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| Registros recuperados: 28 | |
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| Pommepuy, Monique; Dupray, Elisabeth; Guillaud, Jean-francois; Derrien, A; L'Yavanc, Jacky; Cormier, M. |
| The behaviour of fecal bacteria was investigated in a turbid estuary which is also a shellfishing area. Sediments are polluted by sewage by the way of settlement, fecal bacteria mixed with estuarine water being able to survive a very long time (T90 are about several days). By measuring the increase of salt tolerance of the strains grown in natural estuarine organic matter, it was demonstrated that Escherichia coli is able to support the salinity of coastal water. Moreover, because light penetration is obstructed by suspended matter, the solar bactericidal effect is very low. A close relationship between T90 and light intensity received by the bacteria is found. These mechanisms can explain the low die-off rate found in turbid areas. |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00267/37860/35941.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. |
| 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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| Repecaud, Michel; Degres, Yves; Bernard, Nathalie; Allenou, Jean-pierre; Aoustin, Yannick; Arrondeau, Jean-pierre; Bouget, Jean-francois; Bucas, Karenn; Daniel, Anne; Guillaud, Jean-francois; Hamon, Michel; Jegou, Paul; Laes, Agathe; Le Roux, Dominique; Le Piver, David; Quemener, Loic; Rolin, Jean-francois; Rudelle, Tiphaine; Legrand, Jacques; Vuillemin, Renaud. |
| The automated monitoring of physico-chemical parameters in the coastal zone has been using large buoys and fixed infrastructures. A better understanding of many estuaries is needed in order to fulfil the agenda and requirements of the European Water Framework Directive. In order to address the fluxes of nutrients as well as algal blooms and low oxygen events, the "TROPHIMATIQUE" project has developed a new generation of instruments able to be deployed in sea waters. The smaller size of the new instruments is intended to facilitate the maintenance. A new multi-parameter probe has been developed. The measurements of all nutrients are performed thanks to the CHEMINI flow injection analysers for nitrate, ammonia, silicate and phosphate. A sampler using similar... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00107/21807/20276.pdf |
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| Menesguen, Alain; Aminot, Alain; Belin, Catherine; Chapelle, Annie; Guillaud, Jean-francois; Joanny, Michel; Lefebvre, Alain; Merceron, Michel; Piriou, Jean-yves; Souchu, Philippe. |
| In order to be able to count the cases of coastal eutrophication and to propose methods to monitor as well as to reduce these phenomena, first of all it is necessary to precisely define the word eutrophication itself. Instead of the strict etymological definition, that is to say a progression of the enrichment of a medium, we will rather retain the concept of a state enriched at a point such as it causes harmful effects on the ecosystem, and nuisances to man's activities. Based on the average chemical equations of the organic matter synthesis/degradation in the sea, this operational definition thus puts forwards the harmful consequences of enrichment, i.e. the production of an excessive algal biomass, sometimes unbalanced from the point of view of... |
| Tipo: Text |
Palavras-chave: Alexandrium; Phaeocystis; Monostroma; Ulva; Dilution plume; Water trapping; Anoxia; Nitrogen and phosphorus loadings; Red tides; Phytoplankton blooms; Green tides; Eutrophication; Alexandrium; Phaeocystis; Monostroma; Ulva; Panache de dilution; Confinement; Anoxie; Phosphate; Nitrate; Apports terrigènes; Eaux colorées; Blooms phytoplanctoniques; Marées vertes; Eutrophisation. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/rapport-22.pdf |
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| Gohin, Francis; Lampert, Luis; Guillaud, Jean-francois; Herbland, Alain; Nezan, Elisabeth. |
| A phytoplankton bloom was observed in late winter 2000, on the continental shelf offshore of southern Brittany, in northwestern Bay of Biscay. This bloom appeared initially along the 120-m isobath, in stratified and clear waters, at the interface between the oceanic water and the plumes of southern Brittany rivers (mainly the Loire and Vilaine). The development of the bloom was triggered by favourable meteorological conditions, characterised by solar irradiance reaching the maximum level expected for that period of the year. Outside of the bloom area, the phytoplankton photosynthesis was irradiance limited: inshore, because of the stronger attenuation of the light; offshore, because of the weak stratification. The hydrological conditions at the onset of... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Coscinodiscus; Algal bloom; Phytoplankton; Ocean colour; Satellite sensing. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-463.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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| Aminot, Alain; Guillaud, Jean-francois; Andrieux, Francoise. |
| The Bay of Seine receives the French river with the highest nutrient concentrations, especially phosphorus. Dissolved (phosphate) and particulate phosphorus fluxes have been determined from fortnightly serial data collected by the Port Autonome de Rouen. These determinants exhibit behaviour opposite to that of the river flow: phosphate concentration decreases hyperbolically and particulate phosphorus increases linearily. An approach based on the rate of domestic effluent treatment agrees well (20%) with the measured phosphate flux. The determination of the main particulate phosphorus forms (adsorbed, apatite, non-apatite inorganic, organic) was undertaken over the whole estuarine salinity range. The speciation of particulate phosphorus exhibits a great... |
