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Registros recuperados: 19
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Addressing the measurement of particulate organic and inorganic phosphorus in estuarine and coastal waters ArchiMer
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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Alexandrium minutum growth controlled by phosphorus An applied model ArchiMer
Chapelle, Annie; Labry, Claire; Sourisseau, Marc; Lebreton, Carole; Youenou, Agnes; Crassous, Marie-pierre.
Toxic algae are a worldwide problem threatening aquaculture public health and tourism Alexandrium a toxic dinoflagellate proliferates in Northwest France estuaries (i e the Penze estuary) causing Paralytic Shellfish Poisoning events Vegetative growth and in particular the role of nutrient uptake and growth rate are crucial parameters to understand toxic blooms With the goal of modelling in situ Alexandrium blooms related to environmental parameters we first try to calibrate a zero-dimensional box model of Alexandrium growth This work focuses on phosphorus nutrition Our objective is to calibrate Alexandrium minutum as well as Heterocapsa triquetra (a non-toxic dinoflagellate) growth under different rates of phosphorus supply other factors being optimal and...
Tipo: Text Palavras-chave: Toxic algal blooms; Alexandrium; Phosphorus uptake; Models; Competition; Northwest France.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00018/12901/9905.pdf
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Competition for phosphorus between two dinoflagellates: A toxic Alexandrium minutum and a non-toxic Heterocapsa triquetra ArchiMer
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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Comprendre, Prédire et Agir sur les efflorescences toxiques. Jusqu'où peut-on aller aujourd'hui dans le cas d'Alexandrium minutum en Penzé ? ArchiMer
Chapelle, Annie; Andrieux, Francoise; Fauchot, Juliette; Guillaud, Jean-francois; Labry, Claire; Sourisseau, Marc; Verney, Romaric.
Tipo: Text
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00105/21651/19232.pdf
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Dynamique du phosphore et rôle comme facteur limitant de la production planctonique dans le panache de la Gironde sur le plateau continental Sud Gascogne ArchiMer
Labry, Claire.
This study was supported by the Atlantic working site of the « Programme National d’Océanographie Côtière » (PNOC, PNEC since 1999). The objectives were (1) to check the existence and to understand the mechanisms of winter phytoplankton blooms in the bay of Biscay influenced by the Gironde waters (2) to determine the limiting nutrient of the primary production associated to these blooms and to follow the seasonal evolution of the limiting nutrient, (3) to understand the consequences of this early limitation on the structuration of algal populations in spring. Since phosphorus was supposed to be the major limiting nutrient of algal growth in the Gironde plume, the different forms of the phosphorus cycle as well as the bacterial compartment, central in this...
Tipo: Text Palavras-chave: Golfe de Gascogne; Gironde; Phytoplancton; Bactéries; Phosphates; Phosphore organique; Dissous; Phosphatases; Bay of Biscay; Gironde; Phytoplankton; Bacteria; Phosphate; Dissolved organic phosphorus; Phosphatases.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00013/12463/9298.pdf
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Etude écophysiologique et paramétrisation du rôle du phosphore sur la croissance d'Alexandrium minutum, espèce responsable d'eaux colorées toxiques en estuaire de Penzé, et de son principal compétiteur Heterocapsa triquetra - Rapport final PNEC-ART3 ArchiMer
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,...
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Ano: 2004 URL: http://archimer.ifremer.fr/doc/00105/21598/19178.pdf
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Étude sur la prolifération de la micro algue Alexandrium minutum en rade de Brest ArchiMer
Chapelle, Annie; Le Bec, Claude; Amzil, Zouher; Dreanno, Catherine; Guillou, Laure; Klouch, Khadidja; Labry, Claire; Le Gac, Mickael; Pineau-guillou, Lucia; Siano, Raffaele; Abernot, Chantal; Andrieux, Francoise; Caradec, Florian; Destombe, Christophe; Dia, A.; Doner, Anne; Duval, Julia; Gouriou, Jeremie; Lazure, Pascal; Le Brun, Luc; Le Gal, Dominique; Malestroit, Pascale; Petton, Sebastien; Plus, Martin; Quere, Julien; Savar, Veronique; Schmitt, Sophie; Terre, A.; Youenou, Agnes.
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 élaboré avec la Région Bretagne dans le cadre du développement du port de Brest. L’Ifremer a organisé un échantillonnage dans l’estuaire de la rivière de Daoulas, zone la plus touchée en 2012, au cours des printemps-été 2013 et 2014. Un suivi de la présence d’A. minutum dans les sédiments a également été réalisé en hiver 2014. De ces suivis, des mesures réalisées au laboratoire à ce jour, des simulations du modèle Prévimer ainsi que des résultats du réseau Rephy et Velyger, il ressort que: * La rade de Brest peut aujourd’hui être considérée comme une zone à risque pour Alexandrium minutum. En effet, depuis 2012...
