Summary
This study employs environmental DNA metabarcoding to evaluate how cascade hydropower development affects fish communities in the Ganjiang River, China's largest Yangtze tributary. Sampling across 19 sites in wet and dry seasons revealed significantly lower species richness upstream of dams compared to downstream reaches, with fish assemblages strongly influenced by environmental parameters including temperature, oxygen, and nutrients. The findings underscore eDNA metabarcoding as a non-invasive tool for freshwater biodiversity assessment and highlight the importance of considering multiple spatial scales when evaluating ecological impacts of human infrastructure on aquatic ecosystems.
Regional applicability
The methodological approach is directly transferable to United Kingdom river systems; however, the specific ecological findings are contextual to tropical/subtropical Asian hydrology and biodiversity patterns. The cascading dam impact model may have limited applicability to UK hydropower contexts, where river systems typically have fewer dams and different flow regimes, but the eDNA metabarcoding protocol and spatial-scale framework could inform UK freshwater biodiversity monitoring and water resource planning.
Key measures
Fish species richness, community composition, diversity indices via eDNA metabarcoding; water temperature, pH, dissolved oxygen, nutrient concentrations; spatial and seasonal variations across 19 sampling sites
Outcomes reported
The study assessed spatiotemporal patterns of fish diversity and community structure in relation to cascade hydropower development, revealing lower species richness and distinct assemblages in impounded sections upstream of dams compared to downstream reaches. Fish communities were influenced by environmental factors including water temperature, pH, dissolved oxygen, and nutrients, with dam impacts most pronounced at local but also detectable at regional scales.
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