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Auteur (down) Pringault, O.; Viret, H.; Duran, R.
Titre Interactions between Zn and bacteria in marine tropical coastal sediments Type Article scientifique
Année 2012 Publication Revue Abrégée Environ. Sci. Pollut. Res.
Volume 19 Numéro 3 Pages 879-892
Mots-Clés Bacterial diversity; Metal spiking; Microcosms; New Caledonia; T-Rflp; baltic sea sediments; community; coral-reef lagoon; fragment-length-polymorphism; heavy-metals; hypersaline microbial mat; new-caledonia lagoon; polluted anoxic sediments; salins-de-giraud; south-west lagoon; tolerance pict
Résumé Purpose The main goals of this study were (1) to examine the effects of zinc on the microbial community structure of anthropogenically impacted sediments in a tropical coastal ecosystem and (2) to determine whether these microbial benthic communities may enhance the adsorption of zinc. Methods The interactions between zinc and bacteria in tropical sediments were studied in sediment microcosms amended with 2.5 mg L-1 of Zn in the water phase and incubated for 8 days under different environmental conditions, oxic/anoxic and glucose addition. At the end of incubation, microbial structure was assessed by molecular fingerprints (T-RFLP) analysis and Zn speciation in the sediment was determined by sequential extraction. Results In the three studied sediments, Zn spiking resulted in only slight changes in bacterial community structure. In contrast, the addition of low concentrations of glucose (5mM) strongly modified the bacterial community structure: <20% of similarity with the initial structure concomitant with a strong diminution of the specific richness. Overall, these results suggest that highly labile organic matter has a larger impact on microbial structure than heavy metal. These weak impacts of Zn on bacteria diversity might be partly explained by (1) the strong adsorption of Zn in the presence of bacteria and/or (2) the incorporation of Zn into a nonbioavailable fraction. Nevertheless, Zn spiking resulted in significant changes in nutrient cycles, suggesting that bacterial metabolisms were impacted by the heavy metal. This led to an increase in nutrient supplies to the water column, potentially enhancing eutrophication in a nutrient-limited, oligotrophic ecosystem.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0944-1344 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 683
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Auteur (down) Hochard, S.; Pinazo, C.; Rochelle-Newall, E.; Pringault, O.
Titre Benthic pelagic coupling in a shallow oligotrophic ecosystem: Importance of microphytobenthos and physical forcing Type Article scientifique
Année 2012 Publication Revue Abrégée Ecological Modelling
Volume 247 Numéro Pages 307-318
Mots-Clés Benthic pelagic coupling; Microphytobenthos; Modelling; New Caledonia; Oligotrophic shallow ecosystem; Physical forcing
Résumé In coral reef lagoons, microphytobenthos (MPB) primary production can be of the same order of magnitude as coral or macroalgal production. As they are situated in oligotrophic waters, sediments receive low amount of allochtonous nutrients, and their high metabolism cannot be achieved without an efficient nutrient recycling. In oligotrophic environments nutrient exchange between sediments and the water column is considered to be low. However, physical forcing that disturbs the sediment interface may accelerate nutrient exchange. The objectives of this work were to: (i) characterize the benthic trophic status and associated nutrient diffusion fluxes as a function of terrestrial and anthropogenic influence and (ii) investigate the impact of physical forcing on the exchanges at the interface and the response of the water column. For that purpose, a multidisciplinary study was performed in the southwest lagoon of New Caledonia combining field survey, laboratory experiments and mathematical modelling. The field survey indicated that most of the lagoon sediments were autotrophic and presented negligible nutrient fluxes. This suggests an apparent decoupling between the sediment and the water column as long as diffusion is the dominant nutrient exchange mode process. This was confirmed by experimental ex situ incubations that showed bacterial production in the water column was not affected by the presence of sediment. The modelling approach showed that physical forcing, such as sediment erosion or wave driven pore water advection, might enhance the coupling between the sediment and the water column through the release of nutrients and organic matter leading to the stimulation of the bacterioplankton and phytoplankton compartments.
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Volume de collection Numéro de collection Edition
ISSN 0304-3800 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 465
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Auteur (down) Faure, V.; Pinazo, C.; Torréton, J.-P.; Douillet, P.
