Search

Your search keyword '"Nicolas Cassar"' showing total 5 results
Start Over Author "Nicolas Cassar" Publisher springer science and business media llc
5 results on '"Nicolas Cassar"'

1. Open science resources from the Tara Pacific expedition across coral reef and surface ocean ecosystems

Author

Fabien Lombard, Guillaume Bourdin, Stéphane Pesant, Sylvain Agostini, Alberto Baudena, Emilie Boissin, Nicolas Cassar, Megan Clampitt, Pascal Conan, Ophélie Da Silva, Céline Dimier, Eric Douville, Amanda Elineau, Jonathan Fin, J. Michel Flores, Jean François Ghiglione, Benjamin C.C. Hume, Laetitia Jalabert, Seth G. John, Rachel L. Kelly, Ilan Koren, Yajuan Lin, Dominique Marie, Ryan McMinds, Zoé Mériguet, Nicolas Metzl, David A. Paz-García, Maria Luiza Pedrotti, Julie Poulain, Mireille Pujo-Pay, Joséphine Ras, Gilles Reverdin, Sarah Romac, Alice Rouan, Eric Röttinger, Assaf Vardi, Christian R. Voolstra, Clémentine Moulin, Guillaume Iwankow, Bernard Banaigs, Chris Bowler, Colomban de Vargas, Didier Forcioli, Paola Furla, Pierre E. Galand, Eric Gilson, Stéphanie Reynaud, Shinichi Sunagawa, Matthew B. Sullivan, Olivier Thomas, Romain Troublé, Rebecca Vega Thurber, Patrick Wincker, Didier Zoccola, Denis Allemand, Serge Planes, Emmanuel Boss, Gaby Gorsky, Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Global Oceans Systems Ecology & Evolution - Tara Oceans (GOSEE), Université de Perpignan Via Domitia (UPVD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Aix Marseille Université (AMU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Université de Toulon (UTLN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche pour le Développement (IRD [France-Nord])-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay)-European Molecular Biology Laboratory (EMBL)-École Centrale de Nantes (Nantes Univ - ECN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Université australe du Chili, Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), University of Maine, European Molecular Biology Laboratory [Hinxton], Shimoda Marine Research Center, Université de Tsukuba = University of Tsukuba, Centre de recherches insulaires et observatoire de l'environnement (CRIOBE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Nicholas School of the Environment, Duke University [Durham], Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur le Cancer et le Vieillissement (IRCAN), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Institut Fédératif de Recherche - Ressources Marines (IFR MARRES), Université Côte d'Azur (UCA), Laboratoire International Associé Réponse des Organismes et Populations face au Stress Environnemental - Université Côte d’Azur - Centre Scientifique de Monaco (LIA ROPSE), Université Côte d’Azur - Centre Scientifique de Monaco, Laboratoire d'Océanographie Microbienne (LOMIC), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), OSU Stations marines (STAMAR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochrononologie Traceurs Archéométrie (GEOTRAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Weizmann Institute of Science [Rehovot, Israël], Universität Konstanz, Department of Earth Sciences [USC Los Angeles], University of Southern California (USC), Station biologique de Roscoff (SBR), Maison de la Modélisation, de la Simulation et des Interactions [Sophia-Antipolis] (MSI), Oregon State University (OSU), Centro de Investigaciones Biologicas del Noroeste [Mexico] (CONACYT-CIBNOR), Consejo Nacional de Ciencia y Tecnología [Mexico] (CONACYT), Institut de Biologie François JACOB (JACOB), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Processus et interactions de fine échelle océanique (PROTEO), Tara Ocean Foundation, Institut de biologie de l'ENS Paris (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecogéochimie des environnements benthiques (LECOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Centre Scientifique de Monaco (CSM), Ohio State University [Columbus] (OSU), Institute of Microbiology and Swiss Institute of Bioinformatics, Martin Ryan Institute, and National University of Ireland [Galway] (NUI Galway)

Subjects
[SDU]Sciences of the Universe [physics], Ecosystem ecology, Biodiversity
Abstract

The Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58,000 samples. The expedition was designed to systematically study warm coral reefs and included the collection of corals, fish, plankton, and seawater samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide a complete description of the sampling methodology, and we explain how to explore and access the different datasets generated by the expedition. Environmental context data were obtained from taxonomic registries, gazetteers, almanacs, climatologies, operational biogeochemical models, and satellite observations. The quality of the different environmental measures has been validated not only by various quality control steps but also through a global analysis allowing the comparison with known environmental large-scale structures. Such a wide released datasets opens the perspective to address a wide range of scientific questions.

