Glob. Change Biol. https://doi.org/cq2q (2018).

Ocean chemistry is changing due to higher levels of CO2 affecting the carbonate system through alterations in carbonate, bicarbonate and proton concentrations, but also the buffering capacity of seawater. Reduced buffering capacity means further CO2 uptake could lead to greater variability in ocean acidification with implications for marine biology.

Different biological sensitivities to carbonate system changes have been observed in manipulation experiments and it is unclear what influences the responses. To address this question, Sophie Richier of the University of Southampton, National Oceanography Centre, UK and co-authors analyse 17 shipboard manipulation experiments from three research cruises spanning temperate (European coastal) waters to polar seas (Arctic and Southern Ocean). Results show that biological responses to carbonate system changes vary with latitude and the inherent buffer capacity of the location. Phytoplankton size influenced the response, with larger cells — which have thicker microenvironments surrounding them — expected to have greater natural variability of the carbonate system at the cell surface and therefore a greater tolerance to future changes.

These results highlight the importance of considering regional characteristics as well as cell-size effects when predicting ocean acidification effects on marine primary production.