Shrimp mariculture may increase aquatic CO2, CH4, and N2O emissions in semi-indoor and indoor ponds

Abstract

This study revealed the greenhouse gas (GHG) emission patterns during shrimp mariculture in both semi-indoor and indoor ponds. In the semi-indoor ponds, the average carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) concentrations of pond water varied from 1373.0 ± 721.7 μatm, 4.4 ± 1.3 nM, and 14.2 ± 3.5 nM, respectively, at the initiation of stocking to 5296.0 ± 1474.7 μatm, 3.8 ± 0.3 nM, and 28.1 ± 17.9 nM, respectively, in the harvest stage. In the indoor pond, these varied from 562 μatm, 3.5 ± 0.2 nM, and 10.7 ± 0.1 nM, respectively, at the initiation of stocking to 4728.0 μatm, 18.2 ± 0.7 nM, and 94.1 ± 0.6 nM, respectively, in the harvest stage. An upward trend in CO₂ and N₂O concentrations was observed in the water of both semi-indoor and indoor ponds as the culture period progressed. The discharged waters exhibited the highest GHG concentrations, potentially acting as emission hotspots if left untreated. The total average CO₂-equivalent (CO₂-eq) fluxes from pond water during the shrimp mariculture period were 49.8 ± 40.7 mg CO₂-eq m−2 h−1 in the semi-indoor ponds, with 44 % of these GHG emissions attributable to shrimp mariculture practices. In the indoor pond, the fluxes were 101.5 ± 52.6 mg CO₂-eq m−2 h−1, with 86 % of the GHG emissions attributable to shrimp mariculture practices. According to these results, shading effects may increase the GHG emissions from aquaculture pond waters.