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Auteur (up) Bernard, C.; Escalas, A.; Villeriot, N.; Agogué, H.; Hugoni, M.; Duval, C.; Carré, C.; Got, P.; Sarazin, G.; Jézéquel, D.; Leboulanger, C.; Grossi, V.; Ader, M.; Troussellier, M.
Titre Very Low Phytoplankton Diversity in a Tropical Saline-Alkaline Lake, with Co-dominance of Arthrospira fusiformis (Cyanobacteria) and Picocystis salinarum (Chlorophyta) Type Article scientifique
Année 2019 Publication Revue Abrégée Microb Ecol
Volume 78 Numéro 3 Pages 603-617
Mots-Clés Cyanobacteria; Diversity; Extreme environment; Phytoplankton; Picoeukaryote; Thalassohaline lake
Résumé Lake Dziani Dzaha (Mayotte Island, Indian Ocean) is a tropical thalassohaline lake which geochemical and biological conditions make it a unique aquatic ecosystem considered as a modern analogue of Precambrian environments. In the present study, we focused on the diversity of phytoplanktonic communities, which produce very high and stable biomass (mean2014–2015 = 652 ± 179 μg chlorophyll a L−1). As predicted by classical community ecology paradigms, and as observed in similar environments, a single species is expected to dominate the phytoplanktonic communities. To test this hypothesis, we sampled water column in the deepest part of the lake (18 m) during rainy and dry seasons for two consecutive years. Phytoplanktonic communities were characterized using a combination of metagenomic, microscopy-based and flow cytometry approaches, and we used statistical modeling to identify the environmental factors determining the abundance of dominant organisms. As hypothesized, the overall diversity of the phytoplanktonic communities was very low (15 OTUs), but we observed a co-dominance of two, and not only one, OTUs, viz., Arthrospira fusiformis (Cyanobacteria) and Picocystis salinarum (Chlorophyta). We observed a decrease in the abundance of these co-dominant taxa along the depth profile and identified the adverse environmental factors driving this decline. The functional traits measured on isolated strains of these two taxa (i.e., size, pigment composition, and concentration) are then compared and discussed to explain their capacity to cope with the extreme environmental conditions encountered in the aphotic, anoxic, and sulfidic layers of the water column of Lake Dziani Dzaha.
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ISSN 1432-184x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2494
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Auteur (up) Bettarel, Y.; Combe, M.; Adingra, A.; Ndiaye, A.; Bouvier, T.; Panfili, J.; Durand, J.-D.
Titre Hordes of Phages in the Gut of the Tilapia Sarotherodon melanotheron Type Article scientifique
Année 2018 Publication Revue Abrégée Sci Rep
Volume 8 Numéro Pages 11311
Mots-Clés bacterial communities; diversity; fish gut; host; microbiome; physiology; virome; viruses; xenobiotics
Résumé Preliminary studies conducted on the human gastro-intestinal tract have revealed that enteric viral communities play a preponderant role in microbial homeostatis. However to date, such communities have never been investigated in the fish gut. Herein, we examined the main ecological traits of viruses in the digestive tract of a euryhaline fish, the tilapia Sarotherodon melanotheron. Individuals were collected at 8 different sites in Senegal covering a salinity gradient from 3 to 104 parts per thousand, and showing large disparities in their organic pollutant concentrations. Results showed that the gut of S. melanotheron is home to a highly abundant viral community (0.2-10.7 x 10(9) viruses ml(-1)), distinct from the surrounding water, and essentially composed of phages of which a substantial proportion is temperate (the fraction of lysogenized cells-FLC ranging from 8.1 to 33.0%). Also, a positive and significant correlation was detected between FLC and the concentrations of polycyclic aromatic hydrocarbon in sediment, while no clear relationships were found between salinity and any of the microbial parameters considered. Finally, our data suggest that virus-bacteria interactions within the fish intestine are likely sensitive to the presence of particular xenobiotics, which may compromise the balance in the gut microbiota, and subsequently affect the health of their host.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 2045-2322 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2389
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Auteur (up) Bettarel, Y.; Halary, S.; Auguet, J.-C.; Mai, T.C.; Bui, N.V.; Bouvier, T.; Got, P.; Bouvier, C.; Monteil-Bouchard, S.; Christelle, D.
Titre Corallivory and the microbial debacle in two branching scleractinians Type Article scientifique
Année 2018 Publication Revue Abrégée Isme J.
