Date: August 19, 2026
Lanzhou, China: Traditional capture-based fish surveys face great obstacles in mountain rivers with dense cascade hydropower facilities due to complex terrain and harsh hydrological conditions. In this study, researchers conducted systematic environmental DNA (eDNA) metabarcoding investigations across the Bailong River, a typical cascade-dammed mountain river on the boundary of the Tibetan-Loess Plateau. A total of 351 water samples were gathered from 60 sampling sites in summer (high-flow) and winter (low-flow), covering reservoirs, drawdown zones and tailwater segments of 20 hydropower stations.
The molecular survey identified 97 fish species belonging to 12 orders, 29 families and 71 genera, including 14 IUCN threatened fish taxa. Although species detection rates were comparable between summer and winter, MOTU abundance showed significant seasonal divergence. Fish-diversity indices correlated with longitudinal river distance, yet spatial patterns were strongly modulated by seasonal shifts: significant linear correlations occurred in summer, while only fluctuating nonlinear trends were observed in winter. By contrast, fish community composition exhibited no statistically significant differences among three dam-derived habitat types. Notably, datasets hinted at a potential fish miniaturization trend within local assemblages.
This work validates eDNA metabarcoding as a powerful non-invasive monitoring tool for highly modified mountain river ecosystems. It supplies the most comprehensive fish-biodiversity baseline for the Bailong River basin. Researchers suggest prioritizing tributary confluences and tailwater reaches as aquatic conservation redlines and advocate seasonal adaptive dam operations. The study offers replicable methodological references for biodiversity assessment in other cascade-impacted river systems worldwide.
Original Source
Jiang, Y. Zhang, C. Jiang, Z. Su, T. Wang, and Y. Du, "Spatio-Temporal Assessment of Fish Biodiversity in High-Density Cascade Dam Rivers Using Environmental DNA Metabarcoding," Biological Diversity (2026): 1–11.
https://onlinelibrary.wiley.com/doi/10.1002/bod2.70033
Keywords
cascade dam rivers, environmental DNA, fish diversity, habitat, spatial, temporal
About the Author
Tai Wang (Corresponding author): Research Professor at Gansu Fisheries Research Institute, Director of Gansu Key Laboratory of Cold Water Fishes Germplasm Resources and Genetics Breeding. His main research focuses on the monitoring and assessment of aquatic biodiversity in the northeastern Qinghai-Tibet Plateau, as well as germplasm resource evaluation and adaptive evolution of rare and endangered fish species.
About the Journal
Biological Diversity (ISSN: 2994-4139) is a peer-reviewed, international, open-access journal sponsored by the South China Botanical Garden, Chinese Academy of Sciences ((SCBG, CAS), and published in partnership with John Wiley & Sons Australia, Ltd. It is dedicated to advancing biodiversity conservation, safeguarding ecosystem functions and services, and promoting the sustainable utilization of biological resources under global environmental change. The journal welcomes original research, reviews, commentaries, and short communications across a broad spectrum of disciplines, including botany, zoology, microbiology, taxonomy, phylogenetics, genomics, cytology, ecology, climatology, economics, sociology, and real-time policy theory. The journal is indexed in Chemical Abstracts Service (CAS) and Directory of Open Access Journals (DOAJ).
