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Auteur Maloufi, S.; Catherine, A.; Mouillot, D.; Louvard, C.; Couté, A.; Bernard, C.; Troussellier, M. url  doi
openurl 
  Titre Environmental heterogeneity among lakes promotes hyper β-diversity across phytoplankton communities Type Article scientifique
  Année (down) 2016 Publication Revue Abrégée Freshw Biol  
  Volume 61 Numéro 5 Pages 633-645  
  Mots-Clés environmental heterogeneity; meta-community ecology; Phytoplankton; species sorting; turnover  
  Résumé * The extent to which stochastic and deterministic processes influence variations in species communities across space and time remains a central question in theoretical and applied ecology. Despite their high dispersal ability, the composition of phytoplankton communities displays striking spatial variations among lakes even at small spatial scale. * To investigate the mechanisms underlying the distribution of phytoplankton species, we evaluate the contribution of stochastic, spatial and environmental processes in determining β-diversity patterns of phytoplankton at a regional scale. Phytoplankton communities were surveyed in 50 different lakes from north-central France, a region characterised by strong environmental heterogeneity. * The regional species pool was characterised by extremely high β-diversity levels, which were mainly explained by species replacement (i.e. turnover) rather than by differences in species richness (i.e. nestedness). Null models of random species distribution and spatial processes failed to explain observed β-diversity patterns. At the opposite, local environmental conditions strongly influenced the degree of uniqueness of local phytoplankton communities, with the most contrasted environments, including human-dominated areas, promoting highly distinct phytoplankton communities. * Our results suggest that species-sorting mechanisms that arise from variations in local environmental conditions drive high species turnover at the region scale. Thus, in a landscape strongly impacted by cultural eutrophication, further anthropogenic impacts on aquatic ecosystems would likely induce regional homogenisation of phytoplankton communities. Overall, our study supports the fact that the management of lakes and reservoirs in anthropic landscapes should aim at maintaining environmental heterogeneity while preventing further eutrophication in order to favour the maintenance of high phytoplankton β- and γ-diversity.  
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  ISSN 1365-2427 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1569  
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Auteur Tsiola, A.; Pitta, P.; Fodelianakis, S.; Pete, R.; Magiopoulos, I.; Mara, P.; Psarra, S.; Tanaka, T.; Mostajir, B. url  doi
openurl 
  Titre Nutrient Limitation in Surface Waters of the Oligotrophic Eastern Mediterranean Sea: an Enrichment Microcosm Experiment Type Article scientifique
  Année (down) 2016 Publication Revue Abrégée Microb Ecol  
  Volume 71 Numéro 3 Pages 575-588  
  Mots-Clés Ecology; Eukaryotic phytoplankton; Geoecology/Natural Processes; Heterotrophic prokaryotes; Microbial ecology; Microbiology; Nature Conservation; Prochlorococcus; Synechococcus; Viruses; Water Quality/Water Pollution  
  Résumé The growth rates of planktonic microbes in the pelagic zone of the Eastern Mediterranean Sea are nutrient limited, but the type of limitation is still uncertain. During this study, we investigated the occurrence of N and P limitation among different groups of the prokaryotic and eukaryotic (pico-, nano-, and micro-) plankton using a microcosm experiment during stratified water column conditions in the Cretan Sea (Eastern Mediterranean). Microcosms were enriched with N and P (either solely or simultaneously), and the PO4 turnover time, prokaryotic heterotrophic activity, primary production, and the abundance of the different microbial components were measured. Flow cytometric and molecular fingerprint analyses showed that different heterotrophic prokaryotic groups were limited by different nutrients; total heterotrophic prokaryotic growth was limited by P, but only when both N and P were added, changes in community structure and cell size were detected. Phytoplankton were N and P co-limited, with autotrophic pico-eukaryotes being the exception as they increased even when only P was added after a 2-day time lag. The populations of Synechococcus and Prochlorococcus were highly competitive with each other; Prochlorococcus abundance increased during the first 2 days of P addition but kept increasing only when both N and P were added, whereas Synechococcus exhibited higher pigment content and increased in abundance 3 days after simultaneous N and P additions. Dinoflagellates also showed opportunistic behavior at simultaneous N and P additions, in contrast to diatoms and coccolithophores, which diminished in all incubations. High DNA content viruses, selective grazing, and the exhaustion of N sources probably controlled the populations of diatoms and coccolithophores.  
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  ISSN 0095-3628, 1432-184x ISBN Médium  
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Auteur Sebastian, M.; Smith, A.F.; Gonzalez, J.M.; Fredricks, H.F.; Van Mooy, B.; Koblizek, M.; Brandsma, J.; Koster, G.; Mestre, M.; Mostajir, B.; Pitta, P.; Postle, A.D.; Sanchez, P.; Gasol, J.M.; Scanlan, D.J.; Chen, Y. doi  openurl
  Titre Lipid remodelling is a widespread strategy in marine heterotrophic bacteria upon phosphorus deficiency Type Article scientifique
  Année (down) 2016 Publication Revue Abrégée Isme J.  
