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| Registros recuperados: 11 | |
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| Guarini, Jean-marc; Blanchard, Gerard; Bacher, Cedric; Gros, Philippe; Riera, Pascal; Richard, Pierre; Gouleau, Dominique; Galois, Robert; Prou, Jean; Sauriau, Pierre-guy. |
| Microphytobenthos plays an important role as primary producer in shallow embayments subject to a tidal regime. The present paper aims to characterize the spatial patterns of sedimentary chlorophyll a (chl a) biomass in 2 seasons in the wide intertidal mudflats of the Marennes-Oleron Bay (France); furthermore, it provides estimates of total microphytobenthic biomass. Accordingly, a systematic sampling scheme was performed in June 1995 and in January 1996. On average, biomass was higher in June (ca 120 mg chl a m-2) than in January (ca 85 mg chl a m-2). Moreover, the geostatistical analysis revealed that spatial similarities were propagated over larger distances in June (6 km) than in January (2.2 km). In order to account for this result , we suggest that... |
| Tipo: Text |
Palavras-chave: Marennes Oleron; Intertidal mudflat; Geostatistics; Spatial distribution; Chrlorophyll a; Microphytobenthos. |
| Ano: 1998 |
URL: https://archimer.ifremer.fr/doc/1998/publication-3820.pdf |
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| Legrand, Helene; Herlory, Olivier; Guarini, Jean-marc; Blanchard, Gerard; Richard, Pierre. |
| Atrazine and diuron are two herbicides present in sediments of the intertidal mudflats in the Pertuis Charentais (Atlantic coast, France). They may negatively affect photosynthesis processes in microphytobenthos, the most productive primary producer in these environments. The impact of these herbicides on benthic diatoms was investigated using PAM fluorimetry on natural microalgal communities, once extracted from sediment, by following the variations of the effective quantum yield of PSII (Phi(PSII)) during exposure to atrazine and diuron concentrations in a range 0.1 mu g L-1 (.) 10 mg L-1. No significant effect was noticed for 0.1 mu g L-1 concentrations, but progressive reduction in photosynthetic efficiency, always occurring within 15 min, was... |
| Tipo: Text |
Palavras-chave: Diuron; Atrazine; PAM; Chlorophyll fluorescence; Microphytobenthos. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-3614.pdf |
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| Herlory, Olivier; Richard, Pierre; Blanchard, Gerard. |
| The light response curve methodology for microphytobenthic biofilms was studied by comparing the two most usual approaches used in pulse amplitude modulated (PAM) fluorometry. The non-sequential light curve (N-SLC) method is characterized by independent measures of the photosynthetic activity across a light gradient whereas the rapid light curve (RLC) method consists of successive measures on the same sample exposed to a stepwise increase of light intensities. Experiments were carried out on experimental microphytobenthic biofilms prepared from natural assemblages and acclimated to dark conditions. In preliminary experiments, N-SLCs were constructed from fluorescence induction curves performed at 12 different photon flux densities (PFDs). A minimum of 50 s... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3331.pdf |
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| Herlory, Olivier; Guarini, Jean-marc; Richard, Pierre; Blanchard, Gerard. |
| The spatio-temporal dynamics of the microphytobenthic biofilm was analysed at microscale over a complete day-time emersion period in an intertidal mudflat. The structures of the biofilm were monitored by analysing the variability of the epipelic diatom cover in the horizontal dimension and the kinetics of biomass dispersion in the vertical dimension. Colonisation of the sediment surface by diatoms was rapid (within 15 min); 75% of the biomass contained in the top 1 mm was concentrated in the upper 200 mum, but the cover never reached 100%. This biomass had a higher chlorophyll a/pheopigment ratio than deeper in the sediment, suggesting a better physiological state and a higher photosynthetic potential. The dynamics of the biomass in the upper 200 mum... |
| Tipo: Text |
Palavras-chave: Microphytobenthos; Biofilm; Intertidal mudflat; Spatio temporal dynamics; Microscale. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/00000/10905/7580.pdf |
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| Richard, Pierre; Blanchard, Gerard; Goulletquer, Philippe. |
| The trophic resources of cultivated mussel have! been characterized and their contribution to the food of these molluscs estimated in the Bay of Aiguillon (France) through the analysis of their natural C and N isotope composition. The contribution of terrestrial organic matter (δ(13)C = -27 to -34 %0) to mussel food resources is around 10% along the year, except in winter (15 10 30 %). A large seasonal variation is observed in the utilization of oceanic phytoplanktoll (δ(13)C = -19 to -21.5 %0) and of littoral benthic productions (microphytobenthos and phanerogame detritus,δ(13)C = -12.0 to -16.7 %0). Overall, the main food source of mussels is formed by benthic productions for molluscs grown on poles, in peculiar in the South of... |
| Tipo: Text |
Palavras-chave: Détritus; Production primaire; Isotope stable; Source trophique; Moule. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-2774.pdf |
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| Cariou-le Gall, Valerie; Blanchard, Gerard. |
