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51. Biogeochemical cycling and phyto- and bacterio-plankton communities in a large and shallow tropical lagoon (Terminos Lagoon, Mexico) under 2009–2010 El Niño Modoki drought conditions

Author

Conan, Pascal, primary, Pujo-Pay, Mireille, additional, Agab, Marina, additional, Calva-Benitez, Laura, additional, Chifflet, Sandrine, additional, Douillet, Pascal, additional, Dussud, Claire, additional, Fichez, Renaud, additional, Grenz, Christian, additional, Gutierrez Mendieta, Francisco, additional, Origel-Moreno, Montserrat, additional, Rodríguez-Blanco, Arturo, additional, Sauret, Caroline, additional, Severin, Tatiana, additional, Tedetti, Marc, additional, Torres Alvarado, Rocío, additional, and Ghiglione, Jean-François, additional

Published
2016
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52. Global climate change and local watershed management as potential drivers of salinity variation in a tropical coastal lagoon (Laguna de Terminos, Mexico)

Author

Fichez, Renaud, primary, Archundia, Denisse, additional, Grenz, Christian, additional, Douillet, Pascal, additional, Gutiérrez Mendieta, Francisco, additional, Origel Moreno, Montserrat, additional, Denis, Lionel, additional, Contreras Ruiz Esparza, Adolfo, additional, and Zavala-Hidalgo, Jorge, additional

Published
2016
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53. Spatial and temporal variations of plutonium isotopes (Pu-238 and Pu-239,Pu-240) in sediments off the Rhone River mouth (NW Mediterranean)

Author

Lansard, B., Charmasson, S., Gasco, C., Anton, M. P., GRENZ, Christian, Arnaud, M., Laboratoire d'étude radioécologique du milieu continental et marin (LERCM), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Direction de l'Environnement et de l'Intervention, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Laboratoire d'Etudes Radioécologiques des milieux Continental et marin (IRSN/PRP-ENV/SESURE/LERCM), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), and Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, SEA, GULF, plutonium, INVENTORY, marine sediment, ARTIFICIAL RADIONUCLIDES, SOUTHERN FRANCE, BIOGEOCHEMICAL IMPLICATIONS, CONTINENTAL-MARGIN, LIONS, PLUME, Rhone River, DISPERSION, Gulf of Lions, Mediterranean Sea, contaminant dispersion
Abstract

The dispersion and fate of the Rhone River inputs to the Gulf of Lions (Northwestern Mediterranean Sea) have been studied through the spatial and temporal distributions of plutonium isotopes in continental shelf sediments. Plutonium isotopes (Pu-238 and Pu-239,Pu-240) are appropriate tracers to follow the dispersion of particulate matter due both to their high affinity for particles and their long half-lives. In the Rhone River valley, plutonium isotopes originate from both the weathering of the catchment basin contaminated by global atmospheric fallout, and the liquid effluents released from the Marcoule reprocessing plant since 1961.;This work presents a first detailed study on Pu-238 and Pu-239,Pu-240 distributions in sediments from the Rhone prodelta to the adjacent continental shelf, since the decommissioning of Marcoule in 1997. The vertical distribution of Pu isotopes has been analysed in a 4.75 in long core sampled in 2001 at the Rhone mouth. Despite this length, plutonium is found at the last 10 cm, manifesting the high sedimentation rate of the prodeltaic area and its ability for trapping fine-grained sediments and associated contaminants. The highest Pu-238 and Pu-239,Pu-240 concentrations reached 1.26 and 5.97 Bq kg(-1) respectively and were found within the layer 280-290 cm. The Pu-238/Pu-239,Pu-240 activity ratios (AR) demonstrated an efficient and huge trapping of the Pu isotopes derived from Marcoule. The fresh sediments, located on the top of the core, show lower plutonium activity concentrations and lower Pu-238/Pu-239,Pu-240 ratios. This decrease is in close relation with the shut down of the Marcoule reprocessing plant in 1997.;In 2001, plutonium isotopes were also analysed in 21 surface sediments located offshore and concentrations ranged from 0.03 to 0.17 Bq kg(-1) for Pu-238 and from 0.33 to 1.72 Bq kg(-1) for Pu-239,24(0). The Pu-238/Pu-239,Pu-240 AR ranged from 0.24 close to the river mouth to 0.06 southwards, indicating the decreasing influence of the Marcoule releases (global fallout AR 0.03-0.05 and Marcoule AR 0.30). This is in good agreement with the main direction spread of the Rhone River plume and the bottom current. This dataset has been compared to those obtained in the same area in 1984 and 1990 in order to follow the time trend in Pit concentrations. This comparison highlights the decrease with time in plutonium concentrations close to the Rhone River mouth, but further away this reduction is not so evident. (c) 2007 Elsevier B.V. All rights reserved.

Published
2007

54. Eutrophication and some European waters of restricted exchange

Author

Teet, Paul, Gilpin, Linda, Erlandsson, Carina, Larsson, Ulf, Kratzer, Susanne, Fouillandf, Eric, Janzen, Carol, Lee, Jae-Young, Grenz, Christian, Newton, Alice, Ferreira, J., Fernandes, Teresa, and Serge, Scory

Abstract

Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002 concerns ‘Oceanographic Applications to Eutrophication in Regions of Restricted Exchange’. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfj.arden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q: It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex‘research’ model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socioeconomic issues that need to be taken into account in managing the trophic status of RREs.

Published
2003

55. Biogeochemical recycling in the south-west lagoon of New Caledonia. A box model approach

Author

Bujan, S, Grenz, Christian, Fichez, Renaud, Douillet, P., Laboratoire d'océanographie et de biogéochimie (LOB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie et de biogéochimie ( LOB ), and Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
modelling, [ SDE.MCG ] Environmental Sciences/Global Changes, biogeochemistry, [SDE.MCG]Environmental Sciences/Global Changes, phytoplankton, New-Caledonia, lagoon
Abstract

A biogeochemical box model describing the south-west lagoon of New-Caledonia was developed in order to simulate the seasonal cycle of carbon and nitrogen. We used fluxes generated by a 3D hydrodynamic model to simulate horizontal exchanges between boxes and added freshwater influxes as nitrogen sources from the land. Average residence time proved to be less than 11 days for the lagoon as a whole. Standard simulations showed baseline values of chlorophyll a between 0.2 and 0.4 μg*L-1. Influences of freshwater influxes proved to be significant (increases up to 1 μg*L-1) only in shallow areas protected from wind exposure and during short periods of heavy rainfall (tropical depressions). Tropical climatic events have reduced impact in space and time and long-term simulations over decades with increased nutrient inputs did not show any significant process of eutrophication. Hydrodynamics seemed to be one of the major control factors with respect to organic matter cycling in the lagoon.

Published
2000

56. Biogeochemical cycling and phyto- and bacterio-planktoncommunities in a large and shallow tropical lagoon (TerminosLagoon, Mexico) under 2009-2010 El Niño Modoki droughtconditions.

Author

Conan, Pascal, Pujo-Pay, Mireille, Agab, Marina, Calva-Benitez, Laura, Chifflet, Sandrine, Douillet, Pascal, Dussud, Claire, Fichez, Renaud, Grenz, Christian, Gutierrez Mendieta, Francisco, Origel-Moreno, Montserrat, Rodríguez-Blanco, Arturo, Sauret, Caroline, Severin, Tatiana, Tedetti, Marc, Alvarado, Rocío Torres, and Ghiglione, Jean-François

Subjects
BIOGEOCHEMICAL cycles, PHYTOPLANKTON, BACTERIOPLANKTON, LAGOONS, BACTERIAL communities, BACTERIAL diversity
Abstract

A large set of biogeochemical (nutrients, dissolved and particulate organic matter), phytoplanktonic (biomass and photosynthetic activity) and bacterial (bacterial diversity and ectoenzymatic activities) parameters were determined to understand how the severe drought period relative to the 2009-2010 El Niño Modoki episode influenced biogeochemical cycling and phyto- and bacterio-plankton communities in Terminos Lagoon (Mexico) potentially prefiguring future environmental conditions due to expected trends in climate change. During the study period, the water column of Terminos Lagoon functioned globally as a sink, and especially as a "nitrogen assimilator", because of high production of particulate and dissolved organic matter although exportation of autochthonous matter to the Gulf of Mexico was weak. Coupling between top-down and bottom-up controls accounted for the diverse responses in phytoplankton productivity. Nitrogen and phosphorus stoichiometry mostly accounted for the heterogeneity in phytoplankton and bacteria distribution in the lagoon. In the Eastern part, we found a clear decoupling between areas enriched in dissolved inorganic nitrogen in the North close to Puerto real coastal inlet and areas enriched in phosphate (PO4) in the South close to the Candelaria estuary. Such a decoupling limited the potential for primary production resulting in an accumulation of dissolved organic carbon and nitrogen (DOC and DON, respectively) close to the river mouth. In the Western part of the lagoon, maximal phytoplankton development resulted from the coupling between Palizada river inputs of nitrate (NO3) and particulate organic phosphorus -PP- (but depleted in PO4) and bacterial activity transforming PP and dissolved organic phosphorus (DOP) to available PO4. The Chumpan River only marginally contributed to PO4 inputs due to its very low contribution to overall river inputs. We also found that a complex array of biogeochemical and phytoplanktonic parameters were the driving force behind the geographical distribution of bacterial community structure and activities. Finally, we showed that nutrients brought by the Palizada River supported an abundant bacterial community of polycyclic aromatic hydrocarbon (PAH)-degraders, which are of significance in this important oil production zone. [ABSTRACT FROM AUTHOR]

