The principal resource human beings have harvested from the sea to date is fish. But the sea contains other riches with enormous but often neglected potential. One of these is seaweed. In countries such as China, Korea, and Japan, seaweed is commonly eaten, currently making up 10% of each person’s daily intake. Seaweed tends to have a very high protein content, more than 25% of its dry weight in the case of many varieties of laminaria, and can be efficiently farmed: global production is estimated at almost 10 million tons annually.
Marine algae also have other potential uses. Some coastal populations have been using seaweed as an organic fertilizer for centuries. With chemical fertilizers threatened by the shortage of petroleum, seaweed could offer an alternative for the future. Traditional Chinese medicine also makes extensive use of seaweed, though in the West its pharmaceutical potential is still to largely untapped outside the cosmetics and beauty industry.
Most importantly, for some years now researchers have been looking into the possibility of using lipid-rich seaweed as a substitute for fossil fuels. Tests have been carried out on a number of varieties with promising results: these are generally unicellular species, with a rapid growth rate, capable of growing in water laden with organic matter, such as the
discharge from a water purification plant. Studies are also being carried out to see if these seaweeds can be used to consume industrial emissions of CO2, the main greenhouse gas.
Finally, plankton—which is a floating mix of unicellular algae and the micro-organisms that feed off them—is another potentially colossal food source from the sea. Some 100,000 tons of krill—small, shrimp-like organisms that are a type of plankton—are farmed each year, mainly for aquaculture purposes. But the krill to be found in the Southern Ocean alone (admittedly difficult harvest) has an estimated biomass of 500 million tons.