Consulta: creatorFacets:"Delmas, Daniel"
Registros recuperados: 35
Data/hora: 15/06/2024 02:27:20

Determining how the pelagic ecosystem over the continental shelf of the Bay of Biscay (NE Atlantic) functions: An approach using mesozooplankton enzyme activities as descriptors
Provedor de dados: 5
Autores: Bergeron, Jean-pierre; Delmas, Daniel; Koueta, Noussithe.
A fisheries research cruise conducted in 2000 offered a first opportunity to take simultaneous measurements of the activities of three enzymes in mesozooplankton samples collected at a regional scale over the continental shelf of the Bay of Biscay in the NE Atlantic, with the aim of characterizing main aspects of the functioning of the biotic environment of small pelagic fish populations. The activity of the digestive endopeptidase trypsin was selected to characterize the assimilation rate of proteins, whereas pyruvate kinase (PK) was chosen as an indicator of carbohydrate assimilation and aspartate transcarbamylase (ATC) provided an overall assessment of mesozooplankton productivity. The Bay of Biscay region is subject to various strong physical driving...
Tipo: Text
Palavras-chave: Trypsin; Pyruvate kinase; Metabolic descriptors; Mesozooplankton; Bay of Biscay; Aspartate transcarbamylase.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6359.pdf

Microbial enzymatic assays in environmental water samples: impact of Inner Filter Effect and substrate concentrations
Provedor de dados: 5
Autores: 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
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00653/76524/77614.pdf

La biodéposition dans les aires ostréicoles. Son rôle dans la concentration de la matière organique et de contaminants potentiels. Son impact sur le sédiment.
Provedor de dados: 5
Autores: 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
Ano: 1989
URL: http://archimer.ifremer.fr/doc/00076/18757/16327.pdf

DYNAPSE - DYNamiques des efflorescences et de la toxicité des espèces phytoplanctoniques nuisibles du genre PSEudo nitzschia en région Loire Bretagne
Provedor de dados: 5
Autores: Belin, Catherine; Chapelle, Annie; Delmas, Daniel; Nezan, Elisabeth; Siano, Raffaele.
Les efflorescences de la diatomée Pseudo-nitzschia sont largement répandues sur les côtes Manche-Atlantique depuis une trentaine d’années (source Rephy). Depuis les années 2000 elles y sont parfois associées des événements toxiques du type ASP (Amnesic Shellfish Poisonning) qui perturbent grandement les pêcheries de coquillages et notamment celles de coquilles Saint Jacques. Les efflorescences et toxicités liées aux Pseudo-nitzschia sont des phénomènes en augmentation sur les côtes françaises mais aussi mondialement. Le genre Pseudo-nitzschia comprend plusieurs espèces très difficiles à identifier en routine or certaines sont toxiques et d’autres pas. Les facteurs environnementaux abiotiques et biotiques contrôlent à la fois la croissance des microalgues...
Tipo: Text
Palavras-chave: Algues toxiques; Pseudo nitzschia; Toxicité des coquillages; Pêcheries; Facteurs environnementaux.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00189/30035/28521.pdf

Premières propositions pour un indice de composition du phytoplancton, basé sur les résultats des méthodes pigments et diversité génétique. Action 3 - Indice Composition - Livrable 1. Rapport final, mars 2015.
Provedor de dados: 5
Autores: Siano, Raffaele; Delmas, Daniel; Lampert, Luis.
Tipo: Text
Palavras-chave: Phytoplancton; Pigments; Indice composition; Diversité pigmentaire; Metabarcoding; Picoplancton; Mamiellophyceae; Chlb; Golfe de Gascogne; Panache de la Gironde; Phytoplankton; Pigments; Composition index; Pigment diversity; Metabarcoding; Picoplankton; Mamiellophyceae; Chlb; Gulf of Biscay; River Gironde plume.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00361/47263/47228.pdf

Conditions d'apparition de densités accrues de dinoflagellés Dinophysis dans le pertuis d'Antioche et les eaux adjacentes. Campagnes Dinopertuis 89
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00174/28532/26916.pdf