| Tipo: Text |
Palavras-chave: PHOSPHORUS; SPECIATION; FLUX; ESTUARY; SEINE. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/00100/21126/18746.pdf |
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| Aminot, Alain; Guillaud, Jean-francois; Kerouel, Roger. |
| The data of hydrology, nutrients and chlorophyll obtained in the Bay of Seine over the period 1978-1994, from 14 océanographie cruises, are synthetised and illustrated by an atlas. The Bay is a typical example of a coastal area influenced by a large river. In winter, the nutrient input is drained off into the eastern Channel. In spring, nutrients are consumed intensively. Silicate is the first that drops to limiting levels. The spring bloom generally begins in the centre-east of the Bay. Chlorophyll a can reach up to 40-70 µg/l during the year, values typical of eutrophic coastal areas. Despite the regular increase of nitrogen inputs, the biomass (as chlorophyll) has not significantly changed over a fifteen year period. |
| Tipo: Text |
Palavras-chave: Chlorophyll; Nutrients; Hydrology; Bay of Seine; Chlorophylle; Nutriments; Hydrologie; Baie de Seine. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/1997/rapport-1428.pdf |
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| Menesguen, Alain; Cugier, Philippe; Loyer, Sophie; Vanhoutte Brunier, Alice; Hoch, Thierry; Guillaud, Jean-francois; Gohin, Francis. |
| The general trend in ecosystem modelling is to improve the spatial resolution by shifting from rough box-models to fine 3D models. Despite the continuous speeding-up of computing, 3D models involving numerous state variables may remain intractable, especially for parameter calibration, when processes with long half-life periods (i.e, from years to decades) are introduced, such as the behaviour of organic matter in sediment and population dynamics of benthic species. In these cases, a first approach can be provided by fast-running box-models, if they take into account the most crucial hydrodynamic properties of the system. In a macrotidal shelf sea such as the English Channel, the long-term horizontal transport can be summarized by the tidal residual... |
| Tipo: Text |
Palavras-chave: English Channel; Stratification; Diatom/dinoflagellate succession; 3D model; Layered box model. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2315.pdf |
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| Billen, Gilles; Cugier, Philippe; Garnier, Josette; Menesguen, Alain; Guillaud, Jean-francois; Durand, I. |
| Le processus d'eutrophisation des milieux marins côtiers, et le développement épisodiques de dinoflagellés qui en est une des manifestations, dépend de manière complexe de l'équilibre des flux d'azote, de phosphore et de silice en provenance des milieux terrestres du bassin versant. Ceux ci sont déterminés par la manière dont les activités humaines sur le bassin versant interagissent avec les processus naturels. La possibilité de prévoir l'effet sur l'eutrophisation marine des mesures prises pour l'amélioration de la qualité des eaux continentales dépend donc à la fois de notre connaissance du fonctionnement des milieux marins et de celui des bassins versants. En vue de développer les outils de modélisation nécessaire pour prévoir l'Etat de la Baie de... |
| Tipo: Text |
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| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00106/21695/19274.pdf |
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| Pénard, Cédric; Ménesguen, Alain; Dumas, Franck; Guillaud, Jean-francois. |
| Eutrophication of French Brittany coastal shelf is a recurrent problem, more and more worrying. This eutrophication exhibits two main forms :– “green tides”, which are constituted by local proliferations and strandings of green macro-algae (particularly the Ulva species) in nitrogen-enriched areas.– phytoplanktonic blooms, which are responsible of coloured water events. Toxic species can be present (Pseudonitzschia, Alexandrium, Dinophysis), and induce banning of shellfish consumption.Several programs and directives compel authorities to initiate actions in order to diminish these problems. (WFD, OSPAR). This implies a better understanding of these phenomena.This work deals with the influences of the plumes of Loire, Vilaine and bay of Brest rivers (Elorn... |
| Tipo: Text |
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| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00480/59153/61782.pdf |
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| Merceron, Michel; Manaud, Francois; Guillaud, Jean-francois; Monbet, Yves. |
| The commercial port of the city of St-Brieuc currently has a limited capacity. It is only accessible for low-tonnage ships, and for this reason, cargo is not allowed, which is a contributing factor to its current traffic being limited to 450,000 tonnes per year. A significant silting-up of the port is diminishing even more its potential for accepting ships. Its future seems, therefore, threatened. Several studies conducted by the Côtes-du-Nord Chamber of Commerce and Industry have concluded that it is necessary to develop a port with greater capacity, which would stimulate the regional economy. Cargo traffic would then reach 1 million tonnes per year, and St-Brieuc would be accessible to heavier-tonnage coasters and would then follow the current growth of... |
| Tipo: Text |
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| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/rapport-2835.pdf |
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| Registros recuperados: 28 | |
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