Methane fluxes from typical marine polyculture ponds of swimming crab with kuruma shrimp and short-necked clam in eastern China

Abstract

Methane (CH 4 ) fluxes at the water-air interface in 2 typical seawater polyculture systems were determined during the farming season. The mean CH 4 fluxes were 66.0 ± 44.1 μg m -2 h -1 in the bispecies polyculture system of swimming crab Portunus trituberculatus with kuruma shrimp Marsupenaeus japonicus (PM) and 68.7 ± 39.5 μg m -2 h -1 in the trispecies polyculture system of swimming crab with shrimp and short-necked clam Ruditapes philippinarum (PMR), and no significant differences were observed between them. CH 4 emissions showed temporal variability during the farming season, peaking in mid-August. The linear mixed-effect model demonstrated that air temperature was the main regulator of CH 4 fluxes rather than the internal physical and chemical properties of the systems. Air, water and sediment temperatures explained 58.9, 61.4 and 55.3% of the CH 4 flux variations in the PM and 64.6, 57.1 and 60.8% of the variations in the PMR, respectively. Reducing organic matter accumulation in the sediment by means of im - proving feeding efficiency and the application of integrated aquaculture are likely to be effective in reducing CH 4 emissions from aquaculture systems.