References of "Servais, Pierre"
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See detailMicrobial Ecology of Lake Kivu
Llirós, Marc; Descy, Jean-Pierre; Libert, Xavier et al

in Descy, Jean-Pierre; Darchambeau, François; Schmid, Martin (Eds.) Lake Kivu, Limnology and Biogeochemistry of a Tropical Great Lake (2012)

We review available data on archaea, bacteria and small eukaryotes in an attempt to provide a general picture of microbial diversity, abundances and microbe-driven processes in Lake Kivu surface and ... [more ▼]

We review available data on archaea, bacteria and small eukaryotes in an attempt to provide a general picture of microbial diversity, abundances and microbe-driven processes in Lake Kivu surface and intermediate waters (ca. 0–100 m). The various water layers present contrasting physical and chemical properties and harbour very different microbial communities supported by the vertical redox structure. For instance, we found a clear vertical segregation of archaeal and bacterial assemblages between the oxic and the anoxic zone of the surface waters. The presence of specific bacterial (e.g. Green Sulfur Bacteria) and archaeal (e.g. ammonia-oxidising archaea) communities and the prevailing physico-chemical conditions point towards the redoxcline as the most active and metabolically diverse water layer. The archaeal assemblage in the surface and intermediate water column layers was mainly composed by the phylum Crenarchaeota , by the recently defined phylum Thaumarchaeota and by the phylum Euryarchaeota . In turn, the bacterial assemblage comprised mainly ubiquitous members of planktonic assemblages of freshwater environments (Actinobacteria, Bacteroidetes and Betaproteobacteria among others) and other less commonly retrieved phyla (e.g. Chlorobi, Clostridium and Deltaproteobacteria). The community of small eukaryotes (<5 µm) mainly comprised Stramenopiles , Alveolata , Cryptophyta , Chytridiomycota , Kinetoplastea and Choanoflagellida, by decreasing order of richness. The total prokaryotic abundance ranged between 0.5 × 10^6 and 2.0 × 10^6 cells mL−1 , with maxima located in the 0–20 m layer, while phycoerythrin-rich Synechococcus-like picocyanobacteria populations were comprised between 0.5 × 10^5 and 2.0 × 10^5 cells mL−1 in the same surface layer. Brown-coloured species of Green Sulfur Bacteria permanently developed at 11m depth in Kabuno Bay and sporadically in the anoxic waters of the lower mixolimnion of the main basin. The mean bacterial production was estimated to 336 mg C m−2 day−1 . First estimates of the re-assimilation by bacterioplankton of dissolved organic matter excreted by phytoplankton showed high values of dissolved primary production (ca. 50% of total production). The bacterial carbon demand can totally be fuelled by phytoplankton production. Overall, recent studies have revealed a high microbial diversity in Lake Kivu, and point towards a central role of microbes in the biogeochemical and ecological functioning of the surface layers, comprising the mixolimnion and the upper chemocline. [less ▲]

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See detailBiogeochemistry of the Congo river: Preliminary data
Darchambeau, François ULg; Borges, Alberto ULg; Wabakanghanzi, José Nlandu et al

Conference (2011, June 03)

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See detailCongo River 2010
Darchambeau, François ULg; Borges, Alberto ULg; Wabakanghanzi, José Nlandu et al

Poster (2010, October 04)

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See detailThe ecology of Lake Kivu: a puzzle solved?
Darchambeau, François ULg; Sarmento, Hugo; Isumbisho, Mwapu et al

Conference (2010, January 14)

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See detailStoichiometry of bacteria and algae in Lake Kivu
Homblette, Nathalie; Darchambeau, François ULg; Heldal, Mikal et al

Poster (2009, January 25)

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See detailOur present understanding of Lake Kivu ecology
Darchambeau, François ULg; Sarmento, Hugo; Isumbisho, Mwapu et al

Conference (2009, January 19)

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See detailCarbon cycling in the mixolimnion of Lake Kivu : results from the CAKI project
Borges, Alberto ULg; Descy, Jean-Pierre; Delille, Bruno ULg et al

Conference (2009, January 19)

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See detailCarbon dioxide fluxes in Lake Kivu
Borges, Alberto ULg; Delille, Bruno ULg; Descy, Jean-Pierre et al

Conference (2007, June 12)

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See detailTrophic links in the lowland River Meuse (Belgium): assessing the role of bacteria and protozoans in planktonic food webs
Joaquim-Justo, Célia ULg; Pirlot, S.; Viroux, L. et al

in Journal of Plankton Research (2006), 28(9), 857-870

Trophic interactions within the plankton of the lowland River Meuse (Belgium) were measured in spring and summer 2001. Consumption of bacteria by protozoa was measured by monitoring the disappearance of H ... [more ▼]