Titre Modelling the spatial and temporal variability of the SW lagoon of New Caledonia II: Realistic 3D simulations compared with in situ data Type Article scientifique
Année 2010 Publication Revue Abrégée Marine Pollution Bulletin
Volume 61 Numéro 7–12 Pages 480-502
Mots-Clés Biogeochemistry; Coupled models; New Caledonia; Physics; lagoon
Résumé Coral reef lagoons are under the growing influence of anthropogenic activities, leading to increasing loads of nutrients and various contaminants. Modelling approaches are a useful tool for studying such a complex coastal environment. In this study, we carried out the development of a three-dimensional coupled hydrodynamical-biogeochemical model of the south-west lagoon of New Caledonia. The biogeochemical model presented in Faure et al. (2006, 2010) was dynamically coupled with a hydrodynamical model (MARS3D) in order to study the short-term variability of the ecosystem. Two simulations (in winter and summer) were then performed from measured initial conditions using realistic wind and irradiance conditions and river inputs. Examinations of the biogeochemical response to these transient meteorological conditions were presented and compared with temporal field data corresponding to the considered periods. Results highlighted the ecosystem functioning, based on the balance of hydrodynamical and biogeochemical processes. Influence of urban and terrigeneous inputs were limited to the coastal zone. The model accurately reproduced the measured Chl.a and bacterial production, highlighting the improvement made on the biogeochemical model. However, the underestimation of some variables in model outputs, in particular nutrients, led us to focus on different inputs, such as sediment inputs which were not taken into account or properly estimated. Moreover, the role of boundary waters appeared crucial and suggested a calibration effort. Last, the final aim of our modelling study will help the development of a useful tool for studying the key processes of the ecosystem of the south-west lagoon of New Caledonia, as well as the examination of the biogeochemical response under different scenarios.
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Volume de collection Numéro de collection Edition
ISSN 0025-326x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 721
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Auteur (down) Cuif, M.; Kaplan, D.M.; Lefèvre, J.; Faure, V.M.; Caillaud, M.; Verley, P.; Vigliola, L.; Lett, C.
Titre Wind-induced variability in larval retention in a coral reef system: a biophysical modelling study in the South-West Lagoon of New Caledonia Type Article scientifique
Année 2014 Publication Revue Abrégée Progress in Oceanography
Volume 122 Numéro Pages 105-115
Mots-Clés Biophysical model; Dascyllus aruanus; Homing; Larval dispersal; New Caledonia; Precompetency; Wind-driven transport
Résumé In the present work, a biophysical dispersal model is used to understand the role of the physical environment in determining reef fish larval dispersal patterns in the South-West Lagoon of New Caledonia. We focus on a reef fish species, the humbug damselfish Dascyllus aruanus, to investigate seasonal variability of simulated larval retention at the scale of a reef patch and at the scale of the lagoon, and to explore links between larval retention and wind variability. The model shows that retention exhibits considerable temporal variability and periodically reaches values much larger than anticipated. Non-zero larval settlement occurs over a large part of the lagoon. Nevertheless, settlement values decrease quickly away from the natal reef and mean dispersal distances are of order 25-35 km. Cross-correlation analyses indicate that weather conditions characterized by strong south east trade winds lead to low retention rates at both local (reef) and regional (lagoon) scales. By contrast, subtropical weather conditions characterized by weak winds result in high retention rates. These results suggest that large-scale weather regimes can be used as proxies for larval retention of the humbug damselfish in the South-West Lagoon of New Caledonia. Nevertheless, relatively small mean dispersal distances suggest that meta-population dynamics occur on relatively small spatial scales.
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Volume de collection Numéro de collection Edition
ISSN 0079-6611 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 318
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Auteur (down) Clua, E.; Séret, B.
Titre Unprovoked fatal shark attack in Lifou Island (Loyalty Islands, New Caledonia, South Pacific) by a great white shark, Carcharodon carcharias Type Article scientifique
Année 2010 Publication Revue Abrégée The American Journal of Forensic Medicine and Pathology
Volume 31 Numéro 3 Pages 281-286
Mots-Clés Animals; Bites and Stings; Exsanguination; Female; Forensic Pathology; Humans; New Caledonia; Sharks; Shock; Thigh
Résumé The case of a fatal, unprovoked shark attack is reported and analyzed. The incident took place on the 30th of September 2007, in the lagoon of Luengoni Bay, Lifou Island (Loyalty Islands, New Caledonia). A young French woman who was snorkeling was severely bitten on the right thigh and died of hemorrhage. An analysis based in particular on the size and color of the shark, the characteristics of the wounds, and the behavior of the shark before and after the bite suggests that the aggressor was a great white shark, Carcharodon carcharias.
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Volume de collection Numéro de collection Edition
ISSN 1533-404x ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 63
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