Effect of carbonate ion concentration and irradiance on calcification in planktonic foraminifera

• Published in: Biogeosciences
• Main Authors: Lombard, F., Rocha, R. E., Bijma, J., Gattuso, J.-P.
• Format: Other/Unknown Material
• Language: English
• Published: 2018
• Subjects: Ocean acidification; Planktonic foraminifera
• Online Access: https://doi.org/10.5194/bg-7-247-2010; https://www.biogeosciences.net/7/247/2010/

The effect of carbonate ion concentration ([CO 3 2− ]) on calcification rates estimated from shell size and weight was investigated in the planktonic foraminifera Orbulina universa and Globigerinoides sacculifer . Experiments on G. sacculifer were conducted under two irradiance levels (35 and 335 μmol photons m −2 s −1 ). Calcification was ca. 30% lower under low light than under high light, irrespective of the [CO 3 2− ]. Both O. universa and G. sacculifer exhibited reduced final shell weight and calcification rate under low [CO 3 2− ]. For the [CO 3 2− ] expected at the end of the century, the calcification rates of these two species are projected to be 6 to 13% lower than the present conditions, while the final shell weights are reduced by 20 to 27% for O. universa and by 4 to 6% for G. sacculifer . These results indicate that ocean acidification would impact on calcite production by foraminifera and may decrease the calcite flux contribution from these organisms.