The Construction Of Functional Biofloc And Aquaculture System And They Apply In Shrimp Culture

Microorganism is an important part of biofloc,and it is also the driving force ofthe stability of water environment and the maximization of the welfare of the breeding objects in the BFT system of zero water exchange.The functional BFT system is constructed by the directional regulation of microbes,which can effectively enhance the biological enhancement efficiency and stabilization of the BFT system.In this paper,the functional BFT system was constructed through the addition of probiotics under the experimental conditions and production conditions,and on this basis,it was applied to the culture of Litopenaeus vannmei and Penaeus monodon.The aim of these studies is to provide scientific basis and technical support for establishing biofloc-based efficient and healthy shrimp culture system.The main results are as follows:1.Using the specific solid waste of Anguilla marmorata from recirculating aquaculture systems,by adding probiotics and carbon source into the ectopic BFT reactor,the floc was cultivated to monitor the nitrogen transformation,the biological characteristics of the floc and the influence of the microbial community structure during the formation of biofloc.The results were as follows:1)there was no significant difference in the diversity of microbial between the fortified and ordinary feces from the the eels feed with probiotic group as feed additive,but there was a significant difference in the relative abundance.2)we evaluated the water treatment capacity ofmature floc in group QJ and group PJ,and the difference between the fortified and ordinary feces was not significant.3)during the process of culture flocculation,the concentration of TAN,NO₂^--N and NO₃^--N in the added bacteria group was significantly lower than that of the non bacteria group,and the ability to remove three nitrogen by adding bacteria in the water treatment ability test was significantly higher than that of the non bacteria group.At the same time,the addition of bacteria has the ability to remove NO₃^--N.4)through the analysis of floc microbial consortia,it is found that the addition of compound of bacillus in the process of flocculation can effectively promote the bacteria to become the dominant bacteria group and to domesticate the functional biofloc with high water treatment ability.2.the functional BFT system was constructed by using the simultaneous pattern of culture and build the systems,and in the process,the Penaeus vannamei culture of different density?300 tail/m³,600 tail/m³ and 900 tail/m³?.The study found that 1)In this pattern,the regular addition of Bacillus subtilis can control TAN concentration in a safe range in the middle and early stage of culture,and control the slow rise of NO₂^--N concentration.2)the stocking density significantly affected the survival rate of Penaeus vannamei,but the low breeding density was favorable for raising the survival rate and specific growth rate of prawns,reducing the feed coefficient,increasing the length and weight of the end-body of the shrimp,and the optimum breeding density for the culture mode of culture and build the systems was 600 tail/m³.3)In the regulation of functional BFT system,nitrifying biofloc system has more advantages than microalgae BFT system and heterotrophic BFT system in maintaining the stability of water quality.3.The nitrifying BFT system was used to breed Penaeus prawns under the high culture density?600 tail/m³and 900 tail/m³?.The study found that:1)the ultra-high density did not significantly affect the yield of Penaeus Penaeus,but the low breeding density could improve the survival rate of the shrimp,reduce the feed coefficient and increase the final weight of the shrimp.2)at the end of the experiment,the yield per unit area of 1.57kg/m² and 1.42kg/m² was obtained with 600 tail/m³?778 tail/m²?and 900 tail/m³?1167 tail/m²?,and the survival rate was 17.68%and 12.37%,respectively.3)in the nitrifying BFT system,the higher density of the culture,the greaterfluctuation of the water quality,the more unstable of the system,so it is necessary to reduce the breeding density properly and maximize the efficiency of the aquaculture in the condition of ensuring the stability of the system.