Published
2016
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62. Oxygen fluxes involving the benthic micro- and macrophytic components in the Thau Lagoon under pre-anoxic conditions

Author

Plante Cuny, Marie-reine, Plante, Raphaël, Mazouni, Nabila, Fontaine, Marie-france, Souchu, Philippe, Deslous-paoli, Jean-marc, Grenz, Christian, Plante Cuny, Marie-reine, Plante, Raphaël, Mazouni, Nabila, Fontaine, Marie-france, Souchu, Philippe, Deslous-paoli, Jean-marc, and Grenz, Christian

Abstract

Measurements of oxygen fluxes at the water-sediment interface (transparent and opaque enclosures) were made on bare sediments inhabited by microphytes on the one hand, and on sediments diversely colonized by macrophytes (macroalgae and seagrasses) on the other hand. Five stations, typical of different biotopes of a Mediterranean shallow lagoon were studied from May to July 1993 in order to observe an anoxic event which usually occurs at that time of the year. Average diurnal respiration of benthic communities ranged from 40 mg (or 1.25 mmol) O-2 m(-2) h(-1) in bare sediments (31 % of the lagoon area) to 76 mg (or 2.37 mmol) O-2 m(-2) h(-1) in sediments with a medium coverage of macroalgae (37 % of the total area) and, finally, to 100 mg (or 3.12 mmol) O-2 m(-2) h(-1) in the denser macrophytic area (32 % of the total area). The highest diurnal gross production was observed in the zone colonized by macroalgae and seagrasses, and especially in corridors between shellfish-cultivation tables (300 mg O-2 m(-2) h(-1), or 9.37 mmol O-2 m(-2) h(-1), equivalent to 113 mg C m(-2) h(-1)). Overall, during this period, net bottom oxygen production was close to nil in ca. 30 %, and positive in 70 % of the lagoon area. The average net oxygen production for the whole lagoon in summer is thus in the order of 100 mg O-2 m(-2) h(-1). In 1993, at the end of July, an anoxic event was avoided due to a period of strong wind., Les flux d'oxygène ont été mesurés à l'interface eau-sédiment (enceintes transparentes et opaques) d'une part, sur des sédiments apparemment nus (mais peuplés de microphytes), et d'autre part sur des sédiments plus ou moins couverts de macrophytes (macroalgues et phanérogames). Cinq stations, caractéristiques des différents biotopes d'une lagune méditerranéenne peu profonde, ont été étudiées de mai à juillet 1993, dans le but de saisir un des épisodes d'anoxie habituels à cette époque. La respiration diurne d'oxygène des communautés benthiques (cloches noires) augmente en moyenne de 40 mg (ou 1,25 mmol) O2 m−2 h−1 sur les sédiments nus, représentant 31 % de la surface totale de la lagune, à 76 mg (ou 2,37 mmol) O2 m−2 h−1 vers les sédiments moyennement peuplés en macroalgues (37 % de la surface totale) et jusqu'à 100 mg (ou 3,12 mmol) O2 m−2 h−1 dans les zones densément peuplées de macrophytes (32 % de la surface totale). La production brute diurne est maximale dans les zones à macrophytes avec phanérogames et en particulier dans les corridors entre les tables ostréicoles (300 mg O2 m−2 h−1 ou 9,37 mmol O2 m−2 h−1, ou encore équivalente à 113 mg C m−2 h−1). À cette période pré-estivale et estivale de l'année, la production nette d'oxygène à la surface des sédiments est nulle pour environ 30 % de la surface de la lagune et positive pour environ 70 % de cette surface. En moyenne pour l'ensemble de la lagune, la production nette due aux végétaux benthiques est d'environ 100 mg O2 m−2 h−1. À la fin de juillet 1993, une crise anoxique a été évitée grâce à un fort coup de vent.

Published
1998
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68. Plutonium Isotope Remobilization from Natural Sediments (Gulf of Lions, Northwestern Mediterranean Sea): Estimation Based on Flume Experiments.

Author

Lansard, Bruno, Charmasson, Sabine, Eyrolle, Frédérique, Arnaud, Mireille, and Grenz, Christian

Subjects
PLUTONIUM isotopes, SEDIMENTS, FLUMES
Abstract

For the last forty years, military and industrial spent-nuclear fuels were reprocessed at the Marcoule plant located along the Rhone valley (France). Low-level plutonium isotopes contained in liquid wastes were released into the Rhone River, which represents the main fresh water input to the western Mediterranean Sea. Over these years, a reservoir of artificial radionuclides was built up both in sediments of the river and in sediments of the Rhone mouth in the Mediterranean Sea. Because of the high affinity of plutonium for suspended particles, coastal sediment could be considered as one of the major sinks for plutonium but not the ultimate one. In fact, this reservoir can act as a delayed source of plutonium for the water column by redissolution, thermal and photochemical reactions, and punctually during resuspension events. Later process occurs largely during most of the year because winds are highly frequent in this region. In 1997, the Marcoule reprocessing plant ceased its activities, leading to a significant decrease in the discharges. Therefore, in the Gulf of Lions, the contribution of the sedimentary source term could become significant. This has provided a unique opportunity to investigate the behaviour of plutonium at the sediment-water interface in a dynamic coastal environment, in order to predict with confidence the ultimate sink. [ABSTRACT FROM AUTHOR]

Published
2003

69. Does chlorophyllide a reduce reliability of chlorophyll a measurements in marine coastal sediments?

Author

Plante-Cuny, Marie-Reine, Barranguet, Christiane, Bonin, Daniel, and Grenz, Christian

Abstract

Pigment concentrations (chlorophyll a, chlorophyllide a and pheopigments a) were measured by HPLC and spectrophotometry with acidification on 57 samples collected in different marine coastal sediments, containing autochthonous microphytes, and with various organic matter contents (plant detritus, biodeposits or hydrocarbons). Statistical analysis shows that the spectrophotometry with acidification, as compared to HPLC, gives reliable values for chlorophyll a. Chlorophyllide a concentrations may be considered as negligible. Though spectrophotometric methods are sometimes questioned when applied to sediments they appear to give easy, quick and good estimates of Chl a contents in benthic microphytes for hydrobiological studies in coastal areas. [ABSTRACT FROM AUTHOR]

Published
1993
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70. Quantification et destinée de la biodéposition en zones de production conchylicole intensive en Méditerranée

