Study On Community Structure And Influencing Factors Of Plankton Bacteria In Ningxia Section Of Yellow River Basin

Water is the source of life of all living things,human survival and development can not be separated from water resources.However,due to the unbalanced development of social economy,the degradation of water ecosystem is serious.The Yellow River is very important for the livelihood of Ningxia residents,sustainable economic development and ecologlical civilization construction.In order to explore the water ecological environment status of the Ningxia section of the Yellow River Basin,the Ningxia section of the Yellow River Basin was divided into nine river systems:Weining Section main stream,Qingshi Section main stream,Weining Section tributary(Qingshui River),Qingshi Section tributary(Wushui River),Weining Section left bank river system,Weining Section right bank river system,Qingshi Section left bank river system,Qingshi Section right bank river system and urban river and lake system.A total of 95 sampling points were set Sampling and analysis of water environmental factors and plankton bacteria in the Ningxia section of the Yellow River Basin were conducted in April,July and October 2021,to study the spatio-temporal distribution characteristics of water environmental factors in the Ningxia section of the Yellow River Basin,and to explore the spatio-temporal heterogeneity of water environmental factors in the Ningxia section of the Yellow River Basin in different seasons.To study the community structure,diversity and spatial and temporal distribution characteristics of plankton bacteria in Ningxia section of the Yellow River Basin,explore the differences in the community structure and diversity of plankton bacteria in different seasons in different river systems,and analyze the main factors affecting the community structure of plankton bacteria.The main results are as follows:(1)The water environmental factors in the Ningxia section of the Yellow River Basin have a certain spatial and temporal heterogeneity.The water temperature(WT)in summer was significantly higher than that in spring and autumn.The total nitrogen(TN)and nitrite nitrogen(NO2-N)in autumn were significantly higher than those in spring and summer.Ammonia nitrogen(NH4+-N)was significantly lower in autumn than in spring and summer.Spatially,the water systems are different The electrical conductivity(EC),salinity(Sal),total dissolved solids(TDS)and fluorine ion(F-)levels are in the order of tributary>drainage ditch,urban river>main stream.The concentrations of Ch1 a and permanganate index(CODMn)were ranked as tributaries,drains,urban rivers and lakes>main streams.(2)The main bacterial phyla in the Ningxia section of the Yellow River Basin were Proteobacteria,Actinomyces,Bacteroidetes,cyanobacteria,Firmicutes,unmentionates,verrucobacteria and Campylobacter.The main bacteria were Flavobacterium,Limnohabitans,Rhodoferax,unidentified_Chloroplast,Pseudomonas,CL500-29_marine_group,hgcI_clade and Candi datus_Aquiluna and Hydrogenophaga.The bacterial community structure in the Ningxia section of the Yellow River Basin has certain temporal and spatial characteristics.(3)The diversity of plankton bacteria in the Weining section of Ningxia River Basin was higher than that in Qingshi section.The diversity of plankton species in Qingshuihe River was higher than that in Kusui River.The species diversity of the left bank of Weining member was higher than that of the left bank of Qingshi member,and the species diversity of the right bank of Weining Member was higher than that of the right bank of Qingshi member.The species richness,species diversity and phylogenetic diversity of the Ningxia section of the Yellow River Basin showed certain seasonal changes.(4)Species richness decreased significantly with WT increasing in the Weining section of Ningxia River Basin;The positive effects of F-and negative effects of Cl-on species richness were observed in the Qingshi Section.The species richness of Qingshuihe River decreased with the increase of pH.When Sal reaches a certain value in the range of 3.86-4.55ppt,it will inhibit the growth of planktic bacteria in the Mizui River.The abundance of plankton bacteria in the left bank drainage of Qingshi Member decreased with the increase of DO.The phytoplankton abundance in the right bank of the Qingshi Member decreased with the increase of Chl a NO2-N was positively correlated with species richness in urban rivers and lakes.Seasonally,the phytoplankton community structure in Weining Section was mainly affected by N and P nutrients in spring and autumn,and WT and Chla in summer.In summer,the plankton community structure of the bluestone segment was related to TN.The tributaries were mainly affected by N and P nutrients in spring,summer and autumn.NH4+-N was the main factor affecting the bacterial community structure in spring.WT and F-significantly affected the phytoplankton community structure in urban rivers and lakes in summer.