| Chloropigments and carotenoids were measured by HPLC in an intertidal muddy sediment of Marennes-Oleron Bay (France). Concentrations were determined as a function of sediment depth at low tide. The analyses were carried out at monthly intervals over 1 yr. Pigment analysis indicated that the microphytobenthic community was dominated by diatoms throughout the sampling year. Chlorophyll b was not encountered at any time or depth, indicating that no input from macrophytic detritus had occurred at the sampling site. There was a large pool of phaeopigments a, of which phaeophorbides were the major forms (75%). A microphytobenthic bloom occurred between March and June during which phaeopigments significantly increased with a high proportion of phaeophorbides... |
| Tipo: Text |
Palavras-chave: Pigment; HPLC; Intertidal mudflat; Microphytobenthos; Seasonal change. |
| Ano: 1995 |
URL: http://archimer.ifremer.fr/doc/00257/36844/36666.pdf |
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| Blanchard, Gerard. |
| Microscale dispersion patterns of meiofauna and microphytobenthos from an oyster pond on the French Atlantic coast were studied through spatial autocorrelation analysis during 2 successive spring periods. Patch size was calculated using correlograms. Both microalgae genera and meiobenthos taxa (except turbellarians in May 1987 and single groups of harpacticoid copepods in April 1988) exhibited patchy distributions. Meiofauna patches ranged from < 4 to 154 cm2, large diatom (> 40 .mu.m) patches from < 4 to 113 cm2 and smaller cell (< 40 .mu.m) patches from < 4 to 79 cm2. High variability in patch size was observed between taxa or genera, between years, and a second aggregation level (small patches within large clumps) was shown by... |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00178/28893/27747.pdf |
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| Blanchard, Gerard; Simon Bouhet, B; Guarini, J. |
| The short-term variability of intertidal microphytobenthic biomass was characterized by analysing a 30-day time series encompassing two spring-neap tide cycles. Chlorophyll-a concentration was measured every day at the beginning and at the end of every diurnal exposure periods. Microalgal biomass exhibited predictible net increases during diurnal exposures due to a positive production-loss balance. In addition, our data series shows that after an environmental disturbance, even though biomass decreased strongly, it converged quickly back to its initial steady-state oscillation pattern. This study supports some fundamental properties of the dynamics of microphytobenthic biomass, as previously predicted in our mathematical model of primary production. |
| Tipo: Text |
Palavras-chave: Diurnal variation; Chlorophyll concentration; Microphytobenthic biomass. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-599.pdf |
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| Bacher, Cedric; Blanchard, Gerard; Bougrier, Serge; Cariou-le Gall, Valerie; Delmas, D.; Deslous Paoli, Jean-marc; Dinet, A.; Garet, Marie-josee; Geairon, Philippe; Jonquieres, Gerard; Laisne, A.; Maffei, E.; Montagna, P. A.; De Montaudouin, Xavier; Morin, S.; Richard, P.; Riera, Pascal; Sauriau, Pierre-guy; Vrignaud, N.. |
| Les cartographies annuelles des biomasses microphytobenthiques ont été réalisées pour le bassin de Marennes-Oléron. Parallèlement les cartographies des caractéristiques sédimentaires ont été établies simultanément aux cartes d'abondance et biomasse macrofauniques en portant un effort particulier sur les densités des compétiteurs des huîtres notamment les Crépidules. Simultanément les études des mécanismes contrôlant le réseau trophique sur la vasière de Brouage ont été poursuivies notamment les relations entre les flux de sels nutritifs et le microphytobenthos. L'importance de ce dernier compartiment dans la nutrition de l'huître a été clairement mis en évidence par l'utilisation des traçeurs isotopiques naturels. Enfin, les caractéristiques de filtration... |
| Tipo: Text |
Palavras-chave: Bassin de Marennes Oléron; Microphytobenthos; Physiologie; Crassostrea gigas; Crépidules; Modèle réseau trophique; Cartographie; Charente-Maritime. |
| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00102/21294/18911.pdf |
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| Haubois, Anne-gaelle; Guarini, Jean-marc; Richard, Pierre; Blanchard, Gerard; Sauriau, Pierre-guy. |
| Spatio-temporal changes in density, breeding cycle, growth and population structure of Hydrobia ulvae (Gastropoda: Prosobranchia) were studied by monthly sampling of a wide bare mudflat in Marennes-Oleron Bay. Four stations, located along a cross-shore transect and characterized by different geomorphological structures, were investigated from March 2000 to February 2001. Hydrobia ulvae was mainly distributed in the upper half part of the mudflat and no individuals were found in the lower part. The breeding cycle extended from March to December and showed two annual peaks, in spring and in autumn. Three cohorts were recruited during the year and showed high growth rates during summer; the parameters of the von Bertalanffy model describing the growth curves... |
| Tipo: Text |
Palavras-chave: Gastropoda; Mudflat; Spatio temporal change; Population dynamic. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-598.pdf |
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| Registros recuperados: 11 | |
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