The world-wide macroalgae industry has increased exponentially over the last 50 years (Fig. 1a,b). Between 2003 and 2012, its average annual growth was 8.13% in quantity and 6.84% in monetary value (Food & Agriculture Organization of the United Nations (FAO), 2014). Over 23 million tons of macroalgae (dry weight) were produced in 2012 from aquaculture, which were worth over six billion US$ (FAO, 2014). Approximately 83% of this biomass is produced for human consumption while the remainder is used as fertilizers, animal feed additives and, increasingly, for medical and biotechnological applications (McHugh, 2003). Seaweeds have a recognized, though barely tapped, potential for biotechnology and sustainable biofuel production (Mazarrasa et al., 2014). A more immediate expansion driver is, however, the prospect that seaweed farming can improve the sustainability of fish and shellfish aquaculture in integrated cultivation initiatives. With an annual growth of nearly 10%, fish farming is the world’s most rapidly expanding food-producing sector and represents a major stake toward meeting soaring global demand for dietary proteins over the forthcoming decades (Duarte et al., 2009). Encouraged by these demands and efforts to reduce the over-exploitation of natural resources, seaweed farming has been expanding rapidly across several continents from south-eastern Asia down to South America and East Africa (Rebourset al., 2014).
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Seaweed culture has perforce to be adopted should the supply of raw material to Industries be uninterrupted ,like in the case of the Japanese and Korean Porphyra industries, the Chinese Laminaria industry and the Philippines Eucfieuma Industry, which are now in the main based on cultured raw material. The culture is at present almost entirely confined to the Orient, reaching its peak of sophistication in Japan and China. The necessity of marine algal cultivation in India and the principles and problems involved therein are discussed by Thivy (1964), Krishnamurthy( 1967) and Chennubhotia (1976).
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Seaweeds which are macroscopic marine algae belong to the primitive non flowering group - Thallophyta. They grow submerged and attached to hard substrata such as stones, rocks and coral reefs along the shallow coasts, lagoons, estuaries and brackishwater habitats of the Andaman - Nicobar and Lakshadweep islands and coastal areas of Tamil Nadu, Kerala, Karnataka, Maharashtra, Gujarat, Goa, Orissa and Andhra Pradesh. Based on their pigmentation and other morphological characteristics they are categorised into three major groupschlorophyceae which is popularly known as green seaweeds, phaeophyceae or brown seaweeds and rhodophyceae or red seaweeds.
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Seaweeds constitute one of the most important marine resources of our country. They grow mostly on rocks or otlier plants as epiphytes in the inter-tidal and subtidal environments of the sea. The seaweed - resources are abundant on the south-east coast of Tamil Nadu, Gujarat coast and around Lakshadweep and Andaman and Nicobar Islands.
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Culture of seaweeds is practiced since ages in countries such as Japan, Ctiina and Korea. Seaweed cultivation is an industry in Japan as a part-time avocation for land farmers and fishermen. The seaweeds cultured mainly in these countries are Porphyra, Undaria, Laminaria, Enteromorpha and Monostroma. In India seaweed culture is yet to develop on commercial lines. While the demand for these seaweeds is for food purposes in foreign countries, their demand in India is for the extraction of two phytochemicals namely agar-agar and algin. In recent years many factories manufaauring these chemicals have come up in India as a consequence of which the demand for the agarophytes and alginophytes has gone up. In order to maintain a continuous supply of this raw material to the industry, methods to augment the supplies through culture practices have to be developed.
In recent years the Central Marine Fisheries Research Institute has been engaged in the cultivation of several economically important seaweeds such as Sargassum wightii, Twbinaria spp., Gracilaria edulis, G. corticata and Gelidiella acerosa which indicated great scope for cultivation. The production rate has been found to be 4.4 kg/m' in the case of G. edulis and 3 kg/m* in the case of G. acerosa in about 80 days for 0.30 kg and 1 kg of seed material introduced respectively. In the case of alginophytes the growth was not encouraging. These culture experiments were conducted by introducing small fragments of the seaweed into the twists of the coir ropes fabricated in the form of a S x 2 m net and tied to fixed poles in inshore waters. In the case of G. acerosa, the substratum along with the plant fragments was tied to the ropes.
The agarophytes thus grown can be processed further for extraction of agar-agar. The extraction could be done by a simple cottage industry method not involving any costly equipment. In the case of Gelidiella agar, freezing and thawing are required to remove the insoluble chemicals. A total of 90 tonnes of G. edulis can be obtained from 3 harvests in a year from a hectare area.
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For centuries, seaweeds of various kinds have been put to several uses in the countries of south and south-east Asia (Chapman and Chapman, 1980). The utilisation of these seaweeds has come up step by step starting with using them as food, later as raw material for industrial, medicinal, pharmaceutical and cosmetic purposes.
The extended coastline of India of about 7500 km long with wide shelf area of 0.451 million sq. km. provide the most suitable environment for seaweed growth. The extensive shallow bays, coral reefs and lagoons, characterised by slow to moderately strong currents coupled with sandy and coralline bottoms make the Indian coastal belts, the ideal habitat for many economic seaweeds.
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In recent years there has been a steady increase in the demand for naturally occuring seaweeds as a result of many seaweed based industries coming up. In order to meet the raw material requirement of these industries attempts have been made in this country to develop suitable seaweed farming techniques by some Institutes notably the CMFRI at its Mandepam. Regional Centre and CSMCRI at its field centre, Mandapam. Experimental culture of economically important seaweeds such as Gracllaria edulis, Gelidiella acerosa and other species was undertaken since 1972 at Mandapam- in these experiments production rates ranging from 3 to 8 times the initial wet weight were obtained. The techniques of seaweed culture, the favourable seasons optimum duration of culture period and the influence of environmental parameters are discussed in this account with notes on economics of seaweed culture. General information on the seaweed resources slong our coasts, their potential for exploitation and culture are also highlighted.
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Disease is one of the major bottlenecks for aquaculture development, costing the industry in excess of US $6 billion each year. The increase in pressure to phase out some traditional approaches to disease control (e.g. antibiotics) is pushing farmers to search for alternatives to treat and prevent disease outbreaks, which do not have detrimental consequences (e.g. antibiotic resistance). We tested the effects of eleven seaweed species and four established fish immunostimulants on the innate immune response (cellular and humoral immunity) of the rabbitfish Siganus fuscescens. All supplements including different seaweeds from the three groups (Chlorophyta, Phaeophyta and Rhodophyta) were included in the fish pellet at 3% (by weight) and had variably positive effects across the four innate immune parameters we measured compared to control fish. Diets supplemented with the red seaweed Asparagopsis taxiformis and the brown seaweed Dictyota intermedia led to the largest boosts in humoral and cellular innate immune defences, including particularly significant increases in haemolytic activity. Diets supplemented with Ulva fasciata also led to promising positive effects on the fish innate immune responses. We conclude that dietary seaweed supplements can boost the immune response of S. fuscescens and thus the top three species highlighted in this study should be further investigated for this emerging aquaculture species and other fish species.
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Survey was conducted during May·June 1988 to study the seaweed distribution and resources along the Kerala coast. Algal collection was made at 15 localities from intertidal and subtidal regions and totally 35 species belonging to 28 genera and 18 families were recorded. The nature of the coastline, places of algal occurrence and their resources are given.
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TRONDHEIM, April 23, 2013 - Seaweed Energy Solutions AS (SES) announced today that it has reached an agreement to acquire 100 percent of Denmark's Seaweed Seed Supply AS, a move that sharply reinforces SES' position as Europe's leading player in large-scale seaweed cultivation for renewable energy and other uses.
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