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| Registros recuperados: 24 | |
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| Lunven, Michel; Guillaud, Jean-francois; Youenou, Agnes; Crassous, Marie-pierre; Berric, Roger; Le Gall, Erwan; Kerouel, Roger; Labry, Claire; Aminot, Alain. |
| A new Fine Scale Sampler (FSS) was designed and used in the Loire River plume (Bay of Biscay, France) in order to study phytoplankton distribution in highly stratified water columns. The FSS consists of a linear array of 15 sampling bottles, set horizontally at 20 cm intervals. Data acquired from the CTD and fluorescence probe of the FSS enable it to be precisely positioned at the depth of the highest density gradient or at the chlorophyll a maximum. The FSS made it possible to investigate fine scale vertical distribution of phytoplankton and relationships with water density, nutrient concentrations or light availability, for spring and summer conditions. Under spring conditions, the entire upper layer exhibited a dominant diatom population (Chaetoceros... |
| Tipo: Text |
Palavras-chave: Plankton patchiness; Density discontinuity; Sampling; Thin layer; Nutrients; Phytoplankton. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-533.pdf |
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| Girault, Mathias; Siano, Raffaele; Labry, Claire; Latimier, Marie; Jauzein, Cecile; Beneyton, Thomas; Buisson, Lionel; Del Amo, Yolanda; Baret, Jean-christophe. |
| Adaptation of cell populations to environmental changes is mediated by phenotypic variability at the single-cell level. Enzyme activity is a key factor in cell phenotype and the expression of the alkaline phosphatase activity (APA) is a fundamental phytoplankton strategy for maintaining growth under phosphate-limited conditions. Our aim was to compare the APA among cells and species revived from sediments of the Bay of Brest (Brittany, France), corresponding to a pre-eutrophication period (1940’s) and a beginning of a post-eutrophication period (1990’s) during which phosphate concentrations have undergone substantial variations. Both toxic marine dinoflagellate Alexandrium minutum and the non-toxic dinoflagellate Scrippsiella acuminata were revived from... |
| Tipo: Text |
Palavras-chave: Climate-change ecology; Microbial ecology. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00679/79097/81568.pdf |
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| Labry, Claire; Erard-le Denn, Evelyne; Chapelle, Annie; Fauchot, Juliette; Youenou, Agnes; Crassous, Marie-pierre; Le Grand, Jacqueline; Lorgeoux, Benedicte. |
| The understanding of the dominance of one species with respect to others is a pertinent challenge in HAB growth dynamics studies and the nutrient supply mode is one of the factors potentially involved. The competition for phosphorus (P) between a toxic species, Alexandrium minutum, and a non-toxic species, Heterocapsa triquetra, was studied (1) along a gradient of P depletion, (2) testing different P depletion degrees before a single PO4 supply and (3) experimenting different PO4 supply frequencies. In conditions Of PO4 depletion, H. triquetra stopped growing after two days both in monospecific and mixed batch cultures whereas A. minutum grew progressively from day 2 until the end of the experiment. This time-lag growth of A. minutum is associated to its... |
| Tipo: Text |
Palavras-chave: Semi continuous culture; Batch culture; Ecophysiology; Pulse; Phosphorus storage; Dinoflagellates; Heterocapsa triquetra; Alexandrium minutum. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4067.pdf |
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| Labry, Claire; Erard-le Denn, Evelyne; Chapelle, Annie; Youenou, Agnes; Crassous, Marie Pierre; Martin-jezequel, Véronique; Le Grand, Jacqueline. |
| Suite à un premier criblage des facteurs environnementaux favorables à la croissance d'Alexandrium minutum comparativement à celle d'une espèce compétitrice en rivière de Penzé, Heterocapsa triquetra (rapport ART3 2002-2003) cette étude vise à préciser et quantifier les réponses physiologiques respectives des deux espèces à différentes conditions d'apports en phosphate (taux de croissance, vitesse d'assimilation des phosphates, capacité à stocker le phosphore intracellulaire). Elle montre qu'Alexandrium minutum a plutôt une stratégie de « stockage », capable d'assimiler rapidement le phosphate après un apport mais le stockant pour une meilleure croissance ultérieure quand la ressource sera à nouveau épuisée. Comparativement, Heterocapsa triquetra aurait,... |
| Tipo: Text |
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| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/00105/21598/19178.pdf |
