Plastic-lined ponds and eco-aquaculture systems had lower CO2 emissions than earthen aquaculture ponds

Abstract

Aquaculture contributes to global CO₂ emission, but the intensity varies across different aquaculture systems. In this study, we compared the CO₂ emission between earthen aquaculture ponds (EAP), plastic-lined ponds (PLAP), and mangrove wetland eco-aquaculture systems (MWEAS) in the coastal region of the Guangxi Province, South China. Results showed that CO₂ emissions varied between −27.28 and 12.39 mg m⁻²h⁻¹ from PLAP and between −17.78 and 14.18 mg m⁻²h⁻¹ from MWEAS, both significantly lower than those from EAP (2.76 to 19.30 mg m⁻²h⁻¹). The largest emission fluxes were observed during the growth stage of the farming period. On average, PLAP and MWEAS acted as CO₂ sinks, whereas EAP acted as a source, and Chlorophyll-a, phosphorus and carbon substrates were the main environmental factors influencing the variation in CO₂ emissions. The overall average CO₂ emission flux from our aquaculture ponds was 2.54 ± 1.11 mg m⁻²h⁻¹, which was much lower than those observed in freshwater and brackish coastal aquaculture ponds, but higher than certain high-salinity aquaculture environments. In summary, enhancing water salinity levels and encouraging the adoption of plastic liners alongside ecological aquaculture systems could serve as effective strategies for mitigating CO₂ emissions in coastal aquaculture.