के सभी प्रकाशन Sanskriti Singh . राँची , भारत
The Seaweed resources in India – prospects and challenges
n 2019–20, India produced over 325 million tons of food grains to feed more than 1.4 billion people. This population is increasing every year. As it grows, demand for food grain production increases. Traditional Indian agriculture is currently at maximum production levels but lacks the capacity to fill the gap between production and demand. The farmlands are further put to more lucrative uses of land for building townships, industrial corridors, commercial establishments, infrastructural facilities etc. Therefore, it is imperative that society must identify alternative resources that will support and supplement the long-term human food demands sustainably with minimal environmental impacts. There is ample evidence of the importance of seaweeds in the context of human food needs and ecological benefits of farming. Economic uses of seaweeds particularly for food, feed, phycocolloids and agro-based products, are well known for centuries and are now being extensively investigated for their application in bio-fuel, neutraceutical, medicinal, personal-care and food additive industries. Direct consumption of seaweeds as food in the form of salads, soups and a number of other food preparations is very common in Southeast Asian countries. Japan, China and Korea stand at the forefront of seaweed utilization in human food preparations, whereas in India, seaweeds are used only for the extraction of industrially important phycocolloids such as agar, alginate and carrageenan.
Global production of seaweeds has been estimated at 30.1 million wet tons in 2016, with 95% of the total produced from culture and the remaining 5% from natural beds. The top seven countries that account for global production of seaweeds are: China, Japan, Korea, Indonesia, Philippines, Malaysia and Vietnam. However, in India, agar and alginate are produced from seaweeds harvested from wild stocks. The present review provides an overview of Indian seaweed resources, their utilization and the associated seaweed industry. Recent initiatives to develop and transform seaweed farming into social enterprises are described. Opportunities and challenges for building a successful seaweed industry in India are also discussed.
India is among the 12 mega-biodiversity nations in the world. India’s coastline is 8100 km long and has an Exclusive Economic Zone (EEZ) of 2.17 million km2 (equal to 66% of total mainland area). Nearly 30% of its human population is, one way or another, dependent on the rich exploitable coastal and marine resources. The Indian coastline, with its different coastal ecosystems, supports luxuriant growth of diverse seaweed populations, having considerable economic importance.
Indian agar production started in 1940 on a cottage-industry scale. Later, a process for industrial manufacture of agar was developed. With the development of the industrial methods, a few processors started agar production This food-grade agar meets most domestic Indian requirements. Food grade agar powder fetches higher prices than agar strips.
Alginate is extracted from wild stocks along the Gulf of Mannar coast. Alginate production has steadily increased from 98 metric tons in 2003–200 metric tons in 2016. SNAP Natural Products and Alginate (P) Ltd. is the major producer. SNAP produces a variety of alginate products, including food, pharmacological, industrial, textile and welding grades. Alginates have been used in a wide range of applications as thickening and gelling agents in the food and feed processing industries. Pharmaceutical industrial concerns utilize alginate coloring agent as stabilizers and in the textile industry as water proofing, paper coating and in wastewater treatment.
The Southeast Indian coast is considered to be most suitable for commercial seaweed cultivation because it has shallow, wide and flat coastal shorelines with moderate wave action, and rich in nutrients including phosphorus and nitrogen. Seawater salinities and temperatures are optimal for seaweed production making the region suitable for commercial seaweed cultivation year round, except during the monsoon season. Essential cultivation supplies including bamboo, rope and anchors are readily available at reasonable prices close to the cultivation sites.
Economics of seaweed cultivation
The bamboo raft system is the preferred method for all industrially valuable Indian seaweeds. Advantages include: raft located in sub-surface seawater column providing adequate sunlight exposure; rafts are easily handled and relocated to suitable locations free from epiphytes and grazing; and bottom nets minimize herbivore grazing of algae. Materials for making rafts (e.g. bamboo, anchor stones, polypropylene rope, etc.) are commonly available close to the farm areas.
Future directions in seaweed culture in India
Indian seaweed cultivation dates back nearly four decades. Cultivation technologies have been developed for several industrially valuable seaweeds over the last 20 years but there are still many challenges to overcome. Challenges include the need for high-temperature-tolerant and fouling- and disease-resistant strains. Most Indian seaweed cultivation is located in near-shore waters, and to overcome inshore challenges an alternative farming strategy including expanding to offshore culture systems is recommended.
Indian seaweed cultivation in near-shore areas faces several challenges. Expansion of cultivation grounds is a major constraint due to water use conflicts with fish landing centers and commercial fishing activities. Human sewage rich in phosphate and nitrate from major municipalities and small towns has negative impacts on seaweed growth. Run-off from land-based agriculture, thermal power plants and chemical factories inundates near-shore waters and contributes to commercial cultivation challenges. Shallow, near-shore seawater temperatures often reach levels that inhibit seaweed growth. These challenges represent contributing reasons to relocate seaweed cultivation operations to offshore sites. Offshore seaweed cultivation has several potential advantages including: elimination of space limitation as vast ocean areas are available; water use conflicts are minimized due to minimal fishing activities; and offshore waters are clean and transparent as agricultural runoff, sewage and industrialized discharges are minimized due to open ocean dispersion. Offshore algal farming has potential disadvantages including: maximum wave height of 5–10 m; current velocity of 2–3 knots; and wind speeds of 35 m s−1 all of which can damage and dislodge the farm infrastructure. Offshore farming units must be able to withstand these dynamic conditions. The development of novel, offshore seaweed farms could play a major role in generating sustainable energy from biomass. Use of special textile mats can simplify seaweed farming and substantially increase yields. .
