Study On Total Organic Carbon And Microbial Composition Analysis In Recirculating Aquaculture

Tianjin city plays an important role in the economic development of the Bohai Sea Economic Zone.In recent years,with the guidance of policy and the strong support from government,the marine aquaculture industry has gradually entered a period of rapid development.But there are still some problems and many disadvantages in the development of small and medium-sized aquaculture enterprises,which includes low production efficiency,high dependence on environmental resources,high energy consumption and heavy environmental pollution pressure caused by the relatively backward production mode.Therefore,in order to respond to the national call for energy conservation and emission reduction,it needs to research and develop an aquaculture model that is simple,efficient,energy-saving,environmentally friendly,healthy and safe.And the development and research are of great practical significance for accelerating the structural reform of the supply side of the industry,improving quality and efficiency,increasing fishermen’s income,and promoting the construction of urban fisheries.Tianjin’s unique geothermal resources have driven the rapidly development of the intensive industrial aquaculture industry,which has enabled the recirculating aquaculture process to achieve the goal of energy conservation and consumption reduction,but the amount of water needing in treatment has increased correspondingly.Among them,the study of structure and function of microbial communities in circulating water systems and organic pollution monitoring and early warning has become a key issue in the improvement of tail water treatment technology.Therefore,the development of new technologies for industrialized tailwater treatment,research and development new process for energy conservation,water conservation,and environmental protection can lay a solid foundation for the sustainable development of Tianjin’s fisheries.In this paper,the total organic carbon analyzer is used to monitor the annual real time variation of TOC content in recirculating seawater for marine aquaculture,to provide the pollution degree data of organic matter for early warning,and to analyze the main environmental factors affecting the temporal and spatial distribution characteristics of TOC,in order to provide scientific basis to make further exploration of the bioavailability of TOC in circulating seawater for marine aquaculture.At the same time,combined with the waterquality,stocking density,disease control,daily management,and highly efficient breeding equipment and other aspects of the circulatory system,the preliminary study on the biofilm microbial community diversity in water and bio-fillers and its function prediction in multi-stage biofilters is conducted in order to help the accumulation of more data for the future development of new technologies for tail water treatment and research and development of micro-ecological preparations for circulatory systems.The detailed experimental results are as follows:1.To gain the annual real time variation of TOC content of different cultured species,the TOC content of the seawater in which the semi-smooth tongue,turbot and grouper is cultured is regularly monitored using a fast and accurate total organic carbon analyzer.The detailed results are as follows: The change regulation of annual real time variation of TOC content in the seawater culturing the turbot is: autumn>summer>spring>winter.The change regulation of annual real time variation of TOC content in the seawater culturing the semi-smooth tongue is as follows: autumn>summer>spring>winter.The change regulation of annual real time variation of TOC content in the seawater culturing the grouper is as follows: summer>autumn>spring>winter.Among them,the change regulation of annual real time variation of TOC content in the seawater culturing the turbot is similar to the annual real time variation of TOC content in the seawater culturing the semi-smooth tongue.2.Correlation analysis is conducted between TOC content and main environmental factors of different cultured species.The CCA analysis method is mainly used to comprehensively analyze the relationships among TOC content and the number of colonies in aquaculture water and environmental factors(temperature,pH,DO,COD,ammonia nitrogen,nitrite nitrogen).According to the analysis,the results show that DO,pH and temperature are the main environmental influencing factor that affect the change of TOC content in the aquaculture water of turbot.DO and temperature are the main environmental influencing factor that affect the change of TOC content in the aquaculture water of the semi-smooth tongue.Ammonia nitrogen,pH and temperature are the main environmental influencing factor that affect the change of TOC content in the aquaculture water of grouper.Among them,temperature is a common environmental influencing factor that affect the change of TOC content in the aquaculture water of all of turbot,semi-smooth tongue and grouper culture water.3.Research on microbial diversity of multi-stage biofilters in circulatory systems.High-throughput sequencing of bacterial diversity in biofilms and aquaculture water of different biofilter by using molecular biology methodsThe results showed that the bacteria of all samples belonged to 27 phyla,and Proteobacteria was the dominant species.The top three bacterial phyla in the nine biofilm samples were: Proteobacteria,which accounted for 49%~66% of the total number of bacteria,and Planctomycetes,which accounted for 5.6%~11.7% next,it is Bacteroidetes,accounting for 15%~36%.The top three bacterial phyla in the water samples from the nine biofilters are Proteobacteria,accounting for 66%~80%,Cyanobacteria,accounting for 5.7%~10.2% and Bacteroides The door(Bacteroidetes)accounts for 5.9%~10.1%.In the biological filter of the recirculating aquaculture system,Nitrospirae was found in all the samples,which mainly plays the role of removing ammonia nitrogen and nitrite.By comparative studying,it found that the bacterial species content on the biofilm was significantly less than that in the aquaculture water(P<0.05),but the microbial diversity was higher than that of the aquaculture water(P<0.05).4.Research on the function of microbial community in multi-stage biofilter in circulatory system.According to the result earned by cluster analysis and PCoA analysis,it showed that there were significant differences in the composition of bacterial community in biofilm and biofilter(P<0.05),and the function of bacterial community also had some differences(P<0.05).By comparison with the KEGG database,six types of bio-metabolic pathway functions were obtained in the function of first-level prediction;and10 sub-functions were obtained in the second-level prediction;all samples were found to have nitrogen metabolism function in the third-order prediction,and the nitrogen metabolic function of the biofilm sample was stronger than sample in the corresponding aquaculture water.