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| Registros recuperados: 36 | |
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| Morelle, Jerome; Schapira, Mathilde; Orvain, Francis; Riou, Philippe; Lopez, Pascal Jean; Pierre-duplessix, Olivier; Rabiller, Emilie; Maheux, Frank; Simon, Benjamin; Claquin, Pascal. |
| Phytoplankton primary production varies considerably with environmental parameters especially in dynamic ecosystems like estuaries. The aim of this study was to investigate short-term primary production along the salinity gradient of a temperate estuary over the course of 1 year. The combination of carbon incorporation and fluorescence methods enabled primary production estimation at short spatial and temporal scales. The electron requirement for carbon fixation was investigated in relation with physical-chemical parameters to accurately estimate primary production at high frequency. These results combined with the variability of the photic layer allowed the annual estimation of primary production along the estuary. Phytoplankton dynamics was closely... |
| Tipo: Text |
Palavras-chave: High frequency; Electron requirement for carbon fixation; Electron transport rate (ETR); Seine estuary. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00429/54020/55470.pdf |
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| Roux, Pauline; Siano, Raffaele; Collin, Karine; Bilien, Gwenael; Sinquin, Corinne; Marchand, Laetitia; Zykwinska, Agata; Delbarre-ladrat, Christine; Schapira, Mathilde. |
| High biomasses of the marine dinoflagellate Lepidodinium chlorophorum cause green seawater discolorations along Southern Brittany (NE Atlantic, France). The viscosity associated to these phenomena has been related to problems in oyster cultivation. The harmful effect of L. chlorophorum might originate from the secretion of Extracellular Polymeric Substances (EPS). To understand whether the EPS are produced by L. chlorophorum or its associated bacteria, or if they are a product of their interaction, batch cultures were performed under non-axenic and pseudo-axenic conditions for three strains. Maximum dinoflagellate cell abundances were observed in pseudo-axenic cultures. The non-sinking fraction of polymers (Soluble Extracellular Polymers, SEP), mainly... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00682/79403/81948.pdf |
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| Collin, Karine; Bizzozero, Lucie; Le Merrer, Yoann; Retho, Michael; Souchu, Philippe; Cochennec-laureau, Nathalie; Schapira, Mathilde; Manach, Soazig. |
| Ce rapport décrit le contexte hydrologique du littoral côtier du Morbihan, Pays de Loire et Nord Vendée, sous l’influence de la Loire et de la Vilaine, durant l’année 2017. Il s’appuie sur les suivis environnementaux réalisés dans le cadre des réseaux REPHY et de la DCE, complétés des données acquises en haute fréquence sur la bouée MOLIT (réseau COAST-HF). |
| Tipo: Text |
Palavras-chave: Hydrologie; DCE; Nutriment; Loire Bretagne; Rephy; Phytoplancton. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00472/58410/60972.pdf |
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| Schapira, Mathilde; Courtay, Gaelle; Francoise, Sylvaine. |
| Au cours des trois années d’étude (2013-2015), les concentrations en acide domoïque particulaire (ADp) sont restées inférieures à 60 ng l-1 sur l’ensemble de la zone et aucun dépassement de seuil n’a été observé dans les coquillages au cours de cette même période. Lors de la crise sanitaire de 2012, des concentrations en ADp de plus de 4000 ng l-1 avaient été mesurées au printemps au cours du bloom de Pseudo-nitzschia et des concentrations en AD très élevées avaient rapidement été observées dans les coquilles Saint Jacques dès le début de l’été. Ces observations suggèrent que des concentrations en ADp inférieures à 100 ng l-1 seraient insuffisantes pour une contamination massive des bivalves filtreurs en baie de Seine. Ces résultats sont en accord avec une... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00400/51107/51891.pdf |
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| Schapira, Mathilde; Buscot, Marie-jeanne; Pollet, Thomas; Leterme, Sophie; Seuront, Laurent. |
| Background Picophytoplankton (i.e. cyanobacteria and pico-eukaryotes) are abundant and ecologically critical components of the autotrophic communities in the pelagic realm. These micro-organisms colonized a variety of extreme environments including high salinity waters. However, the distribution of these organisms along strong salinity gradient has barely been investigated. The abundance and community structure of cyanobacteria and pico-eukaryotes were investigated along a natural continuous salinity gradient (1.8% to 15.5%) using flow cytometry. Results Highest picophytoplankton abundances were recorded under salinity conditions ranging between 8.0% and 11.0% (1.3 × 106 to 1.4 × 106 cells ml-1). Two populations of picocyanobacteria (likely Synechococcus... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00174/28548/26932.pdf |
