Mattio L. auteur aut IRD Dirberg G. auteur aut IRD Payri Claude auteur aut IRD Andréfouët Serge auteur aut IRD text journalArticle eng text/pdf born digital access Sargassum (Phaeophyceae, Fucales) is a genus of worldwide distribution recently recognised to proliferate in several regions of the South Pacific. In New Caledonia, species of this genus naturally structure one of the major lagoon habitats but their extent, composition and biomass remain largely unknown. To fill these gaps in our knowledge over large areas, we applied a combination of remote sensing and in situ methods applied to the Neo Caledonian South West Lagoon. Space borne high resolution Landsat (30-m resolution) and Quickbird (2.4-m resolution) images of the Neo Caledonian South West lagoon were used to estimate the spatial extent of the different beds of interest. Species composition was determined for 11 Sargassum beds and seasonal variations were investigated for four representative beds over an 18 month period using quadrats and transects. Relationships between surface cover and biomass were estimated from seasonal field data sets. Finally, four methods requiring variable levels of sampling effort were designed to estimate the total biomass at the scale of each bed, considering (or not) the specific composition, and spatial and temporal variations. Seven Sargassaceae species were identified. Mean surface cover (24.4-51.6%) and total biomass [3.4-1,461.9 t dry matter (DM)] varied widely between beds. Overall, biomass temporal variations were not significantly different, but species-level variations seemed to be bed-specific. The extent of the 11 beds was 9 km(2); their total biomass was estimated and compared using each of the four methods, and the most precise method provided an estimate of 2,900 t DM. This study demonstrates a way of characterising Sargassum beds, efficiently and on a large scale, using a combination of remotely sensed and in situ data. These methods should be useful for possible future biomonitoring of Sargassum beds in New Caledonia, and in other areas worldwide. specialized Large brown algae Sargassaceae Remote sensing Habitat management Coral reef 036 126 20 5 811-823 2008 0921-8971 https://www.documentation.ird.fr/hor/fdi:010044204 10.1007/s10811-008-9318-4 0921-8971 [F B010044204] https://www.documentation.ird.fr/hor/fdi:010044204 https://www.documentation.ird.fr/intranet/publi/2009/01/010044204.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2009-02-06 2017-08-23 fdi:010044204 fre