Published
2023

2. Widespread phytoplankton blooms triggered by 2019–2020 Australian wildfires

Author

Andrew R. Bowie, Bernadette C. Proemse, Nicolas Cassar, Morgane M. G. Perron, Peter G. Strutton, Shubha Sathyendranath, Jakob Weis, Weiyi Tang, Zuchuan Li, Joan Llort, Thomas Jackson, Christina Schallenberg, Sara Basart, Richard J. Matear, Estrella Sanz Rodriguez, and Barcelona Supercomputing Center

Subjects
Biogeochemical cycle, Phytoplankton algal blooms, Wildfires--Australia, Atmospheric chemistry, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, 01 natural sciences, Algal bloom, Carbon cycle, Phytoplankton, 14. Life underwater, Fire ecology, Argo, 0105 earth and related environmental sciences, Multidisciplinary, Desenvolupament humà i sostenible::Degradació ambiental::Canvi climàtic [Àrees temàtiques de la UPC], Climatic changes, Atmospheric aerosols, Droughts, Oceanography, Deposition (aerosol physics), Marine chemistry, 13. Climate action, Environmental science, Climate model, Canvis climàtics
Abstract

Droughts and climate-change-driven warming are leading to more frequent and intense wildfires1,2,3, arguably contributing to the severe 2019–2020 Australian wildfires4. The environmental and ecological impacts of the fires include loss of habitats and the emission of substantial amounts of atmospheric aerosols5,6,7. Aerosol emissions from wildfires can lead to the atmospheric transport of macronutrients and bio-essential trace metals such as nitrogen and iron, respectively8,9,10. It has been suggested that the oceanic deposition of wildfire aerosols can relieve nutrient limitations and, consequently, enhance marine productivity11,12, but direct observations are lacking. Here we use satellite and autonomous biogeochemical Argo float data to evaluate the effect of 2019–2020 Australian wildfire aerosol deposition on phytoplankton productivity. We find anomalously widespread phytoplankton blooms from December 2019 to March 2020 in the Southern Ocean downwind of Australia. Aerosol samples originating from the Australian wildfires contained a high iron content and atmospheric trajectories show that these aerosols were likely to be transported to the bloom regions, suggesting that the blooms resulted from the fertilization of the iron-limited waters of the Southern Ocean. Climate models project more frequent and severe wildfires in many regions1,2,3. A greater appreciation of the links between wildfires, pyrogenic aerosols13, nutrient cycling and marine photosynthesis could improve our understanding of the contemporary and glacial–interglacial cycling of atmospheric CO2 and the global climate system. Analyses of satellite aerosol observations used in this study were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC. We thank SeaWiFS and MODIS mission scientists and associated NASA personnel for the production of the data used in this research effort. The BGC-Argo data were collected and made freely available by the International Argo Program and the national programs that contribute to it (http://www.argo.ucsd.edu, http://argo.jcommops.org). The Argo Program is part of the Global Ocean Observing System (https://doi.org/10.17882/42182). W.T. is supported by the Harry H. Hess Postdoctoral Fellowship from Princeton University. N.C. is supported by the “Laboratoire d’Excellence” LabexMER (ANR‐10‐LABX‐19) and co-funded by a grant from the French government under the program “Investissements d’Avenir”. S.B. acknowledges the AXA Research Fund for the support of the long-term research line on Sand and Dust Storms at the Barcelona Supercomputing Center (BSC) and CAMS Global Validation (CAMS-84). P.G.S., J.L., M.M.G.P. and A.R.B. are supported by the Australian Research Council Discovery Projects scheme (DP190103504). P.G.S. and J.W. are supported by the Australian Research Council Centre of Excellence for Climate Extremes (CLEX: CE170100023). J.L. is supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 754433. A.R.B. is supported by the Australian Research Council Future Fellowship scheme (FT130100037). R.M. is supported by the CSIRO Decadal Climate Forecasting Project. We thank M. Strzelec, M. East, T. Holmes, M. Corkill, S. Meyerink and the Wellington Park Management Trust for help with installation and sampling the Tasmanian aerosol time-series station; A. Townsend for iron aerosol analyses by ICPMS at the University of Tasmania; and A. Benedetti and S. Remy for providing insights on the validation of aerosol reanalysis. Peer Reviewed "Article signat per 15 autors/es: Weiyi Tang, Joan Llort, Jakob Weis, Morgane M. G. Perron, Sara Basart, Zuchuan Li, Shubha Sathyendranath, Thomas Jackson, Estrella Sanz Rodriguez, Bernadette C. Proemse, Andrew R. Bowie, Christina Schallenberg, Peter G. Strutton, Richard Matear & Nicolas Cassar"

Published
2021

3. Examination of gene repertoires and physiological responses to iron and light limitation in Southern Ocean diatoms

Author

Yajuan Lin, Carly M. Moreno, Nicolas Cassar, Elaine Monbureau, Adrian Marchetti, and Sarah W. Davies

Subjects
0106 biological sciences, 0301 basic medicine, Ecology, 010604 marine biology & hydrobiology, Nitrogen assimilation, fungi, Biology, biology.organism_classification, Photosynthesis, 01 natural sciences, Food web, Physiological responses, 03 medical and health sciences, 030104 developmental biology, Diatom, Abundance (ecology), Low light level, General Agricultural and Biological Sciences, Gene
Abstract

