Including ocean acidification effects on biocalcification through dynamic energy budget modelling

Climate change impacts on ocean biogeochemistry are expected to alter calcium carbonate formation by organisms, necessitating accurate predictive models based on physiological mechanisms. The dynamic energy budget (DEB) theory offer a mechanistic and integrative framework to model organism metabolism under environmental stressors. In this work, we 1) review the physiological and energetic mechanisms of biogenic calcification, 2) propose a generalized approach for inclusion in DEB modelling based on stylized facts, and 3) formulate the effects of saturation state changes on the bioenergetics of calcification. While applicable to any species performing biogenic calcification (microalgae, shellfish, fish, corals), we tested the model on bivalve species for which extensive tissue and shell data are available. The model was successfully applied to larval, juvenile, and adult life stages compared to published data. The model reproduced typical tissue and shell growth patterns under favourable saturation states and we explored the effects of more detrimental values for biocalcification on shell and tissue dynamics. We also identified missing data and experiments that should help calibrate model parameters. This work represents a necessary step to predict the physiological response of biocalcifiers to ocean acidification and provides a mechanistic tool for shell dynamics in nutrient cycling models.