CARBONATE PRODUCTION OF SOME CALCIFYING A LGAE IN A FRENCH-POLYNESIA CORAL-REEF

On the northwestern part of Moorea Island, calcification rates for 8 b enthic species (Halimeda opuntia var hederacea, H. opuntia var. opunti a, H. incrassata f. ovata, H. discoidea, Amphiroa fragilissima, Poroli thon onkodes, Hydrolithon reinboldii and Padina tenuis) were estimated using the total alkalinity method during 24-hours-cycles, spread in t he course of a year. The daily calcification rates vary largely within the taxa. Hamimeda play a major role in the carbonate budget and part icularly in the sediment deposition. The hourly rates vary over a 24-h ours-cycle with a decrease during the night period. Moreover, the calc ification measurements spread in the course of the year exhibit a stro ng seasonality in the carbonate production. Lastly, the annual inorgan ic carbon budget shows that these species play an essential role in th e balance of the reef calcification rates.