ABSTRACT

Sarkar, S.; Rekha, P.N.; Biswas, G.; Ghoshal, T.K.; Ambasankar, K., and Balasubramanian, C.P., 2019. Culture potential of the seaweed, Gracilaria tenuistipitata (Rhodophyta) in brackishwater tide-fed pond system of Sundarban, India. In: Jithendran, K.P.; Saraswathy, R.; Balasubramanian, C.P.; Kumaraguru Vasagam, K.P.; Jayasankar, V.; Raghavan, R.; Alavandi, S.V., and Vijayan, K.K. (eds.), BRAQCON 2019: World Brackishwater Aquaculture Conference. Journal of Coastal Research, Special Issue No. 86, pp. 258-262. Coconut Creek (Florida), ISSN 0749-0208.

Seaweeds are marine macro-algae exploited for the production of commercially important phyco-colloids, such as agar, algin and carrageenan. Natural seaweed stocks are inadequate to meet today's industrial requirements; hence, cultivation of these important resources has become necessary. Seaweed culture in brackishwater environment requires a suitable species, which is adaptable, and accordingly Gracilaria tenuistipitata was identified due to its euryhaline nature, proliferation capacity in turbid waters and bioremediation potential. However, the package of practices for its culture has not been standardized and an attempt was made in the present study to address this issue. Cultivation of the G. tenuistipitata was carried out in a 600-m2 brackishwater tide-fed pond at Kakdwip, West Bengal from September 2017 to February 2018 in low salinity (7-8 ppt) condition with the main objective of investigating the effect of depth and initial stocking intensity on the growth of the seaweed. The study revealed an increasing trend for biomass growth at a water depth between 0–0.3 m and after which the growth rate decreased as time progressed. It was also found that specific growth rate was significantly higher at a depth of 0–0.3 m compared to 0.3-0.6 m and 0.6-1.2 m. The concentration of dissolved inorganic nutrients (NH4-N, NO2-N, NO3-N and PO4-P) below 0.05 mg L-1 appeared sufficient to enable the seaweed to maintain a daily growth rate of more than 2% d-1 at a water depth between 0–0.3 m. The initial stocking density of 25-50 g/m2 with a culture period of one month was found to be optimum for extensive culture of this seaweed in pond system filled with natural estuarine brackishwater throughout the year.

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