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Ano: 2014 URL: http://archimer.ifremer.fr/doc/00254/36487/35029.pdf
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Growth and phosphorus uptake by the toxic dinoflagellate Alexandrium catenella (dinophyceae) in response to phosphate limitation ArchiMer
Jauzein, Cecile; Labry, Claire; Youenou, Agnes; Quere, Julien; Delmas, Daniel; Collos, Yves.
Alexandrium catenella (Whedon et Kof.) Balech has exhibited seasonal recurrent blooms in the Thau lagoon (South of France) since first reported in 1995. Its appearance followed a strong decrease (90%) in phosphate (PO(4)3-) concentrations in this environment over the 1970-1995 period. To determine if this dinoflagellate species has a competitive advantage in PO(4)3--limited conditions in terms of nutrient acquisition, semicontinuous cultures were carried out to characterize phosphorus (P) uptake by A. catenella cells along a P-limitation gradient using different dilution rates (DRs). Use of both inorganic and organic P was investigated from measurements of 33PO(4)3- uptake and alkaline phosphatase activity (APA), respectively. P status was estimated from...
Tipo: Text Palavras-chave: Alexandrium catenella; Alkaline phosphatase; Limitation; Phosphorus; Semicontinuous cultures.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00015/12641/9570.pdf
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High alkaline phosphatase activity in phosphate replete waters: The case of two macrotidal estuaries ArchiMer
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...
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Ano: 2016 URL: http://archimer.ifremer.fr/doc/00337/44840/44428.pdf
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Hydrologie et populations phytoplanctoniques dans le panache de la Loire et en Baie de Vilaine en période estivale : résultats de la campagne VILOIR. ArchiMer
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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Initiation of winter phytoplankton blooms within the Gironde plume waters in the Bay of Biscay ArchiMer
Labry, Claire; Herbland, Alain; Delmas, Daniel; Laborde, P; Lazure, Pascal; Froidefond, J; Jegou, Anne-marie; Sautour, B.
Thermostratification and seasonal Light increase are generally considered the first causes of phytoplankton spring blooms in temperate waters. The objective of this study is to confirm the existence of winter phytoplankton blooms, responsible for the early exhaustion of phosphate, within the Gironde plume waters (southeast Bay of Biscay), and to understand what may initiate them so early. Two cruises, BIOMET 2 and BIOMET 3, were carried out respectively in early (8 to 21 January) and late winter 1998 (25 February to 11 March). An increase of phytoplankton biomass (chl a) between the 2 cruises and non-conservative nutrients observed in late winter confirm an early phytoplankton growth both in the Gironde plume and adjacent oceanic waters. Among factors that...
Tipo: Text Palavras-chave: Vertical attenuation coefficient; Halostratification; Light availability; Winter blooms.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/2001/publication-810.pdf
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Lower trophic levels and detrital biomass control the Bay of Biscay continental shelf food web: Implications for ecosystem management ArchiMer
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...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00057/16851/14329.pdf
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Nutrient and phytoplankton distribution in the Loire River plume (Bay of Biscay, France) resolved by a new Fine Scale Sampler ArchiMer
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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Phytoplankton and bacterial alkaline phosphatase activities in relation to phosphate and DOP availability within the Gironde plume waters (Bay of Biscay) ArchiMer
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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Satellite-derived parameters for biological modelling in coastal waters: Illustration over the eastern continental shelf of the Bay of Biscay ArchiMer
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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Seasonal variation of riverine nutrient inputs in the northern Bay of Biscay (France), and patterns of marine phytoplankton response ArchiMer
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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The Bay of Brest (France), a new risky site for toxic Alexandrium minutum blooms and PSP shellfish contamination ArchiMer
Chapelle, Annie; Le Gac, Mickael; Labry, Claire; Siano, Raffaele; Quere, Julien; Caradec, Florian; Le Bec, Claude; Nezan, Elisabeth; Doner, Anne; Gouriou, Jeremie.
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Ano: 2015 URL: http://archimer.ifremer.fr/doc/00278/38921/37461.pdf
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The role of phosphorus on planktonic production of the Gironde plume waters in the Bay of Biscay ArchiMer
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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Vertical distribution of phytoplankton communities and relationships with physico-chemical parameters resolved by a fine scale sampler ArchiMer
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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