Study On Marine Microbial Community,Respiration Rate And Controlled Factors

The ocean plays an important role in global climate change,with the ability to absorb and store CO2.The ocean carbon cycle has captured our attention.Marine heterotrophic bacteria play a very important role in ocean carbon cycle with their metabolism activities.The respiration represents the consumption or flux of organic matter in the oceans,which is important for the accumulation of organic carbon in sediments or the output of carbon dioxide to the atmosphere.Respiration is essential for measuring the carbon balance in ecosystems.Thus,the study of marine microbe respiration provides a basis for us to better understand the carbon fluxes of marine ecosystems.The detection method of microbial respiration rate is developing now,and the control factors of the prokaryotic respiration rate has been confirmed.However,because of the different method,the research found that respiration rate has a different response to the environmental factors in various sea water ecosystems.There are still many unknowns about the relationship between the microbe respiration rate and its controlled factor.Therefore,the research of Marine heterotrophic bacterioplankton metabolic activity and the influenced factors of these microbial populations is essential for our understanding of carbon flux.To elucidate the ecological characteristics of marine microbes in different environmental conditions,Electron Transport System(ETS)activity measurement has gained acceptance as a routine technique to estimate the Microbial community respiration(MCR).Marine heterotrophic bacterioplankton diversity and its control factors were investigated in the Pearl River estuary.To show the result of different particle size microbe respiration rate in different layers and the effect of algal solution and the environment factor,we added the algal to the Aquatron simulation system.The different size(0.2?m and 0.8?m)MCR was studied in Aquatron Tower Tank for 40 days.At the same time,the bacteria abundance and environment factors in different layers were investigated.The results of the study are as follows:1?Our research showed the carbon flux in the south of South China sea(from the Pearl River to the open ocean)along the contrasting physicochemical characteristics.The overall distribution of marine microbe respiration in the northern South China Sea is characterized by decreasing from the near shore to the open ocean,from the surface to the bottom(except Seats station).To reveal the relationship between environmental conditions and microbes respiration,we studied the the relationship between respiration rate of microbes in the various stations.The respiration rate was positively correlated with the abundance of bacteria,chlorophyll,temperature,and negatively correlated with phosphate,dissolved oxygen,silicate and other abiotic factors showed a significant negative correlation in the northern South China Sea.2?From the coastal area to the open ocean we have got Bacteria and Archaea community and diversity in five stations in the South China Sea.This study found that bacteria and archaea species diversity distribution along the environmental gradient of the Pearl River estuary in South China Sea.We found that the key role for respiration rate of microbes is mainly contributed by the dominant taxa in the environment based on the correlation analysis of microbial abundance,taxonomic diversity and metabolic.The populations of the archaea mainly distributed in the surface seawater is MGII.MG? is the dominant group of the level below 200m in the ocean.The main dominant groups in the continental shelf area and the Depth of Chlorophyll Maximum(DCM)are MG? and MG?.In the surface layer of the continental shelf area was mainly contributed by the ?-and a-proteobacteria;in the deep seawater,the main group is a-proteobacteria and ?-proteobacteria and other groups.3?For the culture experiment,the Aquatron system overcomes the shortcomings of the"bottle experiment",simulates the process of particle organic matter sinking.We studied the influencing factors of the respiration rate of microbial groups under Aquatron culture conditions.The results showed that the 0.2MCR showed a significant positive correlation with the abundance and redox potential of the culture system in the Tower tank surface.0.2 MCR of the bottom and the abundance of bacteria showed significant positive Correlation.The positive correlation between respiration rate and microbial abundance,indicate that the contribution of main microbial population to the 0.2 MCR is heterotrophic microbes.The algae provide the source of organic matter for the respiration rate,and the effect of organic matter on microbial metabolism and abundance is more important.The 0.2MCR in the bottom is s,maller to the surface.Maybe the respiration in the surface influenced the bottom respiration.4.In summary,in the northern part of the South China Sea,the microbial respiration rate is mainly affected by microbial abundance,chlorophyll and temperature,and the main contribution to the respiration rate is the dominant group in this environment.Under the dark culture condition,the Aquatron system overcomes the shortcomings of the "bottle experiment" and simulates the sinking of particle organic matter.The results show that the organic particles are affected by the consumption of the upper prokaryotes in the sinking process.Respiratory rate is mainly controlled by microbial abundance.By comparing the respiration rate between the natural sea water and the simulated system,we found that microbial abundance has a positive correlation with the respiration rate,which is the main factor affecting the respiration rate.The difference is in natural sea water the respiration rate showed a positive correlation with temperature,but for the simulation system,the impact of temperature is not significant.This may be due to the relatively stable temperature of the simulation system,and the input of organic matter affects the microbial respiration rate.