About Seaweed

About Seaweed

Seaweed is increasingly seen as a solution to nutritional deficiency in population. However seaweed cultivation has not taken off in India.


About Seaweed

  • Seaweeds are photosynthetic algae.
  • They are primitive plants and roots, stems and leaves are absent in seaweed.
  • They are macrophytic algae which mean they live in water or moist land surfaces.
  • They grow in the shallow waters in the tidal zone.
  • Seaweeds exhibit highest photosynthesis efficiency due to moist conditions. As a result they contribute to about 50% of all photosynthesis in the world.

Types of seaweed

  • Based on the pigments present in seaweed they are of 3 types:
    • Brown algae
    • Red algae
    • Green algae


  • Red and Green seaweeds are found in subtropical and tropical waters.
  • Brown seaweeds are common in cooler, temperate waters.
  • Asia is prominent in seaweed cultivation with China, Korea and Japan contributing to 80%


  • Seaweeds are used as food, renewable source of energy, pharmaceuticals, cosmetics, textiles, fertilizers

Benefits of Seaweed

  • Edible Seaweeds are low-calorie and nutrient-dense food items.
  • They are rich in vitamins A and C.
  • They are a good source of minerals such as Ca, Mg, Zn, Se and Fe.
  • They also have a high level of vegetable proteins and omega 3 and 6 fatty acids.
  • Since Seaweeds live in water they do not require irrigation.
  • They do not require pesticides, fertilizers.
  • Categorised under vegan diet, they are easily acceptable.


Seaweed Cultivation: Global Scenario

  • China tops the list of countries in seaweed cultivation.
  • Other leaders in seaweed cultivation include North Korea, South Korea, Japan, Philippines, Chile, Norway, Indonesia, USA and India.
  • Seaweed is the staple food in many parts of South East Asia including Philippines, Malaysia, Vietnam, Indonesia, China, Korea and Japan.


In brief: Seaweed Cultivation: Potential in India


  • About 844 seaweed species are reported from India which has a coast line of 7,500 km.
  • Tamil Nadu, Gujarat coasts, Lakshadweep and Andaman and Nicobar islands are abundant in seaweed.
  • Rich seaweed beds are also found around Mumbai, Ratnagiri, Goa, Karwar, Varkala, Vizhinjam and Pulicat inTamil Nadu and Chilka in Orissa.
  • Gulf of Mannar is home to more than 240 seaweed varieties out of which at least 185 are edible ones.


Challenges to seaweed harvesting in India

  • Lack of livelihood security due to low wages and during bad weather
  • Risky as they have to be collected from depths of more than 25 to 30 feet to collect seaweed.
  • Over-exploitation: While India has rich source of seaweed varieties we have focused only on harvesting not cultivation thus leading to over-exploitation.
  • Lack of awareness about health benefits act as hindrance to nutrition transition among population.
  • In the aftermath of 2004 tsunami, the volume of harvest has fallen.


Commonly known seaweed products (important for prelims)

  • Agar-agar
    • Made of red algae
    • Used as food additive as a thickener, emulsifier etc.
    • They are used to absorb glucose and thus used in weight loss diets.
  • Alginates
    • Made of brown algae
    • Form non-toxic gels and are often used in pharmaceuticals, cosmetics, processed food etc.
  • Carrageenans
    • Made of brow algae
    • Used in gelation in ice creams


Section : Environment & Ecology