Special issue  

The BOUM (Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean) experiment has one overall goal: to obtain a better representation of the interactions between planktonic organisms and the cycle of biogenic elements, considering scales from single process to the whole Mediterranean Sea.

It is organized into three main objectives:

• to give a longitudinal description of the biogeochemistry and biological diversity of the Mediterranean Sea during the strongest stratified period;
• to study in three oligotrophic environments located at the center of anticyclonic eddies, the production and fate of organic matter with particular emphasis on the processes which drive the divergence of the stoichiometric ratios of the biogenic elements in the organic matter found in the surrounding water and exported materials;
• to obtain a satisfactory representation of the main biogeochemical fluxes (C, N, P, Si) and the dynamics of the planktonic trophic network, both in situ and by using microcosm experiments.