Stimulation of bacterial exoproteolytic activity by fish farming in coastal marine ponds: Effect on dissolved protein cycling
Provedor de dados: 5
Autores: Garet, Marie-josé; Reymond, Hugues; Delmas, Daniel.
The effect of fish farming on dissolved amino acid concentrations, bacterioplankton abundance and exoproteolytic activity was assessed in 3 experimental marine ponds. Different standing stocks of fish were introduced (semi-intensive pond: 250 g.m(-2); semi-extensive pond: 50 g.m(-2) control pond: 0). Sea bass farming increased dissolved combined amino acid (DCAA) concentrations only in the semi-intensive pond. Bacterial standing stock was unaffected by fish food supply. However, bacterial exoproteolytic activity was strongly stimulated by aquaculture intensification; the average maximal rate of dissolved protein hydrolysis (V-m) increased with intensity (control pond: 1 500 nM.h(-1); semi-extensive pond: 2 600 nM.h(-1) semi-intensive pond: 5 100 nM.h(-1))....
Tipo: Text
Palavras-chave: Activité exoprotéolytique bactérienne; Protéines dissoutes; Intensification de l'aquaculture; Marais maritimes; Bacterial exoproteolytic activity; Dissolved proteins; Aquaculture; Coastal marine ponds.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00336/44766/44701.pdf

Evolutions quantitatives et qualitatives du seston dans une claire à huîtres : relation avec la sédimentation et la biodéposition
Provedor de dados: 5
Autores: Sornin, Jean-marc; Delmas, Daniel; Deslous-paoli, Jean-marc.
Dans un bassin aquacole fermé (claires à huîtres), l'évolution qualitative et quantitative des matières en suspension subit des variations saisonnières directement liées aux capacité de production planctonique. Ainsi, à la fin du printemps et en été, le réchauffement des eaux s'accompagne d'une augmentation de matière organique importante (jusqu'à 17 mg.1(-1). Pendant cette période, la sédimentation naturelle est supérieure à 350 g.m(-2).j(-1). La biodéposition (fèces + pseudofèces) suit l'évolution des capacités de rétention des huîtres. Dans ce type de bassin fermé, cette capacité est liée à la qualité des matières en suspension. En période estivale, les fortes teneurs en matière organique du seston (entre 5 et 17 mg.1(-1)) dispensent les mollusques...
Tipo: Text
Palavras-chave: Crassostrea gigas; Oysters; Biodeposition; Sedimentation; Suspension; Particulate organic matter; Crassostrea gigas; Huîtres; Biodéposition; Sédimentation; Suspension; Matière organique particulaire.
Ano: 1987
URL: http://archimer.ifremer.fr/doc/1987/publication-7309.pdf

Potential Effect of Freshwater Virus on the Structure and Activity of Bacterial Communities in the Marennes-Oléron Bay (France)
Provedor de dados: 5
Autores: 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 &lt; 0.0001) to bacterial production, making this value a good predictor of active cell...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6636.pdf

Lower trophic levels and detrital biomass control the Bay of Biscay continental shelf food web: Implications for ecosystem management
Provedor de dados: 5
Autores: 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
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00057/16851/14329.pdf

Use of SeaWiFS data for light availability and parameter estimation of a phytoplankton production model of the Bay of Biscay
Provedor de dados: 5
Autores: Huret, Martin; Gohin, Francis; Delmas, Daniel; Lunven, Michel; Garcon, Véronique.
Processing SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data provides useful information for the observation and modelling of the phytoplankton production of the Bay of Biscay. Empirical algorithms allow the retrieval of chlorophyll a and non-living Suspended Particulate Matter (SPM) concentrations. These data are used to constrain a coupled 3D physical-biogeochemical model of the Bay of Biscay continental shelf Two issues are investigated, depending on the variable used, to constrain the winter to spring phytoplankton production for the year 2001. First, SPM data is used as forcing data to correct the corresponding state variable of our model. This allows the realistic simulation of the light limited bloom at the end of February 2001, as observed with...
Tipo: Text
Palavras-chave: Bay of Biscay; SeaWiFS; Parameter estimation; Chlorophyll; Suspended Particulate Matter; Physical biogeochemical modelling.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2493.pdf

