Biodiv Sci ›› 2023, Vol. 31 ›› Issue (10): 23095.  DOI: 10.17520/biods.2023095

• Original Papers: Animal Diversity • Previous Articles     Next Articles

Spatial differentiation of fish functional groups in the Yangtze River

Anlun Wang1,2,3, Ping He1,2,3,*(), Xinyuan Long1,2,3   

  1. 1. Chinese Research Academy of Environmental Sciences, Beijing 100012
    2. State Environmental Protection Key Laboratory of Regional Ecological Processes and Functions Assessment, Beijing 100012
    3. State Key Laboratory of Environmental Criteria and Risk Assessment, Beijing 100012
  • Received:2023-03-31 Accepted:2023-06-29 Online:2023-10-20 Published:2023-07-22
  • Contact: *E-mail:


Aim: The composition of fish in large rivers exhibits longitudinal variation along the river influenced by environmental gradients. The River Continuum Concept revolutionized the understanding of river ecosystems by linking changes in river macro-invertebrate trophic functional groups to the differentiation of nutrient sources between upstream and downstream areas. The concept offers a novel framework for studying the distribution patterns of river biomes at large scale, from upstream to downstream. In this study, a dataset encompassing 168 species of fish were used, covering the entire range from Zhimenda, the starting point of the Jinsha River, to the estuary. Functional groups were first classified based on criteria such as body sizes, shapes, feeding habits, and life-history strategies. Subsequently, their distribution patterns as well as their adaptability to environmental factors were investigated across different scales.

Methods: A total of 14 functional groups and 59 combined function groups were classified, and 5 environmental factors were selected: elevation, mean temperature, mean annual temperature range, river width and river slope gradient. The distribution pattern of fish functional groups was analyzed using hierarchical clustering, while ordination analysis was applied to analyze the relationship between environmental factors and fish functional groups at different scales.

Results: The results revealed a primary and secondary differentiation in the distribution of fish functional groups within the Yangtze River: the primary differentiation occurs at Longkaikou, acting as the dividing point, while the secondary differentiation is observed at Shigu, Longkaikou and Downstream of Baihetan Dam. Moving from the upstream to the downstream, fish body sizes transition from small to medium and large, body shapes shift from predominantly fusiform and cylindrical to include compressform appearances. Feeding habits evolve from primarily omnivorous to encompass a more diverse range of feeding functional groups, and life-history strategies transform from opportunistic to periodic and equilibrium strategies. The distribution pattern of fish functional groups is a result of adaptation to spatial differentiation of environmental factors at different scales. Across the larger scale of the entire Yangze River, elevation and temperature, which are associated with climatic features, serve as dominant factors; whereas, as the spatial scale of the study shrinks, the influence of river slope drop associated with topographic features, becomes more prominent and plays the most important role in the I-1 river section at medium scale.

Conclusion: The distribution pattern of fish functional groups is direct outcome of the fish adaptation to environmental differentiation. Furthermore, the specific environment factors that determine the distribution of fish functional groups vary at different scales, consequently affecting the corresponding functional traits of the fish. This study contributes to our understanding of the river continuum theory, the spatial distribution pattern of fish in the Yangtze River, and the environmental adaptation characteristics of fishes.

Key words: the river continuum, the Yangtze River, fish functional groups, spatial differentiation