Fish diversity analysis of artificial lakes in karst plateau based on eDNA metabarcoding technology

【Objective】 To investigate fish diversity of artificial lakes in karst plateau using eDNA metabarcoding technology and to comprehensively assess effects of environmental factors on fish distribution, so as to provide new methods and perspectives for fish diversity assessment in waters of karst area and accumulate basic information for the formation of fish conservation management measures in Hongfeng Lake and Aha Lake.【Method】 Water collected from Hongfeng Lake and Aha Lake were taken as representative samples. eDNA was amplified by PCR with Tele 02 universal primers for teleost fish and high-throughput sequencing was completed on Illumina NovaSeq 6000 sequencing platform;OTU clustering was performed and OTUs tables were generated for high-quality sequences according to 98% similarity, and then fish species information was obtained by gene annotation. PerMANOVA analysis and redundancy analysis(RDA) were performed with R language.【Result】 Thirty-two species of fish were identified in Hongfeng Lake, belonging to 27 genus, 11 families of 5 orders, including 18 species of Cypriniformes fishes, and the difference in fish community structure between the south and north lakes of Hongfeng Lake was not significant(R²=0.08, P=0.562>0.05);33 species of fish were identified in Aha Lake, belonging to 28 genus, 12 families of 6 orders, including 18 species of Cypriniformes fishes, and the difference in the total number of fish detected at each sampling site was not significant. The total number of fish detec-ted at each sampling site did not vary significantly, remaining at 28-32 species. At present, the fish composition of Hongfeng Lake and Aha Lake was mainly Cypriniformes fish, but an ecological invasion of farmed fish, mainly Centrarchiformes fishes was found. Determination coefficient(R²) of the differences between environmental factors and fish community structure in Hongfeng Lake was dissolved oxygen(DO) >total dissolved solids(TDS)=water temperature(WT) >pH>ionic ammonia(NH₄⁺), and DO(P=0.034) was the main environmental factor causing the differences in fish community structure at each sampling site in Hongfeng Lake;determination coefficient(R²) of the differences between environmental factors and fish community structure in Aha Lake was TDS>WT>Tra>NH₄⁺+>DO, and TDS(P=0.005) was the main environmental factor causing the difference in fish community structure among the sampling sites in Aha Lake.【Conclusion】 At present, the fish composition of Hongfeng Lake and Aha Lake is dominated by Cypriniformes fishes, but an ecological invasion of farmed fish, mainly Centrarchiformes fishes is found. eDNA metabarcoding technology has excellent adaptability in karst plateau waters fish diversity evaluation, thus it can quickly monitor the fish community structure and spatial distribution, but universal primers may have amplification preference for some fish;in addition, different artificial lakes are more specific in terms of water physical and chemical factors, therefore, relationship between environmental factors and lake fish communities should be evaluated separately for each lake.