Evaluation of the effect of calcification intensity on the isotopical composition of coccolith calcite

To understand how coccolithophore calcification rates evolved, it is critical to disentangle which environmental parameters controls the flow of energy from photosynthesis to calcification.

The values of coccolith vital effects, the offset of the isotopic composition of coccoliths from abiogenic calcite equilibrium, are not yet unilaterally understood. Models from observations in cultures indicate that such geochemical value is controlled, in some extent, by the changes in calcification intensity (McClelland et al., 2017). However, confirmation from observations in the natural environment remains scarce, up to date.

In order to explore the suitability of coccolith isotopical values to produce consistent estimations of calcification intensity, we analyze d13C values measured in size separated coccoliths from natural assemblages in core top records across different latitudes of the Atlantic Ocean. Micro separation of coccoliths and extraction from sediments are carried out with the application of the method by Minoletti et al. (2009) and serve to produce nearly monospecific size-separated coccolith fractions.

Our preliminary results allow investigation on the variance of size-separated coccolith vital effects together with independent estimations of PIC/POC production (Particulate Inorganic Carbon/Particulate Organic Carbon) and regional changes in environmental conditions trough the Atlantic Ocean.

References:

McClelland, H. L. O., Bruggeman, J., Hermoso, M., & Rickaby, R. E. M. (2017). The origin of carbon isotope vital effects in coccolith calcite. Nature communications, 8(1), 1-16.

Minoletti, F., Hermoso, M., & Gressier, V. (2009). Separation of sedimentary micron-sized particles for palaeoceanography and calcareous nannoplankton biogeochemistry. Nature protocols, 4(1), 14-24.