The Recovery of Predators Modulates Prey Community Organization Through Concomitant Changes in Aquatic Trophic Networks

Aim Restoring predator populations can generate cascading effects on their prey by reshaping ecosystem food webs, yet its consequences for prey community organization and multi‐trophic dynamics remain poorly understood. We aimed to evaluate how native predator recovery shapes prey biodiversity, assembly processes, and trophic dependencies, and to identify the ecological mechanisms linking predator restoration to conservation outcomes. Location Huishui River, a tributary of the Yangtze River Basin in China, which is subject to the national basin‐wide “10‐year fishing ban” policy that has substantially increased native predatory fish populations. Methods We analysed a multi‐year time series of stream fish and aquatic insect communities sampled from 2021 to 2025. α‐ and β‐diversity were quantified taxonomically, functionally, and phylogenetically. Community assembly was assessed using null models, and multi‐trophic interactions were inferred via spatial dependency network modelling incorporating predator incidence and prey body size. Results Predator recovery enhanced aquatic insect diversity at local and regional scales, increasing α‐diversity and promoting greater spatial turnover among sites. These patterns indicated predator‐mediated competitive release, whereby predatory fish may preferentially target abundant and competitively dominant prey, allowing coexistence of more functionally dissimilar and evolutionarily distant taxa. High predation pressure may have drastically reduced overall prey abundance and community size, thereby weakening deterministic assembly signals, increasing demographic stochasticity, and potentially counteracting priority effects at local scales—processes likely contributing to greater spatial heterogeneity among stream sites. Multi‐trophic modelling revealed that fish trophic influence on insect communities intensified with predator incidence and was strongly structured by prey body size. Main Conclusions Rebuilding predator populations can restructure prey biodiversity and trophic networks in ways that enhance ecological heterogeneity and potentially strengthen ecosystem resilience. Our findings highlight top‐down pathways through which predator restoration impacts community assembly and cross‐trophic interactions, offering new insights relevant to conservation biogeography, freshwater restoration, and biodiversity management under global change.