Application Of Environmental DNA Technology In Fish Resources Investigation In The Upper Reach Of Liuchong River

In this study,in April,July,September and November 2019,the traditional fish resources survey method and environmental DNA(environmental DNA,eDNA)technology was used to upstream the Liuchonghe Jiayan Hydropower Station(SP,HMC,SHQ,QXGDQ)and downstream(YJL,XMK)6 sampling points for fish resources survey,with a view to providing background information for the composition of fish resources under the dam above the dam after the formation of the reservoir at the Jiayan Hydropower Station;the applicability and reliability of fish resources survey and provide basic data for the protection and utilization of fish resources in the upper reaches of the Liuchong River.The results are as follows:1.Analysis of the composition of catches in Liuchong RiverThis study used traditional fish resources survey methods to investigate fish resources at 6 sampling points in the upper reaches of Liuchong River from SP to XMK.Due to terrain and other factors,SP and YJL did not collect catches.SP ? XMK 6sampling points respectively collected 0 species,26 species,13 species,4 species,0species,and 31 species of fish.There are 45 species of fish belonging to 38 genera and11 families in 5 orders,of which the Cypriniformes form has the largest proportion,accounting for 68.89% of the total sample.The Simpson ecological dominance index of HMC,SHQ,XMK sampling points is 0.09 ? 0.34,Shannon diversity index is 1.74 ?4.01,Margalef richness index is 0.65 ? 4.87,Pielou evenness index is 1.14 ? 1.26,and the species distribution is all More evenly.In addition,the 45 kinds of catches collected this time were based on the 86 species of fish in the Liuchong River recorded in "Fish Records of Guizhou" s,and the detection rate of the whole basin was 44.19%.2.Using environmental DNA technology to investigate the fish resources in the upper reaches of Liuchong RiverA total of 64 fish species of 51 orders,51 genera and 5 orders in 5 orders were detected by eDNA technology in the four fish resources surveys in the upper reaches of Liuchong River from SP to XMK.Among them,37 species,27 species,32 species,and46 species of fish were detected in April,July,September,and November,respectively,and the Cypriniformes form accounted for the largest proportion in each test result.The Shannon diversity index,Margalef species richness index,Pielou evenness index,and chao1 richness estimation index of the whole watershed all reached the highest in November,and the Simpson ecological dominance index was the smallest.Among them,the Margalef species richness index,chao1 richness estimation index All of them were significantly greater than November,April,July and September(P <0.05).The annual fish species detected at each sampling point were 35,33,34,43,35,and 44 species,of which the carps were the largest,accounting for 63.64% ? 69.70% of the total sample.There was no significant difference in the annual Margalef species richness index and chao1 richness estimation index between the sampling points(P>0.05),while the SP 's annual Shannon diversity index and Pielou evenness index were significantly lower than SHQ and QXGDQ(P<0.05).),Simpson's ecological dominance index is significantly higher than that of SHQ and QXGDQ(P <0.05).51 of the 64 fish species detected by eDNA are documented and harvested in the Liuchong River,and the remaining 13 species without literature and catch fishing records are mostly caused by farming escape and farming water discharge.The type detected.In addition,China's aquaculture species and imported species have spread into the Liuchong River Basin.Taking the 86 species of fish in the Liuchong River recorded in "Fish Records of Guizhou" as a reference,the detection rate of the whole basin is56.98%.3.Comparative analysis of two fish resources survey methodsIn this study,when investigating the fish resources of Liuchong River by traditional fish resources survey methods,SP and YJL failed to collect the catch due to the terrain,etc.,but eDNA technology only needs to take water for detection and is not subject to geographic And other factors.The fish data obtained by these two methods are mainly Cypriniformes,Siluriformes and Perciformes.In terms of detection rate,the detection rate of eDNA technology(56.98%)is higher than the detection rate of traditional fish resource survey methods(44.19%);in fish identification methods,traditional fish resource survey methods mainly use morphological identification methods.Fish are classified,and eDNA technology is to identify species from the genetic level,which is more accurate and faster than traditional fish resource survey methods.Traditional fish resource survey methods are time-consuming and laborious,and eDNA technology is superior to traditional fish resource survey methods in terms of sensitivity,detection rate,and species identification.It has a very broad application prospect in fish resource survey.