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Registros recuperados: 19
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A model of fluff layer erosion and subsequent bed erosion in the presence of the bioturbator, Hydrobia ulvae ArchiMer
Orvain, Francis; Le Hir, Pierre; Sauriau, Pierre-guy.
Previous studies have shown that the gastropod Hydrobia ulvae destabilizes the top layers of fine-grained sediments. This process is mediated by the formation of a "biogenic" fluff layer that includes tracks, faecal pellets and mucus. This fluff layer has been shown to be easily resuspended before general bed erosion. In order to examine how fluff layer and bed. erosion interact, flume experiments were performed with fluid sediments of varying water contents. Ten thousand snails were placed and allowed to crawl for 5 h on the sediment surface, and then the resuspended sediment mass was measured in response to step-wise shear stress increases. Two distinct erosion phases were observed: (1) initial resuspension of the fluff layer and (2) the subsequent bed...
Tipo: Text Palavras-chave: Gastropoda; Erosion sediment; Bioturbation; Cohesive sediment; Marine sediment.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/2003/publication-805.pdf
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A model of sediment transport under the influence of surface bioturbation: generalisation to the facultative suspension-feeder Scrobicularia plana ArchiMer
Orvain, Francis.
Flume experiments were designed to study how sediment erodibility was modified by the facultative suspension-feeder Scrobicularia plana living at different densities in sediment beds of various degrees of compaction. Two separate erosion phases were identified from the resuspension kinetics: (1) erosion of an unconsolidated surficial layer (i.e. fluff layer) and (2) the subsequent bed erosion. S. plana were found to influence both erosion phases: (1) erosion rates of the fluff layer were controlled by bioturbation activities, the extents of which were influenced by bivalve density and the degree of compaction of the sediments, and (2) critical thresholds of the subsequent bed erosion decreased as clam density increased, likely due to depressions in the...
Tipo: Text Palavras-chave: Resuspension; Model; Functional groups; Sediment transport; Bioturbation; Scrobicularia plana; Intertidal mudflat.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-3776.pdf
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Brachyuran crab community structure and associated sediment reworking activities in pioneer and young mangroves of French Guiana, South America ArchiMer
Aschenbroich, Adelaide; Michaud, Emma; Stieglitz, Thomas; Fromard, Francois; Gardel, Antoine; Tavares, Marcos; Thouzeau, Gerard.
This study in French Guiana evaluates the changes of crab assemblages and their bioturbation activities between mangrove early stages (pioneer and young mangrove) and within stages by taking their spatial heterogeneity (tidal channels, flat areas, pools) into account. The results show differences in crab assemblage structure between and within the early stages of mangrove in relation to microhabitat and sediment characteristics. The sediment reworking rates are a function of the biomass or density of particular species (Ucides cordatus, Uca cumulanta) and burrower functional groups. Crab species or functional interaction mediate changes in sediment reworking rates suggesting the need to consider entire benthic communities rather than single species. This...
Tipo: Text Palavras-chave: Mangroves; Crabs; Community composition; Bioturbation; French Guiana; Amazon.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00350/46154/45852.pdf
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Comportement du cadmium et du mercure lors de la diagenèse précoce et flux à l'interface eau-sédiments en zone littorale ArchiMer
Gonzalez, Jean-louis.
The early diagenesis of Cd and Hg has been studied in different coastal areas (vasière Ouest-Gironde, Pertuis d'Antioche, baie de Marennes-Oléron). For these two metals, the fluxes at the sediment-water interface have been calculated. Considering only molecular diffusion, the diffusionnal fluxes of Cd and Hg to the colurnn water are negligible with regard to both the particular fluxes to the sediments and the inputs of the "Gironde" and "Charente" ·,estuaries. The take into account of the different processes which affect the ex changes at the interface (erosion, bioturbation) permits more realistic an estimation of the role of sediments in the geochemical cycle of Cd and Hg. The results show that up to 50% of particular Cd and Hg which are integrated into...
