References of "Descy, J.-P"
     in
Bookmark and Share    
Full Text
See detailAmmonia Oxidising Archaea in the OMZ of a freshwater African Lake
Lliros, M; Ingeoglu, O; Garcia-Armisen, T et al

Poster (2014, May 05)

Detailed reference viewed: 23 (0 ULg)
Full Text
See detailCarbon cycling in a large, meromictic tropical lake (Lake Kivu, East Africa): insights from seasonal monitoring of biogeochemical depth profiles
Morana, C; Darchambeau, F; Muvundja, F et al

Poster (2014, April 27)

Detailed reference viewed: 6 (0 ULg)
Full Text
See detailProduction of dissolved organic matter by phytoplankton and its uptake by heterotrophic prokaryotes in large tropical lakes
Morana, C; Sarmento, H; Descy, J-P et al

Poster (2014, April 27)

Detailed reference viewed: 24 (1 ULg)
Full Text
See detailInorganic and organic carbon spatial variability in the Congo River during high waters (December 2013)
Borges, Alberto ULg; Bouillon, S; Teodoru, C et al

Poster (2014, April 27)

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailCarbon Cycling of Lake Kivu (East Africa): Net Autotrophy in the Epilimnion and Emission of CO2 to the Atmosphere Sustained by Geogenic Inputs
Borges, Alberto ULg; Morana, C; Bouillon, S et al

in PLoS ONE (2014), 9(10), 109500

We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal ... [more ▼]

We report organic and inorganic carbon distributions and fluxes in a large (>2000 km2) oligotrophic, tropical lake (Lake Kivu, East Africa), acquired during four field surveys, that captured the seasonal variations (March 2007–mid rainy season, September 2007–late dry season, June 2008–early dry season, and April 2009–late rainy season). The partial pressure of CO2 (pCO2) in surface waters of the main basin of Lake Kivu showed modest spatial (coefficient of variation between 3% and 6%), and seasonal variations with an amplitude of 163 ppm (between 579±23 ppm on average in March 2007 and 742±28 ppm on average in September 2007). The most prominent spatial feature of the pCO2 distribution was the very high pCO2 values in Kabuno Bay (a small sub-basin with little connection to the main lake) ranging between 11213 ppm and 14213 ppm (between 18 and 26 times higher than in the main basin). Surface waters of the main basin of Lake Kivu were a net source of CO2 to the atmosphere at an average rate of 10.8 mmol m−2 d−1, which is lower than the global average reported for freshwater, saline, and volcanic lakes. In Kabuno Bay, the CO2 emission to the atmosphere was on average 500.7 mmol m−2 d−1 (~46 times higher than in the main basin). Based on whole-lake mass balance of dissolved inorganic carbon (DIC) bulk concentrations and of its stable carbon isotope composition, we show that the epilimnion of Lake Kivu was net autotrophic. This is due to the modest river inputs of organic carbon owing to the small ratio of catchment area to lake surface area (2.15). The carbon budget implies that the CO2 emission to the atmosphere must be sustained by DIC inputs of geogenic origin from deep geothermal springs. [less ▲]

Detailed reference viewed: 4 (0 ULg)
Full Text
See detailLake Kivu: food web structure and energy flows
Descy, J-P; Sarmento, H; Isumbisho, P et al

Conference (2013, August 04)

Detailed reference viewed: 33 (0 ULg)
Full Text
Peer Reviewed
See detailIs the fishery of the introduced Tanganyika sardine (Limnothrissa miodon) in Lake Kivu (East Africa) sustainable?
Guillard, J.; Darchambeau, François ULg; Mulungula, P. M. et al

in Journal of Great Lakes Research (2012), 38(3), 524-533

Limnothrissa miodon, a small pelagic clupeid fish introduced at the end of the 1950s into Lake Kivu, became an important resource for the human populations of this area. The total stock of pelagic fish ... [more ▼]

