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| Registros recuperados: 10 | |
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| Lagaria, A.; Psarra, S.; Lefevre, D.; Van Wambeke, France; Courties, C.; Pujo-pay, M.; Oriol, L.; Tanaka, T.; Christaki, U.. |
| We examined the effects of nutrient additions on rates of (14)C-based particulate and dissolved primary production as well as O(2)-based metabolic rates in surface waters (8 m) of three anticyclonic eddies, located in the Western, Central and Eastern Mediterranean. Ship-board microcosm experiments employing additions of inorganic nitrogen (+N) and phosphorus (+P), alone and in combination (+NP), were conducted in June/July 2008 during the BOUM (Biogeochemistry from the Oligotrophic to the Ultra-oligotrophic Mediterranean) cruise. In all three experiments, particulate primary production was significantly stimulated by the additions of nitrogen (+N, +NP) while no effect was observed with the addition of phosphorus alone (+P). Percent extracellular release of... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24401/22418.pdf |
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| Mella-flores, D.; Mazard, S.; Humily, F.; Partensky, F.; Mahe, F.; Bariat, L.; Courties, C.; Marie, D.; Ras, J.; Mauriac, R.; Jeanthon, C.; Bendif, El Mahdi; Ostrowski, M.; Scanlan, D. J.; Garczarek, L.. |
| Biological communities populating the Mediterranean Sea, which is situated at the northern boundary of the subtropics, are often claimed to be particularly affected by global warming. This is indicated, for instance, by the introduction of (sub) tropical species of fish or invertebrates that can displace local species. This raises the question of whether microbial communities are similarly affected, especially in the Levantine basin where sea surface temperatures have significantly risen over the last 25 years (0.50 +/- 0.11 degrees C in average per decade, P < 0.01). In this paper, the genetic diversity of the two most abundant members of the phytoplankton community, the picocyanobacteria Prochlorococcus and Synechococcus, was examined during two... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24402/22413.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... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00291/40208/38996.pdf |
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| Lucas, Ronan; Courties, C.; Herbland, Alain; Goulletquer, Philippe; Marteau, Anne-laure; Lemonnier, Hugues. |
| In tropical shrimp ponds, the increasing of feed input, concomitantly with the stocking shrimp biomass, induces an eutrophication of the ecosystem. Although difficult to maintain, its stability is required to guarantee the success of the culture. A 110-day period of phytoplankton and bacterioplankton stock and dynamics in an earthen pond (1.2 ha area, 1 m depth) was monitored using flow cytometry to provide baseline information on community characteristics and ecosystem instability. Seven autotrophic cell types were identified over the whole sampling period. Prokaryotic cells included Synechococcus sp., a group named UNK which presented an atypical new flow cytometric signature and picoeukaryotes (PEUK). Nanophytoplankton cells were represented by 4... |
| Tipo: Text |
Palavras-chave: Tropical shrimp aquaculture; Ecosystem shift; Phytoplankton; Bacterioplankton; Vibrio; Flow cytometry. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00029/14068/11312.pdf |
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| Popendorf, K. J.; Tanaka, T.; Pujo-pay, M.; Lagaria, A.; Courties, C.; Conan, Pascal; Oriol, L.; Sofen, L. E.; Moutin, T.; Van Mooy, B. A. S.. |
| Intact polar membrane lipids compose a significant fraction of cellular material in plankton and their synthesis imposes a substantial constraint on planktonic nutrient requirements. As a part of the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM) cruise we examined the distribution of several classes of intact polar diacylglycerolipids (IP-DAGs) across the Mediterranean, and found that phospholipid concentration as a percent of total lipids correlated with phosphate concentration. In addition, the ratios of non-phosphorus lipids to phospholipids - sulfoquinovosyldiacylglycerol (SQDG) to phosphatidylglycerol (PG), and betaine lipids to phosphatidylcholine (PC) - were also found to increase from west to east across the... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24405/22410.pdf |
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| Tanaka, T.; Thingstad, T. F.; Christaki, U.; Colombet, J.; Cornet-barthaux, V.; Courties, C.; Grattepanche, J. -d.; Lagaria, A.; Nedoma, J.; Oriol, L.; Psarra, S.; Pujo-pay, M.; Van Wambeke, France. |
| We investigated the identity of the limiting nutrient of the pelagic microbial food web in the Mediterranean Sea using nutrient manipulated microcosms during summer 2008. Experiments were carried out with surface waters at the center of anticyclonic eddies in the Western Basin, the Ionian Basin, and the Levantine Basin. In situ, the ratio of N to P was always higher in both dissolved and particulate organic fractions compared to the Redfield ratio, suggesting a relative P-starvation. In each experiment, four different treatments in triplicates (addition of ammonium, phosphate, a combination of both, and the unamended control) were employed and chemical and biological parameters monitored throughout a 3-4 day incubation. Temporal changes of turnover time of... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24395/22406.pdf |
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| Thomas, Y.; Garen, Pierre; Courties, C.; Charpy, L.. |
| Spatial and temporal scales of variability in phyto- and bacterioplankton abundance were investigated in a deep atoll lagoon (Ahe, French Polynesia), Ahe Lagoon showed a classical phytoplankton composition, but its picophytoplankton (Prochlorococcus, Synechococcus and picoeukaryotes) concentrations are higher than the mean for Polynesian atoll lagoons. Phyto- and bacterioplankton descriptors were highly variable, with mean CVs of >20% in most cases: day night, day-to-day, vertical, lagoonal and seasonal. Phytoplankton biomass, which was estimated by in vivo fluorescence, was higher in the deep layer than in the upper layer. This pattern was detected on a day night scale, showing transitory vertical gradients, and through long-term events that were... |
| Tipo: Text |
Palavras-chave: Flow cytometry; Picophytoplankton; Nanophytoplankton; Bacterioplankton; Vertical distribution; Day-to-day dynamics; Large-scale heterogeneity; Deep atoll lagoon; French Polynesia. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00003/11425/7963.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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| Dall'Olmo, G.; Boss, E.; Behrenfeld, M. J.; Westberry, T. K.; Courties, C.; Prieur, L.; Pujo-pay, M.; Hardman-mountford, N.; Moutin, T.. |
| The diurnal fluctuations in solar irradiance impose a fundamental frequency on ocean biogeochemistry. Observations of the ocean carbon cycle at these frequencies are rare, but could be considerably expanded by measuring and interpreting the inherent optical properties. A method is presented to analyze diel cycles in particulate beam-attenuation coefficient (c(p)) measured at multiple wavelengths. The method is based on fitting observations with a size-structured population model coupled to an optical model to infer the particle size distribution and physiologically relevant parameters of the cells responsible for the measured diel cycle in c(p). Results show that the information related to size and contained in the spectral data can be exploited to... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00133/24404/22420.pdf |
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| Registros recuperados: 10 | |
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