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.