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Auteur Auguet, J.C.; Montanie, H.; Delmas, D.; Hartmann, H.J.; Huet, V.
Titre Dynamic of virioplankton abundance and its environmental control in the Charente estuary (France) Type Article scientifique
Année 2005 Publication (up) Revue Abrégée Microb Ecol
Volume 50 Numéro 3 Pages 337-349
Mots-Clés Bacteria/isolation & purification Ecosystem *Environment; Controlled France Plankton/*isolation & purification Rivers/chemistry/*microbiology Seasons Viruses/*isolation & purification Water Microbiology
Résumé The Charente River provides nutrient- and virus-rich freshwater input to the Marennes Oleron Basin, the largest oyster-producing region in Europe. To evaluate virioplankton distribution in the Charente Estuary and identify which environmental variables control dynamic of virioplankton abundance, five stations defined by a salinity gradient (0-0.5, 0.6-5, 13-17, 20-24, and higher than 30 PSU) were surveyed over a year. Viral abundance was related to bacterioplankton abundance and activities, photosynthetic pigments, nutrient concentration, and physical parameters (temperature and salinity). On a spatial scale, virus displayed a decreasing pattern seaward with abundance ranging over the sampling period from 1.4x10(7) to 20.8x10(7) viruses mL-1 making virioplankton the most abundant component of planktonic microorganisms in the Charente Estuary. A good correlation was found between viral and bacterial abundance (rs=0.85). Furthermore, bacterial abundance was the most important predictor of viral abundance explaining alone between 66% (winter) and 76% (summer) of viral variability. However, no relation existed between viral abundance and chlorophyll a. Temporal variations in viral distributions were mainly controlled by temperature through the control of bacterial dynamics. Spatial variations of viral abundance were influenced by hydrodynamic conditions especially during the winter season where virioplankton distribution was entirely driven by mixing processes.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1296
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Auteur Auguet, J.C.; Montanie, H.; Lebaron, P.
Titre Structure of virioplankton in the Charente Estuary (France): transmission electron microscopy versus pulsed field gel electrophoresis Type Article scientifique
Année 2006 Publication (up) Revue Abrégée Microb Ecol
Volume 51 Numéro 2 Pages 197-208
Mots-Clés Capsid/chemistry *Electrophoresis; Electron Plankton Rivers/*virology Seasons Seawater/*microbiology/*virology Viruses/genetics/*isolation & purification/ultrastructure *Water Microbiology; Gel; Pulsed-Field Environmental Monitoring/methods France Genome; Viral/genetics *Microscopy
Résumé Changes in the composition of viral communities were investigated along a salinity gradient and at different times by means of transmission electron microscopy (TEM) and pulsed field gel electrophoresis (PFGE). Samples were collected in fresh (Charente River), estuarine (Charente Estuary), and coastal (Pertuis d'Antioche, French Atlantic coast) waters. Both methods revealed similar patterns in viral community structure with a dominance of small viral particles (capsid and genome size). Viruses with a head size below 65 nm made up 71 +/- 5% of total virus-like particles, and virus-like genomes (VLG) below 100 kb accounted for 89 +/- 9% of total VLG. Despite this apparent stability of virioplankton composition over spatial scale (salinity gradient), the occurrence of large viruses (capsid and genome size) in estuarine and seawater samples indicated the presence of viral populations specific to a geographical location. Temporal changes in the structure (capsid and genome size) of viral communities were more pronounced than those reported at the spatial scale. From January to May 2003, seasonal changes in viral abundance and bacterial production occurred concomitantly with an increase in viral genomic diversity (richness), suggesting that virioplankton composition was strongly linked to changes in microbial activity and/or in the structure of the host communities. Although PFGE and TEM yielded complementary results in the description of virioplankton structures, it seems that the use of PFGE alone should be enough for the monitoring of community changes.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1297
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Auteur Diaz, F.; Bănaru, D.; Verley, P.; Shin, Y.-J.
