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| Registros recuperados: 35 | |
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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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| Martin, Jean-louis; Sornin, Jean-marc; Delmas, Daniel; El Sayed, Mohamed A.; Berthet, Brigitte. |
| Au cours de cette étude, nous avons étudié l'impact de la biodéposition sur les bassins conchylicoles. La biodéposition constitue un "concentrateur" de particules fines au niveau du sédiment. Cet impact est particulièrement évident sur les sédiments sableux et concerne la granulométrie, les taux de matière organique, la concentration des métaux et des hydrocarbures. Une étude comparée est faite entre estran sableux et bassin de type "claire" à sédiment argileux. L'impact de la biodéposition sur les sédiments sableux n'est pas irréversible. Le bassin fermé avec un sédiment argileux agit comme un concentrateur-rétenteur de particules et des contaminants potentiels. Ceci souligne le rôle "tampon" des marais maritimes entre milieu continental et milieu marin. |
| Tipo: Text |
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| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/00076/18757/16327.pdf |
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| Delmas, Daniel; Herbland, Alain; Maestrini, Serge; Mornet, Francoise; Morand, Philippe; Spano, Anna-maria; Burgeot, Thierry; Margat, Sylvie; Charpentier, Gabriel; Fillon, Alain; Leguay, Didier; Thomas, Gerard; Bacher, Cedric; Heral, Maurice; Prou, Jean. |
| Environmental and species features which lead to increases in cell density of the D.S.P. Dinoflagellate Dinophysis in inshore and offshore waters of the île de Ré - île d'Oléron area, France (cruises "Dinopertuis89"). Four weekly sampling series have been carried out, within 10 May – 31 May 1989, at 24 stations located from inshore to offshore waters of the "île de Ré" - "île d’Oléron" area, with the aim to investigate (i) whether Dinophysis increases in cell density occur first in offshore waters and then, eventually, are pushed to the coast, or develop simultaneously in the whole area, and (ii) whether there are some environmental conditions which are related to Dinophysis blooms. Depths of sampling have been stated on the bas is of STD profiles. All... |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00174/28532/26916.pdf |
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| Auguet, Jean-christophe; Montanie, Helene; Hartmann, Hans; Lebaron, P.; Casamayor, E. O.; Catala, P.; Delmas, Daniel. |
| Batch culture experiments using viral enrichment were conducted to test the response of a coastal bacterial community to autochthonous (i.e., co-existing) or allochthonous riverine viruses. The effects of viral infections on bacterial dynamics and activity were assessed by epifluorescence microscopy and thymidine incorporation, respectively, whereas the effect of viral infection on bacterial community composition was examined by polymerase chain reaction-single strand conformation polymorphism 16S ribosomal RNA fingerprinting. The percentages of high nucleic acid-containing cells, evaluated by flow cytometry, were significantly correlated (r (2) = 0.91, n = 12, p < 0.0001) to bacterial production, making this value a good predictor of active cell... |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6636.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... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00057/16851/14329.pdf |
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| Crottereau, C; Delmas, Daniel. |
| In order to estimate in situ bacterial exoproteolysis and its contribution to bacterial secondary production (BSP), we studied microbial activities (BSP and kinetics of exoproteolytic activity) in relation to dissolved combined amino acids (DCAA) during the survey of an Atlantic marine pond. In this pond, high concentrations of DCAA (mean = 4.27 mu M), probably generated by zooplankton grazing, allowed large bacterial biomass development and high production (max = 10(11) cells l(-1) and 18.8 x 10(9) cells l(-1) d(-1) respectively). Exoproteolytic enzyme activity (mean V-m = 55.9 mu M d(-1)) was tightly cou pled to bacterial production, suggesting that protein utilization was essential for bacterial growth. Calculation, according to the Michaelis-Menten... |
| Tipo: Text |
Palavras-chave: Bacterioplankton; In situ exoproteolytic hydrolysis rate; Kinetic parameters; DCAA; Marine pond. |
| Ano: 1998 |
URL: https://archimer.ifremer.fr/doc/00446/55803/62288.pdf |
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| Sornin, Jean-marc; Collos, Yves; Delmas, Daniel; Feuillet-girard, Michèle; Gouleau, Daniel. |
| The oyster pond under study has a natural sediment bottom and water is changed only once or twice every month depending on tidal height. Between successive water renewals, the pond is a closed system, equivalent to a batch culture in which sinking and biodeposition of particulate matter are the only sources of organic matter to the bottom. Particulate organic matter enrichment of the sediment in winter is followed by intensive ammonification in summer with very limited nitrification. Seasonal nitrogen budgets involving particulate and dissolved phases show that in summer during batch mode period, ammonium enrichment from the sediment to the overlying water is an order of magnitude higher than the initial nutrient supply in the feed water. This allows a... |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00178/28892/27749.pdf |
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| 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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| Bergeron, Jean-pierre; Delmas, Daniel; Koueta, Noussithe. |
| In the 2000 and 2001 springtime periods, mesozooplankton samples were systematically taken during research cruises devoted to the study of the distribution and abundance of small pelagic fishes in the French part of the Bay of Biscay, NE Atlantic, continental shelf. Simultaneous activities of three enzymes were measured in these mesozooplankton samples, to characterize the main features of ecosystem function at a regional scale. The aim was to assess assimilation rates of carbohydrates, through pyruvate kinase activity, and protein, through trypsin activity, by the mesozooplankton community and the resulting overall productivity, through aspartate transcarbamylase activity. The highest influence on the pelagic environment was the strong difference in the... |
| Tipo: Text |
Palavras-chave: Rivers discharge; Phytoplankton distribution; Anchovy; Nutritional state; RNA/DNA ratio; Mesozooplankton; Metabolic descriptors; North-East Atlantic; Bay of Biscay. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00012/12290/9089.pdf |
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| Delmas, Daniel; Herbland, Alain; Maestrini, Serge. |
| From 22 April to 19 June 1990, 7 stations located off La Rochelle, France, from near-shore ('bassin Marennes-Oleron') to offshore waters (50 m depth contour) were visited 8 times, with the aim of determining whether the toxic dinoflagellates Dinophysis spp. increase in cell density in nutrient-poor offshore water, in nutrient-rich inshore waters, or both, and to determine their vertical distribution in relation to stratification. Temperature stratification developed offshore, but not inshore. In April, few Dinophysis spp. were present offshore and none inshore. In late May, up to 15 X 10(3) cells l(-1) were recorded in the 10 to 15 m layer offshore, whereas inshore waters contained only a few cells l(-1). In late May, a short period of wind partly modified... |
| Tipo: Text |
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| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00190/30141/28772.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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| 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: 35 | |
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