Tipo: Text Palavras-chave: Cadmium; Mercure; Eaux intrstitielles; Diagenèse précoce; Flux; Interface eaux-sédiments; Bioturbation; Modélisation; Cadmium; Mercury; Pore waters; Early diagenesis; Fluxes; Sediment-water interface; Bioturbation; Modelling.
Ano: 1992 URL: http://archimer.ifremer.fr/doc/00442/55402/56920.pdf
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Dynamique et réponse fonctionnelle des foraminifères et de la macrofaune benthiques en zone ostréicole dans les pertuis charentais ArchiMer
Bouchet, Vincent.
In oyster farming areas, organic matter fluxes toward sediment is increased. Pacific oysters (Crassostrea gigas) reject organic-rich faeces and pseudofaeces as a result of filtration process. Organic matter can be consumed by benthic fauna, but in excess it can entails the reduction of benthic faunal species richness, abundance and biomass. Organic matter degradation also induces hypoxic (or anoxic) conditions in the sediment, and production of ammonia and sulfides in toxic concentrations. The main objective of this study is to assess the effects of oyster farming on benthic intertidal ecosystems in the Pertuis Charentais. Benthic macrofauna, living (stained) foraminifera, and physicochemical characteristics of the water column and sediment were used as...
Tipo: Text Palavras-chave: CAT scan; Bioturbation; Macrofauna/foraminifera interaction; Sensible species; Tolerant species; Benthic foraminifera; Benthic macrofauna; Chlorophyl a; Organic matter; Intertidal areas; Pertuis charentais; Oyster farming; CAT scan; Bioturbation; Interaction macrofaune/foraminifères; Espèces sensibles; Espèces tolérantes; Foraminifères benthiques; Macrofaune benthique; Chlorophylle a; Matière organique; Zone intertidale; Pertuis charentais; Ostréiculture.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/these-2582.pdf
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Efectos directos e indirectos de la bioturbación producida por el cangrejo cavador Chasmagnathus granulata en ambientes estuariales OceanDocs
Botto, F..
Universidad Nacional de Mar del Plata, Facultad de Ciencias Exactas y Naturales (Argentina)
Tipo: Theses and Dissertations Palavras-chave: Bioturbation; Sediment analysis; Sediment transport; Comparative studies; Detritus; Population number.
Ano: 2001 URL: http://hdl.handle.net/1834/2956
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Environmental and behavioural factors affecting activity in the intertidal gastropod Hydrobia ulvae ArchiMer
Orvain, Francis; Sauriau, Pierre-guy.
Laboratory microcosms were used to investigate the mud snail Hydrobia ulvac (Pennant) bioturbation activities and behavioural changes in response to snail density, algal food, sediment moisture content, light regime and water cover conditions. Density-dependent kinetics of bioturbated muddy areas were described by von Bertalanffy equations, which provided reliable estimates of mud surface covering rates by snail tracks (m(2) h(-1) snail(-1)), Snails need a wet habitat to be active either covered by seawater or by moving in fluid layers for low-tide conditions. Light and microphytobenthic biomass, which are less potent to affect snail activity, are positively interrelated to increase covering rates in the tested chl a concentrations within the range of 1 -...
Tipo: Text Palavras-chave: Modelling; Intertidal mudflat; Hydrobia ulvae; Environmental factors; Bioturbation; Behaviour.
Ano: 2002 URL: http://archimer.ifremer.fr/doc/2002/publication-3775.pdf
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Free-living nematodes affect oxygen turnover of artificial diatom biofilms ArchiMer
Mathieu, M; Leflaive, J; Ten Hage, L; De Wit, R; Buffan Dubau, E.
The aim of the present study was to examine the effects of biofilm-dwelling nematode activity on the oxygen turnover of cultured diatom biofilms. Oxygen microprofiles were simultaneously measured using the microelectrode technique in biofilms incubated with and without nematodes during short-term (24 h) and medium-term (6 d) experiments. During 24 h nycthemeral incubations, maximum oxygen concentrations and oxygen peak depths of microprofiles, as well as net oxygen production rates, were significantly higher in the diatom biofilms with nematodes. These effects might be dependent on the densities of nematodes. In the present study, significant effects were observed at nematode densities exceeding 100 ind. cm(-2), but not at a density <50 ind. cm(-2)....
