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Auteur Trottet, A.; Leboulanger, C.; Vidussi, F.; Pete, R.; Bouvy, M.; Fouilland, E.
Titre Heterotrophic Bacteria Show Weak Competition for Nitrogen in Mediterranean Coastal Waters (Thau Lagoon) in Autumn Type Article scientifique
Année 2016 Publication Revue Abrégée Microb Ecol
Volume (down) 71 Numéro 2 Pages 304-314
Mots-Clés Bacteria; Dissolved inorganic nitrogen; Ecology; Geoecology/Natural Processes; Inhibitors; Microbial ecology; Microbiology; Nature Conservation; Nitrogen uptake; Phytoplankton; Size fractionation; Water Quality/Water Pollution
Résumé The importance of heterotrophic bacteria relative to phytoplankton in the uptake of ammonium and nitrate was studied in Mediterranean coastal waters (Thau Lagoon) during autumn, when the Mediterranean Sea received the greatest allochthonous nutrient loads. Specific inhibitors and size-fractionation methods were used in combination with isotopic 15N tracers. NO3 − and NH4 + uptake was dominated by phytoplankton (60 % on average) during the study period, which included a flood event. Despite lower biomass specific NH4 + and NO3 uptake rates, free-living heterotrophic bacteria contributed significantly (>30 %) to total microbial NH4 + and NO3 − uptake rates in low chlorophyll waters. Under these conditions, heterotrophic bacteria may be responsible for more than 50 % of primary production, using very little freshly produced phytoplankton exudates. In low chlorophyll coastal waters as reported during the present 3-month study, the heterotrophic bacteria seemed to depend to a greater extent on allochthonous N and C substrates than on autochthonous substrates derived from phytoplankton.
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Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0095-3628, 1432-184x ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1448
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Auteur Grzebyk, D.; Audic, S.; Lasserre, B.; Abadie, E.; de Vargas, C.; Bec, B.
Titre Insights into the harmful algal flora in northwestern Mediterranean coastal lagoons revealed by pyrosequencing metabarcodes of the 28S rRNA gene Type Article scientifique
Année 2017 Publication Revue Abrégée Harmful Algae
Volume (down) 68 Numéro Pages 1-16
Mots-Clés Phytoplankton diversity; Harmful algae; Monitoring; alexandrium dinophyceae; dinoflagellate stoeckeria-changwonensis; domoic acid accumulation; eastern adriatic sea; Metabarcoding; partial lsu rdna; pfiesteria-piscicida dinophyceae; phylogenetic-relationships; pseudo-nitzschia bacillariophyceae; species complex dinophyceae; toxic dinoflagellate
Résumé This study investigated the genetic diversity of phytoplankton communities in six shallow lagoons located on the French coast of the northwestern Mediterranean Sea that represented a trophic gradient ranging from oligotrophic to hypereutrophic. The phytoplankton communities were sampled once a month from spring (May) to the beginning of autumn (September/early October) in 2012 and fractionated by size. Metabarcodes were generated from cDNAs by targeting the D1-D2 region of the 28S rRNA gene and pyrosequenced using Roche 454 technology. Examination of the annotated barcodes revealed harmful algal species not previously documented in these lagoons. Three ichthyotoxic species belonging to Pfiesteriaceae were detected: Luciella masanensis was relatively widespread and abundant in many samples, whereas Pfiesteria piscicida and Stoeckeria changwonensis were found as single barcode sequences. Furthermore, a phylogenetic analysis of barcodes annotated as belonging to Pfiesteriaceae suggested the existence of two previously undescribed clades. The other toxic or potentially harmful dinoflagellates detected through rare barcodes were Dinophysis acuminata, Vulcanodinium rugosum, Alexandrium andersonii and A. ostenfeldii. The two most abundant dinoflagellate taxa were Gymnodinium litoralis and Akashiwo sanguinea with respect to sequence numbers. Four diatom species from the genus Pseudo-nitzschia that potentially produce domoic acid were identified (P. galaxiae, P. delicatissima, P. brasiliana and P. calliantha). These observations are discussed in terms of the literature and monitoring records related to the identified taxa in this Mediterranean area. (C) 2017 Elsevier B.V. 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 1568-9883 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2227
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Auteur Fouilland, E.; Mostajir, B.; Levasseur, M.; Roy, S.; Vidussi, F.; de Mora, S.; Demers, S.
Titre Effect of mixing on the structure of a natural plankton community: a mesocosm study Type Article scientifique
Année 2016 Publication Revue Abrégée Vie et Milieu
Volume (down) 66 Numéro 3-4 Pages 251-259
Mots-Clés Accumulation; Composition; nitrogen; Phytoplankton Biomass; Phytoplankton Species; Structure Of The Pelagic Food Web; Transport Rates; turbulence; Vertical Mixing
Résumé A plankton community (< 202 μm) from the St. Lawrence Estuary was isolated

in four outdoor mesocosms with SLOW and fast mixing regimes. Variations in the concentrations

of nutrients, chlorophyll a (Chl a), nitrogen transport rates and plankton species composition

were monitored over a 10 day period. The vertical mixing times (Tm) for the slow and

fast mixing regimes were 180 and 60 min, corresponding to a vertical eddy diffusivity (Kv) of

2.34 and 7.03 cm2 s–1, respectively. The different mixing regimes had a strong effect on the

physiology of the phytoplankton and the specific structure of the plankton assemblage. The

Slow mixing regime stimulated the development of a mixed community of flagellates, small

diatoms and proto-metazooplankton while the fast mixing regime triggered the development

of a large diatom-dominated community with lower abundances of proto-metazooplankton. At

the end of the 10 day experiment, the Chl a concentrations were 50 % higher in the mesocosms

with the fast mixing regime than in those with the slow mixing regime. These results indicate

that, under low nutrient conditions, higher turbulence gives a competitive advantage to diatoms

and decreases the zooplankton grazing pressure, resulting in net positive growth. Extrapolation

of these results to natural systems suggests that a wind-driven mixing event may increase

the net phytoplankton biomass production of a stratified water column, even if there is no external

input of nutrients.
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Volume de collection Numéro de collection Edition
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Numéro d'Appel MARBEC @ alain.herve @ collection 2082
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Auteur Fournier, J.; Dupuy, C.; Bouvy, M.; Couraudon-Réale, M.; Charpy, L.; Pouvreau, S.; Le Moullac, G.; Le Pennec, M.; Cochard, J.-C.
Titre Pearl oysters Pinctada margaritifera grazing on natural plankton in Ahe atoll lagoon (Tuamotu archipelago, French Polynesia) Type Article scientifique
Année 2012 Publication Revue Abrégée Marine Pollution Bulletin
Volume (down) 65 Numéro 10–12 Pages 490-499
Mots-Clés Clearance rates; French Polynesia; Pinctada margaritifera; Protists; phytoplankton
Résumé
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Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0025-326x ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 770
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Auteur Bouvy, M.; Dupuy, C.; Pagano, M.; Barani, A.; Charpy, L.
Titre Do human activities affect the picoplankton structure of the Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia)? Type Article scientifique
Année 2012 Publication Revue Abrégée Marine Pollution Bulletin
Volume (down) 65 Numéro 10–12 Pages 516-524
Mots-Clés Atoll; Enrichment experience; Human sewage; Picoplankton
Résumé
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Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0025-326x ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 527
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