Environmental Performance of the Red Macroalgae, Gracilaria sp.: A Life Cycle Assessment (LCA) Approach

The environmental sustainability of seaweed cultivation is gaining increased attention due to its potential to mitigate climate change, reduce eutrophication, and provide renewable biomass. This study assesses the environmental performance of the red seaweed Gracilaria sp. using a Life Cycle Assessment (LCA) approach. The analysis encompasses the full cultivation cycle, from seeding to storage, focussing on potential environmental impact categories such as global warming, acidification, eutrophication, ecotoxicity, human carcinogenic and human non-carcinogenic. The functional unit was 1 tonne of dry seaweed. Field data were collected from seaweed aquaculture farms, with a particular focuss on farming systems and environmental outputs, and were analysed using the ReCiPe 2016 v1.1 Midpoint (H) method in SimaPro version 9.3 with the Ecoinvent 3 database. The LCA results indicate the dominance of human carcinogenic impact with 152.98 kg 1,4-DCB, followed by freshwater ecotoxicity with 34.13 kg 1,4-DCB, marine ecotoxicity with 26.83 kg 1,4-DCB and freshwater eutrophication with 24.75 kg P eq. Packaging phase dominates most potential environmental impacts, followed by storage phase compared with other phases. Recommendations for reducing environmental impacts include reducing plastic-based materials, adopting renewable energy sources, integrating multi-trophic aquaculture systems, and conducting further research into nutrient management practices. This study has the potential to be the basis for improving environmental performance in the entire value chain of the seaweed industry towards supporting the implementation of the blue economy and green practices.