*3.1. Weight Analysis*

Where available, ideally, 50 (minimum 38) *G. bulloides* shells were weighed in a preweighed aluminum carrier using a Sartorius CP2P microbalance with a precision of ±1 µg. Average shell masses were calculated by dividing the recorded mass by the total number of foraminifera weighed. Subsequently, for each sample, each shell was weighed separately, in order to estimate standard shell mass deviations. As explained above, performing shell weight analyses on a narrow size fraction of foraminifera constrains the ontogenic stage of the specimens to a certain number of chambers, and thus minimizes size-related weight differences [26–28]). The analytical error, estimated by triplicate measurements of 50 random specimens, ranged from 0.42 to 0.58 µg, which is in accordance with the error of the balance.