Tipo: Text Palavras-chave: Bioturbation; Grazing; Net production rate; Oxygen community metabolism; Microelectrode; Oxygen microprofile; Nematodes; Diatom biofilms.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3607.pdf
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Interacting effects of Hydrobia ulvae bioturbation and microphytobenthos on the erodibility of mudflat sediments ArchiMer
Orvain, Francis; Sauriau, Pierre-guy; Sygut, A; Joassard, Lucette; Le Hir, Pierre.
Microphytobenthos-macrofauna sediment interactions and their effects on sediment erodability were examined in laboratory experiments. Sediment beds were manipulated in a tidal mesocosm to produce diatom mats in exponential or in stationary phases of development after 6, 8 or 11 d of culture. These sediment beds were used in flume experiments to investigate the influence of bioturbation by the gastropod Hydrobia ulvae on both sediment and pigment resuspension as a function of the physiological state of the microphytobenthic mats. In most experiments, only a surface layer was resuspended. A model was used to analyse in detail the contribution of each variable to this surface-layer erosion. Bioturbation was the major factor controlling resuspension, and its...
Tipo: Text Palavras-chave: Sediment; Bioturbation; Erosion; Model; Hydrobia ulvae; Physiological state; Microphytobenthos; Resuspension.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/2004/publication-3780.pdf
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Kinetics of tidal resuspension of microbiota: Testing the effects of sediment cohesiveness and bioturbation using flume experiments ArchiMer
Blanchard, Gérard F; Sauriau, Pg; Cariou-le Gall, Valerie; Gouleau, D; Garet, Mj; Olivier, F.
Resuspension of the top few sediment layers of tidal mud flats is known to enhance planktonic biomass of microbiota (benthic diatoms and bacteria). This process is mainly controlled by tidal shear stress and cohesiveness of mud, and is also influenced by bioturbation activities. Laboratory experiments in a race track flume were performed to test the interactive effects of these factors on both the critical entrainment and resuspension kinetics of microbiota from silt-clay sediments from the Marennes-Oleron Bay, France. The marine snail Hydrobia ulvae was used to mimic surface bioturbation activities. As expected, the kinetics of microbial resuspension versus shear stress were largely controlled by the cohesiveness of silt-clay sediments. However, our...
Tipo: Text Palavras-chave: Microphytobenthos; Bacteria; Resuspension; Bioturbation; Hydrobia ulvae; Shear velocity; Sediment cohesiveness; Flume experiment.
Ano: 1997 URL: http://archimer.ifremer.fr/doc/00337/44789/44480.pdf
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Manila clam Tapes philippinarum culture: Sediment-clam interactions ArchiMer
Goulletquer, Philippe; Robert, Rene; Trut, Gilles.
Manila clam (Tapes philippinarum) culture and sediment interactions were tested by comparing two rearing areas, including an oceanic ('Le-Ferret') and a more estuarine ('Les-Jacquets') sites in the bay of Arcachon (France). The growth of a calibrated clam population (10-mm spat) was monitored in these two areas with a concomitant sediment-water interface survey over a 1.5-year period. Two sites per area, including control and rearing plots, were sampled on a monthly basis. The potential clam farming impacts by bioturbation and interactions were examined at three sediment depths: 0-1, 1-2 and 2-10 cm. Moreover, the main hydrobiological parameters were measured on a weekly basis to establish a relationship between these parameters and sediment-water...
Tipo: Text Palavras-chave: Bay of Arcachon; Tapes philippinarum; Sediment water interface; Bioturbation; Clam culture; Bassin d'Arcachon; Tapes philippinarum; Interface eau sédiment; Bioturbation; Vénériculture.
Ano: 1999 URL: http://archimer.ifremer.fr/doc/1999/publication-864.pdf
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Modelling the effects of macrofauna on sediment transport and bed elevation: Application over a cross-shore mudflat profile and model validation ArchiMer
Orvain, Francis; Le Hir, Pierre; Sauriau, Pierre-guy; Lefebvre, Sebastien.
