The Study Of Microbial Communities And Their Potentiality To Be Environmental Indicators Of Surface Layer Sediments In Xuande Atoll,the South China Sea

Marine sediments are an important part of the marine environment and have a highly diverse microbial ecosystem.The South China Sea is rich in marine resources,but the ecological environment of the South China Sea is threatened due to the development of resources and human activities.As a major player in the material cycle,microorganisms play an important role in maintaining ecological balance and are the main factors for evaluating environmental changes.In this study,surface layer sediments and seawater samples from 39 sites in Xuande Atoll,South China Sea were collected,and analyzing sediments'particle size,physical and chemical indicators of seawater samples.We analyzed the microbial community structure of sediment samples and the correlation between microbial community structure and environmental factors using High-throughput Sequencing technology to explore the potentiality of bacteria to be the environmental factors.The main conclusions are as follows:?1?The hydrodynamic in the Qilianyu were relatively large and the conditions changed greatly,while the hydrodynamic conditions in the Yinlitan and the Shidao were relatively stable.Depth,COD,NH₄⁺,and NO₃^-changed greatly in the study area.?2?Microbial diversity and uniformity changed greatly in the surface layer sediments of Xuande Atoll.And there are differences in microbial community structure between different islands or water depths.The dominant bacteria in the study area were Proteobacteria,Actinobacteria,Bacteroides and Firmicutes.Depth and chemical oxygen demand?COD?in Xuande Atoll were the main environmental factors affecting the microbial community structure and diversity of surface layer sediments.The distribution of Psychrobacter,Vibrio and Pseudoalteromonas were significantly affected by environmental factors.?3?Escherichia-Shigella and Vibrio are pathogenic bacteria with high abundance in the study area.The distribution of Escherichia-Shigella and Vibrio in the study area indicates that the environment was polluted and there are disease risks in the study area.