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| Registros recuperados: 15 | |
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| Wattelez, Guillaume; Dupouy, Cecile; Mangeas, Morgan; Lefevre, Jerome; Touraivane,; Frouin, Robert. |
| Spatial and temporal dynamics of phytoplankton biomass and water turbidity can provide crucial information about the function, health and vulnerability of lagoon ecosystems (coral reefs, sea grasses, etc.). A statistical algorithm is proposed to estimate chlorophyll-a concentration ([chl-a]) in optically complex waters of the New Caledonian lagoon from MODIS-derived remote-sensing reflectance (R-rs). The algorithm is developed via supervised learning on match-ups gathered from 2002 to 2010. The best performance is obtained by combining two models, selected according to the ratio of R-rs in spectral bands centered on 488 and 555 nm: a log-linear model for low [chl-a] (AFLC) and a support vector machine (SVM) model or a classic model (OC3) for high [chl-a].... |
| Tipo: Text |
Palavras-chave: Chlorophyll-a concentration; MODerate resolution Imaging Spectroradiometer (MODIS); Ocean color; Remote sensing; Statistical algorithm; Oligotrophic waters; New Caledonia; Coral lagoon. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00481/59309/62060.pdf |
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| Favareto, Luciane Rafaele; Rudorff, Natalia; Kampel, Milton; Frouin, Robert; Roettgers, Ruediger; Doxaran, David; Murakami, Hiroshi; Dupouy, Cecile. |
| The Eastern Lagoon of New Caledonia (ELNC) is a semi-enclosed system surrounded by an extensive coral reef barrier. The system has been suffering impacts from climate variability and anthropogenic activities, including mining exploitation. Satellite monitoring is thus an essential tool to detect such changes. The present study aimed to assess the bio-optical variability of the ELNC and examine the applicability of ocean colour algorithms, using in situ bio-optical and radiometric data, collected during the March 2014 CALIOPE 2 cruise. The chlorophyll a concentration (Chla) varied from 0.13-0.72 mg.m(-3), and the coastal stations were spectrally dominated by non-algal particles (NAP) and coloured dissolved organic matter (CDOM) (>80% of the total... |
| Tipo: Text |
Palavras-chave: Marine remote sensing reflectance; Bio-optical properties; Ocean colour algorithms; Eastern lagoon of New Caledonia; Southwest Tropical Pacific Ocean. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00481/59306/62063.pdf |
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| Martias, Chloe; Tedetti, Marc; Lantoine, Francois; Jamet, Leocadie; Dupouy, Cecile. |
| The eastern lagoon of New Caledonia (NC, Southwest Pacific), listed as a UNESCO World Heritage site, hosts the world's second longest double-barrier coral reef. This lagoon receives river inputs, oceanic water arrivals, and erosion pressure from ultramafic rocks, enriched in nickel (Ni) and cobalt (Co). The aim of this study was to characterize colored dissolved organic matter (CDOM), as well as to determine its main sources and its possible relationships (through the use of Pearson correlation coefficients, r) with biogeochemical parameters, plankton communities and trace metals in the NC eastern lagoon. Water samples were collected in March 2016 along a series of river/lagoon/open-ocean transects. The absorption coefficient at 350 nm (a(350)) revealed... |
| Tipo: Text |
Palavras-chave: CDOM; Fluorescence; Trace metals; Southwest Pacific; Coral reef lagoon; Rivers. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00481/59307/62061.pdf |
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| 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 |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00457/56824/58659.pdf |
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| 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 |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00448/56007/57515.pdf |
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| 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 |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00348/45893/45572.pdf |
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| Koliyavu, Timoci; Martias, Chloe; Singh, Awnesh; Mounier, Stéphane; Gérard, Philippe; Dupouy, Cecile. |
| Heavy rain events alter the biogeochemical outflows, affects water quality and ecosystem health within the coastal waters of small Pacific Islands. We characterized snapshots of the optical fingerprints of dissolved organic matter (DOM) sources together with the select nutrients, biogeochemical and physical variables for 10 stations in December 2017 in Laucala Bay, Fiji Islands. DOM absorption coefficients and fluorescence components were determined via spectrofluorometry and Parallel Factor Analysis identifying four components: Type M, two terrestrial (humic, fulvic) components, and a protein component linked to marine biological activity. Associations of DOM together with climate variables and the other tested variables were determined via principal... |
| Tipo: Text |
Palavras-chave: DOM absorption; Fluorescence; Biogeochemistry; PARAFAC; EEM spectra; Autochthonous; Allochthonous; Chlorophyll; CDOM; FDOM. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00682/79372/81889.pdf |
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| Roettgers, Ruediger; Dupouy, Cecile; Taylor, Bettina B.; Bracher, Astrid; Wozniak, Slawomir B.. |