Author

Grenz, Christian

Abstract

L'étude des processus de transferts de matière et d'énergie dans les écosystèmes côtiers a été abordée par le biais de l'analyse du fonctionnement des écosystèmes conchylicoles où ces transferts sont amplifiés en raison d'une très forte biomasse monospécifique, concentrée dans un espace restreint. La biodéposition représente le vecteur principal de transfert entre le compartiment pélagique ou benthique "suspendu" et le compartiment benthique sensu stricto. Dans les conditions typiquement méditerranéennes, les études concernant l'émission des fèces et pseudo-fèces sont rares. Pour combler cette lacune et apporter un élément supplémentaire à la connaissance du fonctionnement de tels écosystèmes, une étude in situ de la biodéposition a été entreprise dans deux sites type : une baie largement ouverte: l'Anse de Carteau (Golfe de Fos) et une lagune semi-fermée : l'Etang de Thau. Les mollusques élevés sur cordes suspendues sont de deux types: Crassostrea gigas et Mytilus galloprovincialis à Thau et M. galloprovincialis à Carteau. Cette étude comprend deux volets qui sont, d'une part, la quantification de la biodéposition et celle de ses inter-relations avec les paramètres environnementaux et, d'autre part, le devenir des biodépôts dans le milieu en terme d'évolution biochimique et d'exportation. Le suivi saisonnier de l'évolution de la biodéposition entre fin 1985 et 1987, a permis de définir une relation linéaire à deux facteurs valable pour M. galloprovincialis, élevée sur corde en condition méditerranéenne : BO (mgOrg.g-1.d-1) = 6.35 [MOP (mg.l-1)] + 0.97 [VIT (cm.s-1)] + 1.91 où BO, MOP et VIT représentent respectivement la biodéposition organique par g de chair sèche de moule et par jour, la matière organique particulaire et la vitesse du courant. La comparaison des mesures de biodéposition d'huître et de moule permet de signaler une différence dans le comportement trophique de ces deux mollusques. Pour les plus fortes charges sestoniques rencontrées dans l'étang de Thau, un g de chair d'huître émet plus de fèces et pseudo-fèces dans le milieu que son équivalent moule. A partir des relations linéaires entre BO et la Chlorophylle a, définies respectivement pour les moules et les huîtres, une carte représentant l'impact de la biodéposition organique sur le taux de sédimentation organique a été tracée pour l'étang de Thau. Une amplification d'un facteur 3 à 4 de ce taux de sédimentation, dans les zones conchylicoles, est la conséquence de l'élevage de ces mollusques. Dans le cadre d'un bilan de production portant sur un cycle d'élevage de la moule sur une période de 480 jours pour un cube de 5x5x3 m (soit 75 m3), la biodéposition représentre 11.4 t de matière sèche correspondant à 1.86 t de matière organique contenant 10.20 109 J, sédimentant sur une surface de 25 m2environ. L'évolution des biodépôts a été suivie in situ, d'une part, en mesurant la variation qualitative d'un sédiment enrichi en biodépôts de moules pendant une période de 60 jours, et d'autre part, en estimant les flux à l'interface eau-sédiment dans les zones conchylicoles. Le premier point permet de définir que les processus de minéralisation de la fraction soluble des biodépôts semblent se dérouler en 15 jours en faisant intervenir, pour une grande part, le compartiment bactérien. Le second point, en agrément avec le premier, démontre que les flux de nutriments (NH4, Si(OH)4 et PO4) sont amplifiés sous les installations conchylicoles de Carteau. Globalement, l'examen des échanges azotés à l'interface eau-sédiment fait apparaître un déficit aux dépens de la colonne d'eau. En effet, le sédiment piège la matière organique sédimentée qui peut être l'objet d'un remaniement à plus long terme. L'hydrodynamisme de l'Anse de Carteau, décrit par une modélisation numérique bidimensionnelle, démontre l'existence d'un régime de circulation cellulaire s'établissant dans des conditions de vents de mistral et de SE établies, situations très fréquentes dans ces régions. Les conséquences au niveau du fonctionnement de l'écosystème sont, d'une part, une faible probabilité des phénomènes d'exportation de matière et d'énergie vers la mer ouverte, et d'autre part, la nécessité de considérer dans l'ensemble des bilans, la production régénérée pour expliquer le caractère eutrophe de cette zone, la rapprochant des conditions lagunaires.

Published
1989

71. Rôle de l'espèce ingénieure Upogebia pusilla dans le fonctionnement biogéochimique des écosystèmes intertidaux à herbier (Zostera noltei) du bassin d'Arcachon

Author

PASCAL, Ludovic, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux, Antoine Grémare, Olivier Maire, STAR, ABES, Grémare, Antoine, Maire, Olivier, Garabétian, Frédéric, Chauvaud, Laurent, Grenz, Christian, Rossi, Francesca, Archambault, Philippe, Deflandre, Bruno, and Montaudouin, Xavier de

Subjects
Benthic fluxes, Bioirrigation, Comportement, Seasonality, Parasitisme, Flux benthiques, Image analysis, [SDE.BE] Environmental Sciences/Biodiversity and Ecology, Remaniement sédimentaire, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Parasitism, [SDV.EE.ECO] Life Sciences [q-bio]/Ecology, environment/Ecosystems, Behaviour, Bioturbation, Saisonnalité, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Analyse d’image, Sediment reworking
Abstract

In Arcachon bay, the endobenthic thalassinid crustacean Upogebia pusilla is tightly associated with the intertidal dwarf grass Zostera noltei providing the sediment stability required for the construction of (semi-)permanent burrows. Because of the depth and complex architecture of their burrow (> 30 cm), this high mobile engineer species have been largely ignored in previous studies aiming at better understanding the role of macrobenthic communities in the functioning of seagrass ecosystems and the consequences of their rapid decline. This manuscript presents an integrated study regarding the role played by U. pusillain the functioning of its ecosystem, with particular emphasis on the characterisation and quantification of the relationships between (1) its different activities (burrowing, ventilating,walking…), (2) both bioturbation modes and rates and (3) their respective impacts on the sedimentary biogeochemical dynamics. This work shows that mud shrimp activity leads tohigh mixing and bioirrigation of the surrounding sediment matrix, thus strongly enhancing organic matter mineralisation processes and solute exchanges across the sediment-water interface. Although the influence of U. pusilla on ecological and biogeochemical processes largely depends on environmental conditions (e.g., seasonality and parasitism), altogether my results suggest that the gradual decline of its population in Arcachon bay, as a direct consequence of benthic habitat degradation, may greatly alter the overall functioning of this vulnerable marine ecosystem., Dans le bassin d’Arcachon, le crustacé thalassinidé Upogebia pusilla habite préférentiellement les vasières intertidales colonisées par les zostères naines (Zostera noltei) où il trouve la stabilité sédimentaire indispensable à l’établissement durable de son terrier. Du fait de la profondeur de ce dernier (> 30 cm) et de sa grande mobilité, cette espèce ingénieure a souvent été négligée dans les études antérieures ayant pour objectif de mieux comprendre le rôle des communautés macro-benthiques dans le fonctionnement des herbiers de phanérogames et les conséquences de leur régression rapide. Ce manuscrit présente une étude intégrée du rôle d’U. pusilla dans le fonctionnement de son écosystème en s’attachant particulièrement à caractériser et quantifier les relations entre (1) ses différentes activités (fouissage, ventilation, locomotion, …), (2) les modes de bioturbation qui en résultent et (3)leurs impacts respectifs sur la dynamique biogéochimique sédimentaire. Ce travail montre qu’U. pusilla engendre un remaniement et une bioirrigation intenses de la matrice sédimentaire qui l’entoure. Sa présence stimule ainsi fortement la reminéralisation de la matière organique sédimentée et les échanges de solutés à travers l’interface eau-sédiment.Bien que l’influence d’U. pusilla sur ces processus écologiques et biogéochimiques soit très dépendante des conditions environnementales (e.g., saisonnalité, prévalence parasitaire),l’ensemble de mes résultats suggère que le déclin progressif de ses populations, conséquence directe de la dégradation de son habitat, est susceptible de fortement altérer le fonctionnement global des écosystèmes du bassin d’Arcachon.

Published
2017

72. Developing erosion models for integrated coastal zone management: A case study of The New Caledonia west coast

Author

Morgan Mangeas, Julia Printemps, Pascal Dumas, Gaelle Luneau, Université de la Nouvelle-Calédonie (UNC), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), UMR 228 Espace-Dev, Espace pour le développement, Université de Guyane (UG)-Université des Antilles (UA)-Institut de Recherche pour le Développement (IRD)-Université de Perpignan Via Domitia (UPVD)-Avignon Université (AU)-Université de La Réunion (UR)-Université de Montpellier (UM), Unité de pathologie animale, Institut National de la Recherche Agronomique (INRA), Institut de Recherche pour le Développement (IRD)-Université de Perpignan Via Domitia (UPVD)-Avignon Université (AU)-Université de La Réunion (UR)-Université de Montpellier (UM)-Université de Guyane (UG)-Université des Antilles (UA), Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
Conservation of Natural Resources, Geologic Sediments, Geographic information system, EROSION, ZONE TROPICALE, 010504 meteorology & atmospheric sciences, SYSTEME D'INFORMATION GEOGRAPHIQUE, Rain, Fringing reef, Drainage basin, 010501 environmental sciences, Aquatic Science, Oceanography, 01 natural sciences, Soil, New Caledonia, LAGON, Tropical climate, 14. Life underwater, Integrated coastal zone management, 0105 earth and related environmental sciences, Hydrology, geography, geography.geographical_feature_category, business.industry, ZONE COTIERE, Sediment, Models, Theoretical, 15. Life on land, MODELISATION, Pollution, 6. Clean water, Universal Soil Loss Equation, 13. Climate action, [SDE]Environmental Sciences, Erosion, Environmental science, business, GESTION INTEGREE
Abstract

International audience; The tropical climate and human pressures (mining industry, forest fires) cause significant sediment inputs into the New Caledonia lagoon and are a major cause of degradation of the fringing reefs. The erosion process is spatially characterized on the west coast of New Caledonia to assess potential sediment inputs in the marine area. This paper describes the methodologies that are used to map soil sensitivity to erosion using remote sensing and a geographic information system tool. A cognitive approach, multi-criteria evaluation model and Universal Soil Loss Equation are implemented. This article compares the relevance of each model in order to spatialize and quantify potential erosion at catchment basin scale. These types of studies provide valuable results for focusing on areas subject to erosion and serve as a decision-making tool for the minimization of lagoon vulnerability to the natural and human dynamics on the level of the catchment basins.