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| Lunven, Michel; Guillaud, Jean-francois; Crassous, Marie Pierre; Youenou, Agnes; Gohin, Francis; Huret, Martin; Danielou, Marie-madeleine; Kerouel, Roger; Labry, Claire; Aminot, Alain. |
| Inscrite dans le cadre du Grand Défi Golfe de Gascogne, la campagne VILOIR a été réalisée du 19 au 26 Juin 2003 à bord du Côtes de la Manche avec pour objectif l’étude en période estivale des structures hydrologiques et phytoplanctoniques des panaches de la Loire et de la Vilaine. Elle fait suite, sur la même thématique, à la campagne hivernale NUTRIGAS (2001) et à la campagne printanière GASPROD (2002). |
| Tipo: Text |
Palavras-chave: Surveillance; Littoral; Phytoplancton; Phycotoxines; Bretagne; Pays de Loire. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/00144/25494/23648.pdf |
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| Labry, Claire; Urvoy, Marion. |
| Alkaline phosphatases are the main enzymes required by microorganisms to hydrolyse organic phosphorus into available phosphate in aquatic environments. The investigations of alkaline phosphatase activity (APA) usually generate numerous samples (size fractionation, Michaelis-Menten kinetics). Therefore, convenient and reliable preservation of incubated samples for a deferred analysis would be very useful when measurements cannot be performed right away. The APA of marine pond waters was measured using 4-Methylumbelliferyl phosphate (MUF-P) as the fluorogenic substrate modelling natural organic phosphorus compounds. Where typical inhibitors of other enzymatic activities, such as 1% sodium dodecyl sulfate, mercuric chloride, or buffered solutions of ammonium... |
| Tipo: Text |
Palavras-chave: Alkaline phosphatase activity; Formaldehyde; Inhibition; Enzymes; Aquatic studies; Deferred measurements. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00656/76787/78211.pdf |
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| Lassalle, G.; Lobry, J.; Le Loc'H, F.; Bustamante, Paco; Certain, Gregoire; Delmas, Daniel; Dupuy, C.; Hily, Christian; Labry, Claire; Le Pape, O.; Marquis, Elise; Petitgas, Pierre; Pusineri, Claire; Ridoux, Vincent; Spitz, J.; Niquil, Nathalie. |
| The Bay of Biscay (North-East Atlantic) has long been subjected to intense direct and indirect human activities that lead to the excessive degradation and sometimes overexploitation of natural resources. Fisheries management is gradually moving away from single-species assessments to more holistic, multi-species approaches that better respond to the reality of ecosystem processes. Quantitative modelling methods such as Ecopath with Ecosim can be useful tools for planning, implementing and evaluating ecosystem-based fisheries management strategies. The aim of this study was therefore to model the energy fluxes within the food web of this highly pressured ecosystem and to extract practical information required in the diagnosis of ecosystem state/health. A... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00057/16851/14329.pdf |
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| Labry, Claire; Delmas, Daniel; Herbland, Alain. |
| Previous studies conducted on the continental shelf in the Southeast Bay of Biscay influenced by Gironde waters (one of the two largest rivers on the French Atlantic coast) showed the occurrence of late winter phytoplankton blooms and phosphorus limitation of algal growth thereafter. In this context, the importance of dissolved organic phosphorus (DOP) for both algae and bacteria was investigated in 1998 and 1999 in terms of stocks and fluxes. Within the mixed layer, although phosphate decreased until exhaustion from winter to spring, DOP remained high and phosphate monoesters made up between I I to 65% of this pool. Total alkaline phosphatase activity (APA, V-max) rose gradually from winter (2-8 nM h(-1)) to late spring (100-400 nM h-1), which was mainly... |
| Tipo: Text |
Palavras-chave: Phytoplankton; Phosphate; Gironde; DOP; Bacteria; Alkaline phosphatases. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-608.pdf |
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| Chapelle, Annie; Le Gac, Mickael; Labry, Claire; Siano, Raffaele; Quere, Julien; Caradec, Florian; Le Bec, Claude; Nezan, Elisabeth; Doner, Anne; Gouriou, Jeremie. |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00278/38921/37461.pdf |
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| Gohin, Francis; Loyer, S; Lunven, Michel; Labry, Claire; Froidefond, J; Delmas, Daniel; Huret, Martin; Herbland, Alain. |
