References of "Champenois, Willy"
     in
Bookmark and Share    
Full Text
See detailCorrelation between the acoustic noise field measured in a Posidonia oceanica bed and the photosynthetic activity
Felisberto, P; Zabel, F; Rodriguez, O et al

Poster (2014, May 05)

Detailed reference viewed: 12 (2 ULg)
Full Text
See detailUsing active and passive acoustics to assess O2 production of a Posidonia oceanica meadow
Felisberto, P; Zabel, F; Rodriguez, O et al

Poster (2014, March 04)

Detailed reference viewed: 6 (0 ULg)
See detailYear Round survey of Ocean-Sea Ice-Air Exchanges – the YROSIAE survey
Delille, Bruno ULg; Haskell, T.; Champenois, Willy ULg et al

Conference (2014, March)

YROSIAE survey aimed to carry out a year-round survey of land-fast sea ice focusing on the study of sea ice physics and biogeochemistry in order to a) better understand and budget exchanges of energy and ... [more ▼]

YROSIAE survey aimed to carry out a year-round survey of land-fast sea ice focusing on the study of sea ice physics and biogeochemistry in order to a) better understand and budget exchanges of energy and matter across the ocean-sea ice-atmosphere interfaces during sea ice growth and decay and b) quantify their potential impact on fluxes of climate gases (CO2, DMS, CH4, N2O) to the atmosphere and on carbon and macro- nutrients and micro-nutrients export to the ocean. Ice cores, sea water, brines and exported material were collected at regular intervals about 1 km off cape Evans from November 2011 to December 2011 and from September 2012 to December 2012 in trace-metal clean conditions. Samples are processed to characterize both the vertical distribution and temporal changes of climate gases (CO2, DMS, CH4, N2O), CO2-related parameters (dissolved inorganic carbon, total alkalinity and CaCO3 amount), physical parameters (salinity, temperature, texture, 18O), biogeochemical parameters (macro-nutrients, particulate and dissolved organic carbon, δ13C, δ30Si and δ15N, micro-nutrients - including iron) and biological parameters ( chlorophyll a, primary production within sea ice derived from O2:Ar and O2:N ratios, autotrophic species determination, bacterial cell counts a.s.o.). In addition, we deployed a micro-meterological tower and automatic chambers to measure air-ice CO2 fluxes. Continuous measurements of ice temperature and ice accretion or melting, both at the ice-ocean and the ice-atmosphere interfaces were provided by an “Ice-T” ice mass balance buoy. Sediment traps collected particles below the ice between 10 and 70 m, while dust collectors provided a record of a full suite of trace metal and dust at different levels above the ground. We will present the aims, overall approach and sampling strategy of the YROSIAE survey. In addition we will also discuss CO2 dynamics within the ice and present temporal air-ice CO2 fluxes over the year. We will provide a first budget of air-ice CO2 fluxes during ice growth for Antarctica sea ice and discuss the impact of the snow cover on air-ice CO2 fluxes. [less ▲]

Detailed reference viewed: 30 (5 ULg)
See detailLand-fast sea ice of McMurdo Sound as a source of bio-essential trace metals for primary productivity in the Ross Sea, Antarctica
Schoemann, V.; de Jong, J.T.M.; Tison, J.L. et al

Conference (2014, March)

Iron (Fe) is an essential micronutrient. Its low abundance limits primary productivity in more than 30% of the oceans, including the Southern Ocean, and has a crucial impact on the biogeochemical cycles ... [more ▼]

Iron (Fe) is an essential micronutrient. Its low abundance limits primary productivity in more than 30% of the oceans, including the Southern Ocean, and has a crucial impact on the biogeochemical cycles of carbon and other elements with ultimate influence on the Earth climate system. Other trace metals, like Mn, Zn, Co and Cu are also required for microorganisms cell metabolism and may be (co-) limiting. Previous data on dissolved and particulate Fe concentration data showed that Fe is 10-100 times more concentrated in the sea ice than in underlying seawater and that sea ice melt can deliver up to 70% of the daily Fe supply to the surface waters. According to budget estimates in East Antarctica and in the Weddell Sea, accumulated Fe would largely derive from the underlying seawater rather than from atmospheric inputs. Most of the available data of trace metals in the sea ice concern pack ice and Fe. Only very scarce data exist on land-fast ice and on other trace metal concentrations. In this presentation, the general objective is to assess the role of land-fast ice as a source of Fe and other bio-essential trace metals (e.g. Mn, Zn, Cu, Mo, Cd), its impact on primary productivity and on the biological pump. Samples of sea ice, brines and seawater as well as dusts samples have been collected during the land-based sampling program YROSIAE at Cape Evans (Scott Base, McMurdo Sound, Ross Sea, Antarctica) from Nov 2011 to Dec 2011 and from Aug 2012 to Dec 2012. Dissolved and particulate trace metals concentrations have been measured by a recently developed method, which combines multiple element isotope dilution with preconcentration using the Nobias Chelate PA1 resin and ICP-MS analysis. Concentrations of trace metals in snow collected during the present study are one to up to five orders of magnitude higher than the concentrations previously observed in snow from East Antarctica, showing a much stronger dust input of these metals in McMurdo Sound. When comparing the concentrations obtained in the under-ice seawater with those obtained in the snow at McMurdo Sound, concentrations of Fe, Al, Mn, Co are much lower, whereas concentrations of Cu, Zn and Pb are similar and the concentrations of Ni, Mo and Cd are higher. Inventories of these trace metals in the land-fast sea ice give insights on its role as a source of bio-essential trace metal for the fuelling of the seasonal Ross Sea bloom. Other sources of these trace metals will be addressed and compared. [less ▲]