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| Morelle, Jerome; Schapira, Mathilde; Francoise, Sylvaine; Courtay, Gaelle; Orvain, Francis; Claquin, Pascal. |
| In parallel to phytoplankton community dynamics, transparent exopolymeric particles (TEP) and exopolymeric substances (EPS) were investigated along the salinity gradient of a temperate estuary (Seine estuary, Normandy, France) over the course of a year. The phytoplankton community was mainly dominated by marine diatom species (especially Skeletonema sp., Nitzschia sp., and Paralia sulcata) associated with a spring bloom of pico-eukaryotes and the development of Cryptophyceae in summer. The decreases in species richness and salinity were correlated along the estuary and a significant exponential relationship between species richness and primary production was identified. Concentrations of TEP and EPS (soluble and bound carbohydrates) are highly dynamic in... |
| Tipo: Text |
Palavras-chave: Picophytoplankton; Nanophytoplankton; Exopolymeric substances; Species richness. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00440/55189/56645.pdf |
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| Morelle, Jerome; Schapira, Mathilde; Claquin, Pascal. |
| Exopolysaccharides (EPS) play an important role in the carbon flux and may be directly linked to phytoplankton and microphytobenthos production, most notably in estuarine systems. However the temporal and spatial dynamics of estuarine EPS are still not well understood, nor how primary productivity triggers this variability at these different scales. The aim of this study was to investigate the primary productivity of phytoplankton and EPS dynamics in the Seine estuary over a tidal cycle in three different haline zones over two contrasted seasons. The other objectives was to investigate the origin of pools of soluble carbohydrates (S-EPS) and transparent exopolymeric particles (TEP) in phytoplankton, microphytobenthos or other compartments. High frequency... |
| Tipo: Text |
Palavras-chave: Phytoplankton; Microphytobenthos; PAM fluorometer; Electron transport rate. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00400/51132/51898.pdf |
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| Cochennec-laureau, Nathalie; Schapira, Mathilde; Bouget, Jean-francois; Manach, Soazig; Retho, Michael; Le Merrer, Yoann; Schmitt, Anne; Pierre-duplessix, Olivier; Gabellec, Raoul; Normand, Julien; Combette, Agnes. |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00457/56879/79184.pdf |
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| Schapira, Mathilde; Mcquaid, Christopher D.; Froneman, Pierre W.. |
| Extensive beds of large subtidal kelps are characteristic of many temperate and subpolar coastlines. They provide habitats for a wide range of other species and are sites of high primary production that generate large quantities of water-borne particles and dissolved organic compounds that support distinctive communities of prokaryotes. We measured prokaryotic metabolism along transects from the shore to the outside of three giant kelp forests (Macrocystis pyrifera) located in the shelf waters of the Prince Edward Islands (Southern Ocean). Abundance, heterotrophic production (PHP), respiration rates (R-ETS) and growth efficiencies (PGE) were investigated within the particle-associated (PA) and the free-living (FL) communities. Temperature, salinity and... |
| Tipo: Text |
Palavras-chave: Prokaryotes; Free-living; Particle-associated; Growth efficiency; Kelp; Sub-Antarctic island. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19939/17760.pdf |
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| Foucher, Eric; Blanchard, Michel; Cugier, Philippe; Desroy, Nicolas; Dreanno, Catherine; Fauchot, Juliette; Fifas, Spyros; Guyader, Olivier; Jean, Frederic; Le Gallic, Bertrand; Riou, Philippe; Schapira, Mathilde; Thiebaut, Eric. |
| The King scallop Pecten maximus constitutes the first landed species in terms of tonnage and the second or third one in terms of value for the French fisheries. More than 90% of these landings come from the English Channel indicating that its exploitation is essential to local fleets. The COMANCHE project (Ecosystem Interactions and anthropogenic impacts on King scallops populations in the English Channel) proposed to improve the knowledge of the scallop within the Channel, through an ecosystem-based approach for fisheries, appealing to a wide range of scientific disciplines (physics, chemistry, genetics, ecology, geostatistics, modeling, economics ....). Researches on the spatial location of scallop beds, connectivity by larval dispersal between beds,... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00251/36236/34797.pdf |
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| Garnier, Josette; Riou, Philippe; Le Gendre, Romain; Ramarson, Antsiva; Billen, Gilles; Cugier, Philippe; Schapira, Mathilde; Théry, Sylvain; Thieu, Vincent; Ménesguen, Alain. |