| In biological modelling of the coastal phytoplankton dynamics, the light attenuation coefficient is often expressed as a function of the concentrations of chlorophyll and mineral suspended particulate matter (SPM). In order to estimate the relationship between these parameters over the continental shelf of the northern Bay of Biscay, a set of in situ data has been gathered for the period 1998-2003 when SeaWiFS imagery is available. These data comprise surface measurements of the concentrations of total SPM, chlorophyll, and irradiance profiles from which is derived the attenuation coefficient of the photosynthetically available radiation, K-PAR. The performance of the IFREMER look-up table used to retrieve the chlorophyll concentration from the SeaWiFS... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; SeaWiFS; Sediment; Chlorophyll; Ocean color. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1172.pdf |
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| Chapelle, Annie; Le Bec, Claude; Le Gac, Mickael; Labry, Claire; Amzil, Zouher; Guillou, Laure; Dreanno, Catherine; Pineau-guillou, Lucia. |
| Suite à l’événement de grande ampleur d’efflorescence d’Alexandrium minutum et des toxicités associées en Rade de Brest en 2012, un projet a été monté avec la Région dans le cadre du développement du port de Brest. De juillet à août 2013, l’Ifremer a organisé un échantillonnage serré dans l’estuaire de Daoulas, zone la plus touchée en 2012. De ce suivi et des mesures réalisées au laboratoire à ce jour, ainsi que des résultats du réseau Rephy et Velyger, il ressort que : * Alexandrium minutum s’est développé à nouveau en rade de Brest en 2013 mais à des teneurs inférieures à 2012. * l’épisode de bloom et de toxicité supérieur aux seuils légaux s’est déroulé plus tard qu’en 2012, du 1er juillet jusqu’à 5 août. * les efflorescences et la toxicité ont touché... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00191/30230/28644.pdf |
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| Labry, Claire; Youenou, Agnes; Delmas, Daniel; Michelon, Pascale. |
| The speciation of particulate phosphorus (TPP) into inorganic (PIP) and organic phosphorus (POP), has been scarcely investigated in suspended particulate matter (SPM), contrary to numerous sediment studies. This work evaluates the actual capacity of methods for TPP, POP and PIP determination in SPM to measure efficiently and specifically each pool. Methods were tested on a range of plankton-associated organic and inorganic P compounds, on microalgal cultures and estuarine samples. Then results are specifically discussed reviewing P speciation in phytoplankton. For TPP analysis, the method of Solorzano and Sharp (1980) is recommended compared with that of Aspila et al. (1976), originally dedicated to sediment, as there is one step less, the protocol is more... |
| Tipo: Text |
Palavras-chave: Phosphorus; Speciation; Waters; Phytoplankton; HTC; CWO. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00149/26046/26385.pdf |
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| Labry, Claire; Delmas, Daniel; Youenou, Agnes; Quere, Julien; Leynaert, Aude; Fraisse, Stephane; Raimonet, Melanie; Ragueneau, Olivier. |
| The occurrence of alkaline phosphatase activity (APA) that hydrolyses organic phosphorus into phosphate (PO4) is commonly related to PO4 deficiency of oceanic, coastal and fresh waters. APA is almost never investigated in PO4-rich estuaries, since very low activities are expected to occur. As a consequence, microbial mineralization of organic phosphorus into PO4 has often been ignored in estuaries. In this study, we examined the importance of potential APA and the associated microbial dynamics in two estuaries, the Aulne and the Elorn (Northwestern France), presenting two different levels of PO4 concentrations. Unexpected high potential APA was observed in both estuaries. Values ranged from 50 to 506 nmol L−1 h−1, which range is usually found in very... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00337/44840/44428.pdf |
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| Labry, Claire; Delmas, Daniel; Moriceau, Brivaela; Gallinari, Morgane; Quere, Julien; Youenou, Agnes. |
| Phosphorus (P) limitation of phytoplankton growth is known to affect the accumulation and release of carbohydrates (CHO) by micro-algae. However, relatively little is known about the fate of algal exudates, notably their bacterial degradation. The CHO chemical characterization is also not exhaustive, especially in ‘functional’ pools relevant for phytoplankton physiology (particulate reserve [R] or structural [S] CHO) and for bacterial degradation (dissolved mono- [MDCHO] and polysaccharides [P-DCHO]). In this study, we investigated how P depletion and repletion affect the CHO composition in diatom Thalassiosira weissflogii cultures, and the shortterm response of free and diatom-attached bacteria in terms of abundance and potential βglucosidase activity... |