Published
2010

73. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Robert Le Borgne, Martine Rodier, Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
Nitrogen, STRUCTURE DU PEUPLEMENT, PRODUCTION PRIMAIRE, Population Dynamics, Population, Environment, Aquatic Science, Cyanobacteria, Oceanography, Trichodesmium erythraeum, ABONDANCE, Water column, New Caledonia, LAGON, Aquatic plant, Phytoplankton, ETUDE COMPARATIVE, Seawater, education, Ecosystem, REPARTITION VERTICALE, education.field_of_study, biology, Ecology, FIXATION BIOLOGIQUE DE L'AZOTE, Temperature, MICROORGANISME, Plankton, biology.organism_classification, Pollution, Carbon, CYANOBACTERIE, Trichodesmium, Water Microbiology, Bloom
Abstract

While Trichodesmium erythraeum is prevalent in the semi-closed SW lagoon of New Caledonia, T. thiebautii is dominant in the more open SE lagoon. This led to the comparison of the two species from the results of two high-frequency surveys focused on T. erythraeum (Rodier and Le Borgne, 2008) and T. thiebautii (the present paper). (1) Environmental conditions and triggers of the blooms are the same: calm weather and/or temperature >26 degrees C, and temporary nutrient inputs are required for both; (2) growth rates under favorable conditions are similar (0.14-0.27 d(-1)) but (3) T. thiebautii has lower net ascent rates along the water column during blooming events, due to distinct buoyancy capacities and the resulting vertical distributions; (4) carbon and dinitrogen fixation rates are not significantly different and contribution of Trichodesmium spp. represent less than 35% and 5% of the total phytoplankton carbon and nitrogen requirements, respectively. It is concluded the two species can be mixed in ecological studies, except for their vertical distributions during the bloom periods.

Published
2010

74. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Ken Ridgway, Gérard Eldin, Cécile Dupouy, Martine Rodier, Andres Vega, Christophe Maes, Alexandre Ganachaud, Patrick Marchesiello, Robert Le Borgne, Océan du Large et Variabilité Climatique (OLVAC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques (CAMELIA), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut de Recherche pour le Développement (IRD [Guyane]), Echanges Côte-Large (ECOLA), Centre for Australian Weather and Climate Research, CSIRO Wealth from Oceans National Research Flagship, Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, VENT, UPWELLING, Aquatic Science, Oceanography, 01 natural sciences, Water column, New Caledonia, Water Movements, Computer Simulation, Seawater, 14. Life underwater, Argo, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, TEMPERATURE DE SURFACE, Upwelling, DONNEES SATELLITE, PRODUCTION BIOLOGIQUE, 010604 marine biology & hydrobiology, Biodiversity, Plankton, Models, Theoretical, Mooring, Satellite Communications, Pollution, Current (stream), CIRCULATION OCEANIQUE, Sea surface temperature, ALIS current, 13. Climate action, Climatology, SIMULATION, Remote Sensing Technology, COURANT MARIN, Environmental science, Hydrography, IMPACT SUR L'ENVIRONNEMENT, Environmental Monitoring
Abstract

International audience; The upwelling events that follow strong trade wind episodes have been described in terms of their remarkable signature in the sea surface temperature southwest off New Caledonia. Upwelling brings deeper, and colder waters to the surface, causing 2-4 °C drops in temperature in a few hours, followed by a slower relaxation over several days. Upwelling may sporadically bring nutrients to the surface under certain conditions, and increase the biological productivity. Two multidisciplinary hydrographic cruises allow the impact of upwelling on the chemical and biological properties of the water to be documented. Both cruises took place in austral summer (December 2004 and December 2005), but the first cruise occurred during a strong upwelling event, while the second cruise occurred in calm conditions. The water properties and planktonic composition show important contrasts, with a strong southeastward current (the "ALIS current of New Caledonia") competing with the upwelling system. Our analysis suggests that, while observed productivities are far less than those of typical upwelling systems, some wind events in New Caledonia may contribute to biological activity. A currentmeter mooring, deployed during the second cruise, documents the ocean response to a changing wind field and the local impact of upwelling on currents and temperatures on the water column. The results are discussed, with the help of climatology, Argo float profiler data, satellite data and of a high-resolution numerical simulation.

Published
2010

75. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Laure Carassou, R. Le Borgne, E. Rolland, Dominique Ponton, Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
Chlorophyll, Chlorophyll a, Time Factors, Population Dynamics, Wind, Aquatic Science, Environment, Oceanography, Zooplankton, ABONDANCE, POISSON MARIN, chemistry.chemical_compound, Food Preferences, Water column, LAGON, New Caledonia, Animals, Seawater, Ecosystem, Population Density, geography, geography.geographical_feature_category, Pacific Ocean, Terrigenous sediment, IMPACT DE L'ENVIRONNEMENT, Chlorophyll A, Fishes, Temperature, Estuary, Coral reef, Biodiversity, Plankton, Anthozoa, Pollution, Fishery, RECIF CORALLIEN, chemistry, Environmental science, ZOOPLANCTON, LARVE, Bay, RELATION PREDATEUR PROIE
Abstract

The distribution of zooplanktonic prey of fish larvae was examined in three bays and two lagoonal stations in the Southwest lagoon of New Caledonia. Water column conditions were characterized by increasing chlorophyll a and particulate organic matter (POM) concentrations from the lagoon to the estuarine bay. The mean zooplankton settled volume and total density were significantly higher in the estuarine bay, reaching 35.1 mL m(-3) and 3.5 x 10(5) individuals m(-3), respectively. The total zooplankton density also progressively increased along the sampling period. The composition of assemblages differed between the lagoon and the bays, and was similar in the three bays. Wind speed, surface temperature, chlorophyll a and POM explained these variations, as revealed by a co-inertia analysis (COIA). The prey preferred by fish larvae, i.e. small crustaceans and small copepods, were more abundant in bays. Sheltered bays, most influenced by terrigenous inputs, are likely to provide the best feeding conditions.

Published
2010

76. Hydrography and plankton temporal variabilities at different time scales in the southwest lagoon of New Caledonia: a review

Author

Pascal Douillet, Robert Le Borgne, Renaud Fichez, Jean-Pascal Torréton, UR 103 Camélia, Institut de Recherche pour le Développement ( IRD ), Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
DYNAMICS, SALINITE, PACIFIC, Time Factors, Context (language use), METEOROLOGIE, Aquatic Science, Oceanography, LAGON, New Caledonia, medicine, Water Movements, Seawater, Precipitation, WEST LAGOON, Ecosystem, Shore, TEMPERATURE DE SURFACE, geography, geography.geographical_feature_category, [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, Temperature, Tropics, Pelagic zone, Plankton, Seasonality, INPUTS, medicine.disease, SEASONAL-VARIATIONS, Pollution, VARIATION INTERANNUELLE, Climatology, BAY, Environmental science, Seasons, Hydrography, PLANCTON, COMMUNITIES, CORAL-REEF LAGOON
Abstract

International audience; The New Caledonia SW lagoon is wide (5-20 nautical miles) and semi-closed. It is influenced by both the open ocean and the high island within a meteorological context subject to seasonal, inter-annual and longer term variations. The short-term variability (>1 day) of meteorological, hydrographical and planktonic parameters is illustrated by a 5-month long time series and is linked to local or remote wind, and precipitation. Seasonal and inter-annual variabilities, inferred from a 10-year long station by spectral analysis, appear clearly for all parameters. Seasonality is the main scale of variability as the island lies near the tropic of Capricorn. Inter-annual variability of a 3-4 year periodicity is poorly related to the Southern oscillation index (an equatorial climatic index), stressing the need for a separate tropical index. Long term trends appear on several parameters but their reliability depends on the length of the records. Considering only the longest records (1958-2005), surface temperature appears to have increased since the end of the 1960s in Noumea area. Finally, as a result of greater terrestrial influence, shallower depths, and longer water turnover times close to shore, the temporal variability amplitude decreases from the shore to the barrier reef.

