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Auteur Williamson, P.; Wallace, D.W.R.; Law, C.S.; Boyd, P.W.; Collos, Y.; Croot, P.; Denman, K.; Riebesell, U.; Takeda, S.; Vivian, C.
Titre Ocean fertilization for geoengineering: A review of effectiveness, environmental impacts and emerging governance Type Article scientifique
Année (up) 2012 Publication Revue Abrégée Process Saf. Environ. Protect.
Volume 90 Numéro 6 Pages 475-488
Mots-Clés Geoengineering; Governance; Negative emission technologies; Ocean fertilization; Southern Ocean; atmospheric; carbon-dioxide; community response; diatom bloom; equatorial; iron; mesoscale iron enrichment; microbial response; pacific; perpetual salt fountain; phytoplankton bloom; southern-ocean; sub-arctic pacific
Résumé Dangerous climate change is best avoided by drastically and rapidly reducing greenhouse gas emissions. Nevertheless, geoengineering options are receiving attention on the basis that additional approaches may also be necessary. Here we review the state of knowledge on large-scale ocean fertilization by adding iron or other nutrients, either from external sources or via enhanced ocean mixing. On the basis of small-scale field experiments carried out to date and associated modelling, the maximum benefits of ocean fertilization as a negative emissions technique are likely to be modest in relation to anthropogenic climate forcing. Furthermore, it would be extremely challenging to quantify with acceptable accuracy the carbon removed from circulation on a long term basis, and to adequately monitor unintended impacts over large space and time-scales. These and other technical issues are particularly problematic for the region with greatest theoretical potential for the application of ocean fertilization, the Southern Ocean. Arrangements for the international governance of further field-based research on ocean fertilization are currently being developed, primarily under the London Convention/London Protocol. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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ISSN 0957-5820 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 741
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Auteur Auguet, J.C.; Casamayor, E.O.
Titre Partitioning of Thaumarchaeota populations along environmental gradients in high mountain lakes Type Article scientifique
Année (up) 2013 Publication Revue Abrégée FEMS Microbiology Ecology
Volume 84 Numéro 1 Pages 154-164
Mots-Clés amoA gene Euryarchaeota Freshwater Nitrogen Plankton SAGMGC
Résumé We investigated the spatial distribution and diversity of ammonia-oxidizing Archaea (AOA) across gradients of pH, trophic status and altitude in a set of high mountain lakes (Limnological Observatory of the Pyrenees, north-east Spain). Both phylogeny- and taxonomy-based approaches revealed well-defined AOA community patterns with pH as the main potential driving environmental factor. The I.1a and SAGMGC-1 Thaumarchaeota clusters, and their potentially associated amoA gene variants (clusters Fresh 5 and Soil/Fresh 1, respectively) showed highest relative abundances in the most oligotrophic lakes. Euryarchaeota (i.e. HV-Fresh cluster, Methanomicrobiales and Thermoplasmatales) dominated in lakes with higher trophic status. Phylogenetic diversity (PD) in Pyrenean lakes was 1.5- to 2.3-fold higher than the PD from an equivalent number of globally distributed marine and soil sites. We observed segregated distributions for SAGMGC-1, preferentially distributed in the lakes with the lowest pH (< 5) and the highest nitrite concentration (> 0.12 μm), and I.1a in lakes with lower nitrite and dissolved organic carbon concentrations below 0.5 mg L-1. Overall, these results showed strong selection by local environmental conditions, unveiled new ecological niches for freshwater SAGMGC-1 in low pH oligotrophic lakes, and suggested specific and successful adaptations of planktonic archaea to the high mountain lakes landscape. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1309
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Auteur Garrido, M.; Cecchi, P.; Vaquer, A.; Pasqualini, V.
Titre Effects of sample conservation on assessments of the photosynthetic efficiency of phytoplankton using PAM fluorometry Type Article scientifique
Année (up) 2013 Publication Revue Abrégée Deep-Sea Res. Part I-Oceanogr. Res. Pap.
