Control measures of biofloc-technology aquaculture under light condition

Abstract:

By using the method of experimental ecology, the water in the early stage of BFT aquaculture was used as the experimental material.The effects of bacteria free predators (protozoa etc., group AC), group with shrimp order supplemented with glucose (group GS) and single dose of glucose (group G) on bacteria and plankton in water were investigated. The results show that the biomass of rotifer, phytoplankton and concentration of chlorophyll-a in group GS were significantly higher than those in control group (P<0.05) in 120 h, while the biomass of rotifer and the phytoplankton in the group G had no significant difference from the control group (P>0.05) during the whole experiment (P>0.05), so the bottom-up effect of the sequential batch addition of glucose was more obvious than that of the one-off addition, and the top-down effect of group GS with large predators was not obvious. The total number of bacteria in the experimental group and the control group was higher than 5×10⁵ cells/mL. The highest peak number of bacteria was (13.10±3.79)×10⁵ cells/mL in group AC, which reduced the predation pressure on the bacteria and promoted the growth of the bacteria after removing the bacterial predator. The dissolved organic carbon concentration and dissolved total nitrogen concentration in the group AC were always higher than those of other groups. In the group GS, group G and the control group, the concentrations of dissolved organic carbon, total dissolved nitrogen and phosphate were basically consistent.Killing bacterial predator released a large amount of dissolved organic matter, adding appropriate amount of glucose, and adding shrimp had no obvious effect on the water quality of culture. Killing bacterial predator released a large amount of dissolved organic matter. Adding appropriate amount of glucose and adding shrimp had no obvious effect on the water quality of culture. The results provide the basis for control measures on sunshine biofloc-technology aquaculture in production.