Consulta: creatorFacets:"Uitz, Julia"
Registros recuperados: 12
Data/hora: 11/06/2024 01:29:26

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

Community-Level Responses to Iron Availability in Open Ocean Planktonic Ecosystems
Provedor de dados: 5
Autores: Caputi, Luigi; Carradec, Quentin; Eveillard, Damien; Kirilovsky, Amos; Pelletier, Eric; Karlusich, Juan J. Pierella; Vieira, Fabio Rocha Jimenez; Villar, Emilie; Chaffron, Samuel; Malviya, Shruti; Scalco, Eleonora; Acinas, Silvia G.; Alberti, Adriana; Aury, Jean-marc; Benoiston, Anne-sophie; Bertrand, Arnaud; Biard, Tristan; Bittner, Lucie; Boccara, Martine; Brum, Jennifer R.; Brunet, Cedric; Busseni, Greta; Carratala, Anna; Claustre, Herve; Coelho, Luis Pedro; Colin, Sbastien; D'Aniello, Salvatore; Da Silva, Corinne; Del Core, Marianna; Dore, Hugo; Gasparini, Stephane; Kokoszka, Florian; Jamet, Jean-louis; Lejeusne, Christophe; Lepoivre, Cyrille; Lescot, Magali; Lima-mendez, Gipsi; Lombard, Fabien; Lukes, Julius; Maillet, Nicolas; Madoui, Mohammed-amin; Martinez, Elodie; Mazzocchi, Maria Grazia; Neou, Mario B.; Paz-yepes, Javier; Poulain, Julie; Ramondenc, Simon; Romagnan, Jean-baptiste; Roux, Simon; Manta, Daniela Salvagio; Sanges, Remo; Speich, Sabrina; Sprovieri, Mario; Sunagawa, Shinichi; Taillandier, Vincent; Tanaka, Atsuko; Tirichine, Leila; Trottier, Camille; Uitz, Julia; Veluchamy, Alaguraj; Vesela, Jana; Vincent, Flora; Yau, Sheree; Kandels-lewis, Stefanie; Searson, Sarah; Dimier, Cline; Picheral, Marc; Bork, Peer; Boss, Emmanuel; De Vargas, Colomban; Follows, Michael J.; Grimsley, Nigel; Guidi, Lionel; Hingamp, Pascal; Karsenti, Eric; Sordino, Paolo; Stemmann, Lars; Sullivan, Matthew B.; Tagliabue, Alessandro; Zingone, Adriana; Garczarek, Laurence; D'Ortenzio, Fabrizio; Testor, Pierre; Not, Fabrice; D'Alcala, Maurizio Ribera; Wincker, Patrick; Bowler, Chris; Iudicone, Daniele; Gorsky, Gabriel; Jaillon, Olivier; Karp-boss, Lee; Krzic, Uros; Ogata, Hiroyuki; Pesant, Stephane; Raes, Jeroen; Reynaud, Emmanuel G.; Sardet, Christian; Sieracki, Mike; Velayoudon, Didier; Weissenbach, Jean.
Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities we explored the comprehensive bio‐oceanographic and ‐omics datasets from Tara Oceans in the context of the iron products from two state‐of‐the‐art global scale biogeochemical models. We obtained novel information about adaptation and acclimation towards iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole sub‐communities co‐varying with...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00475/58680/61184.pdf

Globally Consistent Quantitative Observations of Planktonic Ecosystems
Provedor de dados: 5
Autores: Lomnard, Fabien; Boss, Emmanuel; Waite, Anya M.; Vogt, Meike; Uitz, Julia; Stemman, Lars; Sosik, Heidi M.; Schulz, Jan; Romagnan, Jean-baptiste; Picheral, Marc; Pearlman, Jay; Ohman, Mark D; Niehoff, Barbara; Möller, Klas O; Miloslavich, Patricia; Lara-lpez, Ana; Kudela, Raphael; Lopes, Ribens M; Kiko, Rainer; Karp-boss, Lee; Jaffe, Jules S; Iversen, Morten H; Irisson, Jean-olivier; Fennel, Katja; Hauss, Helena; Guidi, Lionel; Gorsky, Gaby; Giering, Sarah L.c.; Gaube, Peter; Gallager, Scott; Dubelaar, George; Cowen, Robert K; Carlotti, François; Briseno-avena, Christian; Berline, Léo; Benoit-bird, Kelly; Bax, Nicholas; Batten, Sonia; Ayata, Sakina Dorothée; Artigas, Luis Felipe; Appeltans, Ward.
In this paper we review the technologies available to make globally quantitative observations of particles in general—and plankton in particular—in the world oceans, and for sizes varying from sub-microns to centimeters. Some of these technologies have been available for years while others have only recently emerged. Use of these technologies is critical to improve understanding of the processes that control abundances, distributions and composition of plankton, provide data necessary to constrain and improve ecosystem and biogeochemical models, and forecast changes in marine ecosystems in light of climate change. In this paper we begin by providing the motivation for plankton observations, quantification and diversity qualification on a global scale. We...
Tipo: Text
Palavras-chave: Plankton; Imaging; OceanObs; Autonomous platforms; Global observing; EOVs; ECVs.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00490/60217/63585.pdf

