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International audience; By focusing on several sales of Mediterranean red coral beads that the Marseilles merchant François Garnier and his commission agent François Tiran made in Smyrna around 1680, this paper brings an insight into Eurasian trade during the early modern period, and the variety of links and means that were employed to circulate the goods involved. Moreover, it helped us understand the specific mechanisms of commercial activity in the main Levant port towards the end of the 17 th century and to identify the roles and actions of the men in charge of this trade. Using Smyrna as a 'laboratory', this research focused on the exportation of Mediterranean red coral to Asia, thus giving us a deeper understanding of the traders' practices and intricate workings of exchange, but more specifically on the work of the Marseilles and Armenian traders in a difficult commercial niche, which in fact generated good profits when the products were of high quality and the market had been well-studied.; L’analyse de quelques ventes de grains de corail rouge de Méditerranée du marchand marseillais François Garnier et de son commissionnaire François Tiran à Smyrne autour de l’année 1680 permet d’entrevoir la variété des maillons et des moyens de la circulation des marchandises dans le commerce eurasiatique de l’époque moderne. Elle donne également la possibilité de saisir les ressorts précis de l’activité commerciale dans la principale échelle levantine du XVIIe siècle finissant et de cerner les capacités d’action des hommes qui en ont la charge. À travers le laboratoire smyrniote et une immersion dans la filière d’exportation du corail vers l’Asie, cette recherche a pour objectif d’approcher au plus près les acteurs du négoce, d’examiner leurs pratiques marchandes et les rouages complexes de l’échange. Cette contribution se penche notamment sur le travail des négociants marseillais et arméniens dans une niche commerciale difficile, mais apportant de confortables bénéfices quand les produits sont de qualité et les caractéristiques du marché bien analysées.

International audience; The critically endangered coral species Acropora palmata used to dominate shallow Caribbean reefs but since the early 1980s, populations have dramatically declined. At the Caribbean scale, A. palmata is divided into two genetically divergent lineages and most of previous works investigating population connectivity among populations involved the western line-age (in Florida, the Bahamas, the Mesoamerican Reef System, and the Greater Antilles). Small scale genetic connectivity among A. palmata populations was globally found, possibly enhancing populations' recovery at the local scale. Yet, little is known regarding the genetic connectivity of populations of the eastern lineage, especially those of the Lesser Antilles, a fragmented archipelago located at the edge of the species distribution. Here, we filled this gap by investigating the genetic diversity, population structure and connectivity of A. palmata populations among 36 sampled sites from 11 islands of the Lesser Antilles using 14 hypervariable microsatellite loci. Globally, genetic diversity levels in A. palmata populations from the Lesser Antilles were lower compared to what was previously reported within the Wider Caribbean. The analysis of the genetic structure, crossed with spatial autocorrelation analysis, revealed an isolation-by-distance pattern at both reef and Lesser Antilles scales. A gene dispersal distance of less than a kilometer, and a northward gene flow direction, in agreement with ocean surface currents in the region were found. Altogether, our results suggest a restricted population connectivity and short distance dispersal of A. palmata larvae within the Lesser Antilles further limited by geographic distances among suitable habitat patches. Additionally, our results suggest that southernmost populations are potential sources of larvae for the most northerly islands and have a key role in reseeding A. palmata populations of the Lesser Antilles.

