Boron isotope ratios (δ¹¹B) of foraminifera are a promising proxy for seawater pH and can be used to constrain pCO₂. In this study, we derived calibrations for new foraminiferal taxa which extend the application of the boron isotope proxy. We discuss the origin of different δ¹¹B signatures in species and also discuss the potential of using multispecies δ¹¹B analyses to constrain vertical pH and pCO₂ gradients in ancient water columns to shed light on biogeochemical carbon cycling in the past.