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| Genitsaris, Savvas; Monchy, Sebastien; Breton, Elsa; Lecuyer, Eric; Christaki, Urania. |
| The aim of this study was to analyze planktonic protistan assemblages under different environmental pressures at 2 adjacent coastal stations (inshore and offshore; similar to 6.4 km apart) in the eastern English Channel (EEC). Samples were collected between March 2012 and June 2013, and analyzed using bioinformatic analysis and tag pyrosequencing of the V2-V3 hypervariable region of the 18S rRNA gene. In addition to the taxonomic composition of the protistan communities, the detected operational taxonomic units (OTUs) were sorted into 6 major functional groups based on their trophic roles in marine systems. Comparisons of 13 environmental factors, including physical and chemical variables, indicated significant differences between the 2 stations. However,... |
| Tipo: Text |
Palavras-chave: Unicellular eukaryotes; Community organization; Environmental parameters; Biotic interactions; 18S rRNA; Pyrosequencing; Bioinformatics; Ecological tools. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00373/48450/48765.pdf |
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| Genitsaris, Savvas; Monchy, Sebastien; Viscogliosi, Eric; Sime-ngando, Telesphore; Ferreira, Stephanie; Christaki, Urania. |
| Previous microscopy-based studies in the eastern English Channel have revealed it to be a productive meso-eutrophic coastal ecosystem, characterized by strong repeating patterns in microplankton succession. The present study examines the seasonal structure of the entire protistan community from March 2011 to July 2013, using tag pyrosequencing of the V2-V3 hypervariable region of the 18S rRNA gene. A total of 1242 OTUs and 28 high-level taxonomic groups, which included previously undetected taxa in the area, were identified. The detected OTUs were considered according to taxon-specific traits, which included their trophic role, abundance and specialization level. Taxa differentiation based on specialization level rather than abundance was more informative... |
| Tipo: Text |
Palavras-chave: Unicellular eukaryotes; Tag pyrosequencing; 18S rRNA gene; Succession; Generalists; Specialists. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00373/48454/48738.pdf |
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| Monchy, Sebastien; Grattepanche, Jean-david; Breton, Elsa; Meloni, Dionigia; Sanciu, Giovanna; Chabe, Magali; Delhaes, Laurence; Viscogliosi, Eric; Sime-ngando, Telesphore; Christaki, Urania. |
| Background: Massive phytoplankton blooms, like the recurrent Phaeocystis proliferation observed every year in the Eastern English Channel (EEC), have a significant influence on the overall planktonic community structure and their food web dynamics. As well as being an important area for local fisheries, the EEC is an ideal ecosystem for work on microbial diversity. This is because, although its environmental context is relatively complex, it is reasonably well understood due to several years of monitoring and morphological observations of its planktonic organisms. The objective of our study was to better understand the under-explored microbial eukaryotic diversity relative to the Phaeocystis bloom. Methodology and Principal Findings: The community... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00373/48460/48724.pdf |
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| Landa, Marine; Blain, Stephane; Christaki, Urania; Monchy, Sebastien; Obernosterer, Ingrid. |
| Marine microbes have a pivotal role in the marine biogeochemical cycle of carbon, because they regulate the turnover of dissolved organic matter (DOM), one of the largest carbon reservoirs on Earth. Microbial communities and DOM are both highly diverse components of the ocean system, yet the role of microbial diversity for carbon processing remains thus far poorly understood. We report here results from an exploration of a mosaic of phytoplankton blooms induced by large-scale natural iron fertilization in the Southern Ocean. We show that in this unique ecosystem where concentrations of DOM are lowest in the global ocean, a patchwork of blooms is associated with diverse and distinct bacterial communities. By using on-board continuous cultures, we identify... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53293/54115.pdf |
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| Christaki, Urania; Georges, Clement; Genitsaris, Savvas; Monchy, Sebastien. |
| The spatial and temporal community composition of microzooplankton (dinoflagellates and ciliates) was assessed in the Kerguelen area (Southern Ocean) during the KEOPS2 cruise in early spring (October-November) 2011. This naturally iron-fertilized region was characterized by a complex mesoscale circulation resulting in a patchy distribution of phytoplankton blooms. Collectively, 97 morphospecies of dinoflagellates and ciliates belonging to 41 genera were identified by microscopy, and 202 Alveolata-related OTUs (operational taxonomical units) were retrieved with tag-pyrosequencing. Microscopy and pyrosequencing data were in accordance, in that diatom-consuming dinoflagellates were the most enhanced taxa in the blooms. Dinoflagellates also showed significant... |
| Tipo: Text |
Palavras-chave: Dinoflagellates; Ciliates; Natural iron fertilization; Southern Ocean. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46255/46080.pdf |
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