Silver carp ( Hypophthalmichthys molitrix ) stocking is a widely employed biomanipulation measure to tackle algal bloom in eutrophicated lakes, yet its role in nutrient cycling is still unclear. Through mesocosm experiments, we examined how fish density and environmental factors influenced water quality by comparing fish-mediated nutrient supply with sediment internal loading. Results suggested rapid nitrogen (N) and phosphorus (P) recycling within the water column, even under low ambient nutrient conditions. Fish-mediated nutrient fluxes exceeded sediment internal P loading by 9-fold (high fish density, HD) and 7.5-fold (low fish density, LD), and the HD treatment also enhanced N excretion by 1.7-fold compared with the LD treatment. The HD treatment demonstrated significantly improved phosphorus retention (33.6% vs. 22.8%) and feed efficiency (1.76 g/g vs. 3.06 g/g FCR) but 27% lower growth rates compared to the LD treatment. Elevated temperature intensified N limitation while alleviating P constraints, disrupting the nutrient–algae balance. Binary logistic regression and linear mixed model analyses confirmed that temperature–density interdependence critically regulated chlorophyll a (Chl. a ) dynamics. HD stocking suppressed Chl. a, but warming water temperature attenuated this effect. We propose a conceptual framework for consumer-driven nutrient dynamics in carp-manipulated systems, demonstrating that summer stocking may prove ineffective due to thermal disruption of nutrient–algae coupling, while low densities risk stimulating blooms via incomplete grazing and nutrient supply. These findings highlight the necessity of high-density, seasonally-informed stocking strategies for effective lake restoration. • Temperature-density co-regulation triggers nutrient limitation shifts and governs algal suppression. • High-density silver carp stocking reduces chlorophyll a , but warming attenuates efficacy. • Carp-driven phosphorus flux surpasses sediment internal loading by 9× (high density) and 7.5× (low density). • Conceptual framework integrates consumer-driven nutrient dynamics, revealing decoupled nutrient–algae feedbacks. • High stocking density could improve biomanipulation efficacy but affected by high temperature.
Zhu et al. (2026) studied this question.