Diatoms play a fundamental role at the base of the polar marine food web. In the Southern Ocean, low iron concentrations and light levels control diatom abundance and distribution. Diatoms must therefore employ strategies that allow them to cope when iron and/or light availability is growth limiting. Through a combination of physiological and molecular-based approaches, we have investigated the physiological response to variable iron concentrations and light levels along with the expressed gene repertoires of nine newly isolated diatoms from the Western Antarctic Peninsula (WAP) region of the Southern Ocean. The diatoms ranged across five orders of magnitude in biovolume and displayed various degrees of susceptibility to low iron and light availability. Under the performed laboratory culture conditions, the growth rates of most diatoms decreased more due to low light level rather than low iron concentrations. Additionally, most diatoms were not subject to further reductions in growth rates when grown under combined low-light and iron-limiting conditions, indicating they are less likely to be co-limited by an additive effect. By sequencing the transcriptomes of these diatoms, we identified genes that likely facilitate their growth under variable iron and light conditions commonly present in the Southern Ocean. Specifically, we investigated the presence of 20 key genes involved in iron acquisition and homeostasis, iron usage in photosynthesis and nitrogen assimilation, and protection from reactive oxygen species. When comparing gene repertoires of recently sequenced transcriptomes of diatoms isolated from around the globe, the prevalence of certain genes exhibited biogeographical patterns that clearly distinguish Southern Ocean diatoms from those isolated from other regions.

Published
2017

4. Correction: NanoSIMS single cell analyses reveal the contrasting nitrogen sources for small phytoplankton

Author

Stéphane L'Helguen, Ivona Cetinić, Solange Duhamel, Nicolas Cassar, Jean-François Maguer, Hugo Berthelot, and Seaver Wang

Subjects
Nitrogen, Spectrometry, Mass, Secondary Ion, chemistry.chemical_element, Biology, Microbiology, California, Carbon Cycle, Microbial ecology, Ammonium Compounds, Phytoplankton, Urea, Photosynthesis, Microbial biooceanography, Ecology, Evolution, Behavior and Systematics, Prochlorococcus, Synechococcus, Nitrates, Pacific Ocean, Correction, Biogeochemistry, Flow Cytometry, Carbon, chemistry, Environmental chemistry, Single-Cell Analysis
Abstract

Nitrogen (N) is a limiting nutrient in vast regions of the world's oceans, yet the sources of N available to various phytoplankton groups remain poorly understood. In this study, we investigated inorganic carbon (C) fixation rates and nitrate (NO

Published
2020

5. N2 fixation estimates in real-time by cavity ring-down laser absorption spectroscopy

Author

Jonathan D. Karr, Bruce A. Barnett, Nicolas Cassar, Jean-Philippe Bellenger, and Robert B. Jackson

Subjects
Azotobacter vinelandii, Spectrum analyzer, Absorption spectroscopy, Spectrometer, Acetylene, Spectrum Analysis, Analytical chemistry, chemistry.chemical_element, Biology, Laser, Nitrogen, Cavity ring-down spectroscopy, law.invention, Kinetics, chemistry.chemical_compound, chemistry, law, Nitrogen Fixation, Flame ionization detector, Ecology, Evolution, Behavior and Systematics
Abstract

The most common currency for estimating N2 fixation is acetylene reduction to ethylene. Real-time esti- mates of nitrogen fixation are needed to close the global nitrogen budget and these remain a critical gap in both laboratory and field experiments. We present a new method for continuous real-time measurements of ethylene pro- duction: Acetylene Reduction Assays by Cavity ring-down laser Absorption Spectroscopy (ARACAS). In ARACAS, air in the headspace of an incubation chamber is circulated with a diaphragm pump through a cavity ring-down eth- ylene spectrometer and back to the incubation chamber. This paper describes the new approach and its benefits compared to the conventional detection of ethylene by flame ionization detector gas chromatography. First, the detection of acetylene reduction to ethylene is non-intru- sive and chemically non-destructive, allowing for real-time measurements of nitrogenase activity. Second, the mea- surements are made instantaneously and continuously at ppb levels, allowing for observation of real-time kinetics on time intervals as short as a few seconds. Third, the instrument can be automated for long time periods of measurement. Finally, the technique will be widely accessible by the research community as it can be readily adapted to most existing acetylene reduction protocols and is based on a modestly priced, commercially available instrument. We illustrate its use for measuring N2 fixation using two species, the diazotrophic bacterium Azotobacter vinelandii and the lichen Peltigera praetextata. We also discuss potential limitations of the approach, primarily the implications of leaks in the analyzer, as well as future improvements.

Published
2011

Catalog

Books, media, physical & digital resources
See catalog results