Microbial Eukaryotes Biodiversity And Its Influencing Factors In Beibu Gulf In Summer

Microbial eukaryotes are an important part of eukaryotes.There are many types of microbial eukaryotes with different shapes and sizes.About 71%of the earth's surface is covered by the ocean.In the vast ocean,microbial eukaryotes are everywhere.They act as producers,consumers and decomposers in the aquatic food web and make great contributions to the material and energy cycle.The Beibu Gulf is rich in natural resources.Revealing the structure,composition,diversity,spatial distribution characteristics and influencing factors of microbial eukaryotes community in the typical ecosystem of Beibu Gulf is the basic research content for marine environmental change and evolution.It is of great significance to deal with major global environmental problems such as global climate change and sustainable development of marine economy significance.In this study,21 stations were set up in Tieshangang,Yingpan,Weizhou Island,Xieyang Island and the far west coast of Weizhou Island in the Beibu Gulf to collect seawater and bottom sediments,and detect the physical and chemical environmental factors,including temperature,depth,transparency,salinity,pH,COD,DO,Si O₃-Si,NO₂-N,NO₃-N,NH₄-N,PO₄-P,TOC,TP and TN.High-throughput sequencing technology was used to obtain the abundance,richness and community structure of microbial eukaryotes in these sites.PCo A(Principal Co-ordinates Analysis)and NMDS(Non-Metric Multi-Dimensional Scaling)were used to analyze the differences among microbial eukaryotes communities.Spearman correlation analysis,Mantel test correlation test and CCA were further used to analyze the correlation between microbial eukaryotes community and its influencing factors.The main results are as follows:1.In summer,the surface water of Beihai peninsula is mainly limited by potential N.The eutrophication and organic pollution in the coast of Tieshan port and Yingpan port are relatively serious,and the rest stations are basically good.The main factor affecting the chlorophyll-a content of surface water is the organic matter,which may be related to the strong degradation of marine microorganisms.2.17219 OTUs were detected,including 72 phyla,241 classes,431 orders,516families,990 genera and 1839 species.In the seawater samples of Beibu Gulf,the highest abundance of microbial eukaryotes was Animalia,followed by Eukaryota>Chloroplastida>Fungi>Metazoa>Discoba,and the richness showed as follows:Eukaryota>Animalia>fungi>Chloroplastida>Metazoa>Discoba.While in the sediment samples of Beibu Gulf,the abundance is Eukaryota>Animalia>Chloroplastida>Fungi>Metazoa>Discoba,and the richness was shown as Eukaryota>Animalia>fungi>Chloroplastida>Discoba>Metazoa.3.The alpha diversity of microbial eukaryotes in the coastal waters of Tieshan port and Yingpan port is lower than that of Weizhou Island and its surrounding waters.In contrast,in the sediments,the sea areas of Tieshan port and Yingpan port are higher than those of Weizhou Island and its surrounding areas;The alpha diversity of sediment community is higher than that of seawater.4.According to the results of beta diversity analysis,there are significant differences between the seawater community structure and sediment community.The difference between seawater samples is more obvious than that of sediment,and there is a certain regional difference.The seawater samples from closer geographical locations exhibit more similar in structure than others,however the sediment samples have no obvious regional difference.5.The diversity of microbial eukaryotes in Beibu Gulf was significantly correlated with total nitrogen(TN),salinity,pH,Transparency,DO,PO₄-P,NO₂-N,COD,NH₄-N and Si O₃-Si.In this study,the microbial eukaryotes from Beibu Gulf at summer were comprehensively described,and the basic community structure and its related factors were preliminarily studied.The limitation is that only summer samples were collected,and the community composition and distribution characteristics of microbial eukaryotes in Beibu Gulf in different seasons and years were not clear.