Resource assessment surveys carried out by the Central Salt and Marine Chemicals Research Institute, Bhavnagar and by the Central Marine Fisheries Research Institute, Kochi indicate nearly 10000 to 19000 tonnes (wet biomass) of standmg crop of seaweeds are available in 12 atolls of the Laccadive Archipelago. comprising 114 species belonging to 62 genera. Of these resources, 25% of the standing crop of seaweeds are commercially important and can be exploited for the production of valuable phycocolloids such as agar-agar and alginic acid. The other 75% include edible and carrageenan yielding potential resources. These resources can be taped for industrial purposes either by regulated harvest or by attempting mariculture in the lagoon
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The macroscopic algae comprising the three major classes Ghlorophyceae (green alga<'), Phaeophyceae (brown algae) and Rhodophyceae (red algae), found mostly in the inter-tidal zone on the rocky coasts, are commonly referred as seaweeds. Recently their use as an industrial raw material in the production of agir and algin has created a great dem nd and attempts are under way to augment the resources by aquaculttire practices. The Central Marine Fisheries Research Institute is playing a leading role in developing the techniques of seaweed culture in the Gulf of Mannar and Palls Bay. A gross picture of the seaweed resources along the coasts of mainland of India is available (Thivy, 1958; Rao, 1967. 1970).
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The deepwater seaweed resources survey was carried out during 1986-1991 at the depths ranging from 5 to 22 m in Tamilnadu coast from Dhanushkodi to Kanyakumari. The vegetation of seaweeds and sea grasses occurred in all areas except Dhanushkodi - Mandapam and Manapad – Kanyakumari. A total number of 100 algae and 5 seagrasses were recorded. Among the 100 algal species recorded, 20 species belonged to Chlorophyta, 18 species to Phaeophyta, 61 species to Rhodophyta and 1 species to Cyanophyta. The total estimated standing crop (wet wt.) from 1863 sq. km. sampled area was 75374.5 tonnes consisting of 2750 tonnes of Sargassum spp., 962.5 tonnes of Gracilaria spp., 5262.5 tonnes of Hypnea spp. and 66399.5 tonnes of other seaweeds. The quantitative analysis of economically important seaweeds revealed the feasibility of commercial exploitation of Sargassum from Mandapam to Kilakkarai and Tuticorin areas, Hyphnea from Mandapam to Vembar area and Gracilaria from Vembar to Nallatanni Tivu region. Hydrological data were, also collected from the area surveyed.
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Piants are the real producers of both the land and the sea. They are capable of generating complex organic substances from simple inorganic compounds dissolved in watkr. Without marine and synthesizers of food, elopment of marine animal life would be impossible. important feature of marine vegetation is its lack of variety when compared to the numourous forms characterizing the terrestrial vegetation.
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Approximately 2 gigatons of carbon a year is estimated to diffuse across the air-sea interface into the dissolved CO2 pool of surface ocean water. The total area of algal and seagrass beds along the coasts of Japan is 2,012 km2.We are currently estimating the macrophyte production along the coasts of Japan by estimating the annual net production and carbon content, and it is likely to be a value of ca. 2,700,000 tons of carbon a year. Additionally, the Japanese people have historically used seaweeds as food source.
Economically important genera (Porphyra, Laminaria, Undaria etc.) are cultivated and harvested, with an estimated annual production of cultivated seaweeds of 530,000 tons wet weight. The total amount of annual carbon absorption by seaweed cultivation is estimated to be approximately 32,000 tons, corresponding to 1.2 ％ of the annual macrophyte production along the coasts of Japan. It is also well known that seaweeds have a positive impact on moderately eutrophic water by absorbing nutrients from surrounding waters. Seaweed resources are an important source of carbon fixation.
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Surveys were started by Central Marine Fisheries Research Institute during 1958 to estimate the available seaweed resources in the Mandapam area. Varma and Krishna Rao (1964) made two surveys (a preliminary one in 1958 and the other detailed one during 1 962-63), covering a total area of 234.25 sq km between Dhanushkodi and Hare island. The entire area surveyed was divided into 3 sections, namely Krusadai section. Hare Island section and Outside section. Since very little algae of economic value were present, the Outside section, was not taken into consideration.
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Seaweeds yield valuable phycocolloids like agar-agar and algin which are widely used in many industries. They are also utilised as food, fodder and fertiliser. Survey of natural seaweed resources and investigation of the chemical composition, methods of extraction, ecology, cultivation and other aspects related to their utilisation are therefore of utmost importance. Majority of the economic seaweeds come under three classes namely the Green algae (Chlorophyceae), the Brown algae (Phaeophyceae) and the Red algae (Rhodophyceae) and they are generally restricted to the relatively narrow littoral and sublittorial belts of the marine environment.
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Surveys conducted for the first time recently along the Karala coast have indicated the presence of seaweeds at the following locations: Mullur,Vizhinjam, Kovalam, Chilakaar,Varkala, Edava, Tankasseri, Thirumullavaram, Kovilthottam, Cherai, Azhikkal, Perumpally, Thekkodu, Pallithodu, Chellanam, Kandakadavu, Elathur, Kadalur (Nandi) Madapalli, Tharayi, Tellicherry, Pallikere and Kanutheertha.
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Seaweeds are living and renewable marine resources which have tremenedous commercial importance. Seaweeds are macroscopic algae that grow in the littoral and sublittoral areas of marine environment when there is a suitable rocky or coral substratum.
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Up-to-date information about the unique marine flora of the Hawaiian Islands – its environment, uses, cultivation, conservation, and threats – comes from many sources, and is compiled here for the first time. The seaweed resources of the Hawaiian Islands are taxonomically diverse, biogeographically intriguing, ecologically complex, culturally significant, and economically valuable. Macroalgae, historically and today, are critical components of the marine ecosystem, as well as the diet and culture of people living in the islands. Some Hawaiian seaweeds are known to contain valuable bioactive compounds that have potential medical and pharmaceutical applications. Cultivation of Hawaiian seaweeds is carried out in tanks, ponds, and along the shoreline, both commercially and by “back-yard” farmers. Several community groups are actively working to preserve cultural knowledge, to re-plant the reefs, and to remove invasive algal species. The seaweed resources of Hawaiʻi are cherished, but are at risk. The future of seaweed cultivation, maintenance and revitalization of native populations, and preservation of cultural knowledge relies on the collaborative efforts of all stakeholders.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
Funding for this web portal is provided by the World Wildlife Fund and the University of Hawaii-Hilo.