Vibrio Abundance And Diversity Associated With The Different Environmental Condition In The Eastern Coastal Water Of China

Vibrio is indigenous to the marine environment even though environmental cues regulate its growth and distribution.Many of the species or strains of this genus are pathogenic to humans and other organisms and,thus,have drawn attention.Moreover,evidence shows that their impact may be increasing due to changing environmental conditions.In this thesis,Vibrio dynamics in two distinct regions on the east coast of China,the Luanhe river estuary coast in Qinghuangdao(a temperate region)and the Daya bay coast in Shenzhen(a tropical region),are investigated in relation to different environmental parameters in different seasons.These are the two most densely populated coastal areas in China,which are currently experiencing rapid environmental changes.Quantitative polymerase chain reaction(q PCR)and Vibrio spp.16 S r RNA amplicon sequencing were employed to observe significant seasonal variation in the abundance and composition of the Vibrio community respectively.The trends of abundance of Vibrio spp.in two regions under study are similar: in summer,the increase in temperature,water pollution level due to nutrient contamination and the decrease in dissolved oxygen and salinity enable the high proliferation and abundance of Vibrio;in winter,the decrease in temperature,water pollution levels due to nutrient contamination and increase in dissolved oxygen and salinity inhibit its proliferation,leading to its low abundance.Moreover,prediction model for Vibrio spp.levels in the Luanhe estuarial coast reveals strong relationships with the concentration of total phosphorus and silicate concentrations,while Daya bay exhibits a strong correlation between Vibrio spp.levels and salinity.Besides,in both sites,higher nutrient pollution levels near the estuary lead to higher Vibrio abundance than the offshore.Overall,the results suggest that freshwater influx is primarily responsible for the nutrient load,which favors the survivability of Vibrio spp..The semi-enclosed continental sea in both sites may influence the correlation between Vibrio spp.abundance and similar environmental parameters.Conversely,the predictive models of Vibrio spp.in this two regions reveal different responses of Vibrio spp.to environmental factors in temperate and tropical zones in this study.These provide the understanding in attenuating the effect of abundance and distribution of Vibrio spp.on water quality in estuary and coastal water,and water management and public health protection.