Consulta: creatorFacets:"Van Wambeke, France"
Registros recuperados: 20
Data/hora: 09/06/2024 03:48:55

Impact of dust addition on the metabolism of Mediterranean plankton communities and carbon export under present and future conditions of pH and temperature
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Gazeau, Frédéric; Van Wambeke, France; Maranon, Emilio; Perez-lorenzo, Maria; Alliouane, Samir; Stolpe, Christian; Blasco, Thierry; Leblond, Nathalie; Zancker, Birthe; Engel, Anja; Marie, Barbara; Dinasquet, Julie; Guieu, Cécile.
Although atmospheric dust fluxes from arid as well as human-impacted areas represent a significant source of nutrients to surface waters of the Mediterranean Sea, studies focusing on the evolution of the metabolic balance of the plankton community following a dust deposition event are scarce and none were conducted in the context of projected future levels of temperature and pH. Moreover, most of the experiments took place in coastal areas. In the framework of the PEACETIME project, three dust-addition perturbation experiments were conducted in 300-L tanks filled with surface seawater collected in the Tyrrhenian Sea (TYR), Ionian Sea (ION) and in the Algerian basin (FAST) onboard the R/V “Pourquoi Pas?” in late spring 2017. For each experiment, six tanks...
Tipo: Text
Palavras-chave: Mediterranean Sea; Atmospheric deposition; Plankton community metabolism; Carbon export; Ocean acidification; Ocean warming.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00688/79967/82900.pdf

Vertical and longitudinal gradients in HNA-LNA cell abundances and cytometric characteristics in the Mediterranean Sea
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Van Wambeke, France; Catala, P.; Pujo-pay, M.; Lebaron, P.
Heterotrophic bacterioplankton abundance and production were investigated with depth (down to bathypelagic layers) and with longitude (from 4.9 degrees E to 32.7 degrees E) along a cruise track across the Mediterranean Sea in early summer 2008. Abundances and flow cytometric characteristics (green fluorescence and side scatter signals) of high nucleic acid (HNA) and low nucleic acid (LNA) bacterial cells were determined using flow cytometry. Contrary to what is generally observed, the relative importance of HNA cells, as a percent of total cells, (%HNA, range 30-69%) was inversely related to bacterial production (range 0.15-44 ngC l(-1) h(-1)) although the negative relation was weak (log-log regression r(2) = 0.19). The %HNA as well as the mean side...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00133/24390/22404.pdf

Introduction to the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM) experiment
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Moutin, T.; Van Wambeke, France; Prieur, L.
The overall goal of the BOUM (Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean) experiment was to obtain a better representation of the interactions between planktonic organisms and the cycle of biogenic elements in the Mediterranean Sea (MS), in the context of global climate change and, more particularly, on the role of the ocean in carbon sequestration through biological processes. The BOUM experiment was organized around three main objectives: (1) to give a longitudinal description of the biogeochemistry and the biological diversity of the MS during the strongest stratified period, (2) to study processes at the centre of three anticyclonic eddies, and (3) to obtain a representation of the main biogeochemical fluxes and the...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00133/24384/22400.pdf

Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Van Wambeke, France; Taillandier, Vincent; Deboeufs, Karine; Pullido-villena, Elvira; Dinasquet, Julie; Engel, Anja; Maranon, Emilio; Ridame, Céline; Guieu, Cécile.
The surface mixed layer (ML) in the Mediterranean Sea is a well stratified domain characterized by low macro-nutrient and low chlorophyll content, during almost 6 months of the year. Nutrient dynamics in the ML depend on allochthonous inputs, through atmospheric deposition and on biological recycling. Here we characterize the biogeochemical cycling of N in the ML by combining simultaneous in situ measurements of atmospheric deposition, nutrients, hydrological conditions, primary production, heterotrophic prokaryotic production, N2 fixation and leucine aminopeptidase activity. The measurements were conducted along a 4300 km transect across the central and western open Mediterranean Sea in spring 2017. Dry deposition was measured on a continuous basis while...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00659/77153/78527.pdf

