Study On The Molecular Biodiversity Of Microbial Eukaryotic Plankton In The Xiamen Bay And Pearl River Estuary

Microbial eukaryotes are widely distributed in global oceans,which are fast growing,have a high turnover rate and are important components of the marine ecosystem.Microbial eukaryotes play fundamental ecological roles as primary producers,consumers and decomposers in marine ecosystems.They are involved in regulating the balance of marine ecosystems and are central to food webs and biogeochemical cycles.Compared with prokaryotes,much less studies have been carried out on the molecular diversity of microbial eukaryotes.In recent years,the advance of high-throughput sequencing technology has enabled us to quickly obtain hundreds of thousands to millions of environmental sequences at low cost,allowing to further study community composition of microbial eukaryotes,their dynamic changes and environmental relevance.In addition,most of the current studies on the molecular diversity of microbial eukaryotic plankton are concentrated in open seas,and many gaps exist on the community characteristics of microbial eukaryotes in the bays and estuaries under severe environmental changes.eThe current study investigates the molecular biodiversity of microbial eukaryotic plankton in the Xiamen Bay and Pearl River estuary by high throughput sequencing on both 18S rDNA and rRNA,to explore the community composition,spatial and temporal distribution changes in different environments and the response of microbial eukaryotes to environmental factors.The main results of this study are as follows:(1)"Active"(RNA-based)picoeukaryotic plankton in Xiamen Bay:1)There are obvious seasonal changes in a diversity and B diversity;2)The community composition is dominated by Alveolata,Archaeplastida and Stramenopiles,and shows differences in both seasons and geographical locations;3)The 18S V4 and V9 regions showed different preferences during the sequencing process,and the two complement each other to better reveal the community diversity;4)The relative abundance of abundant species differs in different environments in the same study sea area,and the difference is different in different groups;5)Temperature is the most important factor.It is also affected by nutrients and biological factors.(2)"Total"(DNA-based)and "active"(RNA-based)picoeukaryotic and nanoeukaryotic plankton in Pearl River estuary:1)The community composition is dominated by Alveolata and Stramenopiles,of which Syndiniales is dominated in picoeukaryotic plankton and Dinophyceae and Bacillariophyta are dominated in nanoeukaryotic plankton,and the overall abundance increases from the nearshore to the estuary;2)With the ratio of RNA to DNA as the active characterization,the activity of the main groups increased with the increase of salinity from the estuary to the outside in nanoeukaryotic plankton,but the degree of increase varies according to the biological group,while the activity varied greatly in nanoeukaryotic plankton;3)"Active"microbial eukaryotic groups based on RNA sequencing are more responsive to the environment than those based on DNA sequencing,and the different particle sizes have different focuses.The overall has little to do with the water depth;4)Under the same particle size comparison,the same water mass showed similar community structure,and the diversity of the water mass to the community of microbial eukaryotic plankton in the Pearl River Estuary area could be higher than other environmental factors to a certain extent.