Temporal And Spatial Variation Of Fish Community And River Health Assessment In Lipu River

The Lipu River originates from the North of Lao Mountain in the Jinxiu County,and it flows into Guijiang River after confluence with Gongcheng River and Lijiang River in Pingle County.The study of fish resources in the Lipu River is of great significance to freshwater fish resources in the Guangxi region.Fish in the Lipu River were collected at 11 sampling sites in this study quarterly which aimed to understand the temporal and spatial variations of fish species composition and diversity in Lipu River.Then the index of biological interity based on fish was established,which was to assess the river's health in Lipu River,which is aiming to provide basic data for the study of fish resources in Guangxi and to provide a scientific basis for the protection and management of Lipu River.Main research results were as follows:(1)A total of 21,192 fishes were collected in January,April,July and October 2017,Which was indentified to 94 species,belonging to 6 orders,17 families and 62 genera.Among them,there were Cypriniformes was the most abundant fish(3 Families,61 species,17177 individuals),and followed bySalmoniformes(1 families,1species,1500 individuals),Perciformes(7 families,18 species,1348 individuals),Siluriformes(3 families,10 species,1055 individuals),Synbranchiformes(2 families,3 species,98 individuals),;Cyprinodontiformes(1 families,1 species,14 individuals).The fish in Lipu River tends to be miniaturized.All individuals with less than 50g of fish biomass accounted for 80.23%of the total catch weight,and the fish individuals with individual biomass less than 50g accounted for 98.60%of the total number of fish catches.In addition,only 3 fish individuals with individual fish biomass greater than 300g were collected,accounting for 0.01%of the total number of fish catches.(2)The results of the relative importance index showed that the dominant species in Lipu River during the whole year were Zacco platypus,Opsariichthys bidens,Hemiculterella wui,and Cyprinus carpio.The value of relative importance index of Zacco platypus was 2685(greater than 2000),which was a significant dominant species of the fish community throughout the year,and 3,912 individuals were captured throughout the year,accounting for 18.46%of the total catch of the year.(3)The temporal variations of fish species diversity in Lipu River were unobvious.The Margalef richness index(Dma)was the highest(7.47)in Spring and the lowest(7.18)in Autumn,and the Shannon-wiener diversity index(He')(3.11)and Pielou evenness index(Je')(0.75)in Autumn were slightly higher than those in other seasons.The Simpson dominance index(?)in were the highest Summer(0.1),while it was the lowest in winter(0.08).The spatial variation of fish species diversity in Lipu River were more obvious.The Margalef richness index(Dma)was the highest in Qingshan town(7.14),while it was the smallest in Duomo town(2.40).The Shannon-wiener diversity index(He')and Pielou evenness index(Je')were the highest in Lipu county(2.94 and 0.76),while they were the lowest in Chacheng country(0.65 and 0.22).The resluts showed the fish diversity was the highest in Lipu county,while it was the lowest in Chacheng country.The Simpson dominance index(?)was the highest in Chacheng country(0.74),while it was the lowest in Lipu county(0.08).(4)The analysis results of the non-metric multidimensional scaling(NMDS)and one-way ANOSIM test showed that the fish community in Lipu River had no significant differences among different seasons(P>0.05),but there were significant differences among the sampling sites(P<0.05).There was little difference among the sampling sites in the main stream of Lipu River,while the fish communities in the the main stream were quite different from those in the tributaries.(5)The index of biological integrity based on fish was established in Lipu River.Taking S1(Xiuren town),S10(Malingtown),and S11(Shuangjiang town)as reference sites,five metrics including species richness,Shannon-Wiener's diversity index,percentage of carnivorous fishs,percentage of sensitive fishs,percentage of floating egg fishes were selected from twenty-five candidate metrics by stepwise selection methods,such asdistributing range analysis,discriminatory power analysis and pearson's correlation analysis.The health status of Lipu river was classified into 5 categories,including "Health","Fair","Poor","Very Poor" and "No fish".The results showed that Qingshan town,Lipu county and Pulu country were "fair",and Dongchang town,Longhuai country,Dumo town and Xinping town were "poor" and Chacheng country was "very poor".