Lakes are significant CO2 sources to the atmosphere, with about 0.14 à 0.17 PgC/year at a world scale (Cole et al. 1994). African lakes are characterized by CO2 partial pressures (pCO2) more than twice the world average. The project aims at making a carbon budget of the surface waters of lake Kivu, as well as a budget of the macronutrients which may limit primary production.