Abstract:

Aims: We used eDNA metabarcoding to detect fish diversity in three river systems of Beijing during summer and autumn. The aim of this study is to explore new methods applicable to monitor and protect fish diversity and study the spatio-temporal patterns of fish community in Beijing.
Methods: A total of 34 sites were surveyed simultaneously using the eDNA metabarcoding and ground cage methods. The main processes of the eDNA method are water sample collection and enrichment, DNA extraction with DNeasy Tissue and Blood DNA, PCR amplification with prism of MiFish-U, high-throughput sequencing by Illumina Miseq and bioinformatics analysis. The data of eDNA metabarcoding, environmental factors and human activity were used for statistical analysis between fish communities and influencing factors. The main processes of the ground cage with three replications were placed at each site waiting 24 h to be collected for species identification, and the species with number were recorded for subsequent analysis.
Results: The result showed that 55 fish species were detected by eDNA metabarcoding was higher than that captured by the ground cage (35 species). The fish community composition was dominated by Cypriniformes and Perciformes. The diversity of clearwater fish in mountain rivers is significantly higher than urban rivers. Urban rivers (the Beiyun River System) were dominated by pollution-tolerant species such as Carassius auratus, Pseudorasbora parva and Misgurnus anguillicaudatus, with a relatively homogeneous community structure. Mountain rivers (Chaobai River System and Daqing River System) are dominated by Zacco platypus, Rhynchocypris lagowskii and Opsariichthys uncirostris. The community structure of clearwater fish was affected by electrical conductivity and total dissolved solids in summer but by altitude and temperature in autumn. The correlation between the abundance of clearwater fish with environmental factors and human activities showed that the abundance of clearwater fish decreased significantly with the increase by turbidity of water and human activities, and was significant correlation with altitude and temperature.
Conclusion: The study used eDNA metabarcoding to show the diversity and spatio-temporal patterns of major rivers in Beijing, with a focus on the distribution of clearwater fish. The results demonstrate the feasibility of eDNA metabarcoding for monitoring fish diversity and spatial-temporal distribution in Beijing.

Key words: eDNA metabarcoding, fish community, clearwater fish, biodiversity, river