Fish Diversity In Artificial Lakes In Karst Plateau Based On Environmental DNA Metabarcoding Technology

The karst region of southwest China,centered on the Guizhou plateau,is one of the three major karst concentration areas in the world.The unique geographical environment of the karst plateau makes the organic matter and nutrient conditions of the lakes in this region different from other waters.During the past decades,the water ecology of the region had undergone great changes,such as river fragmentation,eutrophication of water bodies,and biological invasion of exotic species,which had affected the indigenous fish populations in the region to different degrees.In order to protect the fish diversity in the region and develop corresponding fish conservation and management measures,it is urgent to map the characteristics and the current status of fish communities in the karst plateau.In this study,the e DNA metabarcoding technology was used to explore the fish diversity of artificial lakes in the karst plateau,taking Wanfeng Lake,Hongfeng Lake and Aha Lake as representatives,and the main findings are as follows:(1)39 fish species belonging to 9 orders,13 families and 32 genera were monitored in Wanfeng Lake by e DNA metabarcoding technology,including a total of 20 species of Cypriniformes.Theαdiversity index of each sample site varied widely,with 17-27species of fish in each sample site.There were 31 fish species and no endemic fish in the upper basin section of Wanfeng Lake,30 fish species and 1 endemic fish in the middle basin section,and 36 fish species and 5 endemic fish in the basin section of the reservoir area,with significant differences in fish community composition among the basin sections of Wanfeng Lake(R~2=0.22,P<0.01).Dissolved oxygen(P<0.01)and p H(P<0.05)were the main environmental factors causing differences in fish community structure at each site of Wanfeng Lake.(2)32 fish species,belonging to 5 orders,11 families and 27 genus,including 18species of Cypriniformes,were monitored in Hongfeng Lake by e DNA metabarcoding technology.The variation ofαdiversity index was small at each sample site,with 28-30 species of fish in each sample site.In the south lake of Hongfeng Lake,32 species of fish were monitored,and 2 species of endemic fish;in the north lake,30 species of fish were monitored,and there was no endemic fish;the difference in fish community structure between the south and north lakes of Hongfeng Lake was not significant(R~2=0.08,P>0.05).Dissolved oxygen(P<0.05)was the main environmental factor causing the difference in fish community structure at each site of Hongfeng Lake.(3)33 fish species belonging to 6 orders,12 families and 28 genus were monitored in Aha Lake by e DNA metabarcoding technology,including 18 species of Cypriniformes.The variation ofαdiversity index at each sample site was small,with28-32 species of fish monitored at each sample site.Total dissolved solids(P<0.01)was the main environmental factor causing the difference in fish community structure among the sites in Aha Lake.(4)In Wanfeng Lake,e DNA signals of 1 undetermined species of the genus Acipenser,1 undetermined species of the genus Channa,1 undetermined species of the genus Oreochromis,Siniperca scherzeri,Oreochromis niloticus,and Clarias gariepinus and other economic fish were monitored;in Hongfeng Lake,e DNA signals of 2 undetermined species of the genus Siniperca,Micropterus salmoides,Siniperca chuatsi,Neosalanx taihuensis.,Protosalanx chinensis,Hemibagrus guttatus and Silurus meridionalis and other economic fish were monitored,and it should be emphasized that the Culter erythropterus,Parabramis pekinensis,Magalobrame tarminalis,Misgurnus anguillicaudatus,and Monopterus albus,which were monitored in the two fish resource surveys in Hongfeng Lake in 1982 and 2011 were not monitored in this study;1 species of undetermined fish of the genus Channa and 2 species of undetermined fish of the genus Siniperca were monitored in Aha Lake,and the e DNA signals of various economic fishes such as Micropterus salmoides,Siniperca chuatsi,Neosalanx taihuensis,Protosalanx chinensis,Hemibagrus guttatus and Silurus meridionalis were detected;the fishes in the three lakes were mainly Cypriniformes,and a variety of exotic fish were monitored in all three lakes..(5)This study showed that e DNA metabarcoding technology can rapidly detect and analysis the fish community structure and spatial distribution of artificial lakes in karst plateau.The main environmental factors affecting fish community structure in the three lakes were different from each other.Therefore,each lake should be evaluated individually when studying the relationship between environmental factors and fish communities in artificial lakes in karst plateau.