Consulta: creatorFacets:"Rodier, Martine"
Registros recuperados: 14
Data/hora: 07/06/2024 01:59:34

Seasonal dynamics and disturbance of phytoplankton biomass in the wake of Tahiti as observed by Biogeochemical-Argo floats
Provedor de dados: 5
Autores: Sauzède, Raphaëlle; Martinez, Elodie; Pasqueron De Fommervault, Orens; Poteau, Antoine; Mignot, Alexandre; Maes, Christophe; Claustre, Hervé; Uitz, Julia; Maamaatuaiahutapu, Keitapu; Rodier, Martine; Schmechtig, Catherine; Laurent, Victoire.
The South Pacific Subtropical Gyre (SPSG) is a vast and remote area where large uncertainties on variability in phytoplankton biomass and production remain due to the lack of biogeochemical in situ observations. In such oligotrophic environments, ecosystems are predominantly controlled by nutrients depletion in surface waters. However, this oligotrophic character can be disturbed in the vicinity of islands where enhancement of biological activity is known to occur (i.e. the island mass effect, IME). This study mainly focuses on in situ observations showing that an IME can be evidenced leeward of Tahiti (17.7° S–149.5° W), French Polynesia. Concomitant physical and biogeochemical observations collected with two Biogeochemical-Argo (BGC-Argo) profiling...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00421/53295/54108.pdf

Impact of Contrasted Weather Conditions on CDOM Absorption/Fluorescence and Biogeochemistry in the Eastern Lagoon of New Caledonia
Provedor de dados: 5
Autores: Dupouy, Cécile; Röttgers, Rüdiger; Tedetti, Marc; Frouin, Robert; Lantoine, François; Rodier, Martine; Martias, Chloe; Goutx, Madeleine.
New Caledonia (Southwest Pacific), like all tropical Pacific Island countries, is impacted by weather events, climate change, and local anthropogenic forcing. Strong erosion of particles and dissolved organic matter (DOM) from ultramafic rocks, associated with trace metals dissemination (i.e., nickel, manganese and cobalt), potentially affects lagoon waters and coral reefs surrounding the main island. The CALIOPE (CALedonian Inherent Optical PropErties) cruises were performed along the Eastern Lagoon of New Caledonia (ELNC) (400 km, 13 transects from Bay to open ocean, 51 stations) during contrasted meteorological conditions: a dry period (October 2011), a windy situation (March 2014), and a strong rainy event (March 2016). CDOM absorption and fluorescence...
Tipo: Text
Palavras-chave: Chromophoric dissolved organic matter; Fluorescence; New Caledonia; Tropical Pacific; Lagoons; Biooptics; Phytoplankton; Rivers.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00620/73166/72352.pdf

Diazotrophic Trichodesmium impact on UV-Vis radiance and pigment composition in the western tropical South Pacific
Provedor de dados: 5
Autores: Dupouy, Cecile; Frouin, Robert; Tedetti, Marc; Maillard, Morgane; Rodier, Martine; Lombard, Fabien; Guidi, Lionel; Picheral, Marc; Neveux, Jacques; Duhamel, Solange; Charriere, Bruno; Sempere, Richard.
We assessed the influence of the marine diazotrophic cyanobacterium Trichodesmium on the bio-optical properties of western tropical South Pacific (WTSP) waters (18-22 degrees S, 160 degrees E-160 degrees W) during the February-March 2015 OUTPACE cruise. We performed measurements of backscattering and absorption coefficients, irradiance, and radiance in the euphotic zone with a Satlantic MicroPro free-fall profiler and took Underwater Vision Profiler 5 (UPV5) pictures for counting the largest Trichodesmium spp. colonies. Pigment concentrations were determined by fluorimetry and high-performance liquid chromatography and picoplankton abundance by flow cytometry. Trichome concentration was estimated from pigment algorithms and validated by surface visual...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00457/56824/58659.pdf

Seasonal Shifts in Diazotrophs Players: Patterns Observed Over a Two-Year Time Series in the New Caledonian Lagoon (Western Tropical South Pacific Ocean)
Provedor de dados: 5
Autores: Saulia, Emmrick; Benavides, Mar; Henke, Britt; Turk-kubo, Kendra; Cooperguard, Haley; Grosso, Olivier; Desnues, Anne; Rodier, Martine; Dupouy, Cécile; Riemann, Lasse; Bonnet, Sophie.
Coastal and open ocean regions of the Western Tropical South Pacific ocean have been identified as a hotspot of N2 fixation. However, the environmental factors driving the temporal variability of abundance, composition, and activity of diazotrophs are still poorly understood, especially during the winter season. To address this, we quantified N2 fixation rates and the abundance of seven diazotroph phylotypes (UCYN-A1 symbiosis, UCYN-B, UCYN-C, Trichodesmium, Het-1, Het-2, and Het-3) on a monthly basis during two full years (2012 to 2014) at four stations along a coast to open ocean transect in the New Caledonian lagoon. The total nifH gene concentration (sum of all nifH gene copies) clearly decreased from the barrier reef to the shore. Apart from UCYN-B,...
Tipo: Text
Palavras-chave: N-2 fixation; Diazotrophs; NifH; Abundance; New Caledonia.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00658/77027/78307.pdf

