Bilan de l'azote et du phosphore dans le système lagune - bassin versant de Thau

General survey is required to understand the operating conditions of a lagoon. From the available bibliographic data the terms of the balance in Nitrogen and Phosphorus have been drafted by bringing out the nature and the quality of the data, considering the information hetegeneousness. The great masses have been taken into account : stocks in water and sediments, fluxes between lagoon and exterior, exchanges between the various stocks. As far as possible the collected data have been set out yearly and seasonally. Moreover we tried to identify the shell-fish culture area and the rest of the lagoon separately in order to bring out the specifities of each area. This work offers a first clarification on the trends regarding the lagoon control and gives prominence to the priority or supplementary studies to be developped.