Published
2010

77. Integrated coastal zone management perspectives to ensure the sustainability of coral reefs in New Caledonia

Author

Marc Léopold, Gilbert David, Guy Fontenelle, Jocelyne Ferraris, Pascal Dumas, Jean-Brice Herrenschmidt, Écologie et santé des écosystèmes (ESE), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), French National Program for Coastal Environment (PNEC), Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
0106 biological sciences, CONSERVATION DE LA NATURE, Coral reefs, 010501 environmental sciences, Oceanography, 01 natural sciences, LAGON, Environmental protection, Nickel, MESH: Nickel, MESH: Animals, MESH: Ecosystem, Integrated coastal zone management, Nature reserve, Governance, geography.geographical_feature_category, Environmental resource management, Coral reef, Lagoon, Anthozoa, MESH: Mining, Pollution, Geography, MESH: Water Pollutants, Chemical, Government, impact, MESH: Conservation of Natural Resources, Mainland China, Civil society, Conservation of Natural Resources, MESH: Government, Mine, Aquatic Science, Mining, PATRIMOINE MONDIAL, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, New Caledonia, Island economy, GESTION DE L'ENVIRONNEMENT, Animals, pacific islands, 14. Life underwater, World heritage, Reef, Ecosystem, 0105 earth and related environmental sciences, Sustainable development, AIRE MARINE PROTEGEE, business.industry, INDUSTRIE MINIERE, 010604 marine biology & hydrobiology, ZONE COTIERE, Marine reserve, MESH: New Caledonia, RECIF CORALLIEN, MESH: Anthozoa, fisheries, Sustainability, business, GESTION INTEGREE, Water Pollutants, Chemical
Abstract

Based on a pluridisciplinary research programme on New Caledonia's lagoon (2004-2008), this paper addresses economic, ecological and political issues in order to implement integrated coastal zone management (ICZM) in this French Pacific territory. The nickel mining industry constitutes the core of the re-balancing economic and social strategy between the Northern and Southern provinces. But major impacts on the coastal environment of metal-processing plants, harbours, and decades of mine exploitation have released a controversy. A short diachronic analysis suggests that such environmental concerns prompted the emergence of collective actions to among civil society, customary and institutional stakeholders. The inscription of New Caledonia lagoon and reef areas in the UNESCO World Heritage List in 2008 would be both an outcome and a catalyst of this on-going process. Looking beyond the reefs towards the mainland and watersheds for the construction of local socio-ecological systems, we assume that the current stakes could result in the initiation of ICZM in New Caledonia.

Published
2010

78. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Hédouin, Laetitia, Metian, M., Lacoue-Labarthe, T., Fichez, Renaud, Teyssié, J.L., Bustamante, P., Warnau, M., Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
CHAINE ALIMENTAIRE, PHYTOPLANCTON, LAGON, METAL, ANALYSE QUALITATIVE, ANALYSE QUANTITATIVE, MOLLUSQUE, TRACABILITE, ACCUMULATION
Published
2010

79. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Chabanet, Pascale, Guillemot, Nicolas, Kulbicki, Michel, Vigliola, Laurent, Sarramegna, S., Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
RECIF CORALLIEN, POISSON MARIN, BIOMASSE, VARIATION TEMPORELLE, INDUSTRIE MINIERE, VARIATION SPATIALE, SURVEILLANCE, ETUDE COMPARATIVE, DIVERSITE SPECIFIQUE, ABONDANCE, IMPACT SUR L'ENVIRONNEMENT
Published
2010

80. Metal and metalloid bioaccumulation in the Pacific blue shrimp Litopenaeus stylirostris (Stimpson) from New Caledonia: laboratory and field studies

Author

Mohamed M. Eltayeb, Laetitia Hédouin, Marc Metian, Michel Warnau, Jean-Louis Teyssié, Paco Bustamante, Chantal Mugnier, Thomas Lacoue-Labarthe, LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Marine Environment Laboratories [Monaco] (IAEA-MEL), International Atomic Energy Agency [Vienna] (IAEA), IUCN - West Asia/Middle East (WAME) (ICUN), Arabie Saoudite, Centre de Recherche sur les Ecosystèmes Littoraux Anthropisés (CRELA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques (CAMELIA), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut de Recherche pour le Développement (IRD [Guyane]), Laboratoire d'Aquaculture de Calédonie (LAC), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Grenz, Christian (ed.), Le Borgne, Robert (ed.), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Biokinetics, Hepatopancreas, 010501 environmental sciences, Oceanography, 01 natural sciences, biokinetics, contamination, Moulting, Metalloids, Cadmium, biology, Decapoda, Ecology, BIOACCUMULATION, 16. Peace & justice, Pollution, radiotracers, Shrimp, Intestines, CONTAMINATION, CREVETTE, Radiotracers, Metals, Environmental chemistry, Bioaccumulation, METAL, [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology, TRACABILITE, Penaeidae, animal structures, ANALYSE DE LABORATOIRE, moulting, chemistry.chemical_element, metals, Crustacean, Aquatic Science, New Caledonia, Metals, Heavy, Animals, CONTENU STOMACAL, 14. Life underwater, Shellfish, 0105 earth and related environmental sciences, 010604 marine biology & hydrobiology, fungi, biology.organism_classification, chemistry, crustacean, Water Pollutants, Chemical
Abstract

The present work aimed at better understanding metal and metalloid bioaccumulation in the edible Pacific blue shrimp Litopenaeus stylirostris, using both laboratory and field approaches. In the laboratory, the bioaccumulation kinetics of Ag, Cd, Co, Cr, and Zn have been investigated in shrimp exposed via seawater and food, using the corresponding gamma-emitting radiotracers (Ag-110m, Cd-109, Co-57, Cr-51, and Zn-65) and highly sensitive nuclear detection techniques. Results showed that hepatopancreas and intestine concentrated the metals to the highest extent among the blue shrimp organs and tissues. Moulting was found to play a non negligible detoxification role for Co, Cr and, to a lesser extent, Zn. Metal retention by L stylirostris widely varied (from a few days to several months), according to the element and exposure pathway considered (a given metal was usually less strongly retained when ingested with food than when it was taken up from the dissolved phase). In the field study, Ag, As, Cd, Co, Cr, Cu, Mn, Ni, and Zn were analysed in shrimp collected from a New Caledonian aquaculture pond. Metal concentrations in the shrimp muscles were generally relatively low and results confirmed the role played by the digestive organs and tissues in the bioaccumulation/storage/detoxification of metals in the Pacific blue shrimp. Preliminary risk considerations indicate that consumption of the shrimp farmed in New Caledonia is not of particular concern for human health. (C) 2010 Elsevier Ltd. All rights reserved.

Published
2010

81. Geographical aspects of informal reef fishery systems in New Caledonia

Author

Nicolas Guillemot, Isabelle Jollit, Jocelyne Ferraris, Gilbert David, Marc Léopold, Pascale Chabanet, J.M. Lebigre, Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
Rural Population, Marine conservation, Geographic information system, Urban Population, SYSTEME D'INFORMATION GEOGRAPHIQUE, Fishing, Fisheries, Aquatic Science, Oceanography, EFFORT DE PECHE, PECHE MARITIME, ECONOMIE DES PECHES, New Caledonia, Animals, Humans, Reef, Recreation, ANALYSE STATISTIQUE, geography, geography.geographical_feature_category, Geography, business.industry, Subsistence agriculture, Coral reef, Pollution, Fishery, RECIF CORALLIEN, CAPTURE, Socioeconomic Factors, Sustainability, business
Abstract

The coral reefs in New Caledonia have long been used by the local population for subsistence as well as commercial and recreational purposes. The impact of informal fisheries on reef ecosystems illustrated the idiosyncrasies of New Caledonian fisheries in the southwest Pacific. This paper compared informal fishery systems on the southwest coast (close to the capital and economic center of the country) and the northwest coast (where an industrial mining complex has been under development) of New Caledonia to analyze their spatial structure and characteristics. Four geosystems were defined. These depended on the natural, social and economical environments as well as management strategies. The way of life of the fishers proved to be a major factor in how the informal fishery systems were structured. Our observations suggested that ongoing socio-economic changes in New Caledonia have shaped informal fishing activities since the 1900s. The findings from this study validate the suitability of spatial approaches to coral reef fisheries and provide local stakeholders with original management clues for marine resources sustainability.

Published
2010

84. Biogeochemical typology and temporal variability of lagoon waters in a coral reef ecosystem subject to terrigeneous and anthropogenic inputs (New Caledonia)

Author

Philippe Gérard, Renaud Fichez, F. Gutierrez, Sylvain Ouillon, Aymeric Jouon, Sandrine Chifflet, Christian Grenz, Pascal Douillet, Grenz, Christian (ed.), Le Borgne, Robert (ed.), Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques (CAMELIA), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut de Recherche pour le Développement (IRD [Guyane]), Centre d'océanologie de Marseille (COM), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), IRD, Universidad Autonoma Metropolitana Iztapalapa (IRD), Universidad Autonoma Metropolitana - Iztapalapa, OPLC, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Universidad Autonoma Metropolitana Iztapalapa (DCBS), DCBS, Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Biogéochimique (LOPB), Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques ( CAMELIA ), Institut de Recherche pour le Développement ( IRD [Nouvelle-Calédonie] ) -Institut de Recherche pour le Développement ( IRD [Guyanne] ), Centre d'océanologie de Marseille ( COM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de la Méditerranée - Aix-Marseille 2, IRD, Universidad Autonoma Metropolitana Iztapalapa ( IRD ), Institut méditerranéen d'océanologie ( MIO ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Toulon ( UTLN ) -Aix Marseille Université ( AMU ) -Institut de Recherche pour le Développement ( IRD ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Toulon ( UTLN ) -Aix Marseille Université ( AMU ) -Institut de Recherche pour le Développement ( IRD ), Institut de Recherche pour le Développement ( IRD [Nouvelle-Calédonie] ), Universidad Autonoma Metropolitana Iztapalapa ( DCBS ), ECOLA LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales ( LEGOS ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'Océanographie Physique et Biologique ( LOPB ), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Chlorophyll, 0106 biological sciences, SALINITE, Time Factors, 010504 meteorology & atmospheric sciences, SEL NUTRITIF, Oceanography, 01 natural sciences, Trophic status, CYCLE BIOGEOCHIMIQUE, VARIATION TEMPORELLE, LAGON, Cluster Analysis, Water pollution, TEMPERATURE, Trophic level, geography.geographical_feature_category, [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, IMPACT DE L'ENVIRONNEMENT, NIVEAU TROPHIQUE, Coral reef, Anthozoa, Pollution, Seasons, Environmental Monitoring, Biogeochemical cycle, Aquatic Science, Coral reef lagoon, New Caledonia, Animals, Seawater, Ecosystem, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, geography, Chlorophyll A, 010604 marine biology & hydrobiology, Biogeochemistry, Temporal variability, Nutrients, 15. Life on land, RECIF CORALLIEN, Typology, 13. Climate action, Environmental science, Spatial variability, Hydrology, Eutrophication, Water Pollutants, Chemical
Abstract