Modelling N2 fixation related to Trichodesmium sp.: driving processes and impacts on primary production in the tropical Pacific Ocean
Provedor de dados: 5
Autores: Dutheil, Cyril; Aumont, Olivier; Gorgues, Thomas; Lorrain, Anne; Bonnet, Sophie; Rodier, Martine; Dupouy, Cecile; Shiozaki, Takuhei; Menkes, Christophe.
Dinitrogen fixation is now recognized as one of the major sources of bio-available nitrogen in the ocean. Thus, N2 fixation sustains a significant part of the global primary production by supplying the most common limiting nutrient for phytoplankton growth. The Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) improved the data coverage of the western tropical South Pacific, an area recently recognized as a hotspot of N2 fixation. This new development leads us to develop and test an explicit N2 fixation formulation based on the Trichodesmium physiology (the most studied nitrogen fixer) within a 3-D coupled dynamical–biogeochemical model (ROMS-PISCES). We performed a climatological numerical simulation that is able to reproduce the main physical...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00419/53042/53979.pdf

Temporal variability in dissolved inorganic nitrogen fluxes at the sediment-water interface and related annual budget on a continental shelf (NW Mediterranean)
Provedor de dados: 5
Autores: Denis, Lionel; Grenz, Christian; Alliot, Elisabeth; Rodier, Martine.
Sediment-water dissolved inorganic nitrogen fluxes were measured monthly between November 1997 and January 1999 at two sites on the continental shelf in the Gulf of Lions. Exchanges of ammonium, nitrate and nitrite were measured using whole core incubations performed in the laboratory at in situ temperature and in the dark;. Stations were located on the shelf and near the shelf break. Nitrate release represented the major part of total dissolved inorganic nitrogen fluxes (52-98%). At station Soft, nitrate flux doubled from winter-early spring to August (4 to 10 mu mol m(-2) h(-1)). At station R, a large increase (2 to 14 mu mol m(-2) h(-1)) was recorded between December 1997 and January 1998, after which flux tended to decrease. Ammonium flux was generally...
Tipo: Text
Palavras-chave: Flux à l’interface eau–sédiment; Azote inorganique dissous; Variabilité temporelle; Cycle de l’azote; Méditerranée nord occidentale; Sediment-water flux; Dissolved inorganic nitrogen; Temporal variability; Nitrogen cycling; NW Mediterranean.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00323/43371/42839.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: 5
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

Remote Sensing of Trichodesmium spp. mats in the Western Tropical South Pacific
Provedor de dados: 5
Autores: Rousset, Guillaume; De Boissieu, Florian; Menkes, Christophe E.; Lefevre, Jerome; Frouin, Robert; Rodier, Martine; Ridoux, Vincent; Laran, Sophie; Bonnet, Sophie; Dupouy, Cecile.
Trichodesmium is the main nitrogen-fixing species in the South Pacific region, a hotspot for diazotrophy. Due to the paucity of in situ observations, methods for detecting Trichodesmium presence on a large scale have been investigated to assess the regional-to-global impact of these species on primary production and carbon cycling. A number of satellite-derived algorithms have been developed to identify Trichodesmium surface blooms, but determining with confidence their accuracy has been difficult, chiefly because of the scarcity of sea-truth information at time of satellite overpass. Here, we use a series of new cruises as well as airborne observational surveys in the South Pacific to quantify statistically the ability of these algorithms to discern...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00419/53004/53953.pdf

Spatial and temporal variability of zooplankton off New Caledonia (Southwestern Pacific) from acoustics and net measurements
Provedor de dados: 5
Autores: Smeti, Houssem; Pagano, Marc; Menkes, Christophe; Lebourges-dhaussy, Anne; Hunt, Brian P. V.; Allain, Valerie; Rodier, Martine; De Boissieu, Florian; Kestenare, Elodie; Sammari, Cherif.
Spatial and temporal distribution of zooplankton off New Caledonia in the eastern Coral Sea was studied during two multidisciplinary cruises in 2011, during the cool and the hot seasons. Acoustic measurements of zooplankton were made using a shipborne acoustic Doppler current profiler (S-ADCP), a scientific echosounder and a Tracor acoustic profiling system (TAPS). Relative backscatter from ADCP was converted to biomass estimates using zooplankton weights from net-samples collected during the cruises. Zooplankton biomass was estimated using four methods: weighing, digital imaging (ZooScan), ADCP and TAPS. Significant correlations were found between the different biomass estimators and between the backscatters of the ADCP and the echosounder. There was a...
Tipo: Text
Palavras-chave: South Pacific; Acoustics; Zooplankton; Vertical migration; Water masses; Mesoscale dynamics.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00297/40809/39836.pdf

Heterotrophic bacterial production and metabolic balance during the VAHINE mesocosm experiment in the New Caledonia lagoon
Provedor de dados: 5
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

