India is a growing economy. Increasing population, food security, generation of new employment avenues, depletion of non-renewable resources are important domain on the government agenda for socio economic growth. Hence there is a need for cost effective and renewable resources. Seaweed is a source which has potential to meet all the above expectations with multiple benefits. They are macroscopic marine algae with global distribution. Seaweeds have applications in multiple disciplines. Some Asian countries are using this valuable resource to meet their food supply demands from centuries. The presence of commercial products like carrageenan, agar, etc. in seaweeds has increased their industrial application in a greater way for the human welfare.
Algae are easily accessible resources and are abundant in marine ecosystem. Marine ecosystem contains both micro-algae and macro-algae. Macro-algae are also known as seaweeds. They are salt-dwelling marine plants and are commercially valuable resources due to their nutritional richness. Seaweeds are generally classified as green seaweeds (Chlorophyceae), red seaweeds (Rhodophyceae) and brown seaweeds (Phaeophyceae) based on their photosynthetic pigments.
In Indian coastal system, seaweeds are one of valuable marine resources which are less explored. The coastal area of Tamilnadu is rich in seaweed resources. Seaweed is extremely nutritious. Seaweed farming has the potential to transform the lives of coastal communities hence our finance minister, Nirmala Sitharaman, has made good allocation during budget 21–22.
Benefits Of Seaweeds
Seaweeds have multiple benefits. It is extremely nutritious. It has more calcium than milk, more fibre than brown rice while the nori seaweed has more iron than spinach, more vitamin C than orange juice and more protein than soyabean. Consuming Seaweeds provides vital omega-3 nutrients which fish gain by eating these algae. Prominent benefits of seaweeds are deliberated below.
Medicinal value: Due to the therapeutic potential of seaweeds and the presence of various bioactive compounds that can be used to treat wide range of diseases, they are used in the treatment of endocrine diseases like goitre. Seaweeds are also used for wound healing, generally used to treat cough, gastro-intestinal diseases, renal and urologic diseases.
Treatment of waste water: Wastewater purification is vital for the efficient management of water resources, protecting aquatic ecosystems from pollution and a sustainable method of improving water quality standards. Existing wastewater treatment approaches are very expensive and less effective to purify aquaculture effluents due to the presence of high solids content. Seaweed cultivation is an effective, alternative method for wastewater treatment. They absorb and accumulate nitrogen and phosphorus from wastewater and store them in their tissues like a sponge and utilise these nutrients for their growth. Like other plants, seaweeds consume carbon dioxide and release oxygen during wastewater treatment. Thus, seaweeds are an effective alternative approach for aquaculture-generated wastewater treatment to improve water quality.
Animal Feed: Traditionally, seaweeds were utilized as animal feed to meet the nutritional requirements of domestic animals. Seaweed is also a prebiotic that improves the digestive health, boosts immune system and protects against pathogenic infection, thereby increases overall productivity.
Cosmetics:In order to reduce the usage of toxic chemicals and to gain customer’s trust, the cosmetic industry focuses on bio active ingredients. Here is where seaweeds with their utility for extracting biologically active chemicals and abundant resource come in. They are used in fragrance products, anti-aging products, packed and sold as bath salts/water additives along with essential oils. Hence, seaweeds are excellent source for cosmetic products.
Bio-fuel: Seaweeds are considered to be an excellent source for biofuel production due to their high oil content. Low content of lignin is found in seaweeds, hence other carbohydrates like carrageenan, agar and alginic acid can be used for bioethanol production . Since, brown algae contain high amount of carbohydrates compared to green and red algae, they are suitable for bioethanol production.
Biofertilizers. Due to the presence of plant growth-promoting compounds like auxins, gibberellins, ethylene, etc, in seaweeds, they induce seed germination, seedling development, enhance stress tolerance, promote plant growth rate and plant yield. Seaweeds are also used to enrich soil fertility.
The commercial products present in seaweeds
Iodine: Brown seaweeds are used to extract iodine. Iodine is a micro nutrient essential for the living organisms. They play a vital role in the synthesis of thyroid hormones. Dietary intake of seaweeds will also prevent iodine deficiency related diseases like goitre.
Agar: It has wide applications in baking and confectionery industries as stabilisers. It also used as sizing agents in garment and paper industries.
Algin: Also known as alginic acid or alginate, is used as fillers and ointment bases in pharmaceutical products. It is used in weight reduction treatment as well. Alginate is also used in fragrance and anti aging products.
Carrageenan : They have broader application in the pharmaceutical and food industries and are also used in the preparation of cough syrups. Like Agar, Carrageenans are also used in baking and confectioneries.
Seaweed resources in India
A total 830 species of marine algae have been recorded from different parts of the Indian coast including Andaman-Nicobar and Lakshadweep Islands. Generally, Indian seaweeds grow abundantly during September to April and are thereafter less abundant especially in summer.
Seaweed farming in India
Seaweed farming in India is in a very formative and experimental stage. Unlike the situation in many developed countries, Indian seaweeds are harvested manually. Such harvesting is an important source of additional income to more than 10,000 coastal fishermen and fisherwomen.
The over-exploitation of certain natural seaweed resources from specific localities, resulted in depletion and consequent shortage in the supply of raw material. This situation has encouraged development of seaweed resources through cultivation. Additionally, conservation and judicial harvest strategies for sustainable production and utilization of marine algae are now advocated. As a consequence, the Central Salt and Marine Chemicals Research Institute (CSMCRI) initiated programmes on seaweed cultivation and developed technical expertise for the large scale cultivation of. edible and economically important seaweeds.
Seaweed Industry in India
The distribution and abundance of Indian seaweeds vary with coastal habitat, rock layer and tidal amplitude coupled with other prevailing abiotic and biotic factors. Currently there are about 25 actively operating seaweed-based chemical industries which collect seaweeds from selected sites of the Indian coast. Most of these industries are located in the state of Tamil Nadu, close to the main source of raw materials.
Seaweeds are low maintenance plants, they often do not need feed or additional attention once they are planted in a safe environment. Seaweeds contribute to making other industries more sustainable (such as agriculture and aquaculture) and provide a wide range of local economic benefits, including creating jobs in all aspects of production, processing, marketing, technological development and much more.
They are a natural salt replacement, giving salty taste with 70% less sodium. They can be part of the solution to help mitigate biodiversity loss, excess nitrogen (eutrophication), ocean acidification, climate change and land use conflicts. It can also help reduce plastic pollution in the ocean through the adoption of seaweed bioplastics and other biomaterials. Therefore the growth of the seaweed aquaculture industry is good for the economy and for the ocean.
Budgetary provisions for seaweed cultivation
To promote seaweed farming and cultivation, government has proposed to set up a seaweed park in Tamil Nadu. This will provide large scale employment and additional incomes. The government has allocated ₹637 crore for the cultivation of these nutrition-rich marine plants, to be spent over the next five years, mainly as subsidy support. This vocation can give employment to 6–7 lakh people.
With active government support seaweed industry is poised to grow multiple folds in near future with source of income and employment for many. Local support, implementation of government schemes, private Industry support would decide the pace of growth of the industry.