Effects of Eriocheir sinensis bioturbation across nutrient gradients and stocking densities on the dynamics of sediment bacterial communities

Aquaculture intensification can destabilize ecosystems by accelerating sediment nutrient accumulation and perturbing microbial communities; however, the mechanisms linking bioturbation to microbial ecological strategies remain unclear. Here, we investigated how bioturbation and nutrient gradients jointly influence water–sediment interface processes and microbiome functions using an indoor microcosm of an Eriocheir sinensis aquaculture system. High stocking density significantly increased nitrogen and phosphorus release, reinforcing a positive feedback of endogenous nutrient loading. Microbial communities exhibited nutrient-dependent adaptive responses: metabolically active, r-strategist taxa predominated under eutrophic conditions, whereas disturbance favored more resource-efficient K-strategists. Ecological network analysis and partial least squares path modeling indicated that increasing aquaculture density reduced system stability via a sediment-mediated pathway, sediment characteristics, water parameters, microorganisms. This study provides evidence consistent with the ‘Hunger Games’ framework in an aquaculture microcosm, offering theoretical foundations and scientific strategies to mitigate aquaculture eutrophication and optimize ecological aquaculture models. • High-density crab aquaculture amplifies nutrient release. • Bioturbation reduces microbial network complexity and stability via trophic cascades. • PLS-PM cascade identifies sediment TN as a key correlate of community restructuring.