Controls of shell calcification in planktonic foraminifers

In order to better constrain the factors controlling the calcification rate in planktonic foraminifera, and to assess shell weight reliability as an atmospheric CO2 proxy, changes in shell weight in Globigerina bulloides, Neogloboquadrina pachyderma (right coiling) and Globigerinoides ruber (white) have been studied in core samples from the Alboran Sea (Western Mediterranean) between 250 and 160 ka (Marine Isotopic stages 6 and 7). These results suggest that G. bulloides and G. ruber (white) calcification rate is mainly controlled by atmospheric CO2 and water temperature, whereas N. pachyderma (right coiling) shell weight is directly related to optimum growth conditions, since heavier shell weights coincide with more relative abundance of this species due to optimum temperature conditions. Therefore, foraminifer shell weight should be used carefully as an atmospheric CO2 proxy.