Multivariate approach for the retrieval of phytoplankton size structure from measured light absorption spectra in the Mediterranean Sea (BOUSSOLE site)
Provedor de dados: 5
Autores: Organelli, Emanuele; Bricaud, Annick; Antoine, David; Uitz, Julia.
Models based on the multivariate partial least squares (PLS) regression technique are developed for the retrieval of phytoplankton size structure from measured light absorption spectra (BOUSSOLE site, northwestern Mediterranean Sea). PLS-models trained with data from the Mediterranean Sea showed good accuracy in retrieving, over the nine-year BOUSSOLE time series, the concentrations of total chlorophyll a [Tchl a], of the sum of seven diagnostic pigments and of pigments associated with micro, nano, and picophytoplankton size classes separately. PLS-models trained using either total particle or phytoplankton absorption spectra performed similarly, and both reproduced seasonal variations of biomass and size classes derived by high performance liquid...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00185/29655/28031.pdf

Assessing the Variability in the Relationship Between the Particulate Backscattering Coefficient and the Chlorophyll a Concentration From a Global Biogeochemical-Argo Database
Provedor de dados: 5
Autores: Barbieux, Marie; Uitz, Julia; Bricaud, Annick; Organelli, Emanuele; Poteau, Antoine; Schmechtig, Catherine; Gentili, Bernard; Obolensky, Grigor; Leymarie, Edouard; Penkerc'H, Christophe; D'Ortenzio, Fabrizio; Claustre, Herve.
Characterizing phytoplankton distribution and dynamics in the world's open oceans requires in situ observations over a broad range of space and time scales. In addition to temperature/salinity measurements, Biogeochemical-Argo (BGC-Argo) profiling floats are capable of autonomously observing at high-frequency bio-optical properties such as the chlorophyll fluorescence, a proxy of the chlorophyll a concentration (Chla), the particulate backscattering coefficient (b(bp)), a proxy of the stock of particulate organic carbon, and the light available for photosynthesis. We analyzed an unprecedented BGC-Argo database of more than 8,500 multivariable profiles collected in various oceanic conditions, from subpolar waters to subtropical gyres. Our objective is to...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00673/78495/80780.pdf

Deep maxima of phytoplankton biomass, primary production and bacterial production in the Mediterranean Sea
Provedor de dados: 5
Autores: Maranon, Emilio; Van Vambeke, France; Uitz, Julia; Boss, Emmanuel S; Dimier, Céline; Dinasquet, Julie; Engel, Anja; Haentjens, Nils; Perez-lorenzo, Maria; Taillandier, Vincent; Zancker, Birthe.
The deep chlorophyll maximum (DCM) is a ubiquitous feature of phytoplankton vertical distribution in stratified waters that is relevant to our understanding of the mechanisms that underpin the variability in photoautotroph ecophysiology across environmental gradients and has implications for remote sensing of aquatic productivity. During the PEACETIME (Process studies at the air-sea interface after dust deposition in the Mediterranean Sea) cruise, carried out from 10 May to 11 June 2017, we obtained 23 concurrent vertical profiles of phytoplankton chlorophyll a, carbon biomass and primary production, as well as heterotrophic prokaryotic production, in the western and central Mediterranean basins. Our main aims were to quantify the relative role of...
Tipo: Text
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00642/75454/76271.pdf

Two databases derived from BGC-Argo float measurements for marine biogeochemical and bio-optical applications
Provedor de dados: 5
Autores: Organelli, Emanuele; Barbieux, Marie; Claustre, Herve; Schmechtig, Catherine; Poteau, Antoine; Bricaud, Annick; Boss, Emmanuel; Briggs, Nathan; Dall'Olmo, Giorgio; D'Ortenzio, Fabrizio; Leymarie, Edouard; Mangin, Antoine; Obolensky, Grigor; Penkerc'H, Christophe; Prieur, Louis; Roesler, Collin; Serra, Romain; Uitz, Julia; Xing, Xiaogang.
Since 2012, an array of 105 Biogeochemical-Argo (BGC-Argo) floats has been deployed across the world's oceans to assist in filling observational gaps that are required for characterizing open-ocean environments. Profiles of biogeochemical (chlorophyll and dissolved organic matter) and optical (single-wavelength particulate optical backscattering, downward irradiance at three wavelengths, and photosynthetically available radiation) variables are collected in the upper 1000 m every 1 to 10 days. The database of 9837 vertical profiles collected up to January 2016 is presented and its spatial and temporal coverage is discussed. Each variable is quality controlled with specifically developed procedures and its time series is quality-assessed to identify issues...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00662/77389/79010.pdf

