Carbon is use as the main currency in this model.  In our study, the biogeochemical module provides prognostic equations of state for two principal constitutive nutrients (carbon and nitrogen) for 25 phytoplankton species spread in 6 phytoplankton functional groups, 10 mixotrophs functional species, 11 species of microzooplankton and 3 species of copepod-like metazoan zooplankton. It also represents dissolved and particulate organic matter dynamics. Each functional group presented different size classes with metabolisms in respect with their sizes.