  Volume 10 Numéro 4 Pages 968-978  
  Mots-Clés 2 enzymes; agrobacterium-tumefaciens; bacterioplankton groups; Ecology; Mediterranean Sea; mesocosm experiment; microbial food-web; north-atlantic ocean; nutrient limitation; phosphate starvation  
  Résumé Upon phosphorus (P) deficiency, marine phytoplankton reduce their requirements for P by replacing membrane phospholipids with alternative non-phosphorus lipids. It was very recently demonstrated that a SAR11 isolate also shares this capability when phosphate starved in culture. Yet, the extent to which this process occurs in other marine heterotrophic bacteria and in the natural environment is unknown. Here, we demonstrate that the substitution of membrane phospholipids for a variety of non-phosphorus lipids is a conserved response to P deficiency among phylogenetically diverse marine heterotrophic bacteria, including members of the Alphaproteobacteria and Flavobacteria. By deletion mutagenesis and complementation in the model marine bacterium Phaeobacter sp. MED193 and heterologous expression in recombinant Escherichia coli, we confirm the roles of a phospholipase C (PlcP) and a glycosyltransferase in lipid remodelling. Analyses of the Global Ocean Sampling and Tara Oceans metagenome data sets demonstrate that PlcP is particularly abundant in areas characterized by low phosphate concentrations. Furthermore, we show that lipid remodelling occurs seasonally and responds to changing nutrient conditions in natural microbial communities from the Mediterranean Sea. Together, our results point to the key role of lipid substitution as an adaptive strategy enabling heterotrophic bacteria to thrive in the vast P-depleted areas of the ocean.  
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  ISSN 1751-7362 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1624  
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Auteur Cinner, J.E.; Huchery, C.; MacNeil, M.A.; Graham, N.A.J.; McClanahan, T.R.; Maina, J.; Maire, Eva; Kittinger, J.N.; Hicks, C.C.; Mora, C.; Allison, E.H.; D’Agata, S.; Hoey, A.; Feary, D.A.; Crowder, L.; Williams, I.D.; Kulbicki, M.; Vigliola, L.; Wantiez, L.; Edgar, G.; Stuart-Smith, R.D.; Sandin, S.A.; Green, A.L.; Hardt, M.J.; Beger, M.; Friedlander, A.; Campbell, S.J.; Holmes, K.E.; Wilson, S.K.; Brokovich, E.; Brooks, A.J.; Cruz-Motta, J.J.; Booth, D.J.; Chabanet, P.; Gough, C.; Tupper, M.; Ferse, S.C.A.; Sumaila, U.R.; Mouillot, D. url  doi
openurl 
  Titre Bright spots among the world’s coral reefs Type Article scientifique
  Année (down) 2016 Publication Revue Abrégée Nature  
  Volume 535 Numéro 7612 Pages 416-419  
  Mots-Clés Environmental impact; Sustainability; Tropical ecology  
  Résumé Ongoing declines in the structure and function of the world’s coral reefs require novel approaches to sustain these ecosystems and the millions of people who depend on them. A presently unexplored approach that draws on theory and practice in human health and rural development is to systematically identify and learn from the ‘outliers’—places where ecosystems are substantially better (‘bright spots’) or worse (‘dark spots’) than expected, given the environmental conditions and socioeconomic drivers they are exposed to. Here we compile data from more than 2,500 reefs worldwide and develop a Bayesian hierarchical model to generate expectations of how standing stocks of reef fish biomass are related to 18 socioeconomic drivers and environmental conditions. We identify 15 bright spots and 35 dark spots among our global survey of coral reefs, defined as sites that have biomass levels more than two standard deviations from expectations. Importantly, bright spots are not simply comprised of remote areas with low fishing pressure; they include localities where human populations and use of ecosystem resources is high, potentially providing insights into how communities have successfully confronted strong drivers of change. Conversely, dark spots are not necessarily the sites with the lowest absolute biomass and even include some remote, uninhabited locations often considered near pristine. We surveyed local experts about social, institutional, and environmental conditions at these sites to reveal that bright spots are characterized by strong sociocultural institutions such as customary taboos and marine tenure, high levels of local engagement in management, high dependence on marine resources, and beneficial environmental conditions such as deep-water refuges. Alternatively, dark spots are characterized by intensive capture and storage technology and a recent history of environmental shocks. Our results suggest that investments in strengthening fisheries governance, particularly aspects such as participation and property rights, could facilitate innovative conservation actions that help communities defy expectations of global reef degradation.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0028-0836 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1628  
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Auteur Leprieur, F.; Colosio, S.; Descombes, P.; Parravicini, V.; Kulbicki, M.; Cowman, P.F.; Bellwood, D.R.; Mouillot, D.; Pellissier, L. doi  openurl
  Titre Historical and contemporary determinants of global phylogenetic structure in tropical reef fish faunas Type Article scientifique
  Année (down) 2016 Publication Revue Abrégée Ecography  
  Volume 39 Numéro 9 Pages 825-835  
  Mots-Clés biodiversity hotspots; climate-change; community ecology; coral-reefs; damselfishes teleostei; evolutionary origins; genetic-structure; indo-pacific; latitudinal diversity gradient; species richness  
  Résumé Identifying the main determinants of tropical marine biodiversity is essential for devising appropriate conservation measures mitigating the ongoing degradation of coral reef habitats. Based on a gridded distribution database and phylogenetic information, we compared the phylogenetic structure of assemblages for three tropical reef fish families (Labridae: wrasses, Pomacentridae: damselfishes and Chaetodontidae: butterflyfishes) using the net relatedness (NRI) and nearest taxon (NTI) indices. We then related these indices to contemporary and historical environmental conditions of coral reefs using spatial regression analyses. Higher levels of phylogenetic clustering were found for fish assemblages in the Indo-Australian Archipelago (IAA), and more particularly when considering the NTI index. The phylogenetic structure of the Pomacentridae, and to a lower extent of the Chaeotodontidae and Labridae, was primarily associated with the location of refugia during the Quaternary period. Phylogenetic clustering in the IAA may partly result from vicariance events associated with coral reef fragmentation during the glacial periods of the Quaternary. Variation in the patterns among fish families further suggest that dispersal abilities may have interacted with past habitat availability in shaping the phylogenetic structure of tropical reef fish assemblages.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0906-7590 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1633  
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