PRODUCTIVITY OF ROTIFER Brachionus plicatilis CULTURED UNDER BATCH SYSTEM BY USING SUGAR BEET MOLASSES AS A SUBSTITUTE MEDIUM

Abstract

This study deals with the determination of availability of sugar beet molasses as a nutritional enrichment factor for rotifer cultures. A series of experiments under varying conditions such as ratio of sugar beet molasses in the nutrient complex were carried out in order to determine the effectiveness of sugar beet molasses as a carbohydrate and mineral source for the purpose of aquacultural operations. The culture water of Brachionus plicatilis with the salinity of 38% was treated through mechanical filtration and UV sterilization. 1 T cylindro-conical tanks are utilized for rotifer culture. Parameters of culture water were stabilized at values as following; Oxygen concentration:5 to 10 ppm, temperature: 27 0 C and pH:6.8 to 7.4. Rotifers were counted by using Sedgewick Rafter Cell on a daily basis in order to determine increase of number of individuals. The study was conducted as 3 different trial groups, each consisting three separate tanks, so triplicate determinations were obtained. For the Group I, 10% molasses by weight of Culture Selco Plus (200 gr Selco Plus+20 gr molasses per tank) was added 6 times a day with 4 hours’ intervals. For the Group II, 20% molasses by weight of Culture Selco Plus (200gr Selco Plus+40gr molasses per tank) was added and lastly for the control group, Group III, no molasses has been added and 200 gr Culture Selco Plus was only added per tank. The addition of molasses to nutritive complex has a decreasing effect on the number of rotifer and increasing effect on the number of ciliate. From the study, it is clear that sugar beet molasses should not be used as an additional nutritional factor for rotifer cultures due to its decreasing effect on the number rotifers and stimulating effect on the ciliate booming. Addition of 10% and 20% molasses resulted in 31.4% and 23.3% decrease in number of rotifers at the time of T3, respectively. On the other hand, it was observed that addition of molasses in the nutritive complex has not affected on the percentage of rotifers bearing eggs.