Seaweeds are macroscopic marine algae that form an important living resource of the oceans. Though there are about 9200 species of seaweeds in the world, only 221 species are economically important. Over 68.33 lakh tons of brown, red, and green seaweeds are exploited annually for the production of various commercially important phycocolloids such as agar, algin, and carrageenan. Thus, natural seaweed stocks have become inadequate to meet the industrial requirements and hence cultivation of these important resources has become necessary. Asia stands as the world leader in seaweed cultivation and more than 80% is contributed by China, Korea, and Japan.
Seaweed as food in Bangladesh is not as common as in countries like Japan and China. A number of studies show that seaweeds are valuable sources of protein, fiber, fatty acids, vitamins, macro and trace elements, as well as important bioactive compounds. Some compounds of seaweeds control high blood pressure, level of cholesterol, and prevent strokes. These can also be used as a remedy for rheumatism, diarrhea, and for controlling the growth of a tumor.
Also, they have a high level of iodine, justifying the low incidence of hypothyroidism and goiter in the population of the coast Asiatic. Besides, some algae contain significant amounts of vitamins A, B1 (thiamin), B2 (riboflavin), C, and, especially, B12. The coastal zone of Bangladesh enjoys a tropical maritime climate and bestowed with a coastline extends 710 kms along the northern edge of the Bay of Bengal which support luxuriant growth of green, brown and red seaweeds in St. Martin, Inani, and Bakkhali river estuary.
Considering the great demand for these resources in the international market and availability of adequate manpower and interest in the country, seaweed cultivation has a very good prospect and it can be a source of alternative income and livelihoods of the poor also it can be developed as a successful cottage or co-operative sector industry.
Seaweed culture potentialities in Bangladesh Generally, coastal people of Bangladesh are called seaweeds as 'Hazala' and as the food of 'Mog'. Zafar (2005) first started seaweed culture in Bangladesh. Therefore, numerous tropical countries with coastlines are searching for seaweed cultivation as a sustainable alternative livelihood for coastal villagers, particularly as part of coastal management. In Tawi-Tawi (Mindanao, Philippines), seaweed farming is a major source of livelihood among seaweed farmers.
In this context, Bangladesh Fisheries Research Institute (BFRI) through its Marine Fisheries & Technology Station (MFTS), Cox's Bazar initiated seaweed research from 2013 and implementing a development project from 2018 on "Seaweed Culture & Seaweed Product Development in Bangladesh Coast" Research Project with the objectives of development of seaweed culture technique in Bangladesh; investigate the nutritious value of seaweeds; and utilization of seaweeds by producing value-added products.
1. Abundance and seasonality of seaweedsSeaweeds are abundant in St. Martin Island compare to other coastal areas of Bangladesh. From November to April of the year seaweeds are available due to its favorable condition of the sea.
2.Identification of seaweeds in Bangladesh
A total of 138 fresh samples of seaweeds species were identified and preserved with the photograph in Marine Fisheries & Technology Station, BFRI, Cox's Bazar. Based on the results of a long study recently, BFRI has published a book on the abundance, availability, and classification of seaweeds as "Seaweeds of Bangladesh coast on the coast". A total of 138 marine species have been identified in Rhodophyta (69.52%), Phyophyta (35.26%), and Chlorophyta group (26.21%). This book will serve as a guide for students, teachers, farmers, entrepreneurs, researchers, and policymakers alike in the sea-based blue economic development.
3. New seaweed bed
Seaweed Research Team of MFTS, BFRI, Cox's Bazar discovered a new natural seaweed bed from Nuniarchara to Nazirartek areas of the Bakkhali river and Moheshkhali Channel estuary of Cox's Bazar. Hypnea musciformis and Enteromorpha intestinalis are the main available seaweed species of this seaweed bed. Recently they found another seaweed bed in Gongamoti, Kuakata area.
4. Commercially important seaweeds
Besides good export potentials, the introduction of seaweed culture in the country's coastal areas could be an alternative option for the people's source of income. Many edible seaweed species are available on the coast. Attempts should be made to develop products suitable for the Bangladeshi palate and to popularize the same amongst the public.