Volume 12 Numéro 4 Pages 1109-1126
Mots-Clés brown band disease; coral-associated bacteria; diversity; drupella-cornus; great-barrier-reef; network analysis; red-sea; search tool; viral communities; viruses
Résumé The grazing activity by specific marine organisms represents a growing threat to the survival of many scleractinian species. For example, the recent proliferation of the corallivorous gastropod Drupella now constitutes a critical case in all South-East Asian waters. If the damaging effects caused by this marine snail on coral polyps are relatively well known, the indirect incidence of predation on coral microbial associates is still obscure and might also potentially impair coral health. In this study, we compared the main ecological traits of coral-associated bacterial and viral communities living in the mucus layer of Acropora formosa and Acropora millepora, of healthy and predated individuals (i.e., colonized by Drupella rugosa), in the Bay of Van Phong (Vietnam). Our results show a substantial impact of the gastropod on a variety of microbiological markers. Colonized corals harbored much more abundant and active epibiotic bacteria whose community composition shifted toward more pathogenic taxa (belonging to the Vibrionales, Clostridiales, Campylobacterales, and Alteromonadales orders), together with their specific phages. Viral epibionts were also greatly influenced by Drupella corallivory with spectacular modifications in their concentrations, life strategies, genotype richness, and diversity. Novel and abundant circular Rep-encoding ssDNA viruses (CRESS-DNA viruses) were detected and characterized in grazed corals and we propose that their occurrence may serve as indicator of the coral health status. Finally, our results reveal that corallivory can cause severe dysbiosis by altering virus-bacteria interactions in the mucus layer, and ultimately favoring the development of local opportunistic infections.
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ISSN 1751-7362 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2325
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Auteur (up) Blanchet, M.; Pringault, O.; Bouvy, M.; Catala, P.; Oriol, L.; Caparros, J.; Ortega-Retuerta, E.; Intertaglia, L.; West, N.; Agis, M.; Got, P.; Joux, F.
Titre Changes in bacterial community metabolism and composition during the degradation of dissolved organic matter from the jellyfish Aurelia aurita in a Mediterranean coastal lagoon Type Article scientifique
Année 2015 Publication Revue Abrégée Environ Sci Pollut Res
Volume 22 Numéro 18 Pages 13638-13653
Mots-Clés Aurelia aurita; Bacterial diversity; Bacterial growth efficiency; biodegradation; heterotrophic bacteria; jellyfish; Organic matter
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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 0944-1344 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1387
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Auteur (up) Boavida, J.; Becheler, R.; Choquet, M.; Frank, N.; Taviani, M.; Bourillet, J.-F.; Meistertzheim, A.-L.; Grehan, A.; Savini, A.; Arnaud-Haond, S.
Titre Out of the Mediterranean? Post-glacial colonization pathways varied among cold-water coral species Type Article scientifique
Année 2019 Publication Revue Abrégée J. Biogeogr.
Volume 46 Numéro 5 Pages 915-931
Mots-Clés biodiversity; cold-water corals; computer-program; deep-sea; deep-sea corals; genetic-structure; glacial marine refugia; glacial refugia; growth; in-situ; Last Glacial Maximum; Lophelia pertusa; lophelia-pertusa; Madrepora oculata; marine phylogeography; north-atlantic ocean; software
Résumé Aim: To infer cold-water corals' (CWC) post-glacial phylogeography and assess the role of Mediterranean Sea glacial refugia as origins for the recolonization of the northeastern Atlantic Ocean. Location: Northeastern Atlantic Ocean and Mediterranean Sea. Taxon: Lophelia pertusa, Madrepora oculata. Methods: We sampled CWC using remotely operated vehicles and one sediment core for coral and sediment dating. We characterized spatial genetic patterns (microsatellites and a nuclear gene fragment) using networks, clustering and measures of genetic differentiation. Results: Inferences from microsatellite and sequence data were congruent, and showed a contrast between the two CWC species. Populations of L. pertusa present a dominant pioneer haplotype, local haplotype radiations and a majority of endemic variation in lower latitudes. Madrepora oculata populations are differentiated across the northeastern Atlantic and genetic lineages are poorly admixed even among neighbouring sites. Conclusions: Our study shows contrasting post-glacial colonization pathways for two key habitat-forming species in the deep sea. The CWC L. pertusa has likely undertaken a long-range (post-glacial) recolonization of the northeastern Atlantic directly from refugia located along southern Europe (Mediterranean Sea or Gulf of Cadiz). In contrast, the stronger genetic differentiation of M. oculata populations mirrors the effects of long-term isolation in multiple refugia. We suggest that the distinct and genetically divergent, refugial populations initiated the post-glacial recolonization of the northeastern Atlantic margins, leading to a secondary contact in the northern range and reaching higher latitudes much later, in the late Holocene. This study highlights the need to disentangle the influences of present-day dispersal and evolutionary processes on the distribution of genetic polymorphisms, to unravel the influence of past and future environmental changes on the connectivity of cosmopolitan deep-sea ecosystems associated with CWC.
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ISSN 0305-0270 ISBN Médium
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Notes WOS:000471344900007 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2602
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