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Auteur Leruste, A.; Villeger, S.; Malet, N.; De Wit, R.; Bec, B. doi  openurl
  Titre Complementarity of the multidimensional functional and the taxonomic approaches to study phytoplankton communities in three Mediterranean coastal lagoons of different trophic status Type Article scientifique
  Année 2018 Publication (up) Revue Abrégée Hydrobiologia  
  Volume 815 Numéro 1 Pages 207-227  
  Mots-Clés classification; Classification; disturbance; diversity; ecology; Functional entity; Functional traits; lake phytoplankton; marine-phytoplankton; patterns; size; synechococcus; Taxonomic diversity; traits  
  Résumé We used the individual-based multidimensional functional diversity and the taxonomic approaches in a complementary way to describe phytoplankton communities in three coastal lagoons with different eutrophication status in the South of France. We sampled communities during three seasons, i.e., in autumn, spring, and summer. Using classical taxonomy, 107 taxa/morphotypes were identified in the nine communities. The individual-based functional approach allowed grouping these individuals into 20 functional entities according to their values for 5 traits related to trophic adaptations (cell size, mobility, trophic regime, coloniality, and pelagic/benthic life). Some species (e.g., Prorocentrum micans) emerged in multiple functional entities, showing the importance to consider intraspecific variability. The functional description of phytoplankton communities better reflected the hydrological functioning and the different eutrophication status of the lagoons than the taxonomic approach. Specific functional adaptations were identified in the nine communities. For example, phytoplankton organisms with heterotrophic and potentially mixotrophic abilities occurred when the availability of inorganic nutrient decreased, or when organic matter and small preys were potentially the main nutrient resources. The limitation has also favored small cells highly competitive for nutrients. Using functional indices together with taxonomic description has also helped revealing important aspects of community assembly, such as competitive exclusion in summer.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0018-8158 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2322  
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Auteur Bonilla-Findji, O.; Rochelle-Newall, E.; Weinbauer, M.G.; Pizay, M.D.; Kerros, M.E.; Gattuso, J.P. url  doi
openurl 
  Titre Effect of seawater-freshwater cross-transplantations on viral dynamics and bacterial diversity and production Type Article scientifique
  Année 2009 Publication (up) Revue Abrégée Aquat. Microb. Ecol.  
  Volume 54 Numéro 1 Pages 1-11  
  Mots-Clés aquatic systems; Bacterial production; Bacterial richness; bacterioplankton; batch cultures; chesapeake bay; Communities; community composition; dissolved organic-matter; estuarine salinity gradient; growth efficiency; marine; microbial; population-dynamics; Transplantation; Virus  
  Résumé Dilution experiments were carried out to investigate the community composition and the metabolic response of seawater and freshwater bacteria to cross-transplantation, and the effects of nor.-indigenous bacterial hosts on viral dynamics. Changes in viral and bacterial abundance and production, as Well as bacterial respiration, carbon demand and diversity were regularly monitored over a 6 d period. Bacterial production in the transplanted seawater (SB-t) and freshwater (FB-t) bacteria treatments was stimulated up to 256 and 221 %, respectively, compared to controls. The stimulation of bacterial production and carbon demand was accompanied by a decrease in bacterial richness. Net viral production was stimulated by 81% in SB-t and repressed by 75% in FB-t. Transplantation increased the virus-induced mortality of marine bacteria, but decreased it for freshwater bacteria. These results suggest that (1) marine bacteria can readily oxidize freshwater dissolved organic matter, and (2) freshwater viruses might be able to infect marine hosts, thus highlighting their potential role in fueling bacterial growth under resource stress or nutrient-depleted conditions.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0948-3055 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 546  
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Auteur Duval, C.; Thomazeau, S.; Drelin, Y.; Yepremian, C.; Bouvy, M.; Couloux, A.; Troussellier, M.; Rousseau, F.; Bernard, C. doi  openurl
  Titre Phylogeny and salt-tolerance of freshwater Nostocales strains: Contribution to their systematics and evolution Type Article scientifique
  Année 2018 Publication (up) Revue Abrégée Harmful Algae  
  Volume 73 Numéro Pages 58-71  
  Mots-Clés baltic sea; bloom; comb. nova; Cyanobacteria; dolichospermum; genera anabaena; genetics analysis; great oxidation event; hetR; Morphology; nijH; Nostocaceae; Phylogeny; Physiology; planktonic cyanobacteria; polyphasic approach; Polyphasic approach; Salt-tolerance; toxin production  
  Résumé Phylogenetic relationships among heterocytous genera (the Nostocales order) have been profoundly modified since the use of polyphasic approaches that include molecular data. There is nonetheless still ample scope for improving phylogenetic delineations of genera with broad ecological distributions, particularly by integrating specimens from specific or up-to-now poorly sampled habitats. In this context, we studied 36 new isolates belonging to Chrysosporum, Dolichospermum, Anabaena, Anabaenopsis, and Cylindrospermopsis from freshwater ecosystems of Burkina-Faso, Senegal, and Mayotte Island. Studying strains from these habitats is of particular interest as we suspected different range of salt variations during underwent periods of drought in small ponds and lakes. Such salt variation may cause different adaptation to salinity. We then undertook a polyphasic approach, combining molecular phylogenies, morphological analyses, and physiological measurements of tolerance to salinity. Molecular phylogenies of 117 Nostocales sequences showed that the 36 studied strains were distributed in seven lineages: Dolichospermum, Chrysosporum, Cylindrospermopsis Raphidiopsis, Anabaenopsis, Anabaena sphaerica var tenuis/Sphaerospermopsis, and two independent Anabaena sphaerica lineages. Physiological data were congruent with molecular results supporting the separation into seven lineages. In an evolutionary context, salinity tolerance can be used as an integrative marker to reinforce the delineation of some cyanobacterial lineages. The history of this physiological trait contributes to a better understanding of processes leading to the divergence of cyanobacteria. In this study, most of the cyanobacterial strains isolated from freshwater environments were salt-tolerant, thus suggesting this trait constituted an ancestral trait of the heterocytous cyanobacteria and that it was probably lost two times secondarily and independently in the ancestor of Dolichospermum and of Cylindrospermopsis. (C) 2018 Elsevier B.V. All rights reserved.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1568-9883 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2341  
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Auteur Garrido, M.; Cecchi, P.; Vaquer, A.; Pasqualini, V. url  doi
openurl 
  Titre Effects of sample conservation on assessments of the photosynthetic efficiency of phytoplankton using PAM fluorometry Type Article scientifique
  Année 2013 Publication (up) Revue Abrégée Deep-Sea Res. Part I-Oceanogr. Res. Pap.  