Exoproteolytic activity in an Atlantic pond (France): estimates of in situ activity
Provedor de dados: 5
Autores: 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

Nitrogenous nutrient transfers in oyster ponds role of sediment in deferred primary production
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00178/28892/27749.pdf

Acquisition de données complémentaires aux dénombrements, avec les techniques d’analyses pigmentaires et de diversité génétique. Etat d’avancement et premiers résultats. Action Indice Composition. Livrable n° AIV. Rapport final, 16 juillet 2014.
Provedor de dados: 5
Autores: Delmas, Daniel; Siano, Raffaele.
Studies on phytoplankton community diversity cannot be limited microphytoplankton (cells&gt;20 ìm), it is indeed necessary to take into account also the nano (3-20ìm) picophytoplankton (&lt;3 ìm) components. In the frame of this work aimed at studying temporal phytoplankton community diversity two complementary methodologies of phytoplankton sample analysis, pigment and genetic (metarbarcoding) diversity, have been used as alternative to routine morphological analysis carried out at light microscopy. The REPHY station (047-P-016 Concarneau Large) off-shore the Concarneau Bay has been sampled during the annual highest phytoplankton production (March-July 2012) with a frequent sample interval strategy (twice per week). Results obtained by both pigment and...
Tipo: Text
Palavras-chave: Phytoplancton; Structure de taille; Picophytoplancton; Nanophytoplancton; Microphytoplancton; Diversité génétique; Metabarcoding; Taxonomie pigmentaire; Façade atlantique; Baie de Concarneau; Phytoplankton; Size classes; Picophytoplankton; Nanophytoplankton; Microphytoplankton; Genetic diversity; Metabarcoding; Pigment taxonomy; Atlantic coasts; Concarneau Bay.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00361/47260/47225.pdf

Initiation of winter phytoplankton blooms within the Gironde plume waters in the Bay of Biscay
Provedor de dados: 5
Autores: 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

Do river discharge rates drive the overall functioning of the pelagic ecosystem over the continental shelf of the Bay of Biscay (NE Atlantic)? A comparison of two contrasting years with special reference to anchovy (Engraulis encrasicolus L.) nutritional state
Provedor de dados: 5
Autores: 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

Etude chémotaxonomique de la campagne TIC-MOC (mars 2015) – Projet CALHIS
Provedor de dados: 5
Autores: Lampert, Luis; Perrot, Laurie; Delmas, Daniel.
A partir des échantillons collectés lors de la campagne TIC-MOC (mars 2015) sur le plateau continental argentin, des analyses en pigments phytoplanctoniques permettent de quantifier la distribution des principales classes algales par la méthode CHEMTAX. Les Prochlorophycées et cyanobactéries sont essentiellement dominantes dans les eaux chaudes du courant du Brésil, tandis que dans les eaux plus froides du courant des Malouines et la zone de mélange (T°&lt; 20°C), c’est les Haptophytes (Phaeocystis et Emiliania huxleyi) qui dominent la biomasse chlorophyllienne. Des dominances moyennes en dinoflagellés supérieures 30% sont observées dans les deux masses d’eau.
Tipo: Text
Palavras-chave: Chémotaxonomie; Coccolithophoridés; HPLC; Pigments phytoplanctoniques; Patagonie; Plateau continental.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00327/43784/43342.pdf

Environmental conditions which lead to increase in cell density of the toxic dinoflagellates Dinophysis spp. in nutrient-rich and nutrient-poor waters of the French Atlantic coast
Provedor de dados: 5
Autores: 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
Ano: 1992
URL: http://archimer.ifremer.fr/doc/00190/30141/28772.pdf

The role of phosphorus on planktonic production of the Gironde plume waters in the Bay of Biscay
Provedor de dados: 5
Autores: 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 &lt;34.5. P was found to be the first limiting nutrient of winter and spring phytoplankton blooms, based on undetectable phosphate (&lt;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