Tipo: Text Palavras-chave: Modelling; Sediment dynamics; Erodability; Bioturbation; Macrofauna; Biota; Sediment stability.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00079/19055/18610.pdf
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Nutrient fluxes on an intertidal mudflat in Marennes-Oleron Bay, and influence of the emersion period ArchiMer
Feuillet-girard, Michelle; Gouleau, Dominique; Blanchard, Gérard; Joassard, Lucette.
Fluxes of nutrients (NH sub(4) super(+), NO sub(3) super(-), PO sub(4) super(3-) and Si(OH) sub(4)) were studied on an intertidal mudflat in Marennes-Oleron Bay, France, at two different seasons and at different times of the emersion period. Fluxes through the sediment-water interface were both calculated from vertical profiles of nutrient concentration in pore-water (diffusive fluxes, JD) and measured in light and dark benthic mini-chambers (measured fluxes, J sub(0)). Results indicate that ammonia was mainly released in summer while nitrate was mainly taken up in late winter. This uptake from the overlying water was probably due to the coupling of nitrification-denitrification within the sediment. The J sub(0) /J sub(D) ratio further indicates that...
Tipo: Text Palavras-chave: Estran vaseux; Flux de nutriments; Microphytobenthos; Bioturbation; Marennes-Oléron; Intertidal mudflat; Nutrient fluxes; Microphytobenthos; Bioturbation; Marennes-Oleron Bay.
Ano: 1997 URL: http://archimer.ifremer.fr/doc/00038/14893/12220.pdf
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Polychaete tube walls as zonated microhabitats for marine bacteria. ArchiMer
Reichardt, W.
The predominantly anoxic, sulfide-rich sandy sediment of a shallow lagoon at Kiel Fjord was densely inhabited by the polychaete worm Nereis diversicolor (280 cm super(3) m super(-2) of biomass volume). Burrow walls which contrasted by their brown coloration of at least 1.5 mm thickness with the bulk of the reduced black sediment, made up for 6% of the total volume of the 10 cm cores investigated. Only the uppermost mm of the internal surface layer contained detectable O sub(2). As a result of the build up of internal redox gradients, CO sub(2) dark fixation was activated in the burrow walls (by a factor of approximately equals 2). Assays of ribulose-biphosphate carboxylase activities and viable counts of potentially chemoautotrophic bacteria in different...
Tipo: Text Palavras-chave: Nereis diversicolor; Polychaeta; Bacteria; Microorganisms; Carbon cycle; Tube dwellers; Carbon fixation; Burrows; Bioturbation; Sediments.
Ano: 1984 URL: http://archimer.ifremer.fr/doc/1984/acte-990.pdf
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Response of phytoplankton to organic enrichment and shrimp activity in tropical aquaculture ponds: a mesocosm study ArchiMer
Lemonnier, Hugues; Hochard, Sebastien; Nakagawa, Kento; Courties, Claude; Rodier, Martine.
We conducted a mesocosm study to investigate the combined effect of organic enrichment and sediment resuspension by shrimp on phytoplankton communities in shrimp aquaculture ponds. Hence, the factorial design included two factors, i.e., (i) shrimp density with a concomitant increase of feed input resulting in organic enrichment and (ii) with/without access of shrimp to the sediments. Increasing feed input in the system raised the eutrophication state of the environment characterized by an increase in phytoplankton biomass. Bioturbation enhanced (i) mineralization of organic matter via the microbial loop, resulting in faster nutrient recycling, (ii) an increase of primary production, and (iii) buffering capacity against eutrophication consequences. The...
Tipo: Text Palavras-chave: Aquaculture; Litopenaeus stylirostris; Phytoplankton communities; Eutrophication; Bioturbation.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00392/50364/51066.pdf
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Spatio-temporal variations in intertidal mudflat erodability: Marennes-Oleron Bay, western France ArchiMer
Orvain, Francis; Sauriau, Pierre-guy; Le Hir, Pierre; Guillou, Gael; Cann, Philippe; Paillard, Michel.
