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Auteur Meddeb, M.; Niquil, N.; Grami, B.; Mejri, K.; Haraldsson, M.; Chaalali, A.; Pringault, O.; Hlaili, A.S.
Titre (up) A new type of plankton food web functioning in coastal waters revealed by coupling Monte Carlo Markov chain linear inverse method and ecological network analysis Type Article scientifique
Année 2019 Publication Revue Abrégée Ecol. Indic.
Volume 104 Numéro Pages 67-85
Mots-Clés Bacterial multivorous food web; biogenic carbon; Coastal waters; continental-shelf; Ecology; ecosystem attributes; flow networks; Food web modeling; grazing impact; gulf; mediterranean sea; model analysis; Network analysis; Seasonal variations; seasonal-dynamics; trophic network; Trophic structure
Résumé Plankton food webs (PFW) typology is based on different categories of functioning, according to the dominant processes and the role played by heterotrophic bacteria, small vs large phytoplankton, and small vs large zooplankton. Investigating the structure and the function of planktonic food webs in two SW Mediterranean waters (inshore and marine sites) at four seasons, using inverse (LIM-MCMC) and ecological network (ENA) analyses, we identified a new type of food web, called the “bacterial multivorous food web”. This food web adds to the conventional trophic continuum as previously reported. The “bacterial multivorous food web” present in winter showed the lowest primary production among seasons, but highest bacterial production. Several food web ratios characterized this new typology e.g. picophytoplankton net primary production to total primary production varied from 0.20 to 0.28; bacterial to primary production ratio is higher than values reported in global scale (congruent to 1); bacterial net production to the potential protozoan prey net production was high (>0.2). In this special food web, carbon was mostly recycled, with a moderate fraction channeled to deep waters, which lead to a higher retention of carbon inside the ecosystem. This winter PFW also seemed to be the most organized, specialized, stable and mature, as related to common interpretations of ENA. The spring was characterized by herbivorous food web, with highest activity coinciding with low stability. Although less usual, the herbivorous pathway was also observed during summer, in inshore waters. The autumn food webs, which functioned as multivorous or microbial food webs, appeared to be stable and mature. Finally, our study demonstrates the usefulness of food web models derived ratios combined with ecological network analysis indices to conduct evaluation of the structure and functioning of ecosystems and potentially to support management decisions in marine environment.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1470-160x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2596
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Auteur Galand, P.E.; Pereira, O.; Hochart, C.; Auguet, J-C.; Debroas, D.
Titre (up) A strong link between marine microbial community composition and function challenges the idea of functional redundancy Type Article scientifique
Année 2018 Publication Revue Abrégée Isme J.
Volume 12 Numéro 10 Pages 2470-2478
Mots-Clés biosphere; cell; depth; diversity; dynamics; gene; program; sequencing data; short read alignment; waters
Résumé Marine microbes have tremendous diversity, but a fundamental question remains unanswered: why are there so many microbial species in the sea? The idea of functional redundancy for microbial communities has long been assumed, so that the high level of richness is often explained by the presence of different taxa that are able to conduct the exact same set of metabolic processes and that can readily replace each other. Here, we refute the hypothesis of functional redundancy for marine microbial communities by showing that a shift in the community composition altered the overall functional attributes of communities across different temporal and spatial scales. Our metagenomic monitoring of a coastal northwestern Mediterranean site also revealed that diverse microbial communities harbor a high diversity of potential proteins. Working with all information given by the metagenomes (all reads) rather than relying only on known genes (annotated orthologous genes) was essential for revealing the similarity between taxonomic and functional community compositions. Our finding does not exclude the possibility for a partial redundancy where organisms that share some specific function can coexist when they differ in other ecological requirements. It demonstrates, however, that marine microbial diversity reflects a tremendous diversity of microbial metabolism and highlights the genetic potential yet to be discovered in an ocean of microbes.
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Volume de collection Numéro de collection Edition
ISSN 1751-7362 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2435
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Auteur Basset, A.; Barbone, E.; Elliott, M.; Li, B.-L.; Jorgensen, S.E.; Lucena-Moya, P.; Pardo, I.; Mouillot, D.
Titre (up) A unifying approach to understanding transitional waters: Fundamental properties emerging from ecotone ecosystems Type Article scientifique
Année 2013 Publication Revue Abrégée Estuarine Coastal and Shelf Science
Volume Numéro Pages
Mots-Clés climate change; ecotone concept; landscape ecology; transitional waters
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Volume de collection Numéro de collection Edition
ISSN 0272-7714 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 433
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Auteur Fouilland, E.; Tolosa, I.; Bonnet, D.; Bouvier, C.; Bouvier, T.; Bouvy, M.; Got, P.; Le Floc'h, E.; Mostajir, B.; Roques, C.; Sempéré, R.; Sime-Ngando, T.; Vidussi, F.
