Factores que controlan la calcificación de la concha en Neogloboquadrina pachyderma (dextrosa)

Résumé

Samples from core ODP site 977, retrieved in the Alboran Sea (Western Mediterranean Sea), have been studied in order to better constrain the factors controlling the calcification rate in the planktonic foraminifer Neogloboquadrina pachyderma (right coiling). For this purpose, changes in shell weight have been analysed between 245-190 kyr (Marine Isotope Stage 7) and show a clear millennial variability not related with the marine isotope substages. The results obtained suggest that Neogloboquadrina pachyderma (right coiling) calcification rate is directly related to optimum growth conditions, since heavier shell weights coincide with more relative abundance of this species due to optimum temperature conditions. However, it cannot be ruled out a secondary control exerted by surface water [CO3 2-], resulting from the opposite effects of atmospheric CO2 and water temperature. Therefore, this study questions the use of foraminifer shell weight as a proxy of carbonate saturation and atmospheric CO2 in surface waters and suggests that further studies are needed to better understand the processes behind shell calcification in planktonic foraminifers.