Biotic and Abiotic Factors Affecting Productive Performance of Rotifers (Brachionus Plicatilis) Population Produced Under 3 Days Batch Culture System

Rotifers Brachionus plicatilis are being used worldwide to feed early developmental stages of marine finfish and crustaceans. Further, rotifer transmits adequate supplies of micro and macro-nutrients, vitamins, probiotic, and even antibodies to fish larvae. Food type is regarded as the most important criterion that could affect growth and quality of rotifers. There fore, the present work was performed to study the effect of food type, salinity, water temperature, and initial stocking density on the population growth of rotifers. The first experiment was conducted to during the first phase of the present study investigate the effect of four different algal diets: (1) Nannochloropsis oculata life (N), (2) Spirulina platensis powder (S), (3) 50% N. oculata + 50% beaker yeast (NY), and (4) 50% S. platensis + 50% beaker yeast, on rotifer population (as final number/ml) and fatty acid profile of rotifer batch cultured (72 h) was employed. Rotifer culture treatments were conducted in jars (30 liters) with three replicates for each treatment.The results of the firts phase of the study clearly illustrated that NY diet possessed the highest population growth, Eicosapentaenoic acid (EPA), and Docosahexaenoic acid DHA percentage. Depending on the results of the first phase, the diet NY was candidate to investigate the effect of different salinities (25, 27, and 29 ppt), temperatures (26, 28, 30, 32 oC), and initial rotifer stocking densities (50, 100, 150, and 200 Ind./ml) on rotifer population. The results showed that salinity 25 ppt, temperature 28oC, and initial rotifer density 150 pcs/ml possessed the highest rotifer population growth during a 72-hrs batch culture system of rotifer  when fed on 50% N. oculata + 50% beaker yeast (NY) food type