According to the seaweed experts, green and red seaweeds could be suitable for culture in Bangladesh. The seaweed such as Caulerpa, Enteromorpha, Hypnea, Porphyra, Colpomenia, Hydroclathrus, Sargassum sp. rich with protein, amino acids, vitamins, and minerals have multiple uses like as fodder, fertilizer, human food, industrial and pharmaceutical raw materials. The researcher identified 18 species of seaweeds are commercially important in Bangladesh.
* Chlorophyta:(Caulerpa racemosa, Enteromorpha intestinalis, Enteromorpha compressa, Ulva lactuca, Codium fragile)
* Phaeophyta:(Colpomenia sinuosa, Dictyota dichotoma, Hydroclathrus clathratus, Padina tetrastromatica, Padina gymnospora, Sargassum myriocystum, Sargassum oligocystum, Sargassum ilicifolium)
* Rhodophyta (Asparagopsis taxiformis, Hypnea musciformis, Hypnea valentiae, Kappaphycus alvarezii, Porphyra indica)
Seaweed culture methods
Horizontal net: Net design and size: Square- 4m×4m. Net material was coconut fiber rope. Four corners of the nets were tied with rocks or bamboo pole.
Long line: materials used: Coconut rope, Styrofoam float and a bamboo pole. Length: 20 m Floating Raft: materials used: Coconut rope bamboo. Size: 2.5m×5m. Seaweed production After 15 days of transplantation of seaweed seeds and cultured seaweed species can partially be harvested and new buds grow. After then partial harvesting can be done fortnightly.
After total harvest at the end of the 90-day duration of the culture period in Hypnea scientists obtained result maximum biomass 31.61 kg fresh wt.m?2 in Saint Martin, Caularpa racemosa 15.58 kg fresh wt.m?2, Enteromorpha intestinalis 24.50 kg fresh wt.m?2Padina tetrastromatica10.18 kg fresh wt.m?2 and Sargassum oligocystem 18.62 kg fresh wt.m?2 respectively.
Micro-nutrient enrichment study with seaweed salad The contribution of seaweed in our diet was evaluated through the enrichment of fresh salad. In a common vegetable salad, red seaweed (H. musciformis) was added at 10% volume and served as a normal dish. Both the salad was then dried and tested for mineral composition. It was observed that salad enriches with seaweed resulted in higher values of Ca, Na, Fe, and Zn.
Seaweed product development study Processed Hypnea and Padina were used as Salad. Seaweed Hypnea powder was used in Soup, Pizza, and Cake, etc. These food products were consumed by the researchers and other peoples. The flavors and tests of these seaweed food products were good. Also, seaweed can be used as herbarium for decorative purposes.
In Bangladesh, seaweeds have been traditionally utilized as human food by the tribal people. In recent years, few restaurants are often used seaweeds as fresh salads, cooked vegetables, and curry dishes. There is no regular seaweed industry in Bangladesh.
Some local collection of seaweed can occur for two to three months from December to March in the year. Besides Cox's Bazar coast, there is good growth of the edible seaweeds in the Chittagong, Potuakhali, and Sundarbans coast. Besides good export potentials, the introduction of seaweed culture in the country's coastal areas could be an alternative option for the people's source of income.
Attempts should be made to develop products suitable for the Bangladeshi palate and to popularize the same amongst the public. Since it can be easily dried and preserved well, seaweed can be easily transported inland to places where people suffer from thyroid problems due to a lack of iodine. The efforts in seaweed cultivation and its utilization through product and process development could help in meeting the food and nutritional security of the Bangladeshi population as well as augmenting the value of total fisheries export.
However, the successful development of the seaweed industry not only requires appropriate natural environmental conditions and the availability of workable technical methods but also receptive and supportive social and economic conditions. On the economic side, needs, markets, availability of suitable resources, and appropriate systems of property rights are seen as important.
Md. Mohidul Islam, Project Director, "Seaweed Culture & Seaweed Product Development in Bangladesh Coast"
Email: [email protected]
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