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Coral reef fish communities of Uvea (Wallis and Futuna) fringing reefs, mid-lagoon reefs, inner barrier reefs and outer barrier reef slopes were studied along four transects using visual censuses during September 1999. A total of 194 fish species in 33 families were recorded. Labridae (34 species), Pomacentridae (33 species) and Chaetodontidae (23 species) were the main families. The composition of the species suggests that Uvea is located at a faunal junction between Pacific biogeographic regions. Mean density (2.5 fish/m2) was similar to other Pacific reef fish communities whereas mean biomass (43 g/m2) was within the lowest known values. Four fish assemblages were identified along an inshore-offshore gradient and related to substrate characteristics (live corals, dead corals, seagrass, algae and sand): one seagrass bed assemblage, two lagoon assemblages and one outer barrier reef slope assemblage. The major energy intake comes from lower levels of the trophic network, grazers (45.1% biomass) being the main trophic group. Other important trophic categories came from upper trophic levels: macro-carnivores (24.4%) and piscivores (14.5%). Micro-algae ��� grazers ��� piscivores was the most important energy path, before macro-invertebrates ��� macro-carnivores ��� piscivores. Plankton represented a minor resource (only 5% planktivores) during the study, which is unusual. Spatial variations in trophic networks occurred among the four fish assemblages with significant variations for grazers and macro-carnivores, and high variations for piscivores, planktivores and corallivores.

The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump–probe experiments. Among others, the low-α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low-α mode of the experimental set-ups developed at the TEMPO beamline to perform pump–probe experiments with soft X-rays based on photoelectron or photon detection are presented. A 282 kHz repetition-rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two-dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time-resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high-time-resolution pump–probe experiments compared and discussed. Fil: Silly, Mathieu G.. Synchrotron Soleil; Francia Fil: Ferte, Tom. Synchrotron Soleil; Francia Fil: Tordeux, Marie Agnes. Synchrotron Soleil; Francia Fil: Pierucci, Debora. Synchrotron Soleil; Francia Fil: Beaulieu, Nathan. Synchrotron Soleil; Francia Fil: Chauvet, Christian. Synchrotron Soleil; Francia Fil: Pressacco, Federico. Synchrotron Soleil; Francia Fil: Sirotti, Fausto. Synchrotron Soleil; Francia Fil: Popescu, Horia. Synchrotron Soleil; Francia Fil: Lopez Flores, Victor. Synchrotron Soleil; Francia Fil: Tortarolo, Marina del Carmen. Synchrotron Soleil; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sacchi, Maurizio. Universite de Paris Vi. Institut des Nanosciences de Paris; Francia Fil: Jaouen, Nicolas. Synchrotron Soleil; Francia Fil: Hollander, Philippe. Synchrotron Soleil; Francia Fil: Ricaud, Jean Paul. Synchrotron Soleil; Francia Fil: Bergeard, Nicolas. Synchrotron Soleil; Francia Fil: Boeglin, Christine. Synchrotron Soleil; Francia Fil: Tudu, Bharati. Synchrotron Soleil; Francia Fil: Delaunay, Renaud. Universite de Paris VI; Francia Fil: Luning, Jan. Universite de Paris VI; Francia Fil: Malinowski, Gregory. Synchrotron Soleil; Francia Fil: Hehn, Michel. Synchrotron Soleil; Francia Fil: Baumier, Cedric. Université Paris Sud; Francia Fil: Fortuna, Franck. Université Paris Sud; Francia Fil: Krizmancic, Damjan. Elettra - Synchrotron Light Laboratory; Italia Fil: Stebel, Luigi. Elettra - Synchrotron Light Laboratory; Italia Fil: Sergo, Rudi. Elettra - Synchrotron Light Laboratory; Italia Fil: Cautero, Giuseppe. Elettra - Synchrotron Light Laboratory; Italia