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Abstract: 

Chaetoceros calcitrans as high nutritional value and are used to feed adult and larval stages of bivalves, the larvae of some fish and crustaceans and zooplankton. Culture conditions could amend the growth and biochemical composition of  microalgae. Salinity levels, silicate concentrations and  growth phase are the major factor controlling the biomass and fatty acids of marine microalgae. In this study, the effect of salinity, silicate and phases on the biomass and fatty acid of Chaetoceros calcitrans were invesigated. Guillard and Ryther`s modified f/2 media was used as the culture media with different sodium silicate (53, 106, 159, 212µM), different salinity levels (20, 25, 30, 35‰) and different phases (lag, logarithmic; stationary and late stationary). The maximum biomass, 82.34mg/L was reached in the stationary phase, 110.88mg/L was reached  in 25‰ salinity level and 155.49mg/L was reached in 159µM silicate concentration. The biomass and fatty acid tends to increase proportionally with the increase of the growth phase and salinity level, the maximum fatty acid,  5.9% and 5.5%, 4.7% was reached in the stationary phase, 25‰ salinity level and 106µM silicate concentration respectively. The results of this study indicated that PUFAs fatty acids (eicosapentaenoic aicd C20:5n-3 (EPA), docosapentaenoic acid C22:6n-3 (DHA), alpha-linolenic acid 18:3n-3 (ALA), arachidonic acid C20:4n-6 (AA) were high (>23% TFA) when cultured at the stationary phase, 25‰ salinity level and 106 µM silicate concentration. Based on the results of the present study, Chaetoceros calcitrans culture could be used as larval feed or other purposes cultured using the above nutrient concentrations.

Key words: Biomass, Chaetoceros calcitrans, Fatty acid, Growth phase, Salinity, Silicate