Unveiling the role of the freshwater aquaculture industry in the contribution of greenhouse gas (CO2 and CH4) emissions of tropical India.

The aquaculture industries enhance greenhouse gas (GHG) emissions, causing global carbon cycle alteration and global warming (GW). CH4 and CO2 are two major GHGs responsible for GW, whereas CH4 is the foremost GHG with a higher sustained global warming potential (GWP). Herein, the emissions of GHGs (especially CH4 and CO2) from the freshwater aquaculture and non-aquaculture ponds of tropical India have been investigated using the floating gas chamber method (chamber volume 0.0298 m3 and surface area 0.138 m2). The samples were collected in the month of April 2024 using a spatial distribution technique and analyzed using gas chromatography. The average emissions of CH4 and CO2 were 281.43 and 88.41 μmol m-2 h-1 for aquaculture ponds and 12.44 and 5.22 μmol m-2 h-1 for non-aquaculture ponds, respectively. Water quality, soil/sediment, fish stock density, fish feed, organic matter (chlorophyll-a), etc., of different sample sites influence the emissions of GHGs. The GHGs formation mechanism from various organic matters is established using the methanogenesis pathway. Around 32 % (2010-2020) of agriculture/vegetation lands have been converted into the aquaculture industry, which influenced the GHGs emissions in the study area. GWP for CH4 and CO2 was 292.95 and 3.41 kg m-2 CO2-eq annually on a 100-year scale, respectively, i.e., ∼85.91 times that of CO2, depicting that random construction of aquaculture ponds and abolition of vegetation cover might influence the natural carbon cycling affecting Sustainable Development Goal 13 (Climate action).