Seasonal variation of riverine nutrient inputs in the northern Bay of Biscay (France), and patterns of marine phytoplankton response
Provedor de dados: 5
Autores: 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

Minéralisation de la matière organique et échanges ioniques à l'interface eau-sédiment de l'étang de Berre, Méditerranée
Provedor de dados: 5
Autores: Delmas, Daniel.
The étang de Berre, near Marseilles (France), is an inland brackish basin with a high primary rate of production. In 1966, the diversion of the Durance River introduced important hydrological changes. A study of organic matter mineralization and ionie exchanges at the water-sediment interface has made it possible to distinguish two areas, according to the composition of organic matter, mineralization mechanism and ionie transfers. In the North, the high rate of mineral sedimentation leads to a low content of organic matter in the sediment. This organic matter of detrital origin is little affected by mineralization; there is, however, high production of ammonium nitrogen, which is released to overlying waters. Nitrates and nitrites undergo denitrification...
Tipo: Text
Palavras-chave: Interface eau-sédiment; Matière organique; Eau interstitielle; Minèralisation; Milieu saumâtre; Water-sediment interface; Organic matter; Lnterstitial water; Mineralization; Brackish basin.
Ano: 1980
URL: http://archimer.ifremer.fr/doc/00122/23317/21142.pdf

Exoproteolytic activity determined by flow injection analysis: its potential importance for bacterial growth in coastal marine ponds
Provedor de dados: 5
Autores: Delmas, Daniel; Legrand, Catherine; Bechemin, Christian; Collinot, Cecile.
The measurement of the fluorescent 4-methyl-7-coumarinylamine released from the hydrolysis of a non-fluorescent peptide model substrate by exoproteolytic enzymes has been adapted to flow injection analysis (FIA). FIA allows samples to be processed very quickly (less than 2 min. for triplicate determinations) with good sensitivity (&lt; 0.1 muM) and reproducibility (relative standard deviation &lt; 3 % at the 0.2 muM level). In a coastal marine pond, exoproteolytic activity was closely related to bacterioplankton biomass. The high activity measured in pond water (maximum velocity: V(M) almost-equal-to 1.46 to 2.54 muM.h-1) emphasizes the importance of dissolved protein hydrolysis for bacterial growth and for dissolved organic nitrogen cycling. The mean...
Tipo: Text
Palavras-chave: Activité exoprotéolytique; Protéine dissoute; Analyse en flux continu; Bactérioplancton; Marais maritime; Flow injection analysis; Exoproteolytic activity; Dissolved protein; Bacterioplankton; Coastal marine pond.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/00196/30756/29163.pdf

Phytoplankton spring bloom of the Gironde plume waters in the Bay of Biscay: early phosphorus limitation and food-web consequences
Provedor de dados: 5
Autores: Herbland, Alain; Delmas, Daniel; Laborde, P; Sautour, B; Artigas, F.
During the spring 1995 (2-25 May), a cruise was carried on the RV Poseidon (Germany) on the continental shelf of the south Bay of Biscay. The objective was a comprehensive study of the planktonic food web within the Gironde plume waters. In these waters phosphate was present at very low concentrations (undetectable to &lt; 0.1 mu mol.L-1), whereas nitrate, silicate and ammonium concentrations were much higher (several mu mol.L-1 for nitrate and silicate and 0.5 to 1.0 mu mol.L-1 for ammonium). The size distribution of the phytoplankton biomass (estimated from chlorophyll a measurements by high performance liquid chromatography) and primary production (measured by C-14 in situ method) showed a great proportion of small (40 to 70 % &lt; 3 mu m) and active...
Tipo: Text
Palavras-chave: Phosphate; Phytoplancton; Facteur limitant; Estuaire; Eau côtière; Phosphate; Phytoplankton; Limiting factor; Estuarine water; Coastal water.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/1998/publication-850.pdf

High alkaline phosphatase activity in phosphate replete waters: The case of two macrotidal estuaries
Provedor de dados: 5
Autores: 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
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00337/44840/44428.pdf

