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Updated: May 22, 2026

Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems
Published on: July 30, 2019
Functional traits mediate the effects of habitat changes and fishing on the trophic structure of river fish
Daikui Li1, Yi Yujun1, Zhenyao Shen2
1State Key Laboratory of Regional Environment and Sustainability, School of Environment, Beijing Normal University, Beijing, 100875, China; Key Laboratory of Water and Sediment Science of Ministry of Education, School of Environment, Beijing Normal University, Beijing, 100875, China.
Abstract:
Changes in habitat and human activities in dammed rivers lead to fish community restructuring and shifts in trophic structure related to material and energy cycling. However, how environmental factors influence fish trophic structure remains largely unknown. The causal pathways through which functional traits mediate these effects are also unclear. This study assesses changes in trophic structure of fish communities in the Three Gorges Reservoir and its downstream reaches over the past 30 years. We employed an "environment-trait-trophic structure" framework to explore the influence pathways of two major stressors on trophic structure, focusing on the role of species traits as a mediating factor. Our findings reveal that fish trophic structure underwent dramatic changes early in reservoir impoundment. However, during the later phase of impoundment (reservoir aging period), trends diverged significantly between the reservoir and downstream reaches. Both the reservoir and downstream reaches showed increased trophic diversity. Trait-based analysis identified water surface slope and sediment concentration as key environmental factors affecting trophic structure in the upstream reach. These factors mediate effects by altering the dominance of rheophilic (or benthic) and migratory species. In the downstream reach, fishing pressure and sediment concentration were the main influencing factors, mediating their effects by altering the dominance of rheophilic and migratory species. These results indicate that trophic structure is shaped by distinct mechanisms in reservoir versus natural-flow reaches: fishing pressure dominates downstream, whereas impoundment effects override it in the reservoir. This study highlights the utility of species traits in linking multiple environmental stressors to community trophic structure.
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