Sensitive Determination of the Dissolved Phosphate Pool for an Improved Resolution of Its Vertical Variability in the Surface Layer: New Views in the P-Depleted Mediterranean Sea
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Djaoudi, Kahina; Van Wambeke, France; Coppola, Laurent; D'Ortenzio, Fabrizio; Helias-nunige, Sandra; Raimbault, Patrick; Taillandier, Vincent; Testor, Pierre; Wagener, Thibaut; Pulido-villena, Elvira.
An accurate understanding of the biogeochemistry of dissolved phosphate pool in the upper waters of P-depleted oceanic regions is constrained by the low sensitivity of routine phosphate measurements. In this study, by using the sensitive Liquid Waveguide Capillary Cell method, we report the first extensive cross-basin survey of nanomolar dissolved inorganic phosphate (DIP) and dissolved organic phosphate (DOP) concentration in P-depleted surface waters of the Mediterranean Sea during the stratification period. In the north western Mediterranean Sea (NWMS), DIP above the mixed layer depth (MLD) ranged between 4.9 and 26.5 nM. Along an E-W transect crossing Ionian and Tyrrhenian Seas (E-W transect), DIP above the MLD was lower, ranging between 0.9 and 11.4...
Tipo: Text
Palavras-chave: The Mediterranean Sea; Dissolved inorganic phosphate; Dissolved organic phosphate; N:P ratios; Liquid waveguide capillary cell.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00450/56184/57731.pdf

Evolution of dissolved and particulate chromophoric materials during the VAHINE mesocosm experiment in the New Caledonian coral lagoon (south-west Pacific)
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Tedetti, Marc; Marie, Lauriane; Roettgers, Ruediger; Rodier, Martine; Van Wambeke, France; Helias, Sandra; Caffin, Mathieu; Cornet-barthaux, Veronique; Dupouy, Cecile.
In the framework of the VAHINE project, we investigated the spectral characteristics and the variability of dissolved and particulate chromophoric materials throughout a 23-day mesocosm experiment conducted in the south-west Pacific at the mouth of the New Caledonian coral lagoon (22 degrees 29.073 S-166 degrees 26.905 E) from 13 January to 4 February 2013. Samples were collected in a mesocosm fertilized with phosphate at depths of 1, 6 and 12m and in the surrounding waters. Light absorption coefficients of chromophoric dissolved organic matter (CDOM) [a(g) (lambda)] and particulate matter [a(p) (lambda)] were determined using a point-source integrating-cavity absorption meter (PSICAM), while fluorescent DOM (FDOM) components were determined from...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00348/45893/45572.pdf

The composition and distribution of semi-labile dissolved organic matter across the southwest Pacific
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Panagiotopoulos, Christos; Pujo Pay, Mireille; Benavides, Mar; Van Wambeke, France; Sempéré, Richard.
The distribution and dynamics of dissolved organic carbon (DOC) and dissolved combined neutral sugars (DCNS) were studied across an increasing oligotrophic gradient (−18 to −22°N latitude) spanning from the Melanesian Archipelago (MA) area to the western part of the south Pacific gyre (WGY), in austral summer, as a part of the OUTPACE project. Our results showed DOC and DCNS concentrations exhibited little differences among the MA and WGY areas (0–200m: 55–78µMC for DOC and 1.5–2µMC for DCNS), however, a deeper penetration of DOC was noticeable at 150m depth at the WGY area. This finding was also reflected to the DOC and semi-labile DOC (DOCSL) stocks values (integration 0–200m) for which we found higher values in the WGY than the MA area. The high excess...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00448/56008/57517.pdf