International audience; Environmental conditions are known to influence corals and their associated communities of microorganisms. However, our insights into the impacts of seasonal changes in ultraviolet radiation (UVR) on both coral physiology and microbiome remain very limited. To address this challenge, we maintained the coral Acropora muricata shaded from UVR or under ambient UVR levels during two contrasting seasons, i.e. summer and winter, and assessed the impact of UVR on the coral holobiont at each season. To this end, we analyzed the physiology (e.g., calcification, protein content, photosynthesis-related parameters) and coral microbiota composition, as well as the abundance and composition of the microbial communities and organic matter contents of the surrounding seawater. Our results show major seasonal effects on coral phenotype: (1) a lower host biomass and photosynthesizing, but fast calcifying phenotype in summer, and (2) a higher host biomass and photosynthesizing, but slow calcifying phenotype in winter. UVR had only a significant impact on Symbiodinium functioning. Specifically, high UVR levels reduced photosynthesis efficiency in summer, but an increase in chlorophyll a content may have compensated for this effect. The coral microbiota, which was variable but generally dominated by Endozoicomonas, was not affected by UVR, but its composition differed between seasons. In contrast, UVR had a major, but differential impact on the seawater microbial communities at both seasons. Particularly in summer, bacteria from the Alteromonadaceae were significantly more abundant (15-fold; up to 75%) in seawater under ambient UVR levels. Overall, our study suggests that UVR has only a limited impact on coral holobiont composition and functioning, despite major fluctuations in the surrounding seawater microbiome; seasonal changes in the holobiont are thus mostly driven by other environmental factors.

A new scleractinian coral species, Pachyseris inattesa sp. n., is described from the Red Sea. Despite a superficial resemblance with some species in the agariciid genus Leptoseris with which it has been previously confused, P. inattesa sp. n. has micro-morphological characters typical of the genus Pachyseris. This genus, once part of the Agariciidae, is comprised of five extant species and is widely distributed throughout the tropical Indo-Pacific. It is currently incertae sedis as a result of recent molecular analysis and appears to be closely related to the Euphylliidae. A molecular phylogenetic reconstruction including P. inattesa sp.n., the genus type species P. rugosa, and P. speciosa, all present in the Red Sea, was performed using the mitochondrial intergenic spacer between COI and 16S-rRNA. The results confirm that P. inattesa sp. n. is a monophyletic lineage closely related to the other Pachyseris species examined.

International audience; Global warming is leading to both increases in frequency and intensity of tropical storms, with consequent salinity decrease at shallow reef areas, but also to mass bleaching events and mortality of reef-building corals around the world. Tropical storms can help reef-building corals to reproduce through fragmentation, allowing their expansion throughout the reefs. The combination of high temperature and low salinity may aggravate the effects of coral bleaching. Investigation of alterations at the cellular level will be useful since this is the first detectable response of organisms to changes in environmental conditions. In this study, the long-term oxidative stress induced by elevated temperature (30 °C), low salinity (20 psu), and their combination was studied on fragments of reef-forming corals, and compared to control conditions (26 °C, 33 psu). Determination of oxidative stress biomarkers: lipid peroxidation (LPO); superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities in a long-term experiment (60 days), using nine Indo-Pacific reef-forming coral species, provided useful information that was interpreted in combination with the observed general condition of these organisms (appearance: normal, pale, bleached, dead). High temperature affected the general condition of the species tested to a lower degree than did low salinity. Only two species died at high temperature, while low salinity resulted in the death of all species with the exception of two (P. contigua and G. fascicularis). Oxidative damage was detected in some species, as were antioxidant responses, at high temperature. Coral general condition was severely affected in all species in the low salinity treatment. Galaxea fascicularis and Psammocora contigua were the most resistant to salinity stress, having survived the experimental treatment. Oxidative damage was not detected in these species, but there was an antioxidant response. The high temperature + low salinity (HT + LS) treatment had synergistic effects in the condition of all species. Galaxea fascicularis was the only survivor in the HT + LS treatment. Mortality was high (60%) for this species, oxidative damage was not detected, but an increase in SOD activity revealed an antioxidant response.

