Temperature calibration of Mg/Ca ratios in the intermediate water benthic foraminifer Hyalinea balthica

[1] Core top samples from Indonesian and northeast Atlantic depth transects were used to calibrate Mg/Ca and dO in tests of the calcitic benthic foraminifer Hyalinea balthica to bottom water temperature between 4°C and 13°C. This shallow infaunal species is primarily abundant in neritic to upper bathyal sediments (<600 m). Both linear and exponential calibrations suggest a temperature sensitivity of ∼12% per °C that is ∼4 times higher than observed in other species of deep‐sea benthic foraminifera. Culture experiments support the core top calibration. We find no discernible effect of salinity and saturation on Mg/Ca. Comparison between the measured benthic foraminiferal dO and predicted equilibrium values suggests that on average H. balthica dO is 0.64‰ ± 0.13‰ lower than predicted from