The Seaweeds are macrophytic algae, a primitive type of plants lacking true roots, stems and leaves. The word seaweed gives the wrong impression that it is a useless plant. Seaweeds are wonder plants of the sea and highly useful plants. Seaweeds grow in the shallow waters. Seaweeds are one among the commercially important marine living and renewable resources of India. They contain more than 60 trace elements, minerals, protein, iodine, bromine, vitamins and several bioactive substances therefore, are of great economic value and they serve as both feeding and breeding grounds for invertebrates and fishes. Seaweeds are renewable source of food, energy, chemicals and medicines. They provide valuable source of raw material for industries like health food, medicines, pharmaceuticals, textiles, fertilizers, animal feed etc.

Seaweed farming does not require fresh water, arable land, no deforestation and no fertilizers-all significant drawbacks of land-based farming-thus ocean farms promise to be more sustainable. As a result, according to World Bank, it has negative Carbon Foot Print.

World Bank predicts that achieving a global production of 500 million tons of seaweed by 2050 would absorb 10 million tons of nitrogen, which is 30 percent of the nitrogen estimated to enter in the ocean. Seaweed can also absorb 15 million tons of phosphorus, which is 33 percent of the total phosphorus reached to the ocean by runoff. Seaweed production of 500 million tons would consume 135 million tons of carbon, which is 3.2 percent of the carbon added to seawater each year from greenhouse gas emissions.

India has a coastal line of around 7,500 km, which can be potential seaweed farming zones. The seaweed cultivated in about 0.25 million ha along the Indian coast line can give rise to 30 million ton seaweeds. This can lead to about 43 – 300 million ton CO2 sequestration from the atmosphere depending upon the types of seaweed. Seaweed along the Indian coast is capable to utilize 3017 t/CO2 per day against its emission of 122 t /CO2 per day, indicating net carbon credit 2895 t /day (Kaladharan et al., 2009). Apart from carbon sequestration, seaweed cultivation could generate following benefits:

• Seaweed can be harvested and used to produce biofuels
• Animal husbandry is major source of methane, having high potentiality towards climate change. Seaweed added to cattle food can reduce methane emissions from the sector
• Seaweed could be source of plant growth stimulant and seaweed-based compost could enrich soil
• Seaweed farm would serve as fish breeding farm and improve fish catch