Lake Kivu, 100 km long and 50 km wide, is part of the great lakes of the African Rift and is shared by Democratic Republic of Congo and Rwanda. Its watershed supports high population density, living mainly from fisheries and agriculture, in both countries. Of volcanic origin, this meromictic lake counts only 28 species of fish. The introduction, in the early sixties, of the sardine Limnothrissa miodon in the pelagic zone, allowed the development of an important fishery. However, Limnothrissa introduction resulted in ecological changes, e.g. an alteration of zooplankton community structure from the extinction of a large Daphnia. Some research has been carried out on the biology and ecology of the sardine, but large uncertainties remain about how fish dynamic are driven by environmental conditions. Plankton dynamics, food web, and the role of the microbial loop have been poorly studied. In addition, due to its meromictic character, L. Kivu is a sensitive ecosystem where primary production is highly limited in phosphorus. Moreover, climate change may have significant effects on nutrient cycling and productivity. The 'ECOSYKI' research project, which involves African (from DR Congo and Rwanda) and European scientific partners, aims at studying and modeling the functioning of the pelagic zone of L. Kivu. In addition, the project also emphasizes training of scientists and technicians, as well as the relationships between scientists and managers, i.e. the potential end-users of the results. Furthermore, from the start of this project focused on the pelagic zone, contacts have been taken with scientists from other disciplines in relation with any aspect pertaining to a comprehensive approach of L. Kivu catchment, including erosion, land use and other exploitation of water and land resources. This global vision seems to us crucial to achieve the long-term objective of sustainable development of the L. Kivu area. The three main objectives of the Ecosyki project are thus: 1 Research : Study and modelling of the functioning of the pelagic ecosystem of lake Kivu, for the understanding and the description of the processes driving its productivity ; 2 Training / Impulsion : Contribution to the training and the development of the research structures for their optimal and sustainable functioning ; 3 " User committee " : Contribution to the dissemination of the research results to managers and potential end-users.