| Tipo: Text |
Palavras-chave: P limitation; Phytoplankton; Diatom; Bacteria; Mineralization; Carbohydrate; Glucosidase. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00628/74045/73532.pdf |
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| Lunven, Michel; Guillaud, Jean-francois; Youenou, Agnes; Crassous, Marie-pierre; Berric, Roger; Le Gall, Erwan; Kerouel, Roger; Labry, Claire; Aminot, Alain. |
| Many studies in coastal areas have shown the existence of thin chemical and biological layers. Their thickness and vertical extension are mainly controlled by hydrological and physical forcing. An accurate description of the phytoplankton communities growing within these layers is difficult to obtain without a well-adapted sampling system. A new Fine Scale Sampler (FSS) has been designed in Ifremer in order to study phytoplankton distribution and associated dissolved properties in high stratified water column. This FSS consists in a vertical array of 15 sampling bottles, horizontally laid with 20 cm intervals. Data acquired from a CTD and Fluorescence probe provide a precise FSS positioning at the depth of highest density gradient or at chlorophyll a... |
| Tipo: Text |
Palavras-chave: Surveillance; Littoral; Phytoplancton; Phycotoxine. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/00144/25493/23647.pdf |
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| Labry, Claire; Herbland, Alain; Delmas, Daniel. |
| More and more studies emphasize the status of phosphorus (P) as the principal limiting nutrient of phytoplankton growth, especially in coastal waters under the influence of freshwater discharges. The purpose of the present paper is to investigate the role of P on planktonic production in the waters influenced by the Gironde discharges; the Gironde being one of the two largest rivers on the French Atlantic coast. The survey is based on several cruises made in 1998 and 1999. Two different patterns were observed for waters with salinity below and above 34.5. For waters with salinity <34.5. P was found to be the first limiting nutrient of winter and spring phytoplankton blooms, based on undetectable phosphate (<20 nM), high NO3 : PO4 ratios, typically... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; River plume; Salinity; Water quality analysis; Phytoplankton; Planktonic production. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-690.pdf |
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| Urvoy, Marion; Labry, Claire; Delmas, Daniel; Creac'H, Layla; L Helguen, Stephane. |
| As microbial enzymatic activities initiate the mineralization of organic matter through the microbial loop, it is important to correctly measure those activities and be able to perform inter-study comparisons. Enzymatic activity assays are typically carried out using fluorogenic substrate analogs, such as 4-Methylumbelliferone and 7-Amino-4-methylcoumarin linked to sugar monomers, phosphate group or amino acids. However, methodological divergences can be found in aquatic science literature, potentially leading to misestimated activities. To highlight some of those methodological key points, we first addressed the potential occurrence of an Inner Filter Effect (IFE), a fluorometric artifact that affects the relationship between fluorophore concentration and... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00653/76524/77614.pdf |
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| Guillaud, Jean-francois; Aminot, Alain; Delmas, Daniel; Gohin, Francis; Lunven, Michel; Labry, Claire; Herbland, Alain. |
| Seasonal variations in nutrient inputs are described for the main rivers (Loire and Vilaine) flowing into the northern Bay of Biscay. The river plumes are high in N/P ratio in late winter and spring, but not in the inner plume during the summer. Conservative behavior results in most nutrients entering the estuary and eventually reaching the coastal zone. Temporal and spatial aspects of phytoplankton growth and nutrient uptake in the northern Bay of Biscay distinguish the central area of salinity 34 from the plume area. The first diatom bloom appears offshore in late winter, at the edge of the river plumes, taking advantage of haline stratification and anticyclonic "weather windows." In spring, when the central area of the northern shelf is... |
| Tipo: Text |
Palavras-chave: Northern Bay of Biscay; Phytoplankton; Continental shelf; Riverine inputs; Nutrients. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2354.pdf |
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| Registros recuperados: 24 | |
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