Biofuel production from seaweeds
Seaweeds are appealing potential biofuel feedstock candidates for the production of transportation fuel, as they grow rapidly and exhibit high photosynthetic light harvesting efficiency. Globally, several countries including India have reported efficient conversion of macroalgae to biofuels such as bioethanol, biobutanol, biomethane and biohydrogen. Potential Indian seaweed genera for biofuel production in India include Ulva, Kappaphycus, Gracilaria, Gelidium, Sargassum, etc. Red algal genera including Kappaphycus, Gracilaria and Gelidium have been cultivated in India for phycocolloid production. Due to their potential for large-scale farming, these seaweeds have been examined for their biofuel production potential, utilizing their phycocolloid or cellulose content as substrates. Recently, green seaweeds, mainly Ulva sp., have also emerged as potential feedstock for biofuel production due to their high carbohydrate content, higher growth rates and lack of direct commercial utilization. Several research groups in India are actively working on the growth engineering of seaweeds, bio-refinery techniques for extraction of value-added products and photo-bioreactor design for high biomass production. Biofuel production from residual biomass after extraction of value-added bio-products from seaweeds makes the process economically viable from an industrial perspective.
Opportunities and challenges for establishing successful seaweed industries in India
Bio-fertilizer and bio-stimulants from seaweeds have immense potential in the Indian agriculture sector. Seaweed bio-stimulants increase crop yields and quality, reduce use of chemical fertilizers and help improve the soil fertility. India imports seaweed bio-stimulants worth US $25–30 million annually from Canada, Norway, Indonesia, Philippines and China. There are opportunities to promote indigenous sea weed-based technology for the production of bio-stimulants. Promoting indigenous seaweeds for bio-stimulants will reduce the fertilizer subsidy burden of the Indian exchequer.
Seaweeds have the potential to be used in a broad spectrum of products such as: food, biofuels, chemicals, cosmetics, medicines, etc. The National Bio-fuel Policy of India (2018) targeted 20% blending of biofuels by 2030. It is estimated that, if 460 million tons of fresh seaweed biomass per year could be harvested from a 10 million hectare area (corresponding to about 5% of total EEZ of India), it could generate 6.66 billion liters of bioethanol, which would meet the targeted petrol blending by 2030 in India. Industrial production of biofuel from seaweeds needs to be given top priority.
India’s traditional food practices are different from other Asian seaweed consuming nations. Although 30% of the Indian population lives close to the sea, people are not accustomed to eating seaweed. Formulation of a wide variety of recipes by food technology institutes for adaptation to Indian palates and popularization through social media are needed for promoting seaweed-based foods in India. International collaboration for processing and preparation of seaweed-based foods should be established with the Southeast Asian countries where consumption of seaweed food is popular.
Seaweeds have tremendous business potential for generating revenue and jobs in bioactive and cosmetic sectors as they possess anti-ageing, anti-oxidant and moisturizing properties. However, such applications are not yet developed at the industrial level in India and so an initiative to do so needs to be given priority. Seaweeds with high pharmaceutical and cosmetic applications need to be identified and cultivated at large scale through industrial collaborations. Identifying suitable cultivable and scalable seaweed strains for pharmaceutical and cosmetic applications should be undertaken by an industrial public-sector collaboration.
Several cultivation technologies have been developed through significant Indian research and development efforts, and commercial seaweed farming is being carried out using floating rafts along the southeast coast of India. Such structures are suitable for near-shore waters where low tidal amplitude and minimal tidal influences persist. However, a major portion of the Indian coastline is exposed to the open sea and has high tidal amplitudes. Recently, Tube net method has successfully been developed on the Gujarat coast. Tube-net systems withstand rough sea conditions while producing good biomass yields. Several other culture systems which can withstand high water dynamics in open water areas needs to be developed. Seasonal dependency on Indian seaweed culture represents a crucial challenge needing to be overcome. Monsoon periods in India are associated with occasional occurrence of cyclones and typhoons and create high seawater turbulence and high tidal fluctuations. Cultivation during this period is restricted to seed bank preservation. Land-based cultivation in intensively operated ponds has been done successfully for several species. In India, seaweeds are mainly used for extracting phycocolloids and the high cost of pond-produced seaweeds may not be profitable unless the harvested seaweeds are processed for multiple products e.g. biofuel, bio-stimulants, food, cosmetics and pharmaceuticals Seaweed growers are receiving minimal prices for their harvested seaweeds due to their sale to cottage-level industries for indigenous phycocolloid extraction. Export of dry seaweeds has been banned for several decades. If the ban is lifted and export of dry seaweeds is permitted, farmers will realize higher prices for their seaweeds. Other challenges in seaweed farming affecting crop productivity and quality are crop health issues such as high temperature impacts, diseases which rely on R&D efforts to reduce or eliminate.