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| Pascal, P.y.; Dupuy, C; Mallet, C; Richard, P; Niquil, N. |
| The fate of benthic bacterial biomass in benthic food webs is a topic of major importance but poorly described. This paper describes an alternative method for evaluation of bacterial grazing rate by meiofauna and macrofauna using bacteria pre-enriched with stable isotopes. Natural bacteria from the sediment of an intertidal mudflat were cultured in a liquid medium enriched with 15NH4Cl. Cultured bacteria contained 2.9% of 15N and were enriched sufficiently to be used as tracers during grazing experiments. Cultured bacteria presented a biovolume (0.21 μm3) and a percentage of actively respiring bacteria (10%) similar to those found in natural communities. The number of Operational Taxon Units found in cultures fluctuated between 56 and 75% of that... |
| Tipo: Text |
Palavras-chave: Tracer; Stable isotope; Sediment; Grazing; Bacteria. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4296.pdf |
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| Pascal, P.y.; Dupuy, C; Richard, P; Niquil, N. |
| The majority of sediment dweller foraminifera are deposit feeders. They use their pseudopodia to gather sediment with associated algae, organic detritus and bacteria. Uptake of bacteria by foraminifera have been observed but rarely quantified. We measured uptake of bacteria by the common foraminifera Ammonia tepida using 15N pre-enriched bacteria as tracers. In intertidal flats, seasonal, tidal and circadian cycles induce strong variations in environmental parameters. Grazing experiments were performed in order to measure effects of abiotic (temperature, salinity and irradiance) and biotic (bacterial and algal abundances) factors on uptake rates of bacteria. In mean conditions, A. tepida grazed 78 pgC ind-1 h-1 during the first eight hours of incubation,... |
| Tipo: Text |
Palavras-chave: Trophoecology; Prey abundance; Mudflat; Grazing; Foraminifera; Environmental factor; Bacteria. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4298.pdf |
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| Pascal, Pierre-yves; Dupuy, C; Richard, P; Haubois, A.g.; Niquil, N. |
| Deposit feeders are able to process a considerable volume of sediment, containing large quantities of associated bacteria. However, conclusions concerning the trophic role played by benthic bacteria in marine sediments are still not fully elucidated. This study deals with bacterivory by the gastropod Hydrobia ulvae, one of the most abundant deposit-feeding species in intertidal mudflats in Western Europe. Ingestion rates of bacteria were determined during grazing experiments using 15N preenriched bacteria. Grazing experiments were performed in order to measure effects of abiotic (temperature, salinity and luminosity) and biotic (bacterial and algal abundances) factors on ingestion rates of bacteria by H. ulvae of an intertidal mudflat (Brouage,... |
| Tipo: Text |
Palavras-chave: Mudflat; Nematodes; Ammonia tepida; Environmental factors; Grazing; Bacteria; Gastropod; Hydrobia ulvae; Deposit feeding. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4781.pdf |
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| Leguerrier, D; Degre, Delphine; Niquil, N. |
| Network analysis was used to analyse steady-state models of the food webs of two intertidat mudflat ecosystems: Aiguillon Cove and Brouage Mudflat, on the South-Western Atlantic Coast of France. The aim was to highlight emergent properties of food-web functioning in these two ecosystems and to compare these properties with other coastal ecosystems. Both ecosystems imported detritus in parallel to a high benthic primary production. They were characterised by a high diversity of resources. Both also exported living material, leading to a high quality production, quantified as export of Exergy. This export was mainly composed of cultivated bivalves during the cold season for Brouage Mudflat, and of the migration of grazing fish in Aiguillon Cove during the... |
| Tipo: Text |
Palavras-chave: Atlantic coast; Intertidal mudflat; Network analysis; Inverse analysis; Ecosystem comparison; Food web. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3696.pdf |
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| Hlaili, A; Grami, B; Niquil, N; Gosselin, M; Hamel, D; Troussellier, Marc; Mabrouk, H. |
| The structure and the trophic interactions of the planktonic food web were investigated during summer 2004 in a coastal lagoon of southwestern Mediterranean Sea. Biomasses of planktonic components as well as bacterial and phytoplankton production and grazing by microzooplankton were quantified at four stations (MA, MB, MJ and R) inside the lagoon. Station MA was impacted by urban discharge, station MB was influenced by industrial activity, station MJ was located in a shellfish farming sector, while station R represented the lagoon central area. Biomasses and production rates of bacteria (7-33 mg C m(-3); 17.5-35 mg C m(-3) d(-1)) and phytoplankton (80-299 mg C m(-3); 34-210 mg C m(-3) d(-1)) showed high values at station MJ, where substantial... |
| Tipo: Text |
Palavras-chave: Anthropogenic pressure; Spatial distribution; Planktonic food web; Mediterranean lagoon. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4116.pdf |
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