Change Of Dissolved Oxygen And Reaction Of Bacterial Community In In-pond Raceway Recirculating Aquaculture System(IPRS)

Pond engineering circulating aquaculture system is characterized by "large area of water purification,small area of fish culture",high density of aquaculture,good economic benefits,easy to operate and manage and save resources,with the traditional pond culture incomparable huge advantages.Changes of dissolved oxygen and microflora in largemouth bass aquaculture system may be different from those in traditional ponds when lifting and pushing water devices are added at the front of the aquaculture tank and an oxygenationtray is set at the bottom.This study of 7-November engineering circulating water pond aquaculture system in dissolved oxygen,water temperature and other influence factors are analyzed,and through the Illumina Miseq sequencing platform for high-throughput sequencing,from the density of livestock,breeding area,dissolved oxygen concentration and the change of season,many Angle analyzes the spatial and temporal variation characteristics of bacteria for engineering circulating water pond aquaculture in ecological control,healthy breeding provides a theoretical basis.1.Analysis of growth status and nutritional factors of California perch during the experimentThe growth condition of California bass from July to November was monitored and analyzed,and the results showed that the growth condition of California bass was good during the experiment,and there was no occurrence of major diseases and large-scale drug use.The specific growth rate of California perch increased in the early growth stage(30d-60d)and decreased in the late growth stage(60d-90d).The daily growth weight gain of California perch in the high-density group(25,000 tails/tank)was higher than that in the low-density group(15,000 tails/tank)at 30d-90d.There were significant differences in total protein,total cholesterol and triglycerides in October and November,and significant differences in blood glucose in November.The results showed that water temperature was significantly correlated with glutamate aminotransferase,glutamate grass aminotransferase and triglyceride.There was a significant correlation between blood sugar,dissolved oxygen and phytoplankton.2.Seasonal changes of dissolved oxygen,water temperature and phytoplankton from July to NovemberIn this study,the diurnal change of dissolved oxygen content(DO)in level and vertical direction with reaction of zooplankton and phytoplankton were carried out in August,and seasonal change from July to December.The result of August experiment showed that the maximum of DO in 2 p.m,and lasted to 6p.m In low stocking density channel(15000/110 m2),the DO,zooplankton and phytoplankton density of high stocking density channel(25000/110m2)were more than low stocking density channel on the whole.In diurnal change,DO of different level point(except purification region)gradually decreased with depth increased.There was significant or highly significant correlation between DO,zooplankton and phytoplankton,but the correlation direction were not exactly same.From July to December,there was highly significant correlation between DO and phytoplankton(r=0.616,P<0.01).Scenedesmus,Merismopedia,Euglena cryptomonas Crucigeni were dominant in several months,The density fluctuation of zooplankton was "M" type,the number of rotifera is more than cladocerans and copepoda.The proportion of Trichocerca arrived to 37%in September,the percentage of brachionus between 37%-64%in other months.The diurnal difference of DO gradually decreased,and there was highly correlation(0.814≤r≤0.93,P<0.01)between the diurnal change of DO and water temperature in different month.The result of the assay showed that water temperature is the main factor affect DO diurnal change in level and vertical direction in in-pond raceway recirculating aquaculture system.There were some correlation with zooplankton and phytoplankton as well.There were positive correlation between DO and phytoplankton in seasonal change.The study aims to provide experimental evidence for monitoring DO and ecological control in aquaculture circular pond.3.Dissolved oxygen content and bacterial flora changesMicrobial richness is related to DO;however,the DO seasonal variation in In-pond Raceway Recirculating Culture System(IPRS)may be different to other aquaculture methods.In this study,we analyzed microbial richness between July and November at phylum and genus level based on high-throughput sequencing techniques.There were 41 phyla,1928 OTU in total.The highest microbial abundance was recorded in September.The lowest microbial abundance was recorded in October.In this period of time,the ace index was significantly related to DO.Abundance of Proteobacteria was negatively correlated to water temperature,abundance of Bacteroidetes was negatively correlated to abundance of Cyanobacteria,abundance of Firmicutes was negatively correlated to abundance of zooplankton,and abundance of Actinobacteria was positively correlated to abundance of zooplankton.In October,DO and water temperature were negatively correlated to Shannon index(microbial diversity).In November,both of DO and water temperature were negatively correlated to sobs index(microbial richness)and Shannon index.The most abundant species were Proteobacteria and Actinobacteria in every month,Bacteroidetes,Cyanobacteria,Firmicutes and Fusobacteria were the subdominant populations.Chloroflexi was dominant only in July.According to the analysis at genus level,JG30-KF-CM45,Methylocystis,Roseomonas,Cyanobacteria,Paenibacillus,Novemberosphingobium,Candidatus_Rhodoluna,Rhodobacter,Filimonas and Leadbetterella were the most abundant only in one month..No species was the most abundant in the whole period of time.Our results suggested that the microbial richness increases as DO decreases,both of DO and water temperature significantly affected microbial richness and diversity,these factors affected microbial communities differently depending on the month.