The Temporal And Spatial Distribution Characteristics Of Phytoplankton And Bacteria And Their Relationship With Environmental Factors In The Culture Area Of Porphyra Yezoensis

This paper focuses on the effect of Porphyra yezoensis on phytoplankton and bacterial diversity in aquaculture water.Based on 16 SrDNA,high-throughput sequencing technology was applied to study bacterial diversity in Changdao and Rizhao laver culture area.Phytoplankton technology was used to count and classify phytoplankton in Rizhao laver culture area.The results of the experiment are as follows:(1)The analysis of the environmental factors in the Rizhao sea area:The difference in sea area has a significant effect on dissolved oxygen(p<0.05),the dissolved oxygen in the culture area is higher than that in the coastal and offshore areas.The difference of sea area and month has significant influence on salinity,p H and transparency(p<0.05),the salinity in the offshore area is significantly higher than that in the nearshore and aquaculture areas,the lowest salinity in January and the highest salinity in November;there are significant differences between p H in offshore area and p H in coastal p H and culture area(p<0.05),There were significant differences between the p H in March and the p H of the other months(p<0.05).Different months had significant effects on total suspended solids(TSS),inorganic nitrogen salts,phosphate and silicate concentrations,the results of multiple comparison analysis show that,Low concentrations of nitrate and silicate in February and March,compared with November and January,there was a significant difference(p<0.05);the concentration of phosphate in March is low,compared with February and November,there was a significant difference(p<0.05);the concentration of ammonia nitrogen and nitrite nitrogen in February is low,there is a significant difference compared with that in March(p<0.05).The monthly difference has significant effects on phytoplankton richness,evenness,Shannon index and Simpson index(p<0.05).There is a certain correlation between phytoplankton and environmental factors in culture area: 1)The abundance of phytoplankton is significantly negatively correlated with dissolved organic nitrogen DON,total dissolved nitrogen TDN and dissolved organic carbon DOC and DON/TON;2)Phytoplankton richness was significantly positively correlated with DON,TDN,DOC and Si/DIN,and negatively correlated with particulate organic carbon POC;3)The evenness of phytoplankton is positively correlated with DON,TDN,DOC and DON/TON;4)The Shannon index of phytoplankton has a significant positive correlation with phosphate;5)The Simpson index of phytoplankton has a significant positive correlation with DON and DON/TON.(2)The diversity of water environment in Changdao sea area is rich,the highest abundance of deformed bacterial door(Proteobacteria)was observed.The diversity of bacteria showed a decreasing trend from near shore area,culture area and offshore area.Cluster analysis was carried out based on all the top 20 genus and species with the highest relative abundance,the results are all shown,CDCNS and CDCOS get together first,obviously different from the CDPF area.The dominant bacteria in the exclusive CDPF region include Muricauda,Pseudomonas,Halomonas,Erythrobacter,and Marinobacter.Dissolved oxygen(DO)and p H showed a trend of decreasing from offshore to offshore,total particle suspension(TSS)conversely.The content of NH4+-N in CDPF region is the lowest,and the salinity is the highest.Correlation analysis showed that there was a certain correlation between environmental factors and environmentalmicrobes.The abundance of ammonia bacteria is positively correlated with NH4+-N concentration,the abundance of CDPF area is the lowest and the abundance of CDCOS region is the highest;The distribution of salmonomonas is positively correlated with salinity,the content of salt bacteria in CDPF area was significantly higher than that in other two sea areas.(3)The diversity of water environment in Rizhao sea area is very rich,proteobacteria is the dominant phyla.From the perspective of the whole sea area,the bacterial diversity in Rizhao is shown as follows: the highest in January 2017,February,and the lowest in March,Regional expression is:the bacterial diversity in PF region is the highest and the COS region is the lowest.The microbial community structure in Rizhao sea area is obviously influenced by time,the sea areas corresponding to each sampling should first get together,from the perspective of regional distribution,the bacterial community structure near the shore and the offshore area in February 2017 is significantly different from that in the laver culture area,the other 3 months were near shore edge and seaweed breeding area,which were significantly different from the offshore area.Meanwhile,PCA diagram showed that the similarity of bacterial community structure was March>February>January>November.Analysis of bacterial flora difference between groups by LEFse,the distribution of interregional flora was the largest in November,in November,the distribution of interregional flora was the largest,followed by that in January,and there was almost no significant difference among the regions in February and March.Environmental factors are related to environmental microbes,for example,the Octadecabacter of the Rizhao sea area was positively correlated with p H and NH4+,and the Pseudoruegeria was significantly positively correlated with POC,and the Citrobacter was negatively correlated with the salinity,and the Loktanella was positively correlated with the salinity,POC,and TSS.Halomonas,Psychromonas and Marinomonas are the typical Exotropic bacteria of Porphyra,which are closely related to the growth of Porphyra.