Long-term impacts of mariculture on coastal greenhouse gas, nitrogen, and phosphorus dynamics in China

Mariculture represents one of the most significant anthropogenic perturbations to coastal biogeochemical cycles. As the world’s largest producer, China’s mariculture plays a critical role in global food security, yet its long-term impacts on coastal water chemistry and climate remain poorly quantified. This study presents a comprehensive assessment of greenhouse gas (GHG), nitrogen (N), and phosphorus (P) dynamics in China’s mariculture from 1983 to 2024, combined with projections of future trajectories under twelve development scenarios using long-term reconstruction and scenario-based modeling frameworks.
Our results show that China’s mariculture has consistently acted as a net GHG source, with emissions increasing from 0.02–0.10 Mt in 1983 to 61.60–71.60 Mt in 2024. Concurrently, N and P discharges surged approximately 150-fold. Although extractive species provided substantial mitigation, the annual growth rate of emissions exceeded biological removals by approximately 6%, indicating a widening imbalance between anthropogenic inputs and ecosystem assimilation capacity. A pronounced source–sink divergence was identified, driven by climatic suitability and farming structure. Northern provinces, characterized by extensive macroalgal cultivation, function as persistent nutrient sinks, whereas southern provinces dominated by intensive fed aquaculture have emerged as major emission sources. Projections indicate that without structural adjustment, net N discharges could increase four- to ten-fold by 2030, accompanied by an approximately 50% rise in GHG emissions. Conversely, optimizing species composition and adopting clean energy could enable peak GHG emissions by approximately 2050, carbon neutrality by 2075, and net N removal of nearly 39 kilotons by 2100. These findings provide critical benchmarks for managing anthropogenic influences on coastal chemical processes and support the evidence-based sustainable transformation of the global blue economy.