Determinants of biogenic carbonate flux

Planktic foraminifera, which live in the ocean surface layers from tropical to polar regions, contribute 32–80% of the total deep-marine calcite budget in the global carbonate cycle and also have a substantial impact to the organic carbon export to the ocean interior. However, the contribution of planktic foraminifera in carbon exportation to deep ocean, driven by calcite and organic carbon formation, has not been quantified. The calcite volume of shell is one of the essential proxies to estimate the calcification rate of foraminifera, and to evaluate the impact of foraminifera on global carbonate flux to deep sea floor. Furthermore, internal volume of shell, where the space for cytoplasm, enables to estimate the amount of organic carbon formed by each specimen.

Here we measure the calcite and internal volume of planktic foraminiferal shell for each species using by micro X-ray CT scanning and link them to shell size fraction. Such basic information can be applied into the existing data of species assemblages or standing stock of foraminiferal shell from core and trap samples, and provide the quantitative data of Carbonate/Organic carbon flux in present and past open ocean driven by planktic foraminifera.