Titre (up) Bacterial carbon dependence on freshly produced phytoplankton exudates under different nutrient availability and grazing pressure conditions in coastal marine waters Type Article scientifique
Année 2014 Publication Revue Abrégée FEMS microbiology ecology
Volume 87 Numéro 3 Pages 757-769
Mots-Clés bacteria; carbon coupling; coastal waters; interactions; phytoplankton
Résumé The effects of grazing pressure and inorganic nutrient availability on the direct carbon transfer from freshly produced phytoplankton exudates to heterotrophic bacteria biomass production were studied in Mediterranean coastal waters. The short-term incorporation of (1)(3)C (H(1)(3)CO(3)) in phytoplankton and bacterial lipid biomarkers was measured as well as the total bacterial carbon production (BP), viral lysis and the microbial community structure under three experimental conditions: (1) High inorganic Nutrient and High Grazing (HN + HG), (2) High inorganic Nutrient and Low Grazing (HN + LG) and (3) under natural in situ conditions with Low inorganic Nutrient and High Grazing (LN + HG) during spring. Under phytoplankton bloom conditions (HN + LG), the bacterial use of freshly produced phytoplankton exudates as a source of carbon, estimated from (1)(3)C enrichment of bacterial lipids, contributed more than half of the total bacterial production. However, under conditions of high grazing pressure on phytoplankton with or without the addition of inorganic nutrients (HN + HG and LN + HG), the (1)(3)C enrichment of bacterial lipids was low compared with the high total bacterial production. BP therefore seems to depend mainly on freshly produced phytoplankton exudates during the early phase of phytoplankton bloom period. However, BP seems mainly relying on recycled carbon from viral lysis and predators under high grazing pressure.
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Volume de collection Numéro de collection Edition
ISSN 1574-6941 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 444
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Auteur Ram, P.A.S.; Mari, X.; Brune, J.; Torreton, J.P.; Chu, V.T.; Raimbault, P.; Niggemann, J.; Sime-Ngando, T.
Titre (up) Bacterial-viral interactions in the sea surface microlayer of a black carbon-dominated tropical coastal ecosystem (Halong Bay, Vietnam) Type Article scientifique
Année 2018 Publication Revue Abrégée Elementa-Sci. Anthrop.
Volume 6 Numéro Pages 13
Mots-Clés dissolved organic-matter; marine; communities; seawater; lysogeny; black carbon; variability; viruses; waters; aquatic ecosystems; hexane soot; ocean surface; sea surface microlayer; tropical coastal ocean; viral lysis; virus-bacteria interaction
Résumé Increasing human activity has raised concerns about the impact of deposition of anthropogenic combustion aerosols (i.e., black carbon; BC) on marine processes. The sea surface microlayer (SML) is a key gate for the introduction of atmospheric BC into the ocean; however, relatively little is known of the effects of BC on bacteria-virus interactions, which can strongly influence microbially mediated processes. To study the impact of BC on bacteria-virus interactions, field investigations involving collection from the SML and underlying water were carried out in Halong Bay (Vietnam). Most inorganic nutrient concentrations, as well as dissolved organic carbon, were modestly but significantly higher (p = 0.02-0.05) in the SML than in underlying water. The concentrations of particulate organic carbon (though not chlorophyll a) and of total particulate carbon, which was composed largely of particulate BC (mean = 1.7 +/- 6.4 mmol L-1), were highly enriched in the SML, and showed high variability among stations. On average, microbial abundances (both bacteria and viruses) and bacterial production were 2- and 5fold higher, respectively, in the SML than in underlying water. Significantly lower bacterial production (p < 0.01) was observed in the particulate fraction (> 3 mu m) compared to the bulk sample, but our data overall suggest that bacterial production in the SML was stimulated by particulate BC. Higher bacterial production in the SML than in underlying water supported high viral lytic infection rates (from 5.3 to 30.1%) which predominated over percent lysogeny (from undetected to 1.4%). The sorption of dissolved organic carbon by black carbon, accompanied by the high lytic infection rate in the black carbon-enriched SML, may modify microbially mediated processes and shift the net ecosystem metabolism (ratio of production and respiration) to net heterotrophy and CO2 production in this critical layer between ocean and atmosphere.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 2325-1026 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2276
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