Thermal stress affects organism performance differently depending on the ambient temperature to which they are acclimatized, which varies along latitudinal gradients. This study investigated whether differences in physiological responses to temperature are consistent with regional differences in temperature regimes for the stony coral Oculina patagonica. To resolve this question we experimentally assessed how colonies originating from four different locations characterized by >3°C variation in mean maximum annual temperature responded to warming from 20 to 32°C. We assessed plasticity in symbiont identity, density, and photosynthetic properties, together with changes in host tissue biomass. Results show that, without changes in the type of symbiont hosted by coral colonies, O. patagonica has limited capacity to acclimatize to future warming. We found little evidence of variation in overall thermal tolerance, or in thermal optima, in response to spatial variation in ambient temperature. Given that the invader O. patagonica is a relatively new member of the Mediterranean coral fauna our results also suggest that coral populations may need to remain isolated for a long period of time for thermal adaptation to potentially take place. Our study indicates that for O. patagonica, mortality associated with thermal stress manifests primarily through tissue breakdown under moderate but prolonged warming (which does not impair symbiont photosynthesis and, therefore, does not lead to bleaching). Consequently, projected global warming is likely to causes repeat incidents of partial and whole colony mortality and might drive a gradual range contraction of Mediterranean corals. This study was partially funded by the Journal of Experimental Biology Travelling fellowship (RR-M), by the Centre Scientifique de Monaco, and James Cook University (MH). The work contributes to the EU project: ‘Mediterranean Sea Acidification under a changing climate’ (MedSeA; grant agreement 265103).

Coral bleaching events are predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes depends on many factors, including the magnitude of thermal stress and irradiance. The interactions among these two factors, and in particular with ultra-violet radiation (UVR), the most harmful component of light, are more complex than assumed, and are not yet well understood. This paper explores the individual and combined effects of temperature and UVR on the metabolism of Acropora muricata, one of the most abundant coral species worldwide. Particulate and dissolved organic matter (POM/DOM) fluxes and organic matter (OM) degradation by the mucus-associated bacteria were also monitored in all conditions. The results show that UVR exposure exacerbated the temperature-induced bleaching, but did not affect OM fluxes, which were only altered by seawater warming. Temperature increase induced a shift from POM release and DOM uptake in healthy corals to POM uptake and DOM release in stressed ones. POM uptake was linked to a significant grazing of pico- and nanoplankton particles during the incubation, to fulfil the energetic requirements of A. muricata in the absence of autotrophy. Finally, OM degradation by mucus-associated bacterial activity was unaffected by UVR exposure, but significantly increased under high temperature. Altogether, our results demonstrate that seawater warming and UVR not only affect coral physiology, but also the way corals interact with the surrounding seawater, with potential consequences for coral reef biogeochemical cycles and food webs., Summary: This study explores the individual and combined effects of temperature and UVR on the metabolism of Acropora muricata, and on the organic matter release and degradation by the associated bacteria.

International audience; This study assesses changes in subtidal benthic communities on the largest reef flat in Reunion, Saint-Gilles La Saline, using several types of surveys. Temporal and spatial trends are documented over a 22 year period (1987-2009), thus spanning the 1998 and 2000s bleaching events. The most plausible explanations for the observed trends are proposed. We chose two sites that are characterized by two types of community and metabolism: (1) an oligotrophic site dominated by Acropora corals (Site-Toboggan), where sea-urchins are numerous and macroalgae rare and (2) a dystrophic site dominated by non-Acropora corals, mostly massive and submassive, where macroalgae abound and sea-urchins are almost absent (Site-Planch'Alizés). Results are presented in three parts : Part 1 : general trends of the communities, part 2 : primary producers, part 3 : living corals. Part 1 presents three surveys. Survey 1 reports status and trends across the reef flats in 1993, 1996, and 2002, with all attached benthic components reported at the level of the species where possible. Survey 2 reports composition and changes in associated sedentary organisms such as sea urchins, holothurids, and the Pomacentridae fish Stegastes. Survey 3 focuses on the period 1998 to 2009 on permanent transects established in 1987 and monitored periodically, partly as a contribution to the Global Coral Reef Monitoring Network (GCRMN). In general, community structures at both locations remained stable, with primary producer coverage around 5% at Toboggan (T) and around 60% at Planch'Alizés (P). Living coral coverage averaged around 17% at both sites, but it was dominated by Acropora on Site-T (68%) and by massive corals on Site-P (88%). Regular echinoids were very abundant at T but almost absent from P, while the opposite was true for holothurids. The territorial damselfish Stegastes was of comparable abundance at both sites (

