François M. M. Morel, Blanke Professor of Geosciences
 
The ongoing rise in atmospheric CO2 is increasing the dissolved CO2 concentration in the surface ocean, decreasing its pH, and consequently  modifying the chemistry of many seawater constituents.  These chemical changes in turn affect the ocean biota via a multitude of mechanisms. For example, the decrease in the degree of saturation of calcium carbonate makes it harder for calcifying organisms to precipitate their mineral structures.  The decrease in pH changes the bioavailability of essential algal nutrients such as iron. Most directly, the increase in CO2 may change the composition of the biomass, e.g., its C:N ratio.  Such biological effects potentially lead to major perturbations in marine biogeochemical cycles — including notably the biological export of CO2 to the abyss — and may provide a key feedback, negative or positive, on the CO2 buildup in the atmosphere and surface ocean.  This research project is based on a series of mechanistic hypotheses on the biological effects of ocean acidification and comprises laboratory experiments as well as oceanographic field studies.