Particle size shapes the prokaryotic microbial communities in mangrove sediments:A case study of Sanya,China

The prokaryotic microbial communities in the sediments play crucial roles in the ecological functions of mangrove ecosystems.Therefore,the environmental factors that affect the structures of these prokaryotic microbial communities could indirectly participate in the regulation of mangrove functions,which is of great value for mangrove studies.The particle size(PS)of soils is recently demonstrated as a key environmental factor for shaping the microbial communities;however,this hypothesis has rarely been tested for mangrove environments.A case study of three tropical mangroves from Sanya,China was performed in this work to assess the influence of PS on the prokaryotic microbial community structures of bacteria,archaea,diazotrophs,and denitrifiers in the sediments.Results showed the variability in the spatial scale and the stability in the temporal scale for the prokaryotic communities,indicating that the tropical mangrove sediments could be a versatile but stable environment.Among the collected environmental factors,PS,salinity,and humidity had the greatest impacts,and PS mostly affected the structures of these prokaryotic communities based on its highest R^2 values of canonical correspondence analysis,Mental test,and linear fitting(p≤0.05).Furthermore,PS was positively correlated with the diversity and abundance of diazotrophic communities and negatively correlated with the abundances of methanogenic communities including Methanobacteriaceae,Methanospirillaceae,Methanoregulaceae,and Methanosaetaceae.Former studies show the increasing trend of PS caused by the rise of sea level and the intensification of human activities.Therefore,our findings indicate that PS could be a potential intermediate that links climate change and human activities with the possible ecological function migration of mangroves;meanwhile,the increase of PS could in turn release the stress of these environmental changes by increasing the abundance and diversity of the diazotrophic community and decreasing the abundances of methanogens.

Effects of Biostimulation-Bioaugmentation on Coastal Microbial Community in an in situ Mesocosm System

Globally,various types of pollution affect coastal waters as a result of human activities.Bioaugmentation and biostimulation are effective methods for treating water pollution.However,few studies have explored the response of coastal prokaryotic and eukaryotic communities to bioaugmentation and biostimulation.Here,a 28-day outdoor mesocosm experiment with two treatments(bioaugmentation-A and combined treatment of bioaugmentation and biostimulation-AS)and a control(untreated-C)were carried out.The experiment was conducted in Meishan Bay to explore the composition,dynamics,and co-occurrence patterns of prokaryotic and eukaryotic communities in response to the A and AS using 16S rRNA and 18S rRNA gene amplicon sequencing.After treatment,Gammaproteobacteria and Epsilonproteobacteria were significantly increased in group AS compared to group C,while Flavobacteriia and Saprospirae were significantly reduced.Dinoflagellata was significantly reduced in AS compared to C,while Chrysophyta was significantly reduced in both AS and A.Compared to C,the principal response curve analyses of the prokaryotic and eukaryotic communities both showed an increasing trend followed by a decreasing trend for AS.Furthermore,the trends of prokaryotic and eukaryotic communities in group A were similar to those in group AS compared with group C,but AS changed them more than A did.According to the species weight table on principal response curves,a significant increase was observed in beneficial bacteria in prokaryotic communities,such as Rhodobacterales and Oceanospirillales,along with a decrease in autotrophs in eukaryotic communities,such as Chrysophyta and Diatom.Topological properties of network analysis reveal that A and AS complicate the interactions between the prokaryotic and eukaryotic communities.Overall,these findings expand our understanding of the response pattern of the bioaugmentation and biostimulation on coastal prokaryotic and eukaryotic communities.