International audience; The dinoflagellate microalga Symbiodinium sustains coral reefs, one of the most diverse ecosystems of the biosphere, through mutualistic endosymbioses with a wide diversity of benthic hosts [1]. Despite its ecological and economic importance, the presence of Symbiodinium in open oceanic waters remains unknown, which represents a significant knowledge gap to fully understand the eco-evolutionary trajectory and resilience of endangered Symbiodinium-based symbioses. Here, we document the existence of Symbiodinium (i.e., now the family Symbiodiniaceae [2]) in tropical- and temperate-surface oceans using DNA and RNA metabarcoding of size-fractionated plankton samples collected at 109 stations across the globe. Symbiodinium from clades A and C were, by far, the most prevalent and widely distributed lineages (representing 0.1% of phytoplankton reads), while other lineages (clades B, D, E, F, and G) were present but rare. Concurrent metatranscriptomics analyses using the Tara Oceans gene catalog [3] revealed that Symbiodinium clades A and C were transcriptionally active in the open ocean and expressed core metabolic pathways (e.g., photosynthesis, carbon fixation, glycolysis, and ammonium uptake). Metabarcodes and expressed genes of clades A and C were detected in small and large plankton size fractions, suggesting the existence of a free-living population and a symbiotic lifestyle within planktonic hosts, respectively. However, high-resolution genetic markers and microscopy are required to confirm the life history of oceanic Symbiodinium. Overall, the previously unknown, metabolically active presence of Symbiodinium in oceanic waters opens up new avenues for investigating the potential of this oceanic reservoir to repopulate coral reefs following stress-induced bleaching.

The issue of ensuring that growing communities in small island countries have access to safe water and adequate sanitation is examined in Kiribati, whose islands are spread over three million square kilometres in the central Pacific. Its coral island communities have water supply and sanitation problems among the most difficult in the world. Formulaic developed-world approaches, models, techniques and toolboxes that do not consider the social and cultural context have had little success. Changes in approach at the international, national and local levels are called for, and the resourcing of village-level water and sanitation committees would return ownership and control in rural communities to its traditional base. Development (2008) 51, 282–287. doi:10.1057/dev.2008.18

For diploid organisms, haplotype determination usually requires sequencing cloned polymerase chain reaction (PCR) products or comparing the genotypes of several individuals. We found out that phase could be reconstructed from direct sequencing of mixed PCR products by combining for each individual the complementary information contained in its forward and reverse chromatograms, provided these products had different lengths. When applied to the internal transcribed spacer 2 (ITS2) from corals of the genus Pocillopora, this new method allowed us to identify two dominant sequence types in some specimens; however, sequencing cloned PCR products from the same specimens yielded more variants, including possible PCR-generated recombination artifacts.

We present a 47-year-long record of sea surface temperature (SST) derived from Sr/Ca and U/Ca analysis of a massive Porites coral which grew at ∼ 4150 calendar years before present (B.P.) in Vanuatu (southwest tropical Pacific Ocean). Mean SST is similar in both the modern instrumental record and paleorecord, and both exhibit El Nino-Southern Oscillation (ENSO) frequency SST oscillations. However, several strong decadal-frequency cooling events and a marked modulation of the seasonal SST cycle, with power at both ENSO and decadal frequencies, are observed in the paleorecord, which are unprecedented in the modern record.

