Ocean Acidification

The increase in human induced atmospheric CO₂ level leads to an increase in ocean acidification (OA). Mitigation of this increase by storage of CO₂ in abandoned marine oil and gas reservoirs is seen as an interesting cost effective solution. However, this involves a risk of CO₂ loss causing localised reductions in seawater pH. In this paper we report on the effects of CO₂ enhancement on the growth of the bivalve Cerastoderma edule in mesocosms. The experiments show significant reductions in shell length, shell weight and cockle flesh dry weight at increased CO₂ level suggesting both direct (shell erosion) and indirect (metabolic) effects. Indirect effects were analysed and interpreted using a Dynamic Energy Budget model by describing changes in 3 metabolic processes: assimilation, maintenance, and growth. Based on cockle size data only we could not differentiate between these processes, however, by using variability of DEB parameter values in 11 bivalve species, we showed growth to be the least relevant process.

Klok C., Wijsman J. W. M., Kaag K. & Foekema E., in press. Effects of CO2 enrichment on cockle shell growth interpreted with a Dynamic Energy Budget model. Journal of Sea Research. Article (subscription required).