International audience; Considering the growing concern about the impact of anthropogenic inputs on coral reefs and coral reef lagoons, surprisingly little attention has been given to the relationship between those inputs and the trophic status of lagoon waters. The present paper describes the distribution of biogeochemical parameters in the coral reef lagoon of New Caledonia where environmental conditions allegedly range from pristine oligotrophic to anthropogenically influenced. The study objectives were to: (i) identify terrigeneous and anthropogenic inputs and propose a typology of lagoon waters, (ii) determine temporal variability of water biogeochemical parameters at time-scales ranging from hours to seasons. Combined ACP-cluster analyses revealed that over the 2000 km2 lagoon area around the city of Nouméa, "natural" terrigeneous versus oceanic influences affecting all stations only accounted for less than 20% of the spatial variability whereas 60% of that spatial variability could be attributed to significant eutrophication of a limited number of inshore stations. ACP analysis allowed to unambiguously discriminating between the natural trophic enrichment along the offshore-inshore gradient and anthropogenically induced eutrophication. High temporal variability in dissolved inorganic nutrients concentrations strongly hindered their use as indicators of environmental status. Due to longer turn over time, particulate organic material and more specifically chlorophyll a appeared as more reliable nonconservative tracer of trophic status. Results further provided evidence that ENSO occurrences might temporarily lower the trophic status of the New Caledonia lagoon. It is concluded that, due to such high frequency temporal variability, the use of biogeochemical parameters in environmental surveys require adapted sampling strategies, data management and environmental alert methods.

Published
2010

85. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

A Carroll, Mehdi Adjeroud, J M Fernandez, Peter Harrison, Lucie Penin, Biologie et écologie tropicale et méditerranéenne [2007-2010] (BETM), Université de Perpignan Via Domitia (UPVD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), ARC Centre of Excellence for Coral Reef Studies (CoralCoE), James Cook University (JCU), Grenz, Christian, and Le Borgne, Robert

Subjects
0106 biological sciences, Cnidaria, STRUCTURE DU PEUPLEMENT, Fringing reef, Coral, [SDE.MCG]Environmental Sciences/Global Changes, Scleractinia, Environment, Aquatic Science, Oceanography, 010603 evolutionary biology, 01 natural sciences, ABONDANCE, SUBSTRAT, ANALYSE DE CORRESPONDANCE, New Caledonia, LAGON, Animals, 14. Life underwater, JUVENILE, Reef, Ecosystem, Population Density, geography, geography.geographical_feature_category, biology, Ecology, 010604 marine biology & hydrobiology, IMPACT DE L'ENVIRONNEMENT, Coralline algae, Biodiversity, Coral reef, Anthozoa, biology.organism_classification, CORAIL, Pollution, Species richness
Abstract

International audience; We investigated the spatial distribution of adult and juvenile coral assemblages in the southwestern lagoon of New Caledonia, from disturbed fringing reefs within bays, to oceanic barrier reefs. Generic richness, abundance, and percent cover were highly variable at this scale, but no clear cross-shelf gradient was found. Rather, community composition was more related to reef biotopes. Correlations and canonical correspondence analyses revealed that composition and abundance of coral assemblages were related to substrate types (cover of turf algae and cover of encrusting coralline algae), but not to water quality or metal concentrations in sediments. We found a strong relationship between juvenile and adult distribution for all dominant genera, which suggests that recruitment processes are also a major factor structuring these populations. The densities of juveniles and their proportion in the coral assemblages were relatively low, which implies that replenishment capacities and potential for recovery are probably limited for these reefs.

Published
2010

87. Inherent optical properties and satellite retrieval of chlorophyll concentration in the lagoon and open ocean waters of New Caledonia

Author

Sylvain Ouillon, Cécile Dupouy, Jacques Neveux, Robert Frouin, Guillaume Dirberg, Sébastien Hochard, Hiroshi Murakami, Grenz, Christian (ed.), Le Borgne, Robert (ed.), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie biologique de Banyuls (LOBB), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), EORC, Japan Aerospace Exploration Agency [Tsukuba] (JAXA), Mécanismes adaptatifs : des organismes aux communautés, Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO), and University of California-University of California

Subjects
0106 biological sciences, OC4v4 algorithm, Chlorophyll, Optical Phenomena, 010504 meteorology & atmospheric sciences, Backscattering, Oceanography, 01 natural sciences, chemistry.chemical_compound, LAGON, ABSORPTION, Turbidity, Absorption (electromagnetic radiation), MODELE BIO OPTIQUE, media_common, biology, Lagoon, Satellite Communications, Pollution, CHLOROPHYLLE, Trichodesmium, Ocean color, Algorithms, Environmental Monitoring, media_common.quotation_subject, Aquatic Science, Absorption, New Caledonia, OCEAN, ALGORITHME, Phytoplankton, Seawater, 14. Life underwater, Bio-optical model, Ecosystem, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Pacific Ocean, DONNEES SATELLITE, 010604 marine biology & hydrobiology, Remote sensing reflectance, COULEUR, Pelagic zone, biology.organism_classification, REFLECTANCE, chemistry, Environmental science, Bio-optical properties
Abstract

International audience; The retrieval of chlorophyll-a concentration from remote sensing reflectance (Rrs) data was tested with the NASA OC4v4 algorithm on the inner New Caledonian lagoon (Case 2) and adjacent open ocean (Case 1) waters. The input to OC4v4 was Rrs measured in situ or modeled from water's inherent optical properties (2001-2007). At open ocean stations, backscattering and absorption coefficients were correlated with chlorophyll (R2 = 0.31-0.51, respectively), in agreement with models for Case 1 waters. Taking spectrofluorometric measurement as reference, the OC4v4 model leads to an average underestimation of 33% of the chlorophyll concentration. For the lagoon waters, OC4v4 performed inadequately because the backscattering coefficient, highly correlated with turbidity and suspended matter (R2 = 0.98), was poorly correlated to chlorophyll (R2 = 0.42). The OC4v4 performance was better in deep lagoon waters for stations with a TDT index (Tchla × depth/turbidity) higher than 19 mg m−2 NTU−1 (R2 = 0.974, bias = 10.2%). Global Imager Rrs provided a good estimate of Tchla (R2 = 0.79, N = 28) in the deeper part of the lagoon.

Published
2010

88. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Anne Leroy, Patrick Marchesiello, Nicolas C. Jourdain, Jérôme Lefèvre, Christophe E. Menkès, Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-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)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Météo-France Direction Interrégionale de la Nouvelle Calédonie (DIRNC), Météo-France, Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Météo France [Nouméa], Météo France, Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
VARIATION SAISONNIERE, 010504 meteorology & atmospheric sciences, Atmospheric circulation, VENT, Mesoscale meteorology, Wind, 010501 environmental sciences, Aquatic Science, Oceanography, Atmospheric sciences, 01 natural sciences, CLIMATOLOGIE, Mesoscale models, MODELE, New Caledonia, Synoptic scale meteorology, Water Movements, South Pacific convergence zone, 14. Life underwater, INTERACTION OCEAN ATMOSPHERE, Weather, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Orographic lift, ANALYSE STATISTIQUE, Geography, Ocean current, Scatterometer winds, Reproducibility of Results, Madden–Julian oscillation, Jet stream, Models, Theoretical, Pollution, CIRCULATION OCEANIQUE, 13. Climate action, Climatology, Weather regime, Island-scale circulation, Environmental Monitoring
Abstract

International audience; The local climate and island-scale circulation around New Caledonia is investigated using a 4-km resolution mesoscale atmospheric model in concert with QuikSCAT scatterometer winds at 12.5-km resolution. The mesoscale atmospheric weather regimes are first examined through an objective classification applied to the remote sensed winds for nine warm seasons from 1999 to 2008. Four main weather types are identified. Their corresponding synoptic-scale circulation reveals that they are strongly discernable through the position and intensity of the South Pacific Convergence zone (SPCZ), the mid-latitude systems, and the subtropical jet stream. The link between the mesoscale weather types and the two dominant large-scale modes of variability, namely the Madden-Julian Oscillation (MJO) and the El Niño-Southern Oscillation (ENSO), is also described in terms of their influence on the occurrence of each weather type. It shows that their occurrence is significantly controlled by both MJO and ENSO, through modulation of the SPCZ. The large-scale modes of variability are scaled down to island-scale circulation through synoptic and mesoscale regimes, and are eventually modulated by orographic and thermal control. The island-scale circulation is inferred in this study by applying the compositing method to both observed and simulated winds. Their comparison clearly shows the ability of the mesoscale model to capture the local circulation and its spatial and temporal variability. A scaling analysis conducted from the simulated atmospheric parameters shows that the mountain range of New Caledonia is hydrodynamically steep. As a result of trade-wind obstruction by the mountainous island, the flow is shaped by coastally trapped mesoscale responses, i.e., blocking, flow splitting and corner winds, with a spatial scale of about 150 km. Two main obstacles, Mont Panié and Mont Humboldt play a significant role on the dynamical behavior of the low-level flow, while the diurnal heating cycle in the vicinity of the Mainland strongly modulates the local circulation. Moreover, nocturnal drainage flow of cold air occurs on the leeside slope of Mont Humboldt and inhibits vertical mixing over the ocean, which results in a deceleration of surface winds.