| The extent of light absorption in the near-infrared spectral region (NIR; 700-900 nm) of natural suspended particles was investigated by determining the absorption and mass-specific absorption coefficients of samples from different environments: river, coastal waters, tropical lagoon, and oceanic waters. Large amounts of sample were collected onto glass-fiber filters and measured inside the integrating sphere of a spectrophotometer. The absorption coefficient of particle suspension was also determined for visible wavelengths with a point-source integrating cavity absorption meter. Measurable nonzero particulate absorption in the NIR was determined in all samples, even in algal cultures. It was highest in the river samples (e.g., 1.7 m(-1) at 850 nm),... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00297/40815/39842.pdf |
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| 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 |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00419/53042/53979.pdf |
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| Ouillon, Sylvain; Douillet, Pascal; Petrenko, Anne; Neveux, Jacques; Dupouy, Cecile; Froidefond, Jean-marie; Andrefouet, Serge; Munoz-caravaca, Alain. |
| Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji. Empirical algorithms are tested at... |
| Tipo: Text |
Palavras-chave: Ocean color; Remote sensing; Sediment transport; Suspended matter; Turbidity; New Caledonia; Cuba; Fiji. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00203/31417/29808.pdf |
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| Neveux, Jacques; Lefebvre, Jean-pierre; Le Gendre, Romain; Dupouy, Cecile; Gallois, Francis; Courties, Claude; Gerard, Philippe; Fernandez, Jean-michel; Ouillon, Sylvain. |
| During the Echolag cruise (13 February-8 March 2007), the effect of 16-30 knot trade winds on abundance, community structure and dynamics of phytoplankton was investigated in the southern part of the New Caledonian coral reefs and surrounding oceanic waters. In this area, the coral reefs form two horn-like structures (hereinafter referred to as 'horn reefs'), oriented south-east, and separated by a relatively deep valley. Three repeated samplings at one week intervals of a 32 station array showed that trade winds induce surface water cooling and significant enrichment of mid- and bottom waters above the reef shelf. This enrichment appeared as the result of a general rise of the oceanic thermocline and nitracline due to the combination of trade winds and... |
| Tipo: Text |
Palavras-chave: Chlorophyll; Phycoerythrin; Flow cytometry; Phytoplankton; In vivo fluorescence; Growth rate; Trade winds; Lagoon; Internal wave; New Caledonia. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00013/12437/9258.pdf |
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| Spungin, Dina; Belkin, Natalia; Foster, Rachel; Stenegren, Marcus; Caputo, Andrea; Pujo-pay, Mireille; Leblond, Nathalie; Dupouy, Cecile; Bonnet, Sophie; Berman-frank, Ilana. |
| The fate of diazotroph (N2 fixers) derived carbon (C) and nitrogen (N) and their contribution to vertical export of C and N in the Western Tropical South Pacific Ocean was studied in OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment). Our specific objective during OUTPACE was to determine whether autocatalytic programmed cell death (PCD) is an important mechanism affecting diazotroph mortality and a factor regulating the vertical flux of organic matter and thus the fate of the blooms. We sampled at three long duration (LD) stations of 5 days each (LDA, LDB, and LDC) where drifting sediment traps were deployed at 150, 325 and 500 m depths. LDA and LDB were characterized by high chlorophyll a (Chl a) concentrations (0.2–0.6 µg L−1) and dominated... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00419/53048/53985.pdf |
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| Roettgers, Ruediger; Doxaran, David; Dupouy, Cecile. |
| The accurate determination of light absorption coefficients of particles in water, especially in very oligotrophic oceanic areas, is still a challenging task. Concentrating aquatic particles on a glass fiber filter and using the Quantitative Filter Technique (QFT) is a common practice. Its routine application is limited by the necessary use of high performance spectrophotometers, distinct problems induced by the strong scattering of the filters and artifacts induced by freezing and storing samples. Measurements of the sample inside a large integrating sphere reduce scattering effects and direct field measurements avoid artifacts due to sample preservation. A small, portable, Integrating Cavity Absorption Meter setup (QFT-ICAM) is presented, that allows... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00298/40949/40044.pdf |
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| Dupouy, Cecile; Wattelez, Guillaume; Lefevre, Jerome; Juillot, Farid; Andreoli, Remi; Lille, Didier; Murakami, Hiroshi; Roettgers, Rudiger; Frouin, Robert. |
| Shortly after strong rains or tropical storms, chlorophyll-a concentration (Chla), turbidity, and colored dissolved organic matter (CDOM) in the lagoon of New Caledonia may be tripled. This effect is visible as far as 50 km offshore. The Eastern Coast of New Caledonia is more impacted than the Western Coast because of its geomorphological structure. Higher frequency and intensity of the rains, and the dominance of highly erosive lateritic formations resulted from deep weathering of ultramafic rocks. At the deeper parts of the lagoon (> 20 m), increases of Chla, turbidity, and CDOM absorption can be detected by satellite imagery with their plumes extending off shore as a result of wind-driven circulation in the lagoon. Such -increases agree with the... |
| Tipo: Text |
Palavras-chave: Minerals; Phytoplankton; CDOM; FDOM; Ocean color; Reflectance; New Caledonia; Tropical Pacific Ocean; Lagoons. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00481/59308/62064.pdf |
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| 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 |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00419/53004/53953.pdf |
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| Registros recuperados: 15 | |
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