Life Cycle Assessments of Bivalve Aquaculture: A Systematic Review and Meta‐Analysis

Abstract

Bivalve aquaculture is generally considered a low-impact food system with ecosystem co-benefits. Yet its net contributions to climate change (CC), eutrophication (E), and broader ecosystem stewardship remain uncertain. To address this, we analyzed 31 life cycle assessment studies of bivalve farming. Reported impacts varied substantially. Median values were 385 kg CO2-eq t−1 for CC (interquartile range [IQR]: 164–612.2), 0.25 kg PO43−-eq t−1 for E (IQR: 0.15–0.49), 0.014 kg N-eq t−1 for marine eutrophication (ME) (IQR: 0.00–0.50), 1.86 kg SO2-eq t−1 for acidification (A) (IQR: 0.56–6.26), and 10,772 MJ t−1 for energy demand (ED) (IQR: 7231–16,383). High-impact processes were mainly linked to electricity and fuel use, plastic infrastructure, and transport. Reported co-benefits included nutrient removal and potential carbon storage in shells. Regression analysis showed that methodological choices influenced CC and ME, whereas species differences were significant only for ME. Meta-analysis revealed high heterogeneity across studies (I2 = 90% for CC and 85% for E). Distinct species patterns emerged. Mussels showed lower CC but variable E outcomes. Oysters showed moderate CC but relatively higher E burdens. Clam showed more variable results and was sensitive to carbon accounting assumptions. Accounting for shell carbon sequestration influenced CC but had little effect on E. Overall, bivalve aquaculture shows variability across studies. Outcomes are strongly influenced by methodological choices and species differences. Claims of climate neutrality remain sensitive to methodology and should be evaluated alongside nutrient trade-offs. Standardized methods and broader geographic coverage are needed for robust sustainability assessments and comparisons.