Recent molecular phylogenetic studies have shown that most traditional families of zooxanthellate shallow-water scleractinians are polyphyletic, whereas most families mainly composed of deep-sea and azooxanthellate species are monophyletic. In this context, the family Dendrophylliidae (Cnidaria, Scleractinia) has unique features. It shows a remarkable variation of morphological and ecological traits by including species that are either colonial or solitary, zooxanthellate or azooxanthellate, and inhabiting shallow or deep water. Despite this morphological heterogeneity, recent molecular works have confirmed that this family is monophyletic. Nevertheless, what so far is known about the evolutionary relationships within this family, is predominantly based on skeleton macromorphology, while most of its species have remained unstudied from a molecular point of view. Therefore, we analysed 11 dendrophylliid genera, four of which were investigated for the first time, and 30 species at molecular, micromorphological and microstructural levels. We present a robust molecular phylogeny reconstruction based on two mitochondrial markers (COI and the intergenic spacer between COI and 16S) and one nuclear (rDNA), which is used as basis to compare micromorphogical and microstructural character states within the family. The monophyly of the Dendrophylliidae is well supported by molecular data and also by the presence of rapid accretion deposits, which are ca. 5 μm in diameter and arranged in irregular clusters, and fibres that thicken the skeleton organized in small patches of a few micrometres in diameter. However, all genera represented by at least two species are not monophyletic, Tubastraea excluded. They were defined by traditional macromorphological characters that appear affected by convergence, homoplasy and intraspecific variation. Micromorphogical and microstructural analyses do not support the distinction of clades, with the exception of the organization of thickening deposits for the Tubastraea clade.

15 pages; International audience; The scleractinian coral Acropora millepora is one of the most studied species from the Great Barrier Reef. This species has been used to understand evolutionary, immune and developmental processes in cnidarians. It has also been subject of several ecological studies in order to elucidate reef responses to environmental changes such as temperature rise and ocean acidification (OA). In these contexts, several nucleic acid resources were made available. When combined to a recent proteomic analysis of the coral skeletal organic matrix (SOM), they enabled the identification of several skeletal matrix proteins, making A. millepora into an emerging model for biomineralization studies. Here we describe the skeletal microstructure of A. millepora skeleton, together with a functional and biochemical characterization of its occluded SOM that focuses on the protein and saccharidic moieties. The skeletal matrix proteins show a large range of isoelectric points, compositional patterns and signatures. Besides secreted proteins, there are a significant number of proteins with membrane attachment sites such as transmembrane domains and GPI anchors as well as proteins with integrin binding sites. These features show that the skeletal proteins must have strong adhesion properties in order to function in the calcifying space. Moreover this data suggest a molecular connection between the calcifying epithelium and the skeletal tissue during biocalcification. In terms of sugar moieties, the enrichment of the SOM in arabinose is striking, and the monosaccharide composition exhibits the same signature as that of mucus of acroporid corals. Finally, we observe that the interaction of the acetic acid soluble SOM on the morphology of in vitro grown CaCO3 crystals is very pronounced when compared with the calcifying matrices of some mollusks. In light of these results, we wish to commend Acropora millepora as a model for biocalcification studies in scleractinians, from molecular and structural viewpoints.

International audience; The principal architects of coral reefs are the scleractinian corals; these species are divided in two major clades referred to as "robust'' and "complex'' corals. Although the molecular diversity of the "complex'' clade has received considerable attention, with several expressed sequence tag (EST) libraries and a complete genome sequence having been constructed, the "robust'' corals have received far less attention, despite the fact that robust corals have been prominent focal points for ecological and physiological studies. Filling this gap affords important opportunities to extend these studies and to improve our understanding of the differences between the two major clades. Here, we present an EST library from Stylophora pistillata (Esper 1797) and systematically analyze the assembled transcripts compared to putative homologs from the complete proteomes of six well-characterized metazoans: Nematostella vectensis, Hydra magnipapillata, Caenorhabditis elegans, Drosophila melanogaster, Strongylocentrotus purpuratus, Ciona intestinalis and Homo sapiens. Furthermore, comparative analyses of the Stylophora pistillata ESTs were performed against several Cnidaria from the Scleractinia, Actiniaria and Hydrozoa, as well as against other stony corals separately. Functional characterization of S. pistillata transcripts into KOG/COG categories and further description of Wnt and bone morphogenetic protein (BMP) signaling pathways showed that the assembled EST library provides sufficient data and coverage. These features of this new library suggest considerable opportunities for extending our understanding of the molecular and physiological behavior of "robust'' corals.

