Environmental performance of marine aquaculture in China: A critical structured narrative review of system-specific risks, ecosystem services, and adaptive governance

Abstract

China’s marine aquaculture sector is essential to aquatic food supply and coastal employment, yet its environmental performance varies markedly among fed finfish and crustacean systems, filter-feeding bivalves, macroalgal farms, and integrated multi-trophic aquaculture (IMTA). This critical structured narrative review synthesizes evidence on nutrient discharge, organic deposition, benthic alteration, hydrodynamic modification, disease and chemical risks, nutrient bioextraction, ecological carrying capacity, and adaptive monitoring in coastal marine systems. Unlike a systematic review, the approach uses an explicit search framework and structured synthesis questions to compare mechanisms and boundary conditions, but it does not claim exhaustive retrieval, formal risk-of-bias scoring, or pooled effect estimation. Evidence indicates that fed systems are principal sources of nitrogen, phosphorus, and particulate organic waste, whereas shellfish and seaweed can remove nutrients through harvest but may also generate context-dependent effects through biodeposition, food depletion, shading, flow modification, and density-dependent competition. Bay-scale observations reinforce this scale dependence: winter monitoring in Sansha Bay reported mean nitrate and phosphate concentrations of 31.3 ± 10.5 and 2.26 ± 0.84 μM, respectively, with most observations meeting a eutrophic classification, while long-term shellfish-seaweed culture in Sanggou Bay has shown comparatively limited benthic deterioration under some conditions but stronger seasonal stress during warmer months. IMTA can improve nutrient recovery and diversify production, although performance depends on trophic matching, spatial configuration, hydrodynamics, harvest timing, biosecurity, and market viability. The review concludes that sustainable transition requires bay-scale nutrient budgets, water and sediment indicators linked to predefined management triggers, feed and stocking controls, harvest-based accounting for extractive species, site-specific carrying-capacity assessment, and performance-based licensing. China’s future mariculture policy should therefore distinguish farming systems based on their environmental functions and regulate cumulative effects at the spatial scale at which they occur.