential for mitigating both climate change and other environmental issues, such as agricultural runoff.

[89][90] Seaweed farming can be mixed with other aquaculture, such as shellfish, to improve water bodies, such as in the practices developed by American non-profit GreenWave.

[89] The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate recommends "further research attention" as a mitigation tactic.

The project uses 13-metre long "Eco-anchors" that cover the surface with a marine life habitat using materials such as oyster shells, wood, and cork.