Comparaison d'estimateurs de régