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| Van Wambeke, France; Catala, P.; Pujo-pay, M.; Lebaron, P.. |
| Heterotrophic bacterioplankton abundance and production were investigated with depth (down to bathypelagic layers) and with longitude (from 4.9 degrees E to 32.7 degrees E) along a cruise track across the Mediterranean Sea in early summer 2008. Abundances and flow cytometric characteristics (green fluorescence and side scatter signals) of high nucleic acid (HNA) and low nucleic acid (LNA) bacterial cells were determined using flow cytometry. Contrary to what is generally observed, the relative importance of HNA cells, as a percent of total cells, (%HNA, range 30-69%) was inversely related to bacterial production (range 0.15-44 ngC l(-1) h(-1)) although the negative relation was weak (log-log regression r(2) = 0.19). The %HNA as well as the mean side... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24390/22404.pdf |
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| Ternon, E.; Guieu, C.; Ridame, C.; L'Helguen, S.; Catala, P.. |
| The Mediterranean Sea is a semi-enclosed basin characterized by a strong thermal stratification during summer during which the atmosphere is the main source of new nutrients to the nutrient-depleted surface layer. From aerosol sampling and microcosm experiments performed during the TransMed BOUM cruise (June-July 2008) we showed that: (i) the Mediterranean atmosphere composition (Al, Fe, P) was homogeneous over similar to 28 degrees of longitude and was a mixture with a constant proportion of anthropogenic contribution and a variable but modest contribution of crustal aerosols. This quite stable composition over a one month period and a long transect (similar to 2500 km) allowed to define the Mediterranean atmospheric "background" that characterizes the... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24399/22405.pdf |
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| Christaki, U.; Lefevre, D.; Georges, C.; Colombet, J.; Catala, P.; Courties, C.; Sime-ngando, T.; Blain, S.; Obernosterer, I.. |
| Microbial food web dynamics were determined during the onset of several spring phytoplankton blooms induced by natural iron fertilization off Kerguelen Island in the Southern Ocean (KEOPS2). The abundances of heterotrophic bacteria and heterotrophic nanoflagellates, bacterial heterotrophic production, bacterial respiration, and bacterial growth efficiency, were consistently higher in surface waters of the iron-fertilized sites than at the reference site in HNLC (high nutrient low chlorophyll) waters. The abundance of virus-like particles remained unchanged, but viral production increased by a factor of 6 in iron-fertilized waters. Bacterial heterotrophic production was significantly related to heterotrophic nanoflagellate abundance and viral production... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00291/40208/38996.pdf |
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| Lamy, D.; Jeanthon, C.; Cottrell, M. T.; Kirchman, D. L.; Van Wambeke, France; Ras, J.; Dahan, O.; Pujo-pay, M.; Oriol, L.; Bariat, L.; Catala, P.; Cornet-barthaux, V.; Lebaron, P.. |
| Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24398/22417.pdf |
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| Talarmin, A.; Van Wambeke, France; Catala, P.; Courties, C.; Lebaron, P.. |
| The surface of the Mediterranean Sea is a low-phosphate-low-chlorophyll marine area where marine heterotrophic prokaryotes significantly contribute to the biogeochemical cycles of all biogenic elements such as carbon, notably through the mineralization of dissolved organic compounds. Cell-specific leucine incorporation rates were determined in early summer in the open stratified Mediterranean Sea. The bulk leucine incorporation rate was on average 5 +/- 4 pmol leu l(-1) h(-1) (n = 30). Cell-specific 3H-leucine incorporation rates were assayed using flow cytometry coupled to cell sorting. Heterotrophic prokaryotes (Hprok) were divided into cytometric groups according to their side scatter and green fluorescence properties: high nucleic acid containing cells... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24394/22407.pdf |
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| Auguet, Jean-christophe; Montanie, Helene; Hartmann, Hans; Lebaron, P.; Casamayor, E. O.; Catala, P.; Delmas, Daniel. |
| 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 (r (2) = 0.91, n = 12, p < 0.0001) to bacterial production, making this value a good predictor of active cell... |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6636.pdf |
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