Large methane emission from freshwater aquaculture ponds revealed by long-term eddy covariance observation

Quantifying Methane Emissions from Aquaculture Ponds in China

“…The use of aerators in aquaculture ponds significantly reduces CH 4 emissions in freshwater-culture ponds, which is consistent with previous studies (Figure 3E; Table S2). 5,35 Aeration in aquaculture ponds, aiming to increase fish performance by farmers, could improve the oxygen supply to sediment and water column and therefore inhibit CH 4 production but enhance CH 4 36,37 Moreover, we found that drainage could significantly enhance CH 4 emission in mariculture ponds (Figure 3F; Table S2). 38 Despite more exposure to oxygen, the drop of water level during drainage could result in a large proportion of CH 4 stored in the sediment being released because of the of hydrostatic pressure that holds CH 4 bubbles in place.…”

“…(3) Only experiments reporting CH 4 flux data, methods of measurement, and detailed information of the ponds (must include location, surface area, and depth) were selected, and the surface area must be less than 0.1 km 2 ; (4) Experiments in the same pond but using different management practices were considered as different individuals; (5) Ponds that had undergone multiple cultured species transitions were excluded. As a result, a total of 29 papers and 55 field experiments in aquaculture ponds were selected, including 34 experiments in freshwater-culture ponds and 21 experiments in mariculture ponds.…”

“…The use of aerators in aquaculture ponds significantly reduces CH 4 emissions in freshwater-culture ponds, which is consistent with previous studies (Figure 3E; Table S2). 5,35 Aeration in aquaculture ponds, aiming to increase fish performance by farmers, could improve the oxygen supply to sediment and water column and therefore inhibit CH 4 production but enhance CH 4 oxidation. 36,37 Moreover, we found that drainage could significantly enhance CH 4 emission in mariculture ponds (Figure 3F; Table S2).…”

“…Despite accounting for only 8.6% of the total area of global lakes and ponds, ponds smaller than 0.001 km 2 are found to contribute 41% of diffusive CH 4 emissions from global lakes and ponds . Among global small ponds, aquaculture ponds are hotspots of CH 4 emissions due to substantial carbon input by regular addition of feed or manure. , For example, higher CH 4 emission rates were observed in aquaculture ponds than natural wetlands and in aquaculture ponds with feed supply than those without feed supply. , To date, there have been some efforts to investigate the large-scale CH 4 emissions from aquaculture ponds by extrapolating short-term field measurements, large uncertainties, however, still exist due to limited data availability and inadequate understanding of CH 4 emissions under different human management regimes. , Due to the limitation, CH 4 emissions from aquaculture ponds are not well assessed and represented in current global methane budget, urging more investigation on aquaculture emissions.…”

“…4 Among global small ponds, aquaculture ponds are hotspots of CH 4 emissions due to substantial carbon input by regular addition of feed or manure. 5,6 For example, higher CH 4 emission rates were observed in aquaculture ponds than natural wetlands and in aquaculture ponds with feed supply than those without feed supply. 7,8 To date, there have been some efforts to investigate the large-scale CH 4 emissions from aquaculture ponds by extrapolating short-term field measurements, large uncertainties, however, still exist due to limited data availability and inadequate understanding of CH 4 emissions under different human management regimes.…”