Charpy,-L.; Charpy-Roubaud,-C.J. Phosphorus budget in an atoll lagoon. PROCEEDINGS-OF-THE-SIXTH-INTERNATIONAL- CORAL-REEF-SYMPOSIUM,-TOWNSVILLE,-AUSTRALIA,-8th-12th- AUGUST-1988.-VOLUME-2:-CONTRIBUTED-PAPERS-MINI- SYMPOSIUM-1-TO-10-14. Choat,-J.H.;Barnes,- D.;Borowitzka,-M.A.;Coll,-J.C.;Davies,-P.J.;Flood,- P.;Hatcher,-B.G.;et-al.-eds.. 1988. pp. 547-550. The different states of phosphorus (mineral, organic, dissolved and particulate) were studied between 1982 and 1987 in the oceanic and lagoon waters and sediment pore waters of the atoll of Tikehau. Fluxes associated with the different forms of phosphorus were measured or estimated. The percentages of phosphorus forms in the lagoon are 58% for the dissolved organic (DOP), 23% for the phosphates (PO sub(4)) and 18% for the particulate organic (POP). Living POP is composed by 28% of phytoplankton, 20% of heterotrophs < 5 mu m, 26% of heterotrophs 5 mu m-35 mu m and 26% of zooplankton (35 mu m - 2000 mu m). Phosphate flux from sediment give all the phosphorus required by phytobenthic production. Detritus probably come from reef production. POP exportation from the lagoon represents only 2.5% of phytoplankton production.