Titre Implementation of an end-to-end model of the Gulf of Lions ecosystem (NW Mediterranean Sea). II. Investigating the effects of high trophic levels on nutrients and plankton dynamics and associated feedbacks Type Article scientifique
Année 2019 Publication (up) Revue Abrégée Ecological Modelling
Volume 405 Numéro Pages 51-68
Mots-Clés End-to-end model; Fisheries; Food web functioning; Plankton; Two-ways coupling
Résumé The end-to-end OSMOSE-GoL model parameterized, calibrated and evaluated for the Gulf of Lions ecosystem (Northwestern Mediterranean Sea) has been used to investigate the effects of introducing two-ways coupling between the dynamics of Low and High Trophic Level groups. The use of a fully dynamic two-ways coupling between the models of Low and High Trophic Levels organisms provided some insights in the functioning of the food web in the Gulf of Lions. On the whole microphytoplankton and mesozooplankton were found to be preyed upon by High Trophic Levels planktivorous groups at rates lower than 20% and 30% of their respective natural mortality rates, but these relatively low rates involved some important alterations in the infra-seasonal and annual cycles of both High and Low Trophic Levels groups. They induced significant changes in biomass, fisheries landings and food web interactions by cascading effects. Spatial differential impacts of High Trophic Levels predation on plankton are less clear except in areas in which primary productivity is high. Higher predation rates on plankton groups were encountered within the area of the Rhone river’s influence and in areas associated to the presence of mesoscale eddies in the Northwestern part of the Gulf of Lions, especially. Generally, the pressure of the High Trophic Levels predation was the highest in areas of highest biomass whatever the plankton group considered. The two-ways coupling between Low and High Trophic Levels models revealed both bottom-up and top-down controls in the ecosystem with effects on planktivorous species similar to those observed in the field. The use of the end-to-end model enabled to propose a set of potential mechanisms that may explain the observed decrease in small pelagic catches by the French Mediterranean artisanal fisheries over the last decade.
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ISSN 0304-3800 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2577
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Auteur Delpy, F.; Albouy-Boyer, S.; Pagano, M.; Thibault, D.; Blanchot, J.; Guilhaumon, F.; Molinero, J.C.; Bonnet, D.
Titre Identifying the drivers of abundance and size of the invasive ctenophore Mnemiopsis leidyi in Northwestern Mediterranean lagoons Type Article scientifique
Année 2016 Publication (up) Revue Abrégée Marine Environmental Research
Volume 119 Numéro Pages 114-125
Mots-Clés Blooms; Driving factors; Gelatinous plankton; Invasive species; Mediterranean lagoons; Mnemiopsis leidyi
Résumé Acknowledged as among the worst invasive marine species, Mnemiopsis leidyi has spread through European Seas since the mid-1980’s. Here we report a bimonthly survey conducted in 2010–11 in three lagoons (Bages-Sigean, Thau and Berre) and at two adjacent coastal stations (Sète and SOMLIT-Marseille) along the French Mediterranean coast. M. leidyi was present only in Berre and Bages-Sigean with maximum abundances observed in late summer. M. leidyi adults were present year round in Berre with the largest organisms (∼6 cm) observed in April. In Bages-Sigean, they occurred in sufficient abundance to be recorded by fishermen between August and November. Multiple linear regressions highlighted that abundance in both lagoons was mainly influenced by direct effects of salinity and chlorophyll-a, and temperature to a lesser extent. While M. leidyi has not yet been recorded in Thau, the lagoon is continually monitored to detect the potential establishment of M. leidyi.
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ISSN 0141-1136 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1554
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Auteur Larras, F.; Rimet, F.; Gregorio, V.; Bérard, A.; Leboulanger, C.; Montuelle, B.; Bouchez, A.
Titre Pollution-induced community tolerance (PICT) as a tool for monitoring Lake Geneva long-term in situ ecotoxic restoration from herbicide contamination Type Article scientifique
Année 2016 Publication (up) Revue Abrégée Environ Sci Pollut Res
Volume 23 Numéro 5 Pages 4301-4311
Mots-Clés Atmospheric Protection/Air Quality Control/Air Pollution; Atrazine; Copper; Ecotoxicology; Environmental Chemistry; Environmental Health; Environment, general; Phytoplankton; Pollution-induced community tolerance (PICT); Restoration; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution
Résumé Chemical monitoring revealed a regular decrease in herbicide concentration in Lake Geneva since last decades that may be linked to an ecotoxic restoration of nontarget phytoplanktonic communities. The Pollution-induced community tolerance (PICT) approach was tested as a tool to monitor the ecotoxic restoration of Lake Geneva for herbicides from 1999 to 2011. We conducted monthly assessments in 1999 and in 2011 for the tolerance of the phytoplankton communities to two herbicides (atrazine and copper), using PICT bioassays. The taxonomical composition of the communities was determined on the same collecting dates. The herbicide concentration decrease during the 12 years significantly influenced the composition of communities. The PICT monitoring indicated that a significant tolerance decrease in the community to both herbicides accompanied the herbicide concentration decrease. PICT measurements for atrazine and copper also changed at the intra-annual level. These variations were mainly due to community composition shifts linked to seasonal phosphorus and temperature changes. PICT monitoring on a seasonal basis is required to monitor the mean tolerance of communities. PICT appeared to be a powerful tool that reflected the toxic effects on environmental communities and to monitor ecotoxic ecosystem restoration.
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ISSN 0944-1344, 1614-7499 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1557
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