Trophic interactions within the plankton of the lowland River Meuse (Belgium) were measured in spring and summer 2001. Consumption of bacteria by protozoa was measured by monitoring the disappearance of H-3-thymidine-labelled bacteria. Metazooplankton bacterivory was assessed using 0.5-mu m fluorescent microparticles (FMPs), and predation of metazooplankton on ciliates was measured using natural ciliate assemblages labelled with FMPs as tracer food. Grazing of metazooplanklon on flagellates was determined through in situ incubations with manipulated metazooplankton densities. Protozooplankton bacterivory varied between 6.08 and 53.90 mg C m(-3) day(-1) (i.e. from 0.12 to 0.86 g C-1 bacteria g C-1 protozoa day(-1)). Metazooplankton, essentially rotfiers, grazing on bacteria was negligible compared with grazing by protozoa (similar to 1000 times lower). Predation of rotfiers on heterotrophic flagellates (HFs) was generally low (on average 1.77 mg C m(-3) day(-1), i.e. 0.084 g C-1 flagellates g C-1 rotfiers day(-1)), the higher contribution of HF in the diet of rotfiers being observed when Keratella cochlearis was the dominant metazooplankter. Predation of rotfiers on ciliates was low in spring samples (0.56 mg C m(-3) day(-1), i.e. 0.014 g C-1 ciliates g C-1 rotfiers day(-1)) in contrast to measurements performed in July (8.72 mg C m(-3) day(-1), i.e. 0.242 g C-1 ciliates g C-1 rotfiers day(-1)). The proportion of protozoa in the diet of rotfiers was low compared with that of phytoplankton (< 30% of total carbon ingestion) except when phytoplankton biomass decreased below the incipient limiting level (ILL) of the main metazooplantonic species. In such conditions, protozoa (mainly ciliates) constituted similar to 50% of total rotfier diet These results give evidence that microbial organisms play a significant role within the planktonic food web of a eutrophic lowland river, ciliates providing an alternative food for metazooplankton when phytoplankton becomes scarce. [less ▲]

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See detailTrophic links in the lowland river Meuse (Belgium): importance of the predation exerted by rotifers on bacterio- and protozooplankton.
Joaquim-Justo, Célia ULg; Pirlot, S; Viroux, Laurent et al

Conference (2003, June 07)

Trophic interactions within the plankton of the lowland river Meuse (Belgium) were measured in Spring and Summer (2001). Consumption of bacteria by protozoa was measured by monitoring the radioactivity ... [more ▼]

Trophic interactions within the plankton of the lowland river Meuse (Belgium) were measured in Spring and Summer (2001). Consumption of bacteria by protozoa was measured by monitoring the radioactivity disappearance of 3H-thymidine labelled bacteria. The proportion of protozoan bacterivory attributable to flagellates and ciliates was determined with fluorescently labelled bacteria (FLB). Metazooplankton bacterivory was assessed with 0.5 µm fluorescent microparticles (FMPs) and predation of metazooplankton on ciliates was measured by using natural ciliate assemblages labelled with FMPs as tracer food. Grazing of metazooplankton on flagellates was determined through in situ incubations with manipulated metazooplankton densities. flagellates were the main bacterial consumers their grazing being 91  10 % of total bacterial grazing. Metazooplankton, essentially rotifers, grazing on bacteria was negligible compared to grazing by protozoa and to bacterial production. Protozoa grazing balanced bacterial production in early samplings but was lower in July. Predation of rotifers on heterotrophic flagellates (HF) was generally low (1.765 3.432 mg C m-3 d-1 ), the higher contribution of HF in the diet of rotifers being observed when Keratella cochlearis was the dominant metazooplankter. Predation of rotifers on ciliates was low in the first samples (0.557  0.004 mg C m-3 d-1) in contrast to measurements performed in July (8.722  1.363 mg C m-3d-1). The proportion of protozoa in the diet of rotifers was generally low compared to phytoplankton (< 30% of total carbon ingestion) except when phytoplankton biomass decreased below the incipient limiting level (ILL) of the main metazooplantonic species. In such conditions, protozoa (mainly ciliates) constituted ca. 50% of total rotifer food. These results give evidence that microbial organisms play an important role within the plankton of the river Meuse, ciliates providing an alternative food for metazooplankton when phytoplankton becomes scarce. [less ▲]

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See detailTrophics relationships between planktonic micro-organisms in the river Meuse (Belgium): a carbon budget
Servais, Pierre; Gosselain, Véronique; Joaquim-Justo, Célia ULg et al

in Arch. Hydrobiol (2000)

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See detailEtude d'un écosystème fluvial perturbé : influence de la pollution d'origine industrielle et domestique sur les premiers niveaux de la chaine trophique
Descy, Jean-Pierre; Servais, Pierre; Thomé, Jean-Pierre ULg et al

Report (1992)

Le but du programme de recherches était de décrire le fonctionnement d'un milieu fluvial soumis à des pollutions diverses, principalement d'origine industrielle et domestique. Il visait entre autres à ... [more ▼]

Le but du programme de recherches était de décrire le fonctionnement d'un milieu fluvial soumis à des pollutions diverses, principalement d'origine industrielle et domestique. Il visait entre autres à complèter les connaissances fondamentales acquises au cours de recherches antérieures sur la Meuse. [less ▲]

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See detailEtude écologique de la haute Meuse belge et modélisation du fonctionnement de l'écosystème aquatique
Billen, Gilles; Descy, Jean-Pierre; Everbecq, Etienne ULg et al

Report (1985)

L'objectif de l'étude est de développer un modèle de l'écosystème aquatique qui permette d'évaluer l'impact (non radiologique) des rejets de centrales nucléaires sur l'écosystème de la haute Meuse belge ... [more ▼]

L'objectif de l'étude est de développer un modèle de l'écosystème aquatique qui permette d'évaluer l'impact (non radiologique) des rejets de centrales nucléaires sur l'écosystème de la haute Meuse belge. Les variables modélisées étaient les variables physico-chimiques, la biomasse et la production phytoplanctonique ainsi que la biomasse et l'activité bactérienne. [less ▲]

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