Freshwater Fish Crisis: Biodiversity Loss Threatens Asian Ecosystems

Research conducted by the Chinese Research Institute of Environmental Sciences, with financial support from the Biodiversity Survey and Assessment Project of the Ministry of Ecology and Environment, China, has highlighted the alarming state of freshwater fish diversity in the Chishui River Basin of the Yangtze River, China. The study, which employed environmental DNA techniques to survey 52 sites, identified 77 species of fish belonging to six orders, 62 genera, and 18 families, with the dominant orders being Cypriniformes, Siluriformes, and Perciformes. The research found that the Shannon-Wiener and richness indices of the tributaries in the upstream section were significantly higher than those of the tributaries in the downstream section, indicating a decline in biodiversity.

Key Takeaways:

• The Chishui River Basin, a critical ecosystem in the Yangtze River system, is facing a significant threat to its freshwater fish biodiversity, with 96,031 valid fish sequences read and 77 species identified through environmental DNA techniques.
• The study revealed that the dominant orders of fish in the Chishui River Basin were Cypriniformes, Siluriformes, and Perciformes, with 71 native species, including 16 endemic fishes from the upper reaches of the Yangtze River.
• The research found a significant difference in biodiversity between the upstream and downstream tributaries of the Chishui River, with the Datong River being the most diverse secondary tributary.
• The study highlighted the influence of altitude and electrical conductivity on fish diversity in the Chishui River Basin.
• The researchers emphasized the need for continued efforts to protect freshwater biodiversity and additional research to understand the complex interplay between human activity and environmental factors.
• The study was conducted in collaboration with researchers from the State Key Laboratory of Environmental Criteria and Risk Assessment and was supported by the Biodiversity Survey and Assessment Project.
• The findings of the study have significant implications for the conservation of freshwater fish biodiversity in the Chishui River Basin and the Yangtze River system as a whole.

Statistics:

• 96,031 valid fish sequences were read from 52 sites in the Chishui River Basin.
• 77 species of fish were identified through environmental DNA techniques, with 71 native species and 6 exotic species.
• 16 endemic species from the upper reaches of the Yangtze River were identified.
• The Shannon-Wiener and richness indices of the tributaries in the upstream section were significantly higher than those of the tributaries in the downstream section.

Sources:

• Study On Fish Diversity and Drivers Based On Environmental Dna In Chishui River, China. Sustainability, 2025;17(11):4922.
• Chinese Research Institute of Environmental Sciences, State Key Laboratory of Environmental Criteria and Risk Assessment, Beijing 100012, People's Republic of China.