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Auteur Albo-Puigserver, M.; Navarro, J.; Coll, M.; Layman, C.A.; Palomera, I.
Titre Trophic structure of pelagic species in the northwestern Mediterranean Sea Type Article scientifique
Année 2016 Publication Revue Abrégée J. Appl. Dev. Psychol.
Volume 47 Numéro Pages 27-35
Mots-Clés anchovy engraulis-encrasicolus; biscay northeast atlantic; Community structure; diet composition; food-web; Food web; hake merluccius-merluccius; horse mackerel; Isotopic niche; mackerel scomber-japonicus; Pelagic fish; sardine sardina-pilchardus; Seasonal; seasonal-changes; Stable isotopes; stable-isotopes; Trophic segregation
Résumé Ecological knowledge of food web interactions within pelagic marine communities is often limited, impairing our capabilities to manage these ecologically and economically important marine fish species. Here we used stable isotope analyses to investigate trophic interactions in the pelagic ecosystem of the northwestern Mediterranean Sea during 2012 and 2013. Our results suggest that European sardine, Sardina pilchardus, and anchovy, Engraulis encrasicolus, are consumers located at relatively low levels of the pelagic food web. Unexpectedly, the round sardinella, Sardinella aurita, appeared to be located at a higher trophic level than the other small pelagic fish species, although previous studies found similarity in their diets. Isotope data suggested that trophic niches of species within the genera Trachurus spp. and Scomber spp., were distinct. Atlantic bonito Sarda sarda, European hake Merluccius merluccius and European squid Loligo vulgaris, appeared to feed at higher trophic levels than other species. Despite some intraspecific seasonal variability for some species, community trophic structure appeared relatively stable through the year. These data provide an important step for developing models of food web dynamics in the northwestern Mediterranean Sea. (C) 2016 Elsevier B.V. All rights reserved.
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ISSN 0193-3973 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1691
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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 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.; Hartmann, H.J.; Lebaron, P.; Casamayor, E.O.; Catala, P.; Delmas, D.
Titre Potential effect of freshwater virus on the structure and activity of bacterial communities in the Marennes-Oleron Bay (France) Type Article scientifique
Année 2009 Publication Revue Abrégée Microb Ecol
Volume 57 Numéro 2 Pages 295-306
Mots-Clés 16S/genetics Seasons Seawater/microbiology/virology Viruses/*growth & development *Water Microbiology; Bacteria/genetics/*growth & development/*virology Biodiversity Colony Count; Bacterial/genetics France Fresh Water/virology Polymorphism; Microbial DNA Fingerprinting DNA; Ribosomal; Single-Stranded Conformational Population Dynamics RNA
Résumé Batch culture experiments using viral enrichment were conducted to test the response of a coastal bacterial community to autochthonous (i.e., co-existing) or allochthonous riverine viruses. The effects of viral infections on bacterial dynamics and activity were assessed by epifluorescence microscopy and thymidine incorporation, respectively, whereas the effect of viral infection on bacterial community composition was examined by polymerase chain reaction-single strand conformation polymorphism 16S ribosomal RNA fingerprinting. The percentages of high nucleic acid-containing cells, evaluated by flow cytometry, were significantly correlated (r2=0.91, n=12, p<0.0001) to bacterial production, making this value a good predictor of active cell dynamics along the study. While confinement and temperature were the two principal experimental factors affecting bacterial community composition and dynamics, respectively, additions of freshwater viruses had significant effects on coastal bacterial communities. Thus, foreign viruses significantly reduced net bacterial population increase as compared to the enrichment treated with inactivated virus. Moreover, freshwater viruses recurrently and specifically affected bacterial community composition, as compared to addition of autochthonous viruses. In most cases, the combined treatment viruses and freshwater dissolved organic matter helped to maintain or even enhance species richness in coastal bacterial communities in agreement to the 'killing the winner' hypothesis. Thus, riverine virus input could potentially influence bacterial community composition of the coastal bay albeit with modest modification of bulk bacterial growth.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1301
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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 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 Auguet, J.C.; Nomokonova, N.; Camarero, L.; Casamayor, E.O.
Titre Seasonal changes of freshwater ammonia-oxidizing archaeal assemblages and nitrogen species in oligotrophic alpine lakes Type Article scientifique
Année 2011 Publication Revue Abrégée Appl Environ Microbiol
Volume 77 Numéro 6 Pages 1937-1945
Mots-Clés 16S/genetics Seasons Spain; Ammonia/*metabolism Archaea/classification/genetics/*metabolism Biodiversity Fresh Water Molecular Sequence Data Nitrogen/*metabolism Oxidoreductases/genetics Phylogeny Polymerase Chain Reaction RNA; Ribosomal
Résumé The annual changes in the composition and abundance of ammonia-oxidizing archaea (AOA) were analyzed monthly in surface waters of three high mountain lakes within the Limnological Observatory of the Pyrenees (LOOP; northeast Spain) using both 16S rRNA and functional (ammonia monooxygenase gene, amoA) gene sequencing as well as quantitative PCR amplification. The set of biological data was related to changes in nitrogen species and to other relevant environmental variables. The whole archaeal assemblage was dominated by phylotypes closely related to the crenarchaeal 1.1a group (58% +/- 18% of total 16S rRNA gene sequences), and consistent structural changes were detected during the study. Water temperature was the environmental variable that better explained spring, summer, and winter (ice-covered lakes) archaeal assemblage structure. The amoA gene was detected year round, and seasonal changes in amoA gene composition were well correlated with changes in the archaeal 16S rRNA gene pool. In addition, copy numbers of both the specific 1.1a group 16 rRNA and archaeal amoA genes were well correlated, suggesting that most freshwater 1.1a Crenarchaeota had the potential to carry out ammonia oxidation. Seasonal changes in the diversity and abundance of AOA (i.e., amoA) were better explained by temporal changes in ammonium, the substrate for nitrification, and mostly nitrite, the product of ammonia oxidation. Lacustrine amoA gene sequences grouped in coherent freshwater phylogenetic clusters, suggesting that freshwater habitats harbor typical amoA-containing ecotypes, which is different from soils and seas. We observed within the freshwater amoA gene sequence pool a high genetic divergence (translating to up to 32% amino acid divergence) between the spring and the remaining AOA assemblages. This suggests that different AOA ecotypes are adapted to different temporal ecological niches in these lakes.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1304
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