Ocean Acidification

Purpose

Life cycle assessment (LCA) can be used to understand the environmental impacts of the shellfish aquaculture and wild harvest industries. To date, LCA of shellfish exclude carbon dioxide (CO₂) release from bivalve shell production when quantifying global warming potential per functional unit. In this study, we explain the rationale for including CO₂ released during shell production in LCA of bivalves, demonstrate a method for estimating this CO₂ release, and apply the method to previous studies to demonstrate the importance of including CO₂ from shell production in LCA.

Methods

A simple approach for calculating CO₂ from bivalve shell production was developed utilizing the seacarb package in R statistical software. The approach developed allows for inclusion of site-specific environmental parameters such as water temperature, salinity, pH, and pCO₂ when calculating CO₂ release from shell production. We applied the method to previously published LCA of bivalve production systems to assess the impact of including this CO₂ source in the LCA. The past studies include aquaculture and wild harvest production strategies and multiple bivalve species.

Results and discussion

When we recalculated the total kg CO₂ released in past studies including CO₂ release from shell production, the additional CO₂ release increased the total global warming impact category (CO₂ equivalents) in cradle-to-gate studies by approximately 250% of the original reported value. Discussion of our results focuses on the importance of different components of our calculations and site-specific environmental parameters. We make predictions on how the magnitude and importance of CO₂ released during shell production could change due to climate change and ocean acidification, and provide suggestions on how CO₂ release from shell production can be reduced through careful selection of aquaculture facility location and aquaculture practices.

Conclusions

We provide a method for including CO₂ from shell release in LCA of bivalves and recommend that future LCA of bivalves include this CO₂ as part of the global warming impact category.

Ray N. E., O’Meara T., Wiliamson T., Izursa J.-L. & Kangas P. C., 2018. Consideration of carbon dioxide release during shell production in LCA of bivalves. The International Journal of Life Cycle Assessment 23(5): 1042–1048. Article (subscription required).