A portable erosion device (ERIS) was deployed in November 2000 and May 2001 to investigate the spatio-temporal variation of fine-grained sediment erosion over a transect on the intertidal mudflats of Marennes-Oleron Bay, western France. The objective was to relate changes in bed erodability over diurnal emersion periods to bioturbation, rapid changes in sediment characteristics, and microphytobenthos biomass. Macrofaunal assemblages were dominated by the bivalve, Scrobicularia plana, on the upper mudflat, and by the gastropod, Hydrobia ulvae. on the middle mudflat. A power relationship was obtained where tau(cr) was plotted as a function of sediment density. Results from the upper part of the mudflat deviated from this relationship due to bioturbation by...
Tipo: Text Palavras-chave: EPS; Microphytobenthos; Erodability; Intertidal mudflat; Sediment; Scrobicularia plana; Hydrobia ulvae; Bioturbation; Resuspension; Eris.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3779.pdf
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Temporal variability of benthic-pelagic coupling in shallow enclosed environment: A case study with eutrophying shrimp ponds ArchiMer
Hochard, Sébastien; Royer, Florence; Hubert, Morgane; Lemonnier, Hugues.
The evolution of benthic pelagic coupling was followed in two semi-intensive shrimp ponds in New Caledonia, with a special emphasis on the role of microphytobenthos (MPB). Three distinct periods could be identified. During the first period, MPB activity led to relative decoupling between the water column and the sediment, both compartments being autotrophic with low nutrients exchanges. During the second period, the sediment operated at the edge of a functional switch between autotrophy and heterotrophy. The amplitude of nutrient fluxes depended of the pool considered (DIN, DIP) and showed light dark variation. In the last period, sediment switched to heterotrophy with the establishment of benthic-pelagic coupling concomitantly to a massive sediment...
Tipo: Text Palavras-chave: Tropical aquaculture; Shrimp; Eutrophication; Benthic-pelagic coupling; Microphytobenthos; Bioturbation.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00485/59681/62754.pdf
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The influence of sediment cohesiveness on bioturbation effects due to Hydrobia ulvae on the initial erosion of intertidal sediments: A study combining flume and model approaches ArchiMer
Orvain, F; Sauriau, Pierre-guy; Bacher, Cedric; Prineau, Michel.
Laboratory experiments performed in a recirculating flume were designed to quantify the bioturbation influence of the mud snail Hydrobia ulvae, one of the most abundant deposit feeders on European intertidal mudflats. Variations in sediment moisture content that occur between bedforms in shore-normal, ridge and runnel systems of intertidal mudflats were added to the model definition. Sediment erosion thresholds, erosion rates and the microalgal pigment composition of resuspended material were quantified for different H. ulvae densities (0, 1000, 5000, 10 000 and 50 000 snails m(-2)) and applied bed shear stresses. Two different sediment moisture contents were tested. In the absence of macrofauna, recorded turbidities increased up to the maximum applied...
Tipo: Text Palavras-chave: Model; Flume; Chloropigments; Ridges and tunnels; Mudflat; Sediment; Hydrobia ulvae; Bioturbation; Resuspension.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3774.pdf
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Transformation de la phase solide à travers l’estuaire de la Loire en relation avec son environnement chimique et biologique ArchiMer
Thibault De Chanvalon, Aubin.
Before reaching the ocean, riverine particles from the Loire watershed undergo important chemical transformations in the estuary. This study aims to identify and characterize main processes involving iron (and to a lesser extent Al, Mn, PO4 3- and rare earths elements). Suspended particulate matter data show that 15% of their iron is lost through the estuary. Reductive iron dissolution during deposition periods is likely to explain most of this loss. However, estuarine sediments are characterized by high spatial heterogeneity due to macrofaunal activities. To overcome this difficulty, new methodologies of high resolution and two-dimensional analyses and calculation of pore water, sediment and benthic meiofauna were developed. These developments enable to...
Tipo: Text Palavras-chave: Estuaire; Fer; Phosphore; Nitrate; Foraminifère benthique; Diagenèse précoce; Loire; Bioturbation; Estuary; Iron; Phosphorus; Nitrate; Benthic foraminifera; Precocious diagenesis; Loire; Bioturbation.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00498/60932/64325.pdf
Registros recuperados: 19
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