Limnothrissa miodon, a small pelagic clupeid fish introduced at the end of the 1950s into Lake Kivu, became an important resource for the human populations of this area. The total stock of pelagic fish populations of this lake was estimated in 2008 by two hydroacoustic surveys, using an EK60 split-beam sounder (frequency 70. kHz). The total fish stocks were estimated to be approximately 5000. t in the rainy season and 6000 tons in the dry season. These values are similar to previous estimations performed in the 1980s. During 2008, the stock did not fluctuate throughout the seasons; however, the spatial distributions were different in the two hydrological seasons. Interestingly, the L. miodon stock has appeared to remain stable over the last two decades, which suggests that the pelagic fishery in Lake Kivu has not been overexploited and that it is sustainable. © 2012 Elsevier B.V. [less ▲]

Detailed reference viewed: 21 (2 ULg)
Full Text
Peer Reviewed
See detailVariability of carbon dioxide and methane in the epilimnion of Lake Kivu
Borges, Alberto ULg; Bouillon, S.; Abril, G. et al

in Descy, J.-P.; Darchambeau, François; Schmid, M. (Eds.) Lake Kivu: Limnology and biogeochemistry of a tropical great lake (2012)

We report a dataset of the partial pressure of CO2 (pCO2) and me-thane concentrations (CH4) in the surface waters of Lake Kivu ob-tained during four cruises covering the two main seasons (rainy and dry ... [more ▼]

We report a dataset of the partial pressure of CO2 (pCO2) and me-thane concentrations (CH4) in the surface waters of Lake Kivu ob-tained during four cruises covering the two main seasons (rainy and dry). Spatial gradients of surface pCO2 and CH4 concentrations were modest in the main basin. In Kabuno Bay, pCO2 and CH4 concentra-tions in surface waters were higher, owing to the stronger influence of subaquatic springs from depth. Seasonal variations of pCO2 and CH4 in the main basin of Lake Kivu were strongly driven by deepen-ing of the epilimnion and the resulting entrainment of water charac-terized by higher pCO2 and CH4 concentrations. Physical and chem-ical vertical patterns in Kabuno Bay were seasonally stable, owing to a stronger stratification and smaller surface area inducing fetch limi-tation of wind driven turbulence. A global and regional cross-system comparison of pCO2 and CH4 concentrations in surface waters of lakes highlights the peculiarity of Kabuno Bay in terms of pCO2 values in surface waters. In terms of surface CH4 concentrations, both Kabuno Bay and the main basin of Lake Kivu are at the lower end of values in lakes globally, despite the huge amounts of CH4 and CO2 in the deeper layers of the lake. [less ▲]

Detailed reference viewed: 118 (25 ULg)
Full Text
Peer Reviewed
See detailDiet overlap between the newly introduced Lamprichthys tanganicanus and the Tanganyika sardine in Lake Kivu, Eastern Africa
Masilya, M. P.; Darchambeau, François ULg; Isumbisho, M. et al

in Hydrobiologia (2011), 675(1), 75-86

This study evaluates the possible competition for food between Lamprichthys tanganicanus, recently introduced in Lake Kivu, and Limnothrissa miodon, which has been the basis of the pelagic fishery in this ... [more ▼]

This study evaluates the possible competition for food between Lamprichthys tanganicanus, recently introduced in Lake Kivu, and Limnothrissa miodon, which has been the basis of the pelagic fishery in this lake for several decades. Since 2006, L. tanganicanus has expanded in the lake and its numbers have increased in the captures, raising concern for the sardine fishery. We carried out a 2-year monthly survey, based on experimental captures in littoral and pelagic stations, which demonstrated the invasive dispersal of L. tanganicanus in littoral and pelagic waters. The diet of both species was determined on the basis of gut content analyses, taking into account the influence of site and season, and a diet overlap index was calculated. In the pelagic zone, where almost all size classes of both species were present and essentially fed upon mesozooplankton, the diet overlap was high. This situation stems from the fact that L. tanganicanus has colonized the pelagic zone in Lake Kivu, likely in search for more abundant mesozooplankton. Inshore, the diet overlap between the two species was lower, as L. tanganicanus consumed a broad range of food, whereas L. miodon strongly selected insects and, chiefly for the largest specimens, fishes. These results suggest a likelihood of interspecific competition, particularly offshore, where mesozooplankton is the main available food type, and call for further monitoring of the sardine fishery, to assess a possible impact of the invader. © 2011 Springer Science+Business Media B.V. [less ▲]