Microbial food webs and metabolic state across oligotrophic waters of the Mediterranean Sea during summer
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Christaki, U.; Van Wambeke, France; Lefevre, D.; Lagaria, A.; Prieur, L.; Pujo-pay, M.; Grattepanche, J. -d.; Colombet, J.; Psarra, S.; Dolan, J. R.; Sime-ngando, T.; Conan, Pascal; Weinbauer, M. G.; Moutin, T.
The abundance and activity of the major members of the heterotrophic microbial community - from viruses to ciliates - were studied along a longitudinal transect across the Mediterranean Sea in the summer of 2008. The Mediterranean Sea is characterized by a west to east gradient of deepening of DCM (deep chlorophyll maximum) and increasing oligotrophy reflected in gradients of biomass and production. However, within this well documented longitudinal trend, hydrological mesoscale features exist and likely influence microbial dynamics. Here we present data from a W-E transect of 17 stations during the period of summer stratification. Along the transect the production and fate of organic matter was investigated at three selected sites each one located in the...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00133/24400/22422.pdf

Potential bioavailability of organic matter from atmospheric particles to marine heterotrophic bacteria
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Djaoudi, Kahina; Van Wambeke, France; Barani, Aude; Bhairy, Nagib; Chevaillier, Servanne; Desboeufs, Karine; Nunige, Sandra; Labiadh, Mohamed; Des Tureaux, Thierry Henry; Lefevre, Dominique; Nouara, Amel; Panagiotopoulos, Christos; Tedetti, Marc; Pulido-villena, Elvira.
The surface ocean receives important amounts of organic carbon from atmospheric deposition. The degree of bioavailability of this source of organic carbon will determine its impact on the marine carbon cycle. In this study, the potential availability of dissolved organic carbon (DOC) leached from both desert dust and anthropogenic aerosols to marine heterotrophic bacteria was investigated. The experimental design was based on 16 d incubations, in the dark, of a marine bacterial inoculum into artificial seawater amended with water-soluble Saharan dust (D treatment) and anthropogenic (A treatment) aerosols, so that the initial DOC concentration was similar between treatments. Glucose-amended (G) and non-amended (control) treatments were run in parallel. Over...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00677/78941/81326.pdf

Lack of P-limitation of phytoplankton and heterotrophic prokaryotes in surface waters of three anticyclonic eddies in the stratified Mediterranean Sea
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00133/24395/22406.pdf

Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Lamy, D.; Jeanthon, C.; Cottrell, M. T.; Kirchman, D. L.; Van Wambeke, France; Ras, J.; Dahan, O.; Pujo-pay, M.; Oriol, L.; Bariat, L.; Catala, P.; Cornet-barthaux, V.; Lebaron, P.
Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00133/24398/22417.pdf

Heterotrophic bacterial production and metabolic balance during the VAHINE mesocosm experiment in the New Caledonia lagoon
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Van Wambeke, France; Pfreundt, Ulrike; Barani, Aude; Berthelot, Hugo; Moutin, Thierry; Rodier, Martine; Hess, Wolfgang R.; Bonnet, Sophie.
Studies investigating the fate of diazotrophs through the microbial food web are lacking, although N2 fixation can fuel up to 50 % of new production in some oligotrophic oceans. In particular, the role played by heterotrophic prokaryotes in this transfer is largely unknown. In the frame of the VAHINE (VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific) experiment, three replicate large-volume (∼ 50 m3) mesocosms were deployed for 23 days in the new Caledonia lagoon and were intentionally fertilized on day 4 with dissolved inorganic phosphorus (DIP) to stimulate N2 fixation. We specifically examined relationships between heterotrophic bacterial production (BP) and N2 fixation or primary production, determined...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00342/45331/44792.pdf

Flow cytometric assessment of specific leucine incorporation in the open Mediterranean
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00133/24394/22407.pdf

Microbial community structure in the Western Tropical South Pacific
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bock, Nicholas; Van Wambeke, France; Dion, Moira; Duhamel, Solange.
Accounting for 40 percent of the earth's surface, oligotrophic regions play an important role in global biogeochemical cycles, with microbial communities in these areas representing an important term in global carbon budgets. While the general structure of microbial communities has been well documented in the global ocean, some remote regions such as the Western Tropical South Pacific (WTSP), remain fundamentally unexplored. Moreover, the biotic and abiotic factors constraining microbial abundances and distribution remain not-well resolved. In this study, we quantified the spatial (vertical and horizontal) distribution of major microbial plankton groups along a transect through the WTSP during the austral summer of 2015, capturing important autotrophic and...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00425/53674/54517.pdf