Detailed reference viewed: 64 (7 ULg)
Full Text
See detailSeagrass production: linking individual, community and ecosystem carbon fluxes
Santos, R; Silva, J; Olivé, I et al

Conference (2013)

Detailed reference viewed: 17 (1 ULg)
Full Text
Peer Reviewed
See detailEstablishing research strategies, methodologies and technologies to link genomics and proteomics to seagrass productivity, community metabolism, and ecosystem carbon fluxes
Mazzuca, Silvia; Bjork, M; Beer, S et al

in Frontiers in Plant Science (2013), 4(38), 1-19

A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research.This enables the prediction of change and possibly the ... [more ▼]

A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research.This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 “Seagrasses productivity. From genes to ecosystem management,” is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwa- ter acoustics) gathered at The Station de Recherches Sous-marines et Océanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as “pristine site” where environmental distur- bances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general. [less ▲]

Detailed reference viewed: 63 (14 ULg)
Full Text
See detailStare-Capmed : Présentation générale du projet et exemple d'une action : "Impact de l'ancrage sur la dynamique des herbiers de posidonies".
Michel, Loïc ULg; Champenois, Willy ULg; Borges, Alberto ULg et al

Conference (2012, May 16)

STARE-CAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) est un projet de recherche mis en place par Stareso S.A.S. depuis ... [more ▼]

STARE-CAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) est un projet de recherche mis en place par Stareso S.A.S. depuis janvier 2012. Il a pour objectif d’établir un site de référence à long terme pour la compréhension, par la recherche fondamentale, des processus de l’évolution des écosystèmes méditerranéens côtiers et océaniques en réponse aux changements actuels globaux et locaux des pressions anthropiques. Centré sur la Baie de Calvi et le proche large, il vise à fournir un référentiel basé sur des mesures à haute fréquence qui doivent pouvoir complémenter les réseaux de surveillance basse fréquence et de recherches existants et ainsi faire progresser la compréhension des processus. En outre, le projet doit fournir aux utilisateurs finaux (collectivités locales et régionales, administrations nationales, ...) des orientations de gestion basées sur l’analyse étayée des processus en jeux. Financé par l’Agence de l’eau RMC et la Collectivité Territoriale de Corse, le projet, multidisciplinaire, se décline actuellement selon 10 axes de travail : • Suivi du cadre hydrographique et physico-chimique • Suivi et quantification des pressions anthropiques • Ecosystème planctonique • Benthos de substrat meuble • Benthos de substrat dur et faune vagile • Phanérogames marines et écosystèmes associés • Mouillages et processus d’altération des herbiers de posidonies • Ecotoxicologie et polluants émergents • Bilan CO2 et métabolisme des écosystèmes • Zones protégées, espèces nouvelles, recrutement Pour chacun de ces axes, la stratégie d’échantillonnage est basée sur la comparaison de données obtenues durant des périodes où l’impact anthropique est faible (octobre-avril) avec celles obtenues durant des périodes de pression intense (mai-septembre), et sur la comparaison de données issues de sites de référence peu impactés avec celles provenant de sites où l’impact anthropique est reconnu. A titre d’exemple, le but de l’action "Mouillages et processus d’altération des herbiers de posidonies" est de mettre en évidence les conséquences des altérations liées à l’arrachage de faisceaux de posidonies sur la vitalité de l’herbier. Des zones où la pression de mouillage est reconnue seront définies sur base des travaux de cartographie de l’herbier, également réalisés dans le cadre du projet STARE-CAPMED. Elles seront comparées avec des zones d’herbiers sains témoins par la caractérisation du sédiment (mesures de compacité in situ, mesures des concentrations en O2 et nutriments et du pH de l’eau interstitielle, granulométrie et teneur en matière organique du sédiment, proportions de rhizomes et morts) ainsi que par la définition de l’état physiologique des faisceaux de posidonies (mesures biométriques classiques, analyses des contenus élémentaires en carbone, azote et phosphore) et par l’application d’indices écologiques définis par la DCE (PREI, BIPO, …). Les résultats obtenus permettront d’avoir une vue d’ensemble des processus par lesquels l’impact physique des mouillages de bateaux de plaisance occasionne des dégâts aux herbiers de posidonies. Ils pourront ainsi fournir une base de connaissances solide aux gestionnaires soucieux de limiter cet impact. [less ▲]

