Operation Effect And Engineering Design Of Inner Circulation Culture System Of Litopenaeus Vannamei

As the most important species of prawn culture in China,litopenaeus vannamei has been cultivated for more than 20 years.At present,the cultivation models of penaeus vannamei such as pond culture and high-elevation pond culture mainly update the water quality by changing water,and most of them discharge directly without treatment,which not only wastes a lot of water resources,but also causes certain pollution to the environment.To solve afore-mentioned problem,exploration gives Recirculating water aquaculture system(Recirculating aquaculture systems,RAS),can change the system everyday water amount falls 10%,be regarded as a kind of environment friendly aquaculture pattern,but RAS invests,operation cost and technical requirement are relatively taller,large area is promoted difficulty is bigger.Biological floccules technology(Biofloc technology,BFT)by adding organic carbon source,regulating C/N ratio,increase the number of heterotrophic bacteria in water,the inorganic nitrogen in water by microbes into their components,flocs are prawns second feeding,to control water quality,the purpose of promoting nutrient cycle,reduce feed coefficient,although the technology in water volume is small,but there is also a problem such as technical operation and the management process is more complicated.In view of the above problems,on the basis of full research on the living habits,the space layout of the aquaculture pool and the micro-ecology of the aquaculture pool,a kind of high-density inner circulation culture technology of penaeus vannamei was put forward,and the matrix was built in,so that the aquaculture pool of penaeus vannamei vannamei could be integrated with the cultivation of penaeus vannamei and the purification of water quality.It has the advantages of low input and operation cost,high density,high output,preventing invasion of exogenous pathogens and reducing the incidence of prawn.In this study,coral bone(4%V/V)was used as the biofilm carrier,and the artificial seawater was prepared by using seawater element.Two internal circulating culture systems of penaeus vannamei with salinity of 5‰ and 15‰ were constructed,and the water quality changes in the two stages of water culture and culture were studied.High-throughput sequencing was used to analyze the structure and diversity of microbial community in the process of operation,and to explore the relationship between dominant strains and environmental factors.An inner circulation aquaculture system with 1000 cubic meters of water was designed.The main conclusions are as follows:(1)in the water phase,by adding the nitrifying bacteria preparation,ammonium chloride and sodium nitrite,improve breeding system coral bone matrix of biofilm growth process,adding the ammonium bicarbonate to the water system and water system make the initial concentration of ammonia nitrogen respectively 2 mg/L and 5 mg/L,the water system of ammonia nitrogen concentration after 2 days to detect the,sea water system after eight days to reduce the nitrate nitrogen concentration to detect the way;After 4 days,the concentration of ammonia nitrogen in the fresh water system was reduced to undetectable,while the concentration of nitrite nitrogen in the fresh water system was reduced to undetectable after 13 days.(2)during the aquaculture process,the ammonia nitrogen concentration of the seawater and freshwater aquaculture systems was always below 0.1mg/L,and the average ammonia nitrogen concentration of the seawater and freshwater systems during the whole operation was respectively 0.04mg/L and 0.02mg/L.There was no significant change in the concentration of nitrite nitrogen in the first 65 days,and the average concentration of nitrite nitrogen in seawater system and fresh water system was 0.13mg/L and 0.06mg/L,respectively.After 65 days,the nitrite concentration in the two systems increased to different degrees,and the final peak values of nitrite in the seawater and freshwater aquaculture systems were 3.43mg/L and 0.52mg/L,respectively.(3)the composition of coral bone biofilm communities in the early and late stage of culture was analyzed by high-throughput sequencing.The results showed that the species and abundance of microorganisms on the biofilm increased significantly with the operation of the internal circulating culture system.In the early stage of operation,the biofilms were mainly proteobacteria,bacteroidetes and actinomycetes,accounting for 89.95% and 90.45% of the bacteria in seawater and freshwater systems respectively.At the end of the system operation,the biofilm consisted of proteobacteria,bacteroidetes,firmicutes,actinomycetes and verruca microflora,accounting for 92.6% and 90.46% of the seawater and freshwater systems.A total of 227 genera were detected in the whole operation of seawater inner circulation system and freshwater inner circulation system.In the early stage of system operation,the highest abundance of bacteria in seawater system and freshwater system were Muricauda and unclassified?fseashore flavobacteriaceae,respectively.In the later stage of system operation,Fusibacter was the most abundant bacteria in seawater system and fresh water system,accounting for 22.30% and 24.19%,respectively.(4)in the water system and water system operation early and late are detected with functions of regulating water quality of bacteria species,water system and water system to detect the nitrosation belongs to bacterium(Nitrosomonas),in the late seawater system detect the nitrosation bacteria genera(Nitrosococcus),nitrifying bacteria Pseudomonas(Nitrococcus)and red(Pseudomonas),respectively,accounting for 0.93% of the coral sea water system bone surface microbial overall,0.03% and 3.32%;Nitrobacter was detected at the end of operation of the freshwater system,accounting for 0.70% of the total microorganisms on the surface of coral bones in the freshwater system.(5)a 1000 m cubed internal circulating culture system was designed,which covers an area of 2010m2 and is mainly composed of storage tank,standard seedling pool,culture tank,material room and water quality analysis room.The total cost of infrastructure construction is 568,500 yuan,and the operating cost of each culture cycle is 172,900 yuan.