Organic carbon dynamics in the Mediterranean Sea: An integrated study
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Santinelli, Chiara; Sempere, Richard; Van Wambeke, France; Charriere, Bruno; Seritti, Alfredo.
Total (TOC) and dissolved (DOC) organic carbon vertical profiles were analyzed from 11 stations located in various regions of the Mediterranean Sea, together with the distribution of other physical, chemical and biological parameters. TOC showed the highest concentrations (68-83 mu M) above the pycnocline, followed by a marked decrease to values of 45-48 mu M at 100-200 m. Below 200 m, values of 40-45 mu M were observed. The excess TOC and DOC occurring at each station was calculated by subtracting 48 mu M from the observed concentrations. The stock of the excess TOC and DOC increased eastward; while surface DOC mineralization rates decreased from 1.5 mu M d(-1) to 0.26 mu M d(-1) eastward. The integrated average of the biological parameters in the...
Tipo: Text
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00601/71278/69686.pdf

Spatial patterns of ectoenzymatic kinetics in relation to biogeochemical properties in the Mediterranean Sea and the concentration of the fluorogenic substrate used
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00642/75452/76268.pdf

Impact of dust enrichment on Mediterranean plankton communities under present and future conditions of pH and temperature: an experimental overview
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00688/80015/82994.pdf

Mediterranean nascent sea spray organic aerosol and relationships with seawater biogeochemistry
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Freney, Evelyn; Sellegri, Karine; Nicosia, Alessia; Trueblood, Jonathan T; Rinaldi, Matteo; Williams, Leah R; Prévôt, André Sh; Thyssen, Melilotus; Gregori, Gerald; Haëntjens, Nils; Dinasquet, Julie; Obernosterer, Ingrid; Van Wambeke, France; Engel, Anja; Zancker, Birthe; Desboeufs, Karine; Asmi, Eija; Timmonen, Hilka; Guieu, Cécile.
The organic mass fraction from sea spray aerosol (SSA) is currently a subject of intense research. The majority of this research is dedicated to measurements in ambient air, although recently a small number of studies have additionally focused on nascent sea spray aerosol. This work presents measurements collected during a five-week cruise in May and June 2017 in the central and western Mediterranean Sea, an oligotrophic marine region with low phytoplankton biomass. Surface seawater was continuously pumped into a bubble bursting apparatus to generate nascent sea spray aerosol. Size distributions were measured with a differential mobility particle sizer (DMPS). Chemical characterization of the submicron aerosol was performed with a time of flight aerosol...
Tipo: Text
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00688/80017/82995.pdf

Dynamics and controls of heterotrophic prokaryotic production in the western tropical South Pacific Ocean: links with diazotrophic and photosynthetic activity
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Van Wambeke, France; Gimenez, Audrey; Duhamel, Solange; Dupouy, Cecile; Lefevre, Dominique; Pujo-pay, Mireille; Moutin, Thierry.
Heterotrophic prokaryotic production (BP) was studied in the western tropical South Pacific (WTSP) using the leucine technique, revealing spatial and temporal variability within the region. Integrated over the euphotic zone, BP ranged from 58 to 120 mg C m−2 d−1 within the Melanesian Archipelago, and from 31 to 50 mg C m−2 d−1 within the western subtropical gyre. The collapse of a bloom was followed during 6 days in the south of Vanuatu using a Lagrangian sampling strategy. During this period, rapid evolution was observed in the three main parameters influencing the metabolic state: BP, primary production (PP) and bacterial growth efficiency. With N2 fixation being one of the most important fluxes fueling new production, we explored relationships between...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00448/56007/57515.pdf

The effects of nutrient additions on particulate and dissolved primary production and metabolic state in surface waters of three Mediterranean eddies
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00133/24401/22418.pdf