The marine carbon cycle constitutes a key component of the climate system. It has
been shown that one-fourth of the anthropogenic CO2 emitted to the atmosphere is
absorbed by the ocean, leading to the acidification of the surface ocean and the
modification of seawater carbonate chemistry. This could have major impacts on the
ocean biogeochemical carbon cycling and ecosystem dynamics. Yet, the resulting
feedbacks on climate change are still poorly understood. Interdisciplinary
biogeochemical investigations, assisted by remote sensing, have been conducted
during three consecutive years along the shelf break of the Northern Bay of Biscay
where coccolithophorid blooms dominated by Emiliania huxleyi are frequently and
recurrently observed. Rates of various processes governing the coccolithophore
ecosystem dynamics have been determined and air-sea CO2 fluxes evaluated. The key
results will be presented and discussed to evaluate the role in climate regulation of
calcification, primary production and export processes during coccolithophorid
blooms
