title: Physical and chemical control of the phytoplankton of Ahe lagoon, French Polynesia.
abstract: The environmental characteristics of Ahe deep lagoon (Tuamotu Archipelago, French Polynesia) were studied over 3 years with the aim of explaining the spatial and temporal variability of the natural food available for pearl oysters with a special focus on phytoplankton biomass and global photosynthesis/respiration ratio of the lagoon. Chlorophyll averaged 0.34±0.01 μg L(-1) and our findings did not confirm increased phytoplankton biomass in deep lagoonal waters. Phytoplankton production appears to be limited firstly by nitrogen and respiratory processes overpass photosynthetic processes at least in the north-eastern edge of the atoll. Grazing by pearl oysters in culture seems to decrease the POC concentration but not the phytoplankton biomass. Oysters graze mainly on non chlorophyllian particles.
authors.affiliation: IRD, MIO, UR235, IRD Tahiti, BP 529, 98713 Papeete, French Polynesia. loic.charpy@ird.fr
authors.forename: Loïc
authors.initials: L
authors.lastname: Charpy
authors.forename: Martine
authors.initials: M
authors.lastname: Rodier
authors.forename: Jonathan
authors.initials: J
authors.lastname: Fournier
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Langlade
authors.forename: Nabila
authors.initials: N
authors.lastname: Gaertner-Mazouni
mesh_terms: D000818:Animals; D017756:Aquaculture / Q000379:methods; D018533:Biomass; D002734:Chlorophyll / Q000032:analysis / Q000378:metabolism; D004784:Environmental Monitoring; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D058458:Nitrogen Cycle; D010788:Photosynthesis; D010839:Phytoplankton / Q000502:physiology*; D049911:Pinctada / Q000502:physiology*; D011114:Polynesia; D054712:Salinity; D012623:Seawater / Q000737:chemistry
chemical_list: D002734:Chlorophyll; D009584:Nitrogen