Effect of P depletion on the functional pools of diatom carbohydrates, and their utilization by bacterial communities
Provedor de dados: 5
Autores: 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

Phytoplankton and bacterial alkaline phosphatase activities in relation to phosphate and DOP availability within the Gironde plume waters (Bay of Biscay)
Provedor de dados: 5
Autores: 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

Addressing the measurement of particulate organic and inorganic phosphorus in estuarine and coastal waters
Provedor de dados: 5
Autores: 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

In situ structuring of virioplankton through bacterial exoenzymatic activity: interaction with phytoplankton
Provedor de dados: 5
Autores: Ory, Pascaline; Palesse, S.; Delmas, Daniel; Montanie, Helene.
The abundance and composition of microbial communities were investigated during 2007 in Marennes Oleron Bay (France) in order to characterize the biological relationships governing the planktonic food web. Compared to the results of previous years, there was a lower abundance and a lower magnitude of variations in autotrophic and heterotrophic microbial entities in 2007. Using a Spearman rank correlation analysis, a significant link for biological abundance was only noted between bacteria and ciliates. However, an interesting relationship was highlighted between chlorophyll a and bacterial aminopeptidase and beta-glucosidase exoenzymatic activities. Two characteristic periods of virus-bacteria uncoupling were observed in spring and autumn 2007. Using...
Tipo: Text
Palavras-chave: Virus; Bacteria; Phytoplankton; Diversity; Aminopeptidase.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00050/16099/13571.pdf

Définition d’un indice composition pour le phytoplancton en Manche- Atlantique, à partir des données du micro-phytoplancton du REPHY et des réseaux régionaux, et des mesures complémentaires de la flore phytoplanctonique acquises avec des techniques novatrices. Action 3 – Livrable 1. Propositions pour un indice de composition du phytoplancton, basé sur les résultats des méthodes microscopie, pigments et diversité génétique. Rapport final, février 2016
Provedor de dados: 5
Autores: Hernandez Farinas, Tania; Brun, Melanie; Siano, Raffaele; Delmas, Daniel.
This deliverable is composed of two reports which propose indice of phytoplankton composition, based respectively on the results of pigment and genetic diversity methods, and the results of microscopy method. Proposals based on the results of pigment and genetic diversity methods. The present work is a continuation of several studies carried out in the past (Siano and Delmas, 2013, 2015) on investigating an indicator of phytoplankton diversity using two methods complementary to optical microscopy: the genetic diversity analyzed with metabarcoding (exhaustive analysis of the diversity and relative abundance of OTUs, i.e. groups of sequences identified by their genetic resemblance) and the pigmentary diversity (analysis of the diversity and abundance of...
Tipo: Text
Palavras-chave: Metabarcoding; OTUs; Pigments; Picophytoplancton; Indice composition; Niche ecologique; Mamiellophyceae; Chlorophylle b; Rade de Brest; Bretagne sud; Panache de la Gironde; Denombrements du micro-phytoplancton; Abondance totale; Monotonicite; Linearite; Pressions; Facade Manche-Atlantique; Metabarcoding; OTUs; Pigments; Picophytoplankton; Composition indice; Ecological niche; Mamiellophyceae; Chlorophyll b; Brest Bay; Southern Britain; Gironde plume; Micro-phytoplankton counts; Total abundance; Monotonicity; Linearity; Pressure; Channel-Atlantic coast.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00363/47421/47426.pdf

