Coastal Aquaculture and Mariculture (2+1)

Unit 7 - Culture of Molluscs and Seaweeds

7.3.3. Culture of Seaweeds

Seaweeds are macroscopic algae growing in the sea. They are one of the important marine resources. They are found in shallow coastal areas many of them grow on substratum. They are grouped into green, brown, red and blue green algae. They have been harvested since many centuries. In Japan and China they form staple food. They are also used as fodder and fertilizers.

They contain 60 trace elements whose concentration is higher than terrestrial plants. Seaweeds are the only source of agar, algin and carrageenan – phytochemicals that have wide application in food, confectionary, pharmaceuticals, dairy and paper industries as gelling, stabilizing and thickening agents.

In India there are vast resources of seaweeds near many coasts and estuaries. Andaman and Nicobar Islands and Lakshadweep have rich resources of seaweeds. The total resources of seaweeds in India are about 70,000 tonnes.

Large scale sea farming of aquatic plants originated in Japan around three centuries ago with the culture of ‘nori’ or the laver Porphyra spp., which continues to be the most important cultivated species for human consumption. Culture of Laminaria has advanced rapidly in China. Their use as condiment or vegetable is limited to the oriental countries and among certain ethnic groups.

Their protein content is high (35.6% in dried nori), they also contain high levels of vitamins A, B, B2, B6, B12, C and biotin. They also contain higher amounts of important minerals like calcium and iron than vegetables and fruits. Unsatisfied demand for good quality seaweeds prompted expansion of seaweed culture.