Carbon budget in integrated aquaculture systems with Nile tilapia (Oreochromis niloticus) and Amazon river prawn (Macrobrachium amazonicum)

This study was centred on the carbon budget of Integrated multitrophic aquaculture (IMTA) systems in earthen ponds stocked with the freshwater Amazon river prawn (Macrobrachium amazonicum) and Nile tilapia (Oreochromis niloticus), with or without different added substrates. The experimental design was completely randomized, with three treatments and four replicates. Carbon entered the system mainly through the diet (similar to 58-63%), inlet water (similar to 29-34%) and absorbed gases (similar to 5-7%). Most of it was accumulated in the sediments (similar to 42-70%) or discharged in the outlet water (similar to 12-13%). The tilapias converted similar to 12% of the carbon available into harvested biomass, and the prawns converted only similar to 1%. The retention of carbon inside the ponds from the inlet water was similar to 1 tonne ha(-1), and the atmosphere similar to 0.1-0.3 tonnes ha(-1). The carbon accumulated in the sediment was about 3.5 tonnes ha(-1). Data suggest that the integrated aquaculture in stagnant earthen ponds sequesters high quantities of carbon from the nutrient-rich source water and atmosphere, and the addition of substrates at 50% of pond area do not improve the assimilation of carbon by the farmed species, having a low effect on the carbon budget. (AU)