Response of phytoplankton to organic enrichment and shrimp activity in tropical aquaculture ponds: a mesocosm study
Provedor de dados: 5
Autores: Lemonnier, Hugues; Hochard, Sebastien; Nakagawa, Kento; Courties, Claude; Rodier, Martine.
We conducted a mesocosm study to investigate the combined effect of organic enrichment and sediment resuspension by shrimp on phytoplankton communities in shrimp aquaculture ponds. Hence, the factorial design included two factors, i.e., (i) shrimp density with a concomitant increase of feed input resulting in organic enrichment and (ii) with/without access of shrimp to the sediments. Increasing feed input in the system raised the eutrophication state of the environment characterized by an increase in phytoplankton biomass. Bioturbation enhanced (i) mineralization of organic matter via the microbial loop, resulting in faster nutrient recycling, (ii) an increase of primary production, and (iii) buffering capacity against eutrophication consequences. The...
Tipo: Text
Palavras-chave: Aquaculture; Litopenaeus stylirostris; Phytoplankton communities; Eutrophication; Bioturbation.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00392/50364/51066.pdf

Enhancement of phytoplankton biomass leeward of Tahiti as observed by Biogeochemical-Argo floats
Provedor de dados: 5
Autores: Sauzède, Raphaëlle; Martinez, Elodie; Maes, Christophe; De Fommervault, Orens Pasqueron; Poteau, Antoine; Mignot, Alexandre; Claustre, Hervé; Uitz, Julia; Oziel, Laurent; Maamaatuaiahutapu, Keitapu; Rodier, Martine; Schmechtig, Catherine; Laurent, Victoire.
The South Pacific Subtropical Gyre (SPSG) is a vast and remote oceanic system where the variability in phytoplankton biomass and production is still largely uncertain due to the lack of in situ biogeochemical observations. The SPSG is an oligotrophic environment where the ecosystem is controlled predominantly by nutrient depletion in surface waters. However, this dynamic is altered in the vicinity of islands where increased biological activity occurs (i.e. the island mass effect, IME). This study mainly focuses on in situ observations which show evidence of an IME leeward of Tahiti (17.7°S - 149.5°W), French Polynesia. Physical and biogeochemical observations collected with two Biogeochemical-Argo profiling floats are used to investigate the dynamics of...
Tipo: Text
Palavras-chave: Phytoplankton biomass; Biogeochemical-Argo floats; Island mass effect; South Pacific Subtropical Gyre.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00599/71130/69445.pdf

The Solomon Sea: its circulation, chemistry, geochemistry and biology   explored during two oceanographic cruises
Provedor de dados: 5
Autores: Ganachaud, Alexandre; Cravatte, Sophie; Sprintall, Janet; Germineaud, Cyril; Alberty, Marion; Jeandel, Catherine; Eldin, Gerard; Metzl, Nicolas; Bonnet, Sophie; Benavides, Mar; Heimburger, Lars-eric; Lefevre, Jerome; Michael, Susanna; Resing, Joseph; Queroue, Fabien; Sarthou, Geraldine; Rodier, Martine; Berthelot, Hugo; Baurand, Francois; Grelet, Jacques; Hasegawa, Takuya; Kessler, William; Kilepak, Moyep; Lacan, Francois; Privat, Emilien; Send, Uwe; Van Beek, Pieter; Souhaut, Marc; Sonke, Jeroen E.
The semi-enclosed Solomon Sea in the southwestern tropical Pacific is on the pathway of a major oceanic circuit connecting the subtropics to the equator via energetic western boundary currents. Waters transiting through this area replenish the Pacific Warm Pool and ultimately feed the equatorial current system, in particular the equatorial undercurrent. In addition to dynamical transformations, water masses undergo nutrient and micronutrient enrichment when coming in contact with the coasts, impacting the productivity of the downstream equatorial region. Broadscale observing systems are not well suited for describing the fine-scale currents and water masses properties in the Solomon Sea, leaving it relatively unexplored. Two multidisciplinary oceanographic...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00390/50185/50808.pdf

Introduction to the project VAHINE: VAriability of vertical and tropHlc transfer of diazotroph derived N in the south wEst Pacific
Provedor de dados: 5
Autores: Bonnet, Sophie; Moutin, Thierry; Rodier, Martine; Grisoni, Jean-michel; Louis, Francis; Folcher, Eric; Bourgeois, Bertrand; Bore, Jean-michel; Renaud, Armelle.
On the global scale, N-2 fixation provides the major external source of reactive nitrogen to the surface ocean, surpassing atmospheric and riverine inputs, and sustains similar to 50 % of new primary production in oligotrophic environments. The main goal of the VAriability of vertical and tropHlc transfer of diazotroph derived N in the south wEst Pacific (VAHINE) project was to study the fate of nitrogen newly fixed by diazotrophs (or diazotroph-derived nitrogen) in oceanic food webs, and how it impacts heterotrophic bacteria, phytoplankton and zooplankton dynamics, stocks and fluxes of biogenic elements and particle export. Three large volume (similar to 50 m(3)) mesocosms were deployed in a tropical oligotrophic ecosystem (the New Caledonia lagoon,...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00344/45480/45020.pdf