A system-based analysis of carbon fluxes shows that bivalve aquaculture cannot be considered a marine carbon dioxide removal strategy

Abstract Marine carbon dioxide removal (mCDR) is gaining momentum as part of the global climate mitigation portfolio. Yet as enthusiasm grows, so does the risk of overstating the carbon removal potential of marine activities that were never designed as climate interventions. Among these, bivalve aquaculture is increasingly framed as a nature-based carbon sink. We critically examine whether bivalve farming meets the scientific and policy criteria to qualify as a valid method of mCDR, emphasizing additionality, permanence, accountability, and the obligation for robust monitoring, reporting, and verification (MRV), including life-cycle assessment and certification frameworks. We demonstrate why bivalve farming does not currently qualify as an mCDR pathway. At the organism level, bivalves are not CO₂ sinks: as heterotrophic and calcifying organisms, they release CO₂ through respiration and calcification. Claims that shell inorganic carbon incorporation constitutes net atmospheric CO2 removal have been critically examined and refuted. At the ecosystem scale, hypotheses that bivalve aquaculture enhances the biological carbon pump or stimulates organic carbon sequestration in sediments remain highly uncertain. Empirical evidence is sparse, often methodologically limited, and lacking appropriate baselines, temporal resolution, and ecological realism. Critically, questions of scalability, long-term sequestration, and carbon accountability remain unresolved. Given the urgent need to prioritize reliable, scalable and cost-effective mCDR solutions, we argue that it is highly unlikely—and scientifically unjustified—that bivalve aquaculture can ever be used to obtain carbon credits. Bivalve aquaculture remains a model of sustainable food production that should not be distorted by attributing to it unverified virtues of atmospheric CO₂ removal.