| In this study, we got12samples from three sites (DH9, DH13, DH18) of East ChinaSea shelf and obtained five chemical parameters of environment, TC (total carbon), TN(Total Nitrogen), TP(Total Phosphorus), TOC(Total Organic Carbon) and TIC(TotalInorganic Carbon)by Chemical analysis methods for marine sediment. We analyzed16SrDNA sequence of bacteria and archaea,18S rDNA of eukaryotic microorganisms byconstructing clone library method, and we analyzed the corralation between microbialcommunity structure and environmental factors by R. Thus we got a preliminaryunderstanding on diversity, community structure of bacteria, archaea and eukaryoticmicroorganisms and their influence on ecology.The results of bacterial diversity and phylogenetics showed the sequences obtainedfrom the samples of East China Sea shelf sediment. were categorized into15groups,including Proteobacteria, Chloroflexi, Planctomycetacia, Actinobacteria, Acidobacteria,Bacteroidetes, Flavobacteria, Bacilli, Spirochaetes, Cyanobacteria, Verrucomicrobiae,Nitrospira, Gemmatimonadetes, Deinococci, Clostridia, in which Proteobacteria (accountfor33%of total clones), Chloroflexi (account for9%of total clones), Planctomycetales(account for9%of total clones) were dominant group in this area. The clones of γ-proteobacteria were particularly prominent, accounting for15%of the total clones. Inaddition,14%sequences of bacterial16S rDNA had a low similarity with the sequence inthe NCBI, which may belong to some of the new microbial species that has not yet beendiscovered.Bacterial diversity was different among different sites, and the bacterialdiversity of DH9was less than DH13and DH18. According to layer which we got theclones, most bacterial clones from the second layer of (3-5cm) and the third layer (5-8cm).Based on the results from the PCA(Principal Components Analysis), the distribution ofbacteria interacted with each other. The distribution of Clostridium had a positivecorrelation with bacillus, but the distribution relationship between Chloroflexi andAcidobacteria was relatively distant. Drawing on the consequence of RDA (RedundancyAnalysis), we found that different environmental factors had different affection levels onbacterial diversity, and one environmental factors affect different groups of microorganismswere also discrepancy. The content of TP and TN had a greater impact on distribution ofbacterial diversity than TIC and TC, and TN was positively correlated with the distributionof ε-proteobacteria, and negatively correlated with Bacillus.Archaeal16S rDNA libraries were from two categories: Crenarchaeota and Euryarchaeota. The number of Crenarchaeota clones were predominant in East China Seashelf sediments, taking over45%of the total number of clones, which included four groups:Miscellaneous Crenarchaeotic Group (MCG), Marine Crenarchaeotic Group I (MGI),MarineBenthic Group B (MBGB), MCGI（Miscellaneous Crenarchaeotic Group I）;Euryarchaeota occupying26%of the total clones included nine groups: MarineBenthicGroup D (MBGD), Methanosarcinales, VAL Ⅲ, MarineBenthic Group E (MBGE),Haloarchaea, Marine Crenarchaeotic Group Ⅱ (MG Ⅱ), Anaerobic Methanotrophs3(ANME-3)， Anaerobic Methanotrophs1(ANME-1)， South African Gold MineEuryarchaeotic Group (SAGMEG). There was29%(accounting for85clones) cloneswhich we couldn’t find similar sequences in NCBI, so we hypothesized that it may be somenew archaeal group. According to the distribution of archaeal in three sites, there were morearchaeal diversity in offshore sediments (DH9, DH18) than the area far which was from thesea (DH13). The diversity of Crenarchaeota in the three sites was clinged to consistency.From a stratified sample of cloning statistics,it showed that excepted for DH9, theremaining two sites from the surface to the bottom sediments, the dominant archaea groupturn MGI into MCG. This consequence may due to the location of DH9where was inestuary of river, and the environment changes more frequently. The diversity ofEuryarchaeota was various in different sites. Based on the results of the PCA: thedistribution of MG Ⅱ, VAL Ⅲand MBG B in the three site was highly consistent, and thedistribution of MCG, MBG E, Methanosarcina, MBG D in three sites were clinged toconsistency, and tended to distribute in DH18. The results of RDA showed that the impactof TC and TIC content on archaeal community structure is much smaller than the content ofTP and TN. TN had a positive effection on the distribution of MBG D and TP had a positveimpact on the distribution of MCG.Eukaryotic microorganisms included Protozoa, Fungus, multicellular eukaryoticmicroorganisms and a small amount of Algae, in which protozoa, fungal were predominantin this area. The three sites had a high eukaryotic microbial diversity, DH13had the highestdiversity index, followed by DH18, and diversity of DH9was lowest.This reflected that thediversity of eukaryotic microorganismin in estuarine areas near the coast of East China Seacontinental shelf sediments was low, as far from the shoreline sediments, diversitygradually increased. According to the statistics of the three sites, protozoa tended to appearmainly in shallow sediments, and fungi and part of multicellular microorganisms mainlywere found in relatively deep sediment layers. From the results of PCA, the distribution of fungi and algae in the three sites were close and clones were primarily obtained from DH9.The clones of multicellular eukaryotic microbes were mainly found in DH13, and protozoawere mainly from DH13and DH18.The result of RDA reflected that TC, TIC, TN, TP allhad a great impact on the distribution of eukaryotic microbes. The content of TC was moreapparently correlation with the distribution of multicellular eukaryotic microbes and fungi;The content of TN was negatively correlated with distribution of algae, and TP have asignificant negative correlation with multicellular eukaryotic microorganisms. Thisrevealed that multicellular eukaryotic microorganisms and algae tended to use carbon inthis region, concentration of nitrogen and phosphorus content at this level had an adverseeffect on them. |
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