345 / 2024-09-14 16:34:34

Greenhouse gas emissions in aquaculture ponds at different stages of mangrove wetland restoration

Aquaculture ponds;,GHG emissions,Wetland restoration,Global warming potential

Aquaculture ponds are prevalent worldwide and contribute significantly to greenhouse gas (GHG) emissions. As a result of governmental regulation and environmental concerns, many coastal aquaculture ponds in China are gradually restored to the mangrove forest. The restoration process generally involves three stages: active culturing ponds, abandoned ponds, and recovering ponds with mangroves. However, the quantification of GHG emissions and changes during the recovery process is poorly understood, which limits our understanding of the potential environmental benefits of this restoration process. In this study, the carbon dioxide (CO₂) and methane (CH₄) emissions at the water-atmosphere interface during different recovery stages of aquaculture ponds were measured by floating chamber method in the Zhangjiang Estuary, China, for one year. The results show that the ponds are the source of CH₄, while emissions from abandoned (1.35 g/m²/yr) and recovering ponds (1.65 g/m²/yr) are lower than those from the active culturing ponds (2.09 g/m²/yr). As to the CO₂ emissions, the active culturing ponds (480.57g/m²/yr) and abandoned pond (103.69 g/m²/yr) are the carbon sources, while recovering ponds are the carbon sink (-43.13 g/m²/yr) for the whole year. At the same time, the carbon sequestration capacity of mangrove forests offsets 189% of global warming potential (GWP) in the restoration ponds. Consequently, with the advance of restoration process, as aquaculture activities stopped and vegetation recovered, the greenhouse effect caused by the cultivation can be effectively alleviated by 73.8%. The study provides the fundamental data for completing the carbon emission inventory of China's coastal aquaculture system, and consolidate the theoretical basis for the scientific management and formulation of the emission reduction plan of GHGs of aquaculture system.