LAUSR

Contributions of filamentous and picoplanktonic cyanobacteria to the 26 phytoplankton community structure were examined in New Caledonian waters during the 2001-27 2003 El Nino period at three stations. Morphometric characteristics of diazotrophic filamentous 28 cyanobacteria are given as well as the seasonal and inter-annual variations of their surface areas 29 and integrated abundances. Trichodesmium tenue and T. thiebautii were the dominant species 30 followed by T. erythraeum, altogether accounting for more than 51-80 % of the biomass of the 31 free-living filamentous cyanobacteria. Katagnymene spp. accounted for a smaller percentage 32 (<13.8 % at ocean stations, <3.6 % in the lagoon). R. intracellularis biomass was relatively small 33 (<1 % of total surface area and volume of Trichodesmium trichomes) with the highest 34