Growth performances of three microalgal species in filtered brackishwater with different inorganic media

The growth of three microalgae species, viz., Nannochloropsis oculata, Tetraselmis chui and Chaetoceros muelleri which are commonly used in aquaculture, was investigated using three different inorganic nutrient media: (i) Modified Guillard's f/2 medium (ii) Rix Mix medium and (iii) BFRI medium. Each microalgae species was cultured for 24 days in small- scale with initial inoculation density of 17xl04 cell /ml in the three media with triplicates. N. oculata cultured in modified Guillard's f/2 medium showed superior growth with a mean peak density of 221 ±4.24 x 104 cell/ ml, to Rix Mix medium (141 ± 10.54xl04 cell/ml) and BFRI medium (47±4.94 x 104 cell/ml) on the 16th day of culture at stationary phase. Considering the increase in cell density for 20 days of culture in Rix Mix medium, C. muelleriwas significantly (P<0.05) highest than in other two media. N. oculata cultured in BFRI medium resulted in the poorest growth with a mean peak increase in density of 84±9.19 x 104 cell/ml in 12 days of culture. However, with an increase in cell density, growth of T. chui (182 ± 6.26 x 104 cell/ml) was significantly (P<0.05) higher in BFRI medium than in modified Guillard's f/2 medium. The results of the present study suggest that N. oculata and C. muelleri can be grown very well in both the modified Guillard's f/2 medium and Rix Mix medium. Better growth of T. chui can be obtained while culturing either in BFRI and Rix Mix medium. These three nutrient media used in the present study may be useful for microalgae species culture for establishing green-water culture for suitable target zooplankton, and fish and crustacean larvae in marine and brackishwater hatcheries.

A study on performances of intensification in the farming system of a shrimp farm at Cox's Bazar, Bangladesh

This study examines the harvest and mean production in relation to the stocking of P. monodon fry during the period between March 1992 and October 1994, at the farm owned by M/s Monugung Sea Food Ltd., Cox's Bazar. The analysis shows that production figures were initially up to expectation, but after harvesting 4 crops within 16 months, production sharply decreased. The unexpected high mortality of the growing stock was due to outbreak of an uncontrollabe disease (Vibriosis). Significantly higher variations in production, survival and growth were also noted among the different treatments.