The Influence Of Virus On Marine Ecosystems:Data Analysis And Ecosystem Modelling Study

Viruses are the most abundant biological entities in the ocean.They infect marine bacteria and other organism and play an important role in marine microbial food webs.The dynamics of the virus-host interactions are able to affect the nutrient cycling and energy transfer in marine microbial loop via affect abundance and diversity of the host community.Researches of control factors for virus distribution are limited in worldwide.Also viruses are sometimes neglected and only a few attempts have been made to model the' details of bacterial and phytoplankton viral-induced cell lysis.So we collected large amounts of marine virus data and used a complex viruses-bacteria relationship to modeling microbiological ecosystem.The main finding are:1.Through univariate linear regression analysis,we find the main environmental factors on the controls of virus distribution in the epipelagic zone(above 200m)are salinity,bacterial abundance,phosphate.In the deep waters(below 200m),the main factors are bacterial abundance and temperature.There are correlations between virus-to-bacteria ratio(VBR)and environmental factors in epipelagic zone,but most of the correlations are weak or even statistically insignificant.In the deep waters(below 200m),Temperature and salinity can affect the global VBR distribution.Through multiple linear regression analysis,Environmental factors cannot effectively predict the distribution of global VBR.2.The on-board culture experiments with controlled temperature using these samples showed that the rates of both viral production(VP)and viral decay(VD)increased with temperature,with the change of VP more than that of VD.Based on these data,we established a virus-bacteria model.Our results indicate that the turnover rate of marine viral pool and so that the marine biogeochermical cycles may accelerate with global warming in the future.3.We successfully modeled virus in environmental conditions with variable bacterial mortality and virus module improves simulation in marine bacteria dynamics.Compared to no-virus model,we find the virus model has higher viral-induced bacterial mortality rate in euphotic layer and lower in Secondary surface layer.In this condition,bacterial abundances are smaller in EU and bigger in secondary surface layer.Also refractory dissolved organic carbon(RDOC)production rate,particulate organic matter(POM)sinking rate and f-ratio in virus model are higher than no-virus model.