Detailed reference viewed: 35 (4 ULg)
Full Text
Peer Reviewed
See detailNovel photosynthetic CO2 bioconvertor based on green algae entrapped in low-sodium silica gels
Rooke, J. C.; Léonard, Alexandre ULg; Sarmento, H. et al

in Journal of Materials Chemistry (2011), 21(4), 951-959

A photosynthetic bioreactor for CO2 assimilation has been designed using silica sol-gel immobilisation technologies with the chlorophyta Botryococcus braunii (Kützing) and Chlorella vulgaris (Beijerinck ... [more ▼]

A photosynthetic bioreactor for CO2 assimilation has been designed using silica sol-gel immobilisation technologies with the chlorophyta Botryococcus braunii (Kützing) and Chlorella vulgaris (Beijerinck). The living hybrid gels formed revealed a mesoporosity that enabled diffusion of nutrients and gases, promoting the light and dark photosynthetic reactions from within the bulk of the material. To determine the efficiency of the photosynthetic bioreactor in terms of CO 2 remediation, the activity and viability of the encapsulated cells have been monitored through oximetry, 14C assimilation, pulse amplitude modulation fluorimetry and confocal microscopy, revealing a long term productivity of living hybrid materials capable of photosynthetic processes for at least 80 days. Structural and textural properties of the gels were established through 29Si MAS-NMR and N2 physisorption respectively. © 2011 The Royal Society of Chemistry. [less ▲]

Detailed reference viewed: 18 (0 ULg)
Full Text
Peer Reviewed
See detailVertical distribution of ammonia-oxidizing crenarchaeota and methanogens in the epipelagic waters of Lake Kivu (Rwanda-Democratic Republic of the Congo)
Llirós, M.; Gich, F.; Plasencia, A. et al

in Applied and Environmental Microbiology (2010), 76(20), 6853-6863

Four stratified basins in Lake Kivu (Rwanda-Democratic Republic of theCongo) were sampled in March 2007 to investigate the abundance,distribution, and potential biogeochemical role of planktonic archaea ... [more ▼]

Four stratified basins in Lake Kivu (Rwanda-Democratic Republic of theCongo) were sampled in March 2007 to investigate the abundance,distribution, and potential biogeochemical role of planktonic archaea. We used fluorescence in situ hybridization with catalyzed-reported deposition microscopic counts (CARD-FISH), denaturing gradient gel electrophoresis (DGGE) fingerprinting, and quantitative PCR (qPCR) of signature genes for ammonia-oxidizingarchaea (16S rRNA for marine Crenarchaeota group 1.1a [MCG1] and ammonia monooxygenase subunit A [amoA]). Abundance of archaea ranged from 1 to 4.5% of total DAPI (4'6- diamidino-2-phenylindole) counts with maximal concentrations at theoxic-anoxic transition zone (∼50-m depth). Phylogenetic analysis of the archaeal planktonic community revealed a higher level of richnessof crenarchaeal 16S rRNA gene sequences (21 of the 28 operational taxonomic units [OTUs] identified [75%]) over euryarchaeotal ones (7 OTUs). Sequences affiliated with the kingdom Euryarchaeota were mainly recovered from the anoxic water compartment and mostly grouped into methanogenic lineages (Methanosarcinales and Methanocellales). In turn, crenarchaeal phylotypes were recovered throughout the sampled epipelagic waters (0- to 100-m depth), with clear phylogenetic segregation along the transition from oxic to anoxic water masses. Thus, whereas in the anoxic hypolimnion crenarchaeotal OTUs were mainly assigned to the miscellaneous crenarchaeotic group, the OTUs from the oxic-anoxic transition and above belonged to Crenarchaeota groups 1.1a and 1.1b, two lineages containing most of the ammonia-oxidizing representatives known so far. The concomitant vertical distribution of both nitrite and nitrate maxima and the copy numbers of both MCG1 16S rRNA and amoA genes suggest the potential implication of Crenarchaeota in nitrification processes occurring in the epilimnetic waters of the lake. © 2010, American Society for Microbiology. [less ▲]