Hydro-plankton characteristics and their relationship with sardine and anchovy distributions on the French shelf of the Bay of Biscay
Provedor de dados: 5
Autores: Petitgas, Pierre; Masse, Jacques; Bourriau, Paul; Beillois, Pierre; Bergeron, Jean-pierre; Delmas, Daniel; Herbland, Alain; Koueta, Noussithe; Froidefond, Jean-marie; Santos, Maria.
The spatial pattern in hydro-plankton and fish distributions and their relationship were analysed based on the spring 2000 fisheries acoustic survey. The importance of this survey was that it was a multi-disciplinary platform which collected an extensive set of parameters in the hydro-plankton leading to a potentially finer description of hydro-plankton conditions and fish habitats. More than 50 variables were measured on a grid of stations, in four compartments of the ecosystem: hydrology, nutrients, primary producers and meso-zooplankton. First, a joint analysis of all hydro-plankton compartments was performed using multiple factor analysis (MFA). The method was used to estimate a compromise factorial space common to all compartments in which the...
Tipo: Text
Palavras-chave: Fish environment relationship; Hydro plankton; Habitats; Multiple factor analysis; Spatial pattern.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-3961.pdf

Selective liquid chromatographic determination of trace domoic acid in seawater and phytoplankton: improvement using the o-phthaldialdehyde/9-fluorenylmethylchloroformate derivatization
Provedor de dados: 5
Autores: Devez, Aurelie; Delmas, Daniel.
Domoic acid (DA), a toxin produced worldwide by some species of the genus Pseudo-nitzschia, is responsible for contamination of marine molluscs, mammals, birds, and for human intoxication, and when detected in high levels results in closures of shellfish farms, thus causing severe economic losses to aquaculture. Studies on algal production of DA in cultures and field samples require sensitive methods capable of measuring trace concentrations of domoic acid. Measuring domoic acid concentrations at trace levels is still a significant challenge. A sensitive and reliable double derivatization using o-phthaldialdehyde-mercaptoethanol/9-fluorenylmethylchloroformate (OPA-MeSH/FMOC-Cl) followed by high-performance liquid chromatography with fluorescence detection...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00151/26234/24438.pdf

Microbial interactions in marine water amended by eroded benthic biofilm: A case study from an intertidal mudflat
Provedor de dados: 5
Autores: Montanie, Helene; Ory, Pascaline; Orvain, Francis; Delmas, Daniel; Dupuy, Christine; Hartmann, Hans J.
In shallow macrotidal ecosystems with large intertidal mudflats, the sediment-water coupling plays a crucial role in structuring the pelagic microbial food web functioning, since inorganic and organic matter and microbial components (viruses and microbes) of the microphytobenthic biofilm can be suspended toward the water column. Two experimental bioassays were conducted in March and July 2008 to investigate the importance of biofilm input for the pelagic Microbial and Viral Loops. Pelagic inocula (&lt; 0.6 μ- and &lt; 10 μ filtrates) were diluted either with &lt; 30 kDa-ultrafiltered seawater or with this ultrafiltrate enriched with the respective size-fractionated benthic biofilm or with &lt; 30 kDa-benthic compounds (BC). The kinetics of heterotrophic...
Tipo: Text
Palavras-chave: Mudflats; Virus; Bacteria; HNF; Coastal water.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00166/27691/25883.pdf

Satellite-derived parameters for biological modelling in coastal waters: Illustration over the eastern continental shelf of the Bay of Biscay
Provedor de dados: 5
Autores: 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

Growth and phosphorus uptake by the toxic dinoflagellate Alexandrium catenella (dinophyceae) in response to phosphate limitation
Provedor de dados: 5
Autores: 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

Les glucides et l'évolution de la matière organique dans les sédiments marins
Provedor de dados: 5
Autores: Delmas, Daniel.
Carbohydrates have been analysed in arder to establish the state of organic matter in sediment. Samples were collected bath in neritic and oceanic (Orgon croises) areas. Reported data demonstrate that the insoluble-carbohydratesfsoluble-carbohydrates ratio (1/S) is a good indicator of organic matter evolution. In sediments, 1/S values ranging from 6 to 8 are associated with slightly-degraded organic matter, whereas values higher than 10 and eyen up to 30 relate to highly-degraded material. Furthermore, 1/S and CjN ratios generally show the same profile in sediments. The balance betweeh soluble (S) and insoluble (1) carbohydrates depends on the early stages of organic matter evolution, the soluble fraction being more easily degraded; such factors as...
Tipo: Text
Ano: 1983
URL: http://archimer.ifremer.fr/doc/00120/23143/20988.pdf