Published
2010

89. Coastal upwelling, circulation and heat balance around New Caledonia's barrier reef

Author

Patrick Marchesiello, Christophe E. Menkès, Xavier Couvelard, Andres Vega, Jérôme Lefèvre, Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), 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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Grenz, Christian (ed.), and Le Borgne, Robert (ed.)

Subjects
Hot Temperature, 010504 meteorology & atmospheric sciences, COURANT GEOSTROPHIQUE, Wind stress, UPWELLING, Wind, Aquatic Science, Oceanography, 01 natural sciences, Geostrophic current, New Caledonia, Water Movements, Animals, 14. Life underwater, FLUX THERMIQUE, Ecosystem, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, 010505 oceanography, Advection, Ocean current, ETUDE REGIONALE, ZONE COTIERE, Regional ocean circulation, Models, Theoretical, Anthozoa, Pollution, Current (stream), CIRCULATION OCEANIQUE, 13. Climate action, Climatology, SIMULATION, Upwelling, Seasons, Surface water, Geology, Geostrophic wind, Environmental Monitoring, Coastal upwelling
Abstract

International audience; An outstanding characteristic of New Caledonia upwelling is that most events appear limited to the southern half of the western barrier reef. This north-south difference cannot be explained by alongshore variability of the projected wind stress and no strong evidence for alternative explanations has been proposed. A major objective of this paper is to provide the first dynamical analysis of New Caledonia upwelling and its regional environment, based on numerical simulations. Coastal upwelling around New Caledonia is shown to be modulated by a system of geostrophic currents interacting with the island mass. Upwelling velocities are weaker than expected from the two-dimensional Ekman theory, as Ekman divergence is balanced by "coastal geostrophic convergence". The cooling effect of upwelling is also attenuated by alongshore transport of warm water by the Alis current, reminiscent of the Leeuwin current off Western Australia. Nevertheless, coastal upwelling can locally modify the large-scale surface water heat budget, dominated by meridional advection warming and surface cooling. The upwelled waters appear to be mostly of western origin and are transported below the surface by the Subtropical Counter Current before upwelling off New Caledonia. This appears in sharp contrast with the eastern barrier reef where the general warming by meridional advection of tropical surface waters is accentuated by the vigorous western boundary type Vauban current.

Published
2010

90. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

R. Le Borgne, Christian Grenz, Renaud Fichez, Jean-Pascal Torréton, Grenz, Christian (ed.), Le Borgne, Robert (ed.), Laboratoire d'Océanographie Physique et Biologique ( LOPB ), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), PNEC, Laboratoire d'Océanographie Physique et Biogéochimique (LOPB), and Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Conservation of Natural Resources, 010504 meteorology & atmospheric sciences, PRODUCTION PRIMAIRE, [SDE.MCG]Environmental Sciences/Global Changes, Pilot Projects, PROGRAMME DE RECHERCHE, 010501 environmental sciences, Aquatic Science, Oceanography, 01 natural sciences, CYCLE BIOGEOCHIMIQUE, New Caledonia, LAGON, Multidisciplinary approach, Environmental protection, Animals, RECHERCHE PLURIDISCIPLINAIRE, 14. Life underwater, Ecosystem, 0105 earth and related environmental sciences, Tropical Climate, business.industry, Environmental resource management, Biodiversity, Pollution, [ SDE.MCG ] Environmental Sciences/Global Changes, CIRCULATION OCEANIQUE, Environmental science, Interdisciplinary Communication, business, PLANCTON
Abstract

International audience; résumé

Published
2010

91. New Caledonia tropical lagoons : an overview of multidisciplinary investigations

Author

Christian Grenz, Renaud Fichez, Olivier Pringault, Lionel Denis, Laboratoire d'Océanographie Physique et Biologique ( LOPB ), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Grenz, Christian (ed.), Le Borgne, Robert (ed.), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 ( LOG ), Université du Littoral Côte d'Opale-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire d'Océanographie Physique et Biogéochimique (LOPB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])

Subjects
0106 biological sciences, [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, Geologic Sediments, CALCIUM-CARBONATE, VARIATION SAISONNIERE, SEL NUTRITIF, 010501 environmental sciences, Oceanography, SEDIMENT, 01 natural sciences, TROPICAL LAGOON, SOLUTE EXCHANGE, Water column, LAGON, BENTHIC NUTRIENT, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, GREAT-BARRIER-REEF, MICROBIAL ACTIVITY, OXYGENE, Pollution, ORGANIC-MATTER, Benthic zone, Seasons, Biogeochemical cycle, Nitrogen, Benthic fluxes, Aquatic Science, Phosphates, New Caledonia, Sediment–water interface, Seawater, 14. Life underwater, DEEP-SEA, Ecosystem, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Hydrology, Pacific Ocean, SULFATE REDUCTION, Silicates, 010604 marine biology & hydrobiology, Biogeochemistry, Sediment, Pelagic zone, Nutrients, 15. Life on land, Oxygen, VARIATION SPATIALE, Environmental science, Spatial variability, SOUTH-WEST LAGOON
Abstract

In order to quantify the spatial and seasonal variations of sediment oxygen consumption and nutrient fluxes, we performed a spatial survey in the south west lagoon of New Caledonia during the two major seasons (dry and wet) based on a network of 11 sampling stations. Stations were selected along two barrier reef to land transects representing most types of sediments encountered in the lagoon. Fluxes were measured using ex-situ sediment incubations and compared to sediment characteristics. Sediment oxygen consumption (SOC) varied between 500 and 2000 mu mol m(-2). depending on season and stations. Nutrient effluxes from sediment were highly variable with highest fluxes measured in muddy sediments near the coast. Inter-sample variability was as high as seasonal differences so that no seasonally driven temperature effect could be observed on benthic nutrient fluxes in our temperature range. Nutrient fluxes, generally directed from the sediment to the water column, varied between -5.0 and 70.0 mu mol m(-2) h(-1) for ammonia and between 2.5 and +12.5 mu mol m(-2) h(-1) for PO4 and NO2+3. SOC and nutrient fluxes were compared to pelagic primary production rates in order to highlight the tight coupling existing between the benthic and pelagic compartments in this shallow tropical lagoon. Under specific occasions of low pelagic productivity, oxygen sediment consumption and related carbon and nutrient fluxes could balance nearly all net primary production in the lagoon. These biogeochemical estimates point to the functional importance of sediment biogeochemistry in the lagoon of New Caledonia. (C) 2010 Elsevier Ltd. All rights reserved.