Detailed reference viewed: 18 (3 ULg)
Full Text
Peer Reviewed
See detailNovel photobioreactors based on microalgae immobilized in silica gels obtained by "Chimie douce" for biofuel production
Léonard, Alexandre ULg; Rooke, J.; Sarmento, H. et al

in Abstracts of Papers - American Chemical Society, National Meeting (2010)

A new generation of photobioreactors for the clean production of green biofuels is described. It is based on the smart combination of living and inanimate, namely microalgae encapsulated in porous silica ... [more ▼]

A new generation of photobioreactors for the clean production of green biofuels is described. It is based on the smart combination of living and inanimate, namely microalgae encapsulated in porous silica gels. Such hybrid materials would allow for the controlled exploitation of photosynthesis to assimilate atmospheric CO2 and convert it into useful energy sources by using sunlight. The use of biocompatible routes for the immobilization of cyanobacteria has extended the duration of survival up to 40 weeks. [less ▲]

Detailed reference viewed: 38 (0 ULg)
Full Text
Peer Reviewed
See detailCyanobacteria immobilised in porous silica gels: Exploring biocompatible synthesis routes for the development of photobioreactors
Léonard, Alexandre ULg; Rooke, J. C.; Meunier, C. F. et al

in Energy and Environmental Science (2010), 3(3), 370-377

With the aim of designing photobioreactors (PBR) based on a smart exploitation of microalgae for the production of biofuels and metabolites of interest, this paper describes a novel approach where ... [more ▼]

With the aim of designing photobioreactors (PBR) based on a smart exploitation of microalgae for the production of biofuels and metabolites of interest, this paper describes a novel approach where cyanobacteria are entrapped within highly porous silica matrices. With this concept, it would be possible to work with a constant population of organisms for a continuous (and increased) photoproduction of metabolites, in contrast to "one-shot" uses of liquid cultures. Different hybrid materials based on porous silica gels are described with a special emphasis on finding the most appropriate immobilisation conditions for prolonged cell survival. It is found that an aqueous route based on acid-exchanged sodium silicate combined with the use of silica nanoparticles as a gel-strengthening species shows the best results with a high primary production rate post immobilisation and a preservation of the photosynthetic pigments of up to 35 weeks. Oxygen production, though very low, could be evidenced up to 17 weeks after entrapment, demonstrating the suitability of using porous silica matrices in PBR design. © 2010 The Royal Society of Chemistry. [less ▲]

Detailed reference viewed: 7 (2 ULg)
Full Text
Peer Reviewed
See detailHybrid photosynthetic materials derived from microalgae Cyanidium caldarium encapsulated within silica gel
Rooke, J. C.; Léonard, Alexandre ULg; Meunier, C. F. et al

in Journal of Colloid & Interface Science (2010), 344(2), 348-352

Cyanidium caldarium (Tilden) Geitler SAG 16.91 has been encapsulated within a porous silica host structure to target novel photosynthetic hybrid materials suitable for use in solar cells or CO2 fixation ... [more ▼]

Cyanidium caldarium (Tilden) Geitler SAG 16.91 has been encapsulated within a porous silica host structure to target novel photosynthetic hybrid materials suitable for use in solar cells or CO2 fixation. C. caldarium cells are both thermophilic and acidophilic; on account of these tolerances the hybrid materials could be employed in more extreme heat conditions. TEM highlights that the external cell membrane can remain intact after encapsulation. The images reveal an alignment of silica gel around the external membrane of the cell, providing evidence that the cell wall acts as both a nucleation and polymerisation site for silica species and that the silica scaffold formed by the aggregation of colloidal particles, generates a porosity that can facilitate the transport of nutrients towards the cell. Epifluorescence microscopy and UV-visible spectroscopy have revealed the preservation of photosynthetic apparatus post-immobilisation. Productivity studies showed how the presence of silica nanoparticles within the matrix can adversely interact with the exterior cellular structures preventing the production of oxygen through photosynthesis. © 2009 Elsevier Inc. All rights reserved. [less ▲]

Detailed reference viewed: 8 (0 ULg)