Detailed reference viewed: 224 (32 ULg)
See detailFluxes of dimethylsulfide from warming sea ice
Carnat, Gauthier; Zhou, Jiayun; Papakyriakou, Tim et al

Poster (2012, May)

Detailed reference viewed: 11 (0 ULg)
Full Text
See detailA descriptive study of physico-chemical characteristics of Posidonia oceanica litter accumulation
Lepoint, Gilles ULg; Borges, Alberto ULg; Darchambeau, François ULg et al

Poster (2012)

The Mediterranean seagrass Posidonia oceanica meadow losses every fall the major part of its leaf biomass after senescing. These phytodetritus may decay within the meadow, be buried or be exported to ... [more ▼]

The Mediterranean seagrass Posidonia oceanica meadow losses every fall the major part of its leaf biomass after senescing. These phytodetritus may decay within the meadow, be buried or be exported to other habitats. They form large litter accumulations, notably on shallow water sand patches. Such accumulation host many organisms which participate to the degradation of this material. In a first step to understand the dynamics of these accumulations and of their associated biota, we have characterised their physico-chemical heterogeneity at different seasons. We measured the dissolved oxygen, nutrients and sulphide concentrations in interstitial waters from litter accumulations varying regarding their phytodetritus composition, fragmentation level and thickness. Results show that oxygen conditions were highly variable depending on litter thickness but also on local hydrodynamics. Anoxic conditions and presence of sulphide were sometimes measured, particularly in very thick litter or in degraded litter at the end of summer. Colonies of sulphur-oxidising bacteria were observed. Litter accumulations were also often enriched in ammonium and, sometimes, in dissolved phosphorus. It is not clear whether this results from the litter degradation within the accumulation or whether this is a consequence of a barrier effect between sediment and water column. Nevertheless, this makes litter accumulations particularly attractive for micro-phytobenthic producers. Litter accumulations appear as key habitats both to understand the dead-face of seagrass dynamics and its consequence for C cycle in coastal areas and to study the consequence of hypoxia on biodiversity in a natural context. [less ▲]

Detailed reference viewed: 47 (9 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: 115 (25 ULg)
Full Text
Peer Reviewed
See detailSeasonal and interannual variations of community metabolism rates of a Posidonia oceanica seagrass meadow
Champenois, Willy ULg; Borges, Alberto ULg

in Limnology & Oceanography (2012), 57(1), 347-361

We report gross primary production (GPP), community respiration (CR), and net community production (NCP) over a Posidonia oceanica meadow at 10 m in Corsica (Bay of Revellata) based on the open water O2 ... [more ▼]

We report gross primary production (GPP), community respiration (CR), and net community production (NCP) over a Posidonia oceanica meadow at 10 m in Corsica (Bay of Revellata) based on the open water O2 mass balance from a data set of hourly measurements with an array of three O2 optodes deployed from August 2006 to October 2009. The method was checked by comparison with discrete measurements of metabolic rates derived from benthic chamber incubations also based on the diel change of O2. This comparison was satisfactory and actually highlights the potential caveats of benthic incubation measurements related to O2 accumulation in small chambers leading to photorespiration and an underestimation of GPP. Our data confirmed previous P. oceanica meadows GPP and CR values, strong seasonal variations, and net autotrophy. High-resolution data revealed strong interannual variability, with a decrease of GPP by 35% and NCP by 87% during 2006-2007 characterized by a mild and less stormy winter compared with 2007-2008 and 2008-2009. P. oceanica meadows are then expected to decrease export of organic carbon to adjacent communities (decrease of NCP), since a decrease in frequency and intensity of marine storms is expected in the future in the Mediterranean Sea as a result of a northward shift of the Atlantic storm track. [less ▲]

Detailed reference viewed: 205 (27 ULg)