Novel micromorphological characters in combination with molecular studies have led to an extensive revision of the taxonomy and systematics of scleractinian corals. In the present work, we investigate the macro- and micromorphology and the phylogenetic position of the genera Australomussa and Parascolymia, two monotypic genera ascribed to the family Lobophylliidae. The molecular phylogeny of both genera was addressed using three markers, the partial mitochondrial COI gene and the nuclear histone H3 and the ribosomal ITS region. Based on molecular data, Australomussa and Parascolymia belong to the Lobophylliidae and they cluster together with the genera Lobophyllia and Symphyllia within the same clade. While A. rowleyensis and P. vitiensis are closely related based on the three gene regions examined, their macro and micromorphology suggest that these species are distinct, differing in several characters, such as continuity and thickness of the costosepta, the number of septa, septal tooth height, spacing, and shape, and the distribution and shape of granules. Thus, we revise the taxonomic status of the genus Australomussa as a junior synonym of Parascolymia.

Kolodziej, B., Golubic, S., Bucur, I.I., Radtke, G. & Tribollet, A. 2011: Early Cretaceous record of microboring organisms in skeletons of growing corals. Lethaia, Vol. 45, pp. 34–45. A spectacularly preserved assemblage of microbial euendoliths, penetrating into skeletons of growing scleractinian corals, has been recognized in Early Aptian (Early Cretaceous) reef limestone of the Rarau Mountains (East Carpathians, NE Romania). Microboring euendolithic filaments were found in five coral colonies of the suborder Microsolenina. They remained in part well-preserved, often impregnated with iron oxides, which made them visible even in strongly recrystallized parts of coral skeletons. Filaments of a wide range of sizes (2–40 μm in diameter) were concentrated within medium parts of coral septa, oriented along the septa in the direction of the coral growth. The larger filaments were tubular, occurring in bundles and branched into finer, often tapering branches. Their behaviour and organization were quite similar to the modern euendolithic siphonalean chlorophyte Ostreobium. Filament diameters exceeded those reported for the modern species, but covered a similarly wide size range. Narrower frequently branching filaments, 4–8 μm in diameter, resemble distal branching patterns of modern Ostreobium quekettii. Some very thin filaments (ca. 1–2 μm) observed within skeleton or inside the large tubular filaments, sometimes associated with globular swellings, may represent euendolithic fungi. The recrystallization of coral skeleton had limited effect on preservation of euendoliths due to their impregnation with iron oxides; microbial euendoliths were subjected to different taphonomic changes. □Chlorophytes, Early Cretaceous, fungi, microbial euendoliths, Romania, scleractinian corals.

SUMMARY As the effects of climate change have become increasingly visible over the past three decades, coral reefs have suffered from a number of natural and anthropogenic disturbances that have caused a critical decline in coral populations. Among these disturbances are coral diseases, which have appeared with increasing frequency and severity, often in correlation with increases in water temperature. Although the crucial role played by Vibrio species in coral disease has been widely documented, the scientific community does not yet fully understand the infection process of Vibrio or its impact on coral physiology and immunology. Here, we investigated the physiological and transcriptomic responses of a major reef-building coral, Pocillopora damicornis, when exposed to a specific pathogen (Vibrio coralliilyticus) under virulent (increasing water temperature) and non-virulent (constant low temperature) conditions. The infection process was examined by electron microscopy and quantitative reverse-transcription PCR, and coral health was monitored by visual observations and measurements of zooxanthellar density. The results obtained suggest that coral tissue invasion occurs upon increasing water temperature only. Transcriptomic variations were investigated using a suppression–subtractive–hybridization approach, and the expression levels of six candidate immune-related genes were examined during bacterial exposure. These genes correspond to three lectin-like molecules putatively involved in the recognition of pathogens, two metal-binding proteins putatively involved in antibacterial response and one cystein protease inhibitor. The transcription patterns of these selected genes provide new insights into the responses of coral colonies to virulent versus non-virulent bacteria.