Volume 71 Numéro Pages 38-48
Mots-Clés diatom, quantum yield, temperature, parameters; PAM fluorescence, Phytoplankton, Temperature Biguglia lagoon; physiological-responses, marine-phytoplankton, oxygen evolution, benthic; rapid light curves, chlorophyll-a fluorescence, in-vivo,
Résumé Pulse Amplitude Modulated (PAM) fluorometry is now a widely used method for the assessment of phytoplankton fitness, with an increasing popularity in field assessments. It is usually recommended to carry out measurements swiftly after collection, but the number of samples and analytical procedures needed to obtain valuable datasets sometimes makes immediate analysis impracticable, forcing delays between fluorescence measurements. Conservation conditions of samples before analysis may potentially affect their photosynthetic performances but no formal study documenting such impacts appears available in the literature. The aim of this study was to investigate the effects of storage conditions (temperature, duration) on photosynthetic parameters in different phytoplankton communities (characterized in situ by a BBE fluoroprobe) sampled during summer in different environmental locations in a Mediterranean lagoon (Biguglia lagoon, Corsica, France). PAM-fluorescence parameters were measured after three different conservation durations (2-4 h, 6-8 h and 10-12 h after collection) on samples stored at three different temperatures (15 degrees C, 25 degrees C and 35 degrees C). Results showed that storage at the highest temperature severely impacted photosynthetic parameters, with cumulative effects as storage duration increased. For phytoplankton samples collected in warm or tropical environments, storage at “room temperature” (25 degrees C) only appeared a valid option if measurements have to be carried out strictly within a very short delay. Inversely, cooling the samples (i.e. conservation at 15 degrees C) did not induce significant effects, independently of storage duration. Cooling appeared the best solution when sampling-to-analysis delay goes over a few hours. Long-term storage ( > 8 h) should definitively be avoided. (C) 2012 Elsevier Ltd. All rights reserved.
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ISSN 0967-0637 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 552
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Auteur Lafabrie, C.; Garrido, M.; Leboulanger, C.; Cecchi, P.; Grégori, G.; Pasqualini, V.; Pringault, O.
Titre Impact of contaminated-sediment resuspension on phytoplankton in the Biguglia lagoon (Corsica, Mediterranean Sea) Type Article scientifique
Année (up) 2013 Publication Revue Abrégée Estuarine Coastal and Shelf Science
Volume 130 Numéro Pages 70-80
Mots-Clés chemical contamination; coastal ecosystems; elutriate; microcosm experiment; phytoplankton; sediment resuspension
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ISSN 0272-7714 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 642
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Auteur Mostajir, B.; Le Floc'h, E.; Mas, S.; Pete, R.; Parin, D.; Nouguier, J.; Fouilland, E.; Vidussi, F.
Titre A new transportable floating mesocosm platform with autonomous sensors for real time data acquisition and transmission for studying the pelagic food web functioning Type Article scientifique
Année (up) 2013 Publication Revue Abrégée Limnol Oceanogr-Meth
Volume 11 Numéro Pages 394-409
Mots-Clés Oxygen; diatom bloom; fluorescence; phytoplankton; planktonic community; respiration; seawater; technical note; ultraviolet-b radiation; winkler method
Résumé We describe a new transportable floating mesocosm platform with autonomous sensors. The platform has 9 separate units that can be transported by medium-sized research vessels and positioned in coastal waters. The in situ mesocosms are equipped with a set of sensors for measuring water temperature, conductivity, chlorophyll a fluorescence (Chl a), and dissolved oxygen concentration. It can take measurements every 2 min, store these measurements, and transmit them in real time. Each mesocosm has a pump with regulated flow to mix the water column. One of the floating units is used as an in situ observatory to monitor the water temperature and Chl a in the water around the mesocosms as well as weather data and the incident light. The main data logger on the platform sends all the data collected to a remote PC computer. This floating mesocosm platform was successfully deployed in 2010 and 2011 in Mediterranean coastal waters (Thau lagoon and Cretan Sea, respectively). Simultaneous, automatic, high temporal resolution monitoring of physical, chemical, and biological parameters in the mesocosms proved to be a powerful, noninvasive, and effective approach for i) monitoring the variations in physical and chemical parameters in real time and ii) assessing the short-term variations in Chl a and the pelagic food web metabolism (e.g., the community respiration, gross primary production, and net community production) in the mesocosms without any manipulation of water samples.
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ISSN 1541-5856 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 394
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