Reconstructing Global Chlorophyll-a Variations Using a Non-linear Statistical Approach
Provedor de dados: 5
Autores: Martinez, Elodie; Gorgues, Thomas; Lengaigne, Matthieu; Fontana, Clement; Sauzède, Raphaëlle; Menkes, Christophe; Uitz, Julia; Di Lorenzo, Emanuele; Fablet, Ronan.
Monitoring the spatio-temporal variations of surface chlorophyll-a concentration (Chl, a proxy of phytoplankton biomass) greatly benefited from the availability of continuous and global ocean color satellite measurements from 1997 onward. These two decades of satellite observations are however still too short to provide a comprehensive description of Chl variations at decadal to multi-decadal timescales. This paper investigates the ability of a machine learning approach (a non-linear statistical approach based on Support Vector Regression, hereafter SVR) to reconstruct global spatio-temporal Chl variations from selected surface oceanic and atmospheric physical parameters. With a limited training period (13 years), we first demonstrate that Chl variability...
Tipo: Text
Palavras-chave: Machine learning; Phytoplankton variability; Satellite ocean color; Decadel variability; Global scale.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00641/75314/75810.pdf

Recommendations for obtaining unbiased chlorophyll estimates from in situ chlorophyll fluorometers: A global analysis of WET Labs ECO sensors
Provedor de dados: 5
Autores: Roesler, Collin; Uitz, Julia; Claustre, Herve; Boss, Emmanuel; Xing, Xiaogang; Organelli, Emanuele; Briggs, Nathan; Bricaud, Annick; Schmechtig, Catherine; Poteau, Antoine; D'Ortenzio, Fabrizio; Ras, Josephine; Drapeau, Susan; Haentjens, Nils; Barbieux, Marie.
Chlorophyll fluorometers provide the largest in situ global data set for estimating phytoplankton biomass because of their ease of use, size, power consumption, and relatively low price. While in situ chlorophyll a (Chl) fluorescence is proxy for Chl a concentration, and hence phytoplankton biomass, there exist large natural variations in the relationship between in situ fluorescence and extracted Chl a concentration. Despite this large natural variability, we present here a global validation data set for the WET Labs Environmental Characterization Optics (ECO) series chlorophyll fluorometers that suggests a factor of 2 overestimation in the factory calibrated Chl a estimates for this specific manufacturer and series of sensors. We base these results on...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00384/49552/50046.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

Bio-optical anomalies in the world's oceans: An investigation on the diffuse attenuation coefficients for downward irradiance derived from biogeochemical Argo float measurements
Provedor de dados: 5
Autores: Organelli, Emanuele; Claustre, Herve; Bricaud, Annick; Barbieux, Marie; Uitz, Julia; D'Ortenzio, Fabrizio; Dall'Olmo, Giorgio.
Identification of oceanic regions characterized by particular optical properties is extremely important for ocean color applications. The departure from globally established bio-optical models introduces uncertainties in the retrieval of biogeochemical quantities from satellite observations. Thanks to an array of 105 Biogeochemical Argo floats acquiring almost daily downward irradiance measurements at selected wavelengths in the UV and blue region of the spectrum, we re-examined the natural variability of the spectral diffuse attenuation coefficients, Kd(λ), among the world's oceans and compared them to previously established bio-optical models. The analysis of 2847 measurements of Kd(λ) at 380 and 490 nm, within the first optical depth, provided a...
Tipo: Text
Palavras-chave: Bio-optical anomalies; Light attenuation; Biogeochemical Argo floats; Global ocean; Colored dissolved organic matter.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00383/49463/49948.pdf

Surface ocean microbiota determine cloud precursors
Provedor de dados: 5
Autores: Sellegri, Karine; Nicosia, Alessia; Freney, Evelyn; Uitz, Julia; Thyssen, Melilotus; Grégori, Gérald; Engel, Anja; Zäncker, Birthe; Haëntjens, Nils; Mas, Sébastien; Picard, David; Saint-macary, Alexia; Peltola, Maija; Rose, Clémence; Trueblood, Jonathan; Lefevre, Dominique; D’anna, Barbara; Desboeufs, Karine; Meskhidze, Nicholas; Guieu, Cécile; Law, Cliff S.
One pathway by which the oceans influence climate is via the emission of sea spray that may subsequently influence cloud properties. Sea spray emissions are known to be dependent on atmospheric and oceanic physicochemical parameters, but the potential role of ocean biology on sea spray fluxes remains poorly characterized. Here we show a consistent significant relationship between seawater nanophytoplankton cell abundances and sea-spray derived Cloud Condensation Nuclei (CCN) number fluxes, generated using water from three different oceanic regions. This sensitivity of CCN number fluxes to ocean biology is currently unaccounted for in climate models yet our measurements indicate that it influences fluxes by more than one order of magnitude over the range of...
Tipo: Text
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00669/78077/80312.pdf