Vertical Microbial Structure and Network Interactions in the High Dam Reservoir in the Upper Yangtze River
In the upper reaches of the Yangtze River,a series of high dams with large reservoir have led to unique vertical stratifica-tion of water properties such as light,temperature,and oxygen,causing changes in the vertical micro-food web structure.This study focuses on the vertical habitats before typical high dams with large reservoir in the upper reaches of the Yangtze River,name-ly Xiluodu,Xiangjiaba,and Three Gorges Dams.Water samples were collected vertically before the dams at five different depths in 2019 to investigate the characteristics of the vertical habitats and the microbial community structure.The study found that Xiluodu Reservoir experienced dissolved oxygen concentration from 90 m to 140 m in July decreased first and then increased.The Xiluodu Reservoir experienced temperature jump in May at a distance of 40-60 m from the surface of the water body,and in July at a dis-tance of 80-120 m from the surface of the water body.Differences in species composition and abundance were not significant among different depth layers,but Shannon diversity varied,decreasing and then increasing from the surface to the bottom layers.Cyanobacteria abundance varied significantly with depth.Co-occurrence network analysis showed mainly positive interactions among microorganisms at different depths,with the second layer having the highest modularity and complexity.The interaction be-tween algae and bacteria,between algae and protozoa,and between bacteria and protozoa were the main type of interaction between aquatic ecosystem microfood webs,accounting for 81.50%of the total interaction between species.The study indicates that the structure of the vertical micro-food web and species interactions at different depths in frond of the dams vary under the influence of environmental factors such as temperature and dissolved oxygen concentration.
high dam and large reservoirupper Yangtze Riververtical habitatmicrobial-food webcommunity structurenetwork interactions
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