International audience; We investigated the spatial distribution of adult and juvenile coral assemblages in the southwestern lagoon of New Caledonia, from disturbed fringing reefs within bays, to oceanic barrier reefs. Generic richness, abundance, and percent cover were highly variable at this scale, but no clear cross-shelf gradient was found. Rather, community composition was more related to reef biotopes. Correlations and canonical correspondence analyses revealed that composition and abundance of coral assemblages were related to substrate types (cover of turf algae and cover of encrusting coralline algae), but not to water quality or metal concentrations in sediments. We found a strong relationship between juvenile and adult distribution for all dominant genera, which suggests that recruitment processes are also a major factor structuring these populations. The densities of juveniles and their proportion in the coral assemblages were relatively low, which implies that replenishment capacities and potential for recovery are probably limited for these reefs.

The capacity of the Landsat 7 Enhanced Thematic Mapper Plus sensor to classify the shallow benthic ecosytems of New Caledonia (South Pacific) is tested using a novel unsupervised classification method. The classes are defined by using a set of multiple spectral decision rules based on the image spectral bands. A general model is applied to the entire Southwest lagoon (5500 km(2)) and tested on three representative sites: a section of the barrier reef, a cay reef flat rich in corals, and a cay reef flat rich in algae and seagrass beds. In the latter one, the classification results are compared with a locally optimized model, with aerial color photographs and extensive ground-truthed observations. Results show that a reconnaissance of the main benthic habitats in shallow areas (, Le but de cette étude est de tester la capacité des images Landsat 7 Enhanced Thematic Mapper Plus à discriminer les principales classes d’habitats benthiques rencontrées dans les parties peu profondes du système récifal et lagonaire de Nouvelle-Calédonie (Pacifique Sud). Une méthode originale de classification non-supervisée est proposée. Les habitats benthiques correspondent à une combinaison de plusieurs règles de décision établies à partir des bandes radiométriques Landsat. Cette modélisation statistique des habitats benthiques est appliquée au lagon sud-ouest de Nouvelle-Calédonie (5500 km2). Les résultats sont testés sur trois sites témoins contrastés: un platier de récif barrière, un platier d’îlot riche en corail et un platier d’îlot riche en herbiers/algueraies. Pour ce dernier, le résultat est comparé à celui d’un modèle optimisé, construit à échelle locale et validé à partir de photographies aériennes et d’observations de terrain. Les résultats montrent qu’une reconnaissance des différentes classes benthiques est possible pour des fonds peu profonds (< 5 m de profondeur), à l’échelle géomorphologique pour les structures récifales et à l’échelle des habitats pour les herbiers. Toutefois, les résultats bruts du modèle doivent être interprétés en fonction de critères spatiaux pour corriger les confusions entre certaines classes, notamment entre les pentes coralliennes et les herbiers denses.

The coralgal framework within the outer reef margin of many Indo-Pacific reefs exhibits three main shallow-water communities, the environmental significance of which can be inferred by comparison with their modern counterparts. A community dominated by tabular Acropora gr. hyacinthus/cytherea with branching Pocillopora damicornis, P. eydouxi, Montipora digitata, occasional domal faviids and mm-thick crusts of the coralline algae Lithophyllum and Mesophyllum (mainly), typical of the 6 – 15 m paleodepth range; a community including robust-branching Acropora gr. danai/robusta, A. humilis, A. digitifera and subordinate Favia stelligera, Echinopora gemmacea, associated to vermetid gastropods and thick coralline crusts of Hydrolithon cf. onkodes and Neogoniolithon cf. fosliei flourishing in depths less than 6 m; in medium-to-high water-energy settings, a community composed of domal Porites cf. lutea and P. cf. lobata with occasional Acropora gr. danai/robusta and cm-thick crusts of coralline algae in sheltered habitats in depths less than 10 m. These biological assemblages allow us to determine relationships between reef growth and paleobathymetry and, consequently, to reconstruct regional relative sea-level curves. High water-energy reefal assemblages provide stronger evidence for reconstructing sea-level curves than low-energy buildups, because they have generally been controlled by a keep-up growth mode. Subsiding reef sites seem to be more reliable indicators of sea-level variations because they usually present expanded reef sequences.

