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| Obernosterer, Ingrid; Catala, Philippe; Lebaron, Philippe; West, Nyree J.. |
| We investigated the contribution of distinct bacterial groups to bulk abundance and leucine incorporation during a spring phytoplankton bloom induced by natural iron fertilization in the Southern Ocean (Kerguelen Ocean and Plateau Compared Study, January-February 2005). Oligonucleotide probes were designed to target five operational taxonomic units (OTUs) at a narrow phylogenetic level (>= 99% identity of the 16S ribosomal ribonucleic acid [rRNA] gene). During the peak of the phytoplankton bloom, the Roseobacter groups NAC11-7 and RCA, the OTUs SAR92 belonging to Gammaproteobacteria, and the Bacteroidetes OTU Agg58 dominated bulk abundance and leucine incorporation. These four OTUs disappeared with the decline of the bloom, when the cosmopolitan groups... |
| Tipo: Text |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00214/32503/30995.pdf |
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| Obernosterer, Ingrid; Catala, Philippe; Reinthaler, Thomas; Herndl, Gerhard J.; Lebaron, Philippe. |
| The abundance and activity of heterotrophic and autotrophic organisms were determined in the surface microlayer (SML) at marine and estuarine sites in the NW Mediterranean Sea from May to July 2003. At all study sites, community respiration in the SML exceeded that in the subsurface water (SSW) by factors between 1.7 and 28. The abundance of heterotrophic bacteria and the major groups of the autotrophic community displayed consistent, but low enrichment factors (EF) for the SML (mean 1.3). In contrast, EF for the abundance of heterotrophic nanoflagellates and the concentration of particulate organic carbon were, on average, 4 and 7, respectively. Community respiration rates in the SML were related to the concentration of total organic carbon; however, no... |
| Tipo: Text |
Palavras-chave: Surface microlayer; Community respiration; Net community production; Neuston. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00243/35435/33960.pdf |
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| Gazeau, Frédéric; Ridame, Céline; Van Wambeke, France; Alliouane, Samir; Stolpe, Christian; Irisson, Jean-olivier; Marro, Sophie; Grisoni, Jean-michel; De Liège, Guillaume; Nunige, Sandra; Djaoudi, Kahina; Pulido-villena, Elvira; Dinasquet, Julie; Obernosterer, Ingrid; Catala, Philippe; Guieu, Cécile. |
| In Low Nutrient Low Chlorophyll areas, such as the Mediterranean Sea, atmospheric fluxes represent a considerable external source of nutrients likely supporting primary production especially during stratification periods. These areas are expected to expand in the future due to lower nutrient supply from sub-surface waters caused by enhanced stratification, likely further increasing the role of atmospheric deposition as a source of new nutrients to surface waters. Yet, whether plankton communities will react differently to dust deposition in a warmer and acidified environment remains an open question. The impact of dust deposition both in present and future climate conditions was assessed through three perturbation experiments in the open Mediterranean Sea.... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/80015/82994.pdf |
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| Christaki, Urania; Gueneugues, Audrey; Liu, Yan; Blain, Stéphane; Catala, Philippe; Colombet, Jonathan; Debeljak, Pavla; Jardillier, Ludwig; Irion, Solène; Planchon, Frederic; Sassenhagen, Ingrid; Sime Ngando, Telesphore; Obernosterer, Ingrid. |
| Spatial and seasonal dynamics of microbial loop fluxes were investigated in contrasting productivity regimes in the Indian sector of the Southern Ocean. Observations carried out in late summer (February–March 2018; project MOBYDICK) revealed higher microbial biomasses and fluxes in the naturally iron‐fertilized surface waters of Kerguelen island in comparison to surrounding off‐plateau waters. Differences were most pronounced for bacterial heterotrophic production (2.3‐fold), the abundance of heterotrophic nanoflagellates (HNF; 2.7‐fold). Independent of site, grazing by HNF was the main loss process of bacterial production (80–100%), while virus‐induced mortality was low (< 9%). Combining these results with observations from previous investigations... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00649/76109/77064.pdf |
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| Van Wambeke, France; Pulido, Elvira; Catala, Philippe; Dinasquet, Julie; Djaoudi, Kahina; Engel, Anja; Garel, Marc; Guasco, Sophie; Barbara, Marie; Nunige, Sandra; Taillandier, Vincent; Zancker, Birthe; Tamburini, Christian. |
| Ectoenzymatic activity, prokaryotic heterotrophic abundances and production were determined in the Mediterranean Sea. Sampling was carried out in the sub-surface, the deep chlorophyll maximum layer (DCM), the core of the Levantine intermediate waters and in the deeper part of the mesopelagic layers. Michaelis–Menten kinetics were assessed using a large range of concentrations of fluorogenic substrates (0.025 to 50 µM). As a consequence, Km (Michaelis–Menten half-saturation constant) and Vm (maximum hydrolysis velocity) parameters were determined for both low- and high-affinity enzymes for alkaline phosphatase, aminopeptidase (LAP) and β-glucosidase (βGLU). Based on the constant derived from the high-LAP-affinity enzyme (0.025–1 µM substrate concentration... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00642/75452/76268.pdf |
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| Blanchet, Marine; Pringault, Olivier; Panagiotopoulos, Christos; Lefevre, Dominique; Charriere, Bruno; Ghiglione, Jean-francois; Fernandez, Camila; Aparicio, Fran L.; Marrase, Celia; Catala, Philippe; Oriol, Louise; Caparros, Jocelyne; Joux, Fabien. |
| Heterotrophic bacterial communities in marine environments are exposed to a heterogeneous mixture of dissolved organic compounds with different bioreactivity that may control both their activity and composition. The coastal environment is an example of a mixing area where recalcitrant allochthonous organic matter from rivers can encounter labile organic matter from marine phytoplanktonic blooms. The objective of this study was to explore the effects of mixed qualities of dissolved organic matter (DOM) on bacterial community activity (BCA) and bacterial community composition (BCC) and to test for a priming effect when DOM sources are added in combination. Coastal marine bacterial communities were incubated separately with a mixture of amino acids and with... |
| Tipo: Text |
Palavras-chave: Dissolved organic matter; Biodegradation; Coastal waters; Bacterial community composition; Priming effect. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00625/73737/74701.pdf |
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