Published
2010

93. Circulation and suspended sediment transport in a coral reef lagoon: The south-west lagoon of New Caledonia

Author

Richard Laganier, Jérôme Lefèvre, Philippe Bonneton, Pascal Douillet, Franck Dumas, Serge Andréfouët, Patrick Marchesiello, J.P. Lefebvre, Olivier Magand, Sylvain Ouillon, Jean-Michel Fernandez, Renaud Fichez, Jean-Yves Panche, A. Bel Madani, Aymeric Jouon, P. Le Hir, C. Chevillon, R. Le Gendre, Echanges Côte-Large (ECOLA), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Universidad Autonoma Metropolitana Unidad Iztapalapa (UAM), Universidad Autonoma Metropolitana - Iztapalapa, Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), IFREMER (IFREMER), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), Laboratoire de physique hydrodynamique et sédimentaire (DYNECO/PHYSED), Instituto del Mar del Peru (IMARPE), Grenz, Christian (ed.), Le Borgne, Robert (ed.), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Universidad Autonoma Metropolitana, Unidad Iztapalapa (UAM), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), CLIPS, CHANG, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), PNEC Grant NNG04F090G to Serge Andréfouët, Laboratoire de glaciologie et géophysique de l'environnement ( LGGE ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ) -Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ), ECOLA LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales ( LEGOS ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Universidad Autonoma Metropolitana Unidad Iztapalapa ( UAM ), Institut de Recherche pour le Développement ( IRD [Nouvelle-Calédonie] ), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux ( EPOC ), Observatoire aquitain des sciences de l'univers ( OASU ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), Environnements et Paléoenvironnements OCéaniques ( EPOC ), IFREMER ( IFREMER ), Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ), Pôle de recherche pour l'organisation et la diffusion de l'information géographique ( PRODIG ), Université Panthéon-Sorbonne ( UP1 ) -Institut de Recherche pour le Développement ( IRD ) -École pratique des hautes études ( EPHE ) -Université Paris-Sorbonne ( UP4 ) -Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de physique hydrodynamique et sédimentaire ( DYNECO/PHYSED ), Instituto del Mar del Peru ( IMARPE ), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG)

Subjects
0106 biological sciences, Geologic Sediments, Salinity, Time Factors, 010504 meteorology & atmospheric sciences, Climate, Wind, Oceanography, SEDIMENT, 01 natural sciences, Resuspension, Turbidity, VARIATION TEMPORELLE, LAGON, [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, geography.geographical_feature_category, Temperature, MATIERE EN SUSPENSION, Coral reef, Anthozoa, Pollution, Turbidite, Suspended sediment, Seasons, Sediment transport, [ SDU.STU.GL ] Sciences of the Universe [physics]/Earth Sciences/Glaciology, Intertidal zone, Aquatic Science, Coral reef lagoon, New Caledonia, Water Movements, Animals, Seawater, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, 14. Life underwater, ANALYSE QUANTITATIVE, Particle Size, Reef, Ecosystem, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Hydrology, geography, Terrigenous sediment, 010604 marine biology & hydrobiology, Ocean current, TURBIDITE, Models, Theoretical, Inlet, VARIATION SPATIALE, Hydrodynamics, Environmental science, Sediment
Abstract

International audience; The south-west lagoon of New Caledonia is a wide semi-open coral reef lagoon bounded by an intertidal barrier reef and bisected by numerous deep inlets. This paper synthesizes findings from the 2000-2008 French National Program EC2CO-PNEC relative to the circulation and the transport of suspended particles in this lagoon. Numerical model development (hydrodynamic, fine suspended sediment transport, wind-wave, small-scale atmospheric circulation) allowed the determination of circulation patterns in the lagoon and the charting of residence time, the later of which has been recently used in a series of ecological studies. Topical studies based on field measurements permitted the parameterisation of wave set-up induced by the swell breaking on the reef barrier and the validation of a wind-wave model in a fetch-limited environment. The analysis of spatial and temporal variability of suspended matter concentration over short and long time-scales, the measurement of grain size distribution and the density of suspended matter (1.27 kg l−1), and the estimation of erodibility of heterogeneous (sand/mud, terrigenous/biogenic) soft bottoms was also conducted. Aggregates were shown to be more abundant near or around reefs and a possible biological influence on this aggregation is discussed. Optical measurements enabled the quantification of suspended matter either in situ (monochromatic measurements) or remotely (surface spectral measurements and satellite observations) and provided indirect calibration and validation of a suspended sediment transport model. The processes that warrant further investigation in order to improve our knowledge of circulation and suspended sediment transport in the New Caledonia lagoon as well as in other coral reef areas are discussed, as are the relevance and reliability of the numerical models for this endeavour.

Published
2010

94. Plutonium distribution and remobilisation in the sediments off the Rhone River mouth

Author

LANSARD, Bruno, Centre d'océanologie de Marseille (COM), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de la Méditerranée - Aix-Marseille II, GRENZ Christian(grenz@com.univ-mrs.fr), Lansard, Bruno, and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de la Méditerranée - Aix-Marseille 2

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, Rhone prodelta, Plutonium, prodelta du Rhône, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, sediment dynamic, [SDU.STU.GC] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Gulf of Lions, golfe du Lion, dynamique sédimentaire, remobilisation, radionuclides, radionucléides
Abstract

The aim of the present study was to describe the distribution and remobilisation of plutonium (Pu) in the sediments off the Rhone river mouth. Most of the 238Pu and 239,240Pu isotopes introduced into the Rhone River were discharged by the liquid effluents released from the Marcoule reprocessing plant, located 120 km upstream the river mouth. Due to its high affinity for particles and its long half life, 238Pu is a promising tracer to follow the dispersion of particulate matter from the Rhone River to the Mediterranean Sea. During the 3 REMORA cruises, sediment samples were specifically collected in the Rhone prodelta area and more offshore on the whole continental shelf of the Gulf of Lions. The measurements of alpha emitters gave a first detailed spatial distribution of Pu isotope concentrations in surface sediments off the Rhone mouth. Using 137Cs concentrations and their correlations with Pu isotopes, we were able to give a first estimate of Pu inventories for the sediments of the study area. In 2001, plutonium inventories were estimated to 92 ± 7 GBq of 238Pu and 522 ± 44 GBq of 239,240Pu for an area of 500 km2 in front of the Rhone River mouth. Roughly, 50 % of these inventories are trapped in an area of 100 km2 corresponding to the extent of the Rhone prodelta zone. In spring 2002, an ADCP, with current velocity and wave measurements, was moored off the Rhone River mouth. This unique in situ dataset highlights the major role of South-East swells in the erosion of prodeltaic sediments and their dispersion to the South-Westward direction. Plutonium remobilisation was examined using a new experimental design based on sediment resuspension processes studied within a linear recirculating flume. For Gulf of Lions sediments and for a given hydrodynamic stress, remobilisation fluxes raised a maximum of 0.08 Bq.m-2.h-1 for 238Pu and 0.64 Bq.m-2.h-1 for 239,240Pu. A first plutonium budget determined for the study area indicates that at least 85 % of the Pu discharged over the 40 past years by the Marcoule reprocessing plant, are currently trapped in the sediments off the Rhone River mouth. Plutonium remobilisation is potentially an important process but dispersion of contaminated sediments appeared to be limited in space. These results suggest a low exportation of particulate matter introduced by the Rhone River towards the continental shelf of the Gulf of Lions and the North-Western Mediterranean basin., Ce travail pluridisciplinaire a pour objectif d'étudier la distribution et la remobilisation du plutonium (Pu) dans les sédiments situés face à l'embouchure du Rhône. Les isotopes 238Pu et 239,240Pu introduis dans le Rhône sont principalement issus des rejets d'effluents faiblement radioactifs effectués par l'usine de retraitement de Marcoule, située à 120 km de l'embouchure du Rhône. Etant données sa très forte affinité pour la phase particulaire et sa longue période radioactive, le 238Pu présente un intérêt particulier en tant que traceur anthropique du devenir des apports solides du Rhône en Méditerranée. Au cours de ce travail, les 3 campagnes REMORA ont permis d'échantillonner spécifiquement les sédiments du prodelta du Rhône et du plateau continental du golfe du Lion. Des mesures d'émetteurs alpha ont permis d'obtenir une première cartographie détaillée des concentrations des isotopes du Pu dans les sédiments situés face au Rhône. L'étude couplée du 137Cs et des isotopes du Pu a permis d'estimer pour la première fois les inventaires en plutonium de la zone étudiée. En 2001, les stocks sédimentaires de Pu sont estimés à 92 ± 7 GBq en 238Pu et 522 ± 44 GBq en 239,240Pu, pour une aire d'environ 500 km2. Le prodelta du Rhône joue un rôle essentiel dans la séquestration du plutonium puisqu'il piège à lui seul environ 50 % de ces stocks sur une aire de 100 km2. La remobilisation du plutonium a été appréhendée par des expériences originales de remise en suspension en canal à courant linéaire. Pour les sédiments du golfe du Lion et un stress hydrodynamique donné, les flux potentiels de remobilisation atteignent au maximum 0,08 Bq.m-2.h-1 en 238Pu et 0,64 Bq.m-2.h-1 en 239,240Pu. En parallèle, des mesures ADCP de courant et de houle ont été réalisées au printemps 2002 pour étudier in situ la dynamique sédimentaire du prodelta du Rhône. Ces mesures mettent en évidence le rôle prépondérant des houles de Sud-est dans l'érosion des sédiments prodeltaïques et dans leur exportation en direction du Sud-Ouest. Un premier bilan sur le devenir du plutonium indique qu'au minimum 85 % du plutonium rejetés par l'usine de Marcoule, au cours des quarante dernières années, sont actuellement piégés dans les sédiments situés face à l'embouchure du Rhône. Le remobilisation du plutonium est un phénomène potentiellement important mais la dispersion des sédiments contaminés serait relativement limitée dans l'espace. Ces résultats suggèrent alors une faible exportation du matériel particulaire originaire du Rhône vers l'ensemble du plateau continental du golfe du Lion et vers le bassin Nord méditerranéen.

Published
2004

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