The High Density Cultivation Of Brachionus Plicatilis

The rotifer Brachionus plicatilis is a type of tiny multicellular animals. Rotifer has huge economic value, for it is an essential hatch feedstuff for industrial fish larvae breeding and farming. In view of the fact that the widespread application of Brachionus plicatilis in aquaculture at present, this article conducted the experimental study from various cultivation conditions of Brachionus plicatilis, which aimed to achieve high density cultivation of Brachionus plicatilis in small water bodies for productive use, in conformity to the experiments that the optimum water temperatures and seawater salinities for the growth of Brachionus plicatilis were 28-30℃and 22-25. The main contents and results are presented as following:1. Rotifer grew and reproduced better by adopting a combinative diet of Chlorella, Baker's yeast and PSB than just using one of the three baits or a combinative diet of the two. That was not only due to the abundance in diet, which increased rotifer ingestion rate, and what is more important, rotifer can get complementary advantages of the combinative diet of the three baits. The combinative diet improved the nutrition of rotifer and increased unsaturated fatty acids in rotifer.2. The results varied in rotifer growth and reproduction rate by adopting different feeding frequency of baker's yeast as the only bait, whereas the total quanity of the bait kept unchanged. In the low-inoculation density teams of rotifer, it showed no significant difference. However, in the high-inoculation density teams of rotifer, increasing the number of feeding times (eight times per day) resulted in rapid growth rate of rotifer.3. After several days of cultivation, the deterioration of cultibative water quality decreased the growth and reproduction of rotifer gradually, owing to the accumulations of residual diets and rotifer metabolic degradations. In order to eliminate these adverse effects, measures must be taken. Getting the cultivated seawater exchanged entirely after 5 days cultivation was benificial for breeding and sustaining growth of rotifer.4. Since no residues or pollutions had been detected on seawater, environment and human body, ultraviolet disinfection method showed an overwhelming advantage. Meanwhile, in comparison with rotifer cultivated in the bleaching powder disinfection seawater and the ozone disinfection seawater, research tests showed that rotifer cultivated in the seawater, which was disinfected by ultraviolet system (15W) with seawater flow rate at 500L/h, got higher growth rate. Thus UV disinfection was superior to the other two methods of seawater disinfection. 5. The final result of high density cultivation showed that it took 9 days to increase from 209 Brachionus plicatilis/mL to 4,079 Brachionus plicatilis/mL in 40L seawater disinfected by UV as mentioned above. And also it took 10 days to increase from 213 Brachionus plicatilis/mL to 3,150 Brachionus plicatilis/mL in 160L seawater disinfected by UV.