  Volume 71 Numéro Pages 38-48  
  Mots-Clés diatom, quantum yield, temperature, parameters; PAM fluorescence, Phytoplankton, Temperature Biguglia lagoon; physiological-responses, marine-phytoplankton, oxygen evolution, benthic; rapid light curves, chlorophyll-a fluorescence, in-vivo,  
  Résumé Pulse Amplitude Modulated (PAM) fluorometry is now a widely used method for the assessment of phytoplankton fitness, with an increasing popularity in field assessments. It is usually recommended to carry out measurements swiftly after collection, but the number of samples and analytical procedures needed to obtain valuable datasets sometimes makes immediate analysis impracticable, forcing delays between fluorescence measurements. Conservation conditions of samples before analysis may potentially affect their photosynthetic performances but no formal study documenting such impacts appears available in the literature. The aim of this study was to investigate the effects of storage conditions (temperature, duration) on photosynthetic parameters in different phytoplankton communities (characterized in situ by a BBE fluoroprobe) sampled during summer in different environmental locations in a Mediterranean lagoon (Biguglia lagoon, Corsica, France). PAM-fluorescence parameters were measured after three different conservation durations (2-4 h, 6-8 h and 10-12 h after collection) on samples stored at three different temperatures (15 degrees C, 25 degrees C and 35 degrees C). Results showed that storage at the highest temperature severely impacted photosynthetic parameters, with cumulative effects as storage duration increased. For phytoplankton samples collected in warm or tropical environments, storage at “room temperature” (25 degrees C) only appeared a valid option if measurements have to be carried out strictly within a very short delay. Inversely, cooling the samples (i.e. conservation at 15 degrees C) did not induce significant effects, independently of storage duration. Cooling appeared the best solution when sampling-to-analysis delay goes over a few hours. Long-term storage ( > 8 h) should definitively be avoided. (C) 2012 Elsevier Ltd. All rights reserved.  
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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 0967-0637 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 552  
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Auteur Blanchet, M.; Pringault, O.; Panagiotopoulos, C.; Lefevre, D.; Charriere, B.; Ghiglione, J.-F.; Fernandez, C.; Aparicio, F.L.; Marrase, C.; Catala, P.; Oriol, L.; Caparros, J.; Joux, F. doi  openurl
  Titre When riverine dissolved organic matter (DOM) meets labile DOM in coastal waters: changes in bacterial community activity and composition Type Article scientifique
  Année 2017 Publication (up) Revue Abrégée Aquat. Sci.  
  Volume 79 Numéro 1 Pages 27-43  
  Mots-Clés Bacterial community composition; bacterioplankton; biodegradation; carbon; coastal waters; Dissolved organic matter; Fluorescence; growth efficiency; lake water; marine; Mediterranean Sea; open-ocean; Priming effect; rhone river; terrestrial  
  Résumé Heterotrophic bacterial communities in marine environments are exposed to a heterogeneous mixture of dissolved organic compounds with different bioreactivity that may control both their activity and composition. The coastal environment is an example of a mixing area where recalcitrant allochthonous organic matter from rivers can encounter labile organic matter from marine phytoplanktonic blooms. The objective of this study was to explore the effects of mixed qualities of dissolved organic matter (DOM) on bacterial community activity (BCA) and bacterial community composition (BCC) and to test for a priming effect when DOM sources are added in combination. Coastal marine bacterial communities were incubated separately with a mixture of amino acids and with natural riverine DOM or with both sources together for 42 days. Addition of amino acids alone or in combination with riverine DOM led to a similar stimulation of BCA compared to control condition, whereas addition of riverine DOM alone did not modify BCA compared to the control. On the contrary, BCC analyzed by 16S rRNA gene pyrosequencing was not affected by the addition of amino acids alone, but changed dramatically with riverine DOM alone or in combination with amino acids. Our results show that changes in BCA and BCC can be driven by different types of DOM, but that these changes are not necessarily coupled. Moreover, the addition of labile DOM did not modify the microbial decomposition of riverine DOM, nor the BCC, suggesting that a priming effect did not occur under these experimental conditions.  
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  ISSN 1015-1621 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2090  
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