Eutrophication promoted the change of macrophyte community from R strategy to C strategy in Lake Taihu

• R-strategy macrophyte species dominated in Lake Taihu. • Increased eutrophication significantly reduced R-strategy ratio. • Submerged macrophytes adopted more flexible strategies compared to emergent and floating-leaved macrophytes. • Eutrophication influenced macrophyte traits and CSR strategies by affecting light availability more than nutrient levels. Functional traits effectively reflect plants’ ecological strategies in response to environmental changes. This study investigated how lake eutrophication influences macrophyte communities ecological strategies by analyzing leaf functional traits along the eastern littoral zone of Lake Taihu. Using Grime’s CSR framework (C: competitive; S: stress-tolerant; R: ruderal), we compared strategies among different macrophyte life forms (submerged, floating-leaved, and emergent) across a eutrophicaiton gradient. The study sites exhibited varying degrees of eutrophication (from mesotrophication to heavy eutrophication), with significant differences in nutrient contents and light availability. The macrophyte community was predominantly characterized by C and R strategies, with dominance shifting from R to C as eutrophication increased. Different life forms showed distinct responses: Submerged macrophyte transitioned from R to C strategies, floating-leaved macrophytes decreased C strategies proportion with increased S strategies while emergent macrophytes remained stable. Environmental factorss influenced community strategies indirectly through macrophyte traits, with C and S strategies negatively correlation with underwater light availability but positively with nutrient levels. while R strategy showed opposite correlations.This study revealed that reduced underwater light availability, rather than increased nutrient levels,was the primary driver of changes in macrophyte ecological strategies under eutrophication.