The prevailing global trend focused on developing strategies to minimize the environmental impact of aquaculture, thereby striving for environmental sustainability, efficiency, and profitability. To assess the environmental performance of IMTA systems and compare them with their monoculture counterparts, an LCA study was conducted. This comprehensive LCA study encompassed four distinct IMTA labs located in Scotland, Ireland, South Africa, and Brazil. The analysis scope and data inputs encompassed the cultivation and harvest phases of production, creating a cradle-to-farm gate LCA using SimaPro 9.4.0.2 and EF 3.0 (adapted) methodology to evaluate the environmental performance. The chosen methodology is particularly well-suited and recommended for LCA studies of aquaculture systems, considering a total of sixteen impact categories, including climate change, eutrophication, acidification, and ecotoxicity within the EF 3.0 method. 

The assessment generated life cycle indicators for one kilogram of biomass across all IMTA labs (one tonne of edible biomass in IMTA lab South Africa), with a specific focus on emissions and nutrient uptake, especially nitrogen and phosphorus, due to their connections with eutrophication. In the Scotland and Ireland IMTA systems, environmental hotspots were identified, pointing towards areas that could be addressed to enhance the systems' environmental profiles. Interestingly, both the Scotland and Ireland IMTA systems exhibited higher environmental impacts compared to their monoculture counterparts. In the case of Scotland, the cultivation phase showed substantial reductions of -10% in climate change and -98% in eutrophication for freshwater, and -70% for terrestrial eutrophication. In the remaining IMTA labs, particularly Ireland, South Africa, and Brazil, the cultivation phase remained the dominant source of impacts, with percentages as high as 97% in the marine eutrophication category.

Notably, South Africa's IMTA lab successfully integrated the cultivation of Ulva in the effluents of the urchin system, thereby using the cultivated Ulva as direct feed in the early stages of urchin growth and processing it into formulated feed for later stages. This innovation significantly reduced the overall requirement for formulated feed and led to a substantial reduction of 36-46% in the eutrophication category. The overall reduction in the marine eutrophication category was notable, with reductions of 27.48%, 47%, and 47% observed in Ireland, South Africa, and Brazil in the IMTA system when compared to monoculture, highlighting the efficient nutrient retention and utilization in all the IMTA labs. These findings underscore the substantial value of transitioning to sustainable IMTA systems within the context of a circular bioeconomy. This transition not only enhances the utilization of marine resources but also contributes significantly to the broader goal of fostering sustainability in coastal regions.