Three species of corals Stylophora pistillata, Lobophyllia corymbosa and Echinopora gemmacea were collected from Sharm Obhur to study their chemical composition. This information was important in the investigation of their metabolic pathways and their mode of feeding. The concentrations of amino acids in these species were 9.37, 21.35 and 3.09 mg.g(-1) dry weight of coral respectively. Plant pigments were highest in E. gemmacea followed by S. pistillata and then by L. corymbosa. Lipid concentrations in S. pistillata, L. corymbosa and E. gemmacea were 1.90, 8.58 and 1.32 mg.g(-1) of total coral respectively. The fatty acid methyl esters were analyzed in these species and the most abundant saturated acids were 16:0 and 18:0, while unsaturated acids included 16:1, 18:1 and 19:3. The carbohydrate concentrations were 559, 425 and 859 mu g.g(-1) of total coral dry weight. Residual matter was 42.5, 32.8 and 41.39 per cent by weight of total coral. These data suggest a greater reliance on autotrophic feeding in E. gemmacea and S, pistillata and mostly heterotrophic feeding in L. corymbosa., Trois espèces de coraux, Stylophora pistillata, Lobophyllia corymbosa et Echinopora gemmacea ont été prélevés à Sharm Obhur afin d'étudier leur composition chimique. Cette information est utile pour l'étude du métabolisme et du mode de nutrition des coraux. Les concentrations en acides aminés des trois espèces étaient respectivement de 9,37; 21,35 et 3,09 mg·g−1. Les pigments végétaux sont plus importants chez E. gemmacea suivi par S. pistillata puis par L. corymbosa. Le contenu lipidique chez S. pistillata, L. corymbosa et E. gemmacea était respectivement de 1,9; 8,58 et 1,32 mg·g−1 du corail total. L'ester méthylique des acides gras a été analysé chez les trois espèces; les plus abondants parmi les acides saturés étaient le 16:0 et le 18:0, alors que les acides saturés comprenaient le 16:1, le 18:1 et le 19:3. Les contenus en hydrates de carbone des trois espèces étudiécs étaient respectivement de 559, 425 et 859 μg·g−1; dans le même ordre la matière résiduelle représentait 42,5, 32,8 et 41,39% du poids total du corail. Ces données suggèrent une plus grande dépendance d'une nutrition autotrophe chez E. gemmacea et S. pistillata et une nutrition partiellement hétérotrophe chez L. corymbosa.

The progression of a temperature-induced bleaching event on the barrier reef at Passe d'Arue, Tahiti, during March–April 1994 was observed at approximately weekly intervals. The event consisted of selective exaggeration of polyp colours ( Montipora verneuilli, Pocillopora verrucosa ), fluorescence followed by bleaching ( Acropora spp.), partial-complete bleaching ( Fungia spp., Montastraea curta , anemones) and commencement of polyp death. Porites (massive spp.), P. ( Synarea ) rus and melobesoid algae were almost untouched by the event.

Morphological data suggest that, unlike most other groups of marine organisms, scleractinian corals of the genus Stylophora are more diverse in the western Indian Ocean and in the Red Sea than in the central Indo-Pacific. However, the morphology of corals is often a poor predictor of their actual biodiversity: hence, we conducted a genetic survey of Stylophora corals collected in Madagascar, Okinawa, the Philippines and New Caledonia in an attempt to find out the true number of species in these various locations., info:eu-repo/semantics/published