Sustainability is an important issue facing current and future generations. Humanity as a whole will have to take issues of environmental stability and reversing the effects of climate change into serious consideration.
Developing sustainable farming practices are vital to fostering a clean environment that will allow Earth to habitual for centuries to come.
Seaweeds are marine resources of economic importance. They are generally considered to be a sustainable seafood choice. They are fast growing, easy to culture and have very high market prices. About 50% of seaweed species have been found to have economic uses while 15% are economically important edible species.
Seaweeds as a fishery resource is one of the export winners. It ranks third among the fishery exports after tuna and shrimp. They are exported either in raw forms (fresh or dried seaweeds) or processed forms (carrageenan and kelp powder). The major importing countries of seaweeds are France, Denmark, Japan, the USA, and the UK and now present in Africa.
Economic importance of seaweeds
Seaweed is an important source of carrageenan an important ingredient in food and other industrial applications. This carrageenan is used as follows; as a gelling agent for jellies, as a stabilizer for ice cream and toothpaste, as a thickener for catsup and sauces, as a beer clarifier and finally as a binder for patties and meat. Seaweed is mostly valued on the quality of the carrageenan.
Culturing seaweeds in inter-tidal and sub-tidal zones is attractive to coastal households thus they can engage in this form of coastal aquaculture because of the relatively higher cash income that can be derived from this activity compared with small-scale fishing (Nerisa et al., 1991). In addition, seaweed farming provides alternative and/or additional income to fishermen, hence, coastal aquaculture generates income for coastal populations without adding to the alleged over-exploitation of fishery resources in the country.
Commercial seaweed production requires low local production costs and the availability of planting materials either from the wild or from improved strains. Furthermore, labor is provided for by the unemployed people for the labor-intensive operations of seaweed farming thus job opportunities are created. Also, sophisticated energy consuming technologies for drying harvested seaweeds are not required in tropical countries.
If we take for instance seaweed farming in Tanzania’s Zanzibar Island (Unguja), it is a well-established industry that brings in foreign money and gives coastal people, especially women, an opportunity to earn an income for themselves and their families. The industry has also become increasingly important by generating foreign revenue into Zanzibar’s economy and raising farmers’ and communities’ living standards.
In Zanzibar, however, seaweed farming is second only to the tourism industry in terms of foreign exchange earnings. It is the largest marine export product, contributing over 90 percent of Zanzibar’s marine exports in recent years (Msuya,2012).
The income generated by seaweed farming has enabled farmers to improve their standards of living by giving them income to pay school fees, buy uniforms and books for their children, improve the houses in which they live and purchase clothes and food to meet their daily needs.
Seaweed farming, unlike many other forms of aquaculture, results in little impact, or risk of impact, to the surrounding natural environment. As a primary producer, seaweed does not require inputs of feed because it grows by photosynthesizing energy from the sun and absorbing carbon dioxide (CO) and inorganic nutrients directly from the water (MBA Seafood Watch,2014) and by so doing it acts as a major tool to treat coastal pollution in the sea and reduce CO2 in global warming.
Seaweeds act as an important component of marine ecosystems, providing oxygen, food, and habitat for fish and invertebrates.
Aside from being the very most important component in the marine ecosystem’s food chain, seaweeds are directly consumed as human food and can be consumed fresh, dried (flakes or sheets), frozen, cooked, in baked goods or in soups and as components of animal feeds and organic fertilizers.
Seaweeds provide a new renewable source of food, energy, chemicals, and medicines and as well provide a valuable source of raw material for industries like health food, medicines, pharmaceuticals, textiles, fertilizers, animal feed such as finfish, etc.
In some communities, seaweed farming has emerged as the most relevant livelihood strategy.
Given the rising global demand for seaweed-derived products, seaweed farming has the potential to generate further socio-economic benefits to coastal communities in tropical regions.
In Integrated MultiTrophic Aquaculture (IMTA) systems and in nutrient bio extraction systems, whether land-based, coastal or offshore, seaweed can be used as an extractive component to remove inorganic nutrients (Redmond et al., 2014) and mitigate potentially adverse environmental impacts. Seaweeds take up nitrogen, phosphorus and carbon dioxide, which they use for growth and production of proteins and energy storage products. When seaweeds are harvested from the IMTA or nutrient bio extraction systems, the nutrients are also removed from the system.
In the 1980s, there was significant interest in seaweeds as a biomass source for methane production and there is currently renewed interest in seaweed as a biofuel source for ethanol and methanol production.
Other non-food production technologies utilize seaweed cultivation for habitat restoration for potential largescale carbon sinks and as a method of removing heavy metals from marine environments and even as a way to detoxify and remove TNT from seawater.
