Effects of Biofloc on Plankton Abundance in the Water

This study was conducted to evaluate the effects of biofloc on the species and quantity of plankton in pond water. There were four treatments in the experiment: the control, no supplementation; treatment I, pond water supplemented with glucose; treatment II, pond water supplemented with both glucose and Bacillus subtilis; and treatment III, pond water supplemented with Bacillus subtilis only. Water quality, plankton, and biofloc formation were monitored every five days. Results showed that biofloc formation was enhanced by adding glucose to the pond water. The addition of glucose together with Bacillus subtilis shortened the formation time of mature bioflocs by about five days than the supplementation with glucose only. In ponds supplemented with glucose and those supplemented with glucose + bacillus, the ammonia nitrogen, and nitrite nitrogen content in the water column decreased, and the number of cyanobacteria and green algae were significantly inhibited, while the number of zooplankton such as Rotatoria increased during the experimental period.