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| Wattelez, Guillaume; Dupouy, Cecile; Mangeas, Morgan; Lefevre, Jerome; Touraivane,; Frouin, Robert. |
| Spatial and temporal dynamics of phytoplankton biomass and water turbidity can provide crucial information about the function, health and vulnerability of lagoon ecosystems (coral reefs, sea grasses, etc.). A statistical algorithm is proposed to estimate chlorophyll-a concentration ([chl-a]) in optically complex waters of the New Caledonian lagoon from MODIS-derived remote-sensing reflectance (R-rs). The algorithm is developed via supervised learning on match-ups gathered from 2002 to 2010. The best performance is obtained by combining two models, selected according to the ratio of R-rs in spectral bands centered on 488 and 555 nm: a log-linear model for low [chl-a] (AFLC) and a support vector machine (SVM) model or a classic model (OC3) for high [chl-a].... |
| Tipo: Text |
Palavras-chave: Chlorophyll-a concentration; MODerate resolution Imaging Spectroradiometer (MODIS); Ocean color; Remote sensing; Statistical algorithm; Oligotrophic waters; New Caledonia; Coral lagoon. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00481/59309/62060.pdf |
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| Van Wynsberge, Simon; Andrefouet, Serge; Gaertner-mazouni, Nabila; Tiavouane, Josina; Grulois, Daphne; Lefevre, Jerome; Pinsky, Malin L.; Fauvelot, Cecile. |
| Previous seascape genetics studies have emphasized the role of ocean currents and geographic distances to explain the genetic structure of marine species, but the role of benthic habitat has been more rarely considered. Here, we compared the population genetic structure observed in West Pacific giant clam populations against model simulations that accounted habitat composition and configuration, geographical distance, and oceanic currents. Dispersal determined by geographical distance provided a modelled genetic structure in better agreement with the observations than dispersal by oceanic currents, possibly due to insufficient spatial resolution of available oceanographic and coastal circulation models. Considering both habitat composition and... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00387/49791/50345.pdf |
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| Dupouy, Cecile; Wattelez, Guillaume; Lefevre, Jerome; Juillot, Farid; Andreoli, Remi; Lille, Didier; Murakami, Hiroshi; Roettgers, Rudiger; Frouin, Robert. |
| Shortly after strong rains or tropical storms, chlorophyll-a concentration (Chla), turbidity, and colored dissolved organic matter (CDOM) in the lagoon of New Caledonia may be tripled. This effect is visible as far as 50 km offshore. The Eastern Coast of New Caledonia is more impacted than the Western Coast because of its geomorphological structure. Higher frequency and intensity of the rains, and the dominance of highly erosive lateritic formations resulted from deep weathering of ultramafic rocks. At the deeper parts of the lagoon (> 20 m), increases of Chla, turbidity, and CDOM absorption can be detected by satellite imagery with their plumes extending off shore as a result of wind-driven circulation in the lagoon. Such -increases agree with the... |
| Tipo: Text |
Palavras-chave: Minerals; Phytoplankton; CDOM; FDOM; Ocean color; Reflectance; New Caledonia; Tropical Pacific Ocean; Lagoons. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00481/59308/62064.pdf |
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| Rousset, Guillaume; De Boissieu, Florian; Menkes, Christophe E.; Lefevre, Jerome; Frouin, Robert; Rodier, Martine; Ridoux, Vincent; Laran, Sophie; Bonnet, Sophie; Dupouy, Cecile. |
| Trichodesmium is the main nitrogen-fixing species in the South Pacific region, a hotspot for diazotrophy. Due to the paucity of in situ observations, methods for detecting Trichodesmium presence on a large scale have been investigated to assess the regional-to-global impact of these species on primary production and carbon cycling. A number of satellite-derived algorithms have been developed to identify Trichodesmium surface blooms, but determining with confidence their accuracy has been difficult, chiefly because of the scarcity of sea-truth information at time of satellite overpass. Here, we use a series of new cruises as well as airborne observational surveys in the South Pacific to quantify statistically the ability of these algorithms to discern... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00419/53004/53953.pdf |
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| Ganachaud, Alexandre; Cravatte, Sophie; Sprintall, Janet; Germineaud, Cyril; Alberty, Marion; Jeandel, Catherine; Eldin, Gerard; Metzl, Nicolas; Bonnet, Sophie; Benavides, Mar; Heimburger, Lars-eric; Lefevre, Jerome; Michael, Susanna; Resing, Joseph; Queroue, Fabien; Sarthou, Geraldine; Rodier, Martine; Berthelot, Hugo; Baurand, Francois; Grelet, Jacques; Hasegawa, Takuya; Kessler, William; Kilepak, Moyep; Lacan, Francois; Privat, Emilien; Send, Uwe; Van Beek, Pieter; Souhaut, Marc; Sonke, Jeroen E.. |
| The semi-enclosed Solomon Sea in the southwestern tropical Pacific is on the pathway of a major oceanic circuit connecting the subtropics to the equator via energetic western boundary currents. Waters transiting through this area replenish the Pacific Warm Pool and ultimately feed the equatorial current system, in particular the equatorial undercurrent. In addition to dynamical transformations, water masses undergo nutrient and micronutrient enrichment when coming in contact with the coasts, impacting the productivity of the downstream equatorial region. Broadscale observing systems are not well suited for describing the fine-scale currents and water masses properties in the Solomon Sea, leaving it relatively unexplored. Two multidisciplinary oceanographic... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00390/50185/50808.pdf |
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| Cuif, Marion; Kaplan, David; Lefevre, Jerome; Faure, Vincent Martin; Caillaud, Matthieu; Verley, Philippe; Vigliola, Laurent; Lett, Christophe. |
| In the present work, a biophysical dispersal model is used to understand the role of the physical environment in determining reef fish larval dispersal patterns in the South-West Lagoon of New Caledonia. We focus on a reef fish species, the humbug damselfish Dascyllus aruanus, to investigate seasonal variability of simulated larval retention at the scale of a reef patch and at the scale of the lagoon, and to explore links between larval retention and wind variability. The model shows that retention exhibits considerable temporal variability and periodically reaches values much larger than anticipated. Non-zero larval settlement occurs over a large part of the lagoon. Nevertheless, settlement values decrease quickly away from the natal reef and mean... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00170/28115/26326.pdf |
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