| The continental coastal waters of the Eastern Channel, from Normandy to Hauts-de-France, are subject to the major influence of unbalanced nutrient inputs from inflowing rivers. Several episodes of harmful algal blooms (HABs) compromising fishing and shellfish farming activities have been observed at the coast. For a better understanding of how the land-to-sea aquatic continuum functions, the GRAFS-RIVERSTRAHLER river biogeochemical model was implemented to cover the watersheds of 11 rivers flowing into this area (including the Seine) and chained with the ecological marine ECO-MARS3D model, applied to the French Northern coastal zone. Human activities strongly impact on the functioning of coastal ecosystems. Specifically, for these fertile soils of Northern... |
| Tipo: Text |
Palavras-chave: Toxic microalgae; Pseudo-nitzschia spp.; River basins; Nutrient flows; Scenarios; Coastal zone ecosystem; Modelling. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70076/68049.pdf |
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| Schapira, Mathilde; Seuront, Laurent. |
| Despite ample evidence of micro- and small-scale (i.e., millimeter- to meter-scale) phytoplankton and zooplankton patchiness in the ocean, direct observations of nutrient distributions and the ecological importance of this phenomenon are still relatively scarce. In this context, we first describe a simple procedure to continuously sample nutrients in surface waters, and subsequently provide evidence of the existence of microscale distribution of ammonium in the ocean. We further show that ammonium is never homogeneously distributed, even under very high conditions of turbulence. Instead, turbulence intensity appears to control nutrient patchiness, with a more homogeneous or a more heterogeneous distribution observed under high and low turbulence... |
| Tipo: Text |
Palavras-chave: Nutrient patchiness; Turbulence; Phytoplankton; Surge uptake; Nutrient depletion; Turbulent history. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00643/75527/76435.pdf |
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| Pollet, Thoams; Schapira, Mathilde; Buscot, Marie-jeanne; Leterme, Sophie; Mitchell, James G; Seuront, Laurent. |
| he distribution and aminopeptidase activity of prokaryotes were investigated along a natural continuous salinity gradient in a hypersaline coastal lagoon, the Coorong, South Australia. The abundance of prokaryotes significantly increased from brackish to hypersaline waters and different sub-populations, defined by flow cytometry, were observed along the salinity gradient. While four sub-populations were found at each station, three additional ones were observed for 8.3% and 13.4%, suggesting a potential modification in the composition of the prokaryotic communities and/or a variation of their activity level along the salinity gradient. The aminopeptidase activity highly increased along the gradient and salinity appeared as the main factor favouring this... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00174/28549/26933.pdf |
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| Cochennec-laureau, Nathalie; Bizzozero, Lucie; Bonneau, Francoise; Collin, Karine; Fortune, Mireille; Le Merrer, Yoann; Pierre-duplessix, Olivier; Schapira, Mathilde; Schmitt, Anne; Souchu, Philippe. |
| Suivi hydrologique L’année 2017 s’est caractérisée par des températures élevées et un déficit en précipitation sur le bassin versant de la Loire, ce qui la classe parmi les années sèches exceptionnelles avec les années 2003, 2011 et 2015. Les débits de la Loire ont été largement déficitaires. L’ensoleillement soutenu en début d’année et en automne a été toutefois plus faible sur les mois de juillet et septembre. Suivi microbiologique Parmi les 41 stations de surveillance, 9 ont présenté une bonne qualité microbiologique, 31 une qualité moyenne, et une seule station est de mauvaise qualité. Comparativement à l'année 2016, le nombre de stations présentant une tendance à l'amélioration est en augmentation : 4 stations présentent une tendance à l'amélioration... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00461/57312/59406.pdf |
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| Cochennec-laureau, Nathalie; Bizzozero, Lucie; Blouin, Antoine; Bonneau, Francoise; Bouget, Jean-francois; Collin, Karine; Fortune, Mireille; Gabellec, Raoul; Le Merrer, Yoann; Manach, Soazig; Mellor, Alice; Pierre-duplessix, Olivier; Reboul, Sebastien; Retho, Michael; Schapira, Mathilde; Schmitt, Anne; Souchu, Philippe; Stanisiere, Jean-yves; Treguier, Cathy. |
| Ce rapport présente les activités d'observation et de surveillance de la qualité des eaux littorales du Morbihan, de la Loire Atlantique et du Nord Vendée et les résultats des projets de recherche. |
| Tipo: Text |
Palavras-chave: Réseaux de surveillance et d’observation; Qualité des écosystèmes marins littoraux du Morbihan; Pays de Loire; Microbiologie; Phytoplancton; Eutrophisation; Ressources exploitées; Huîtres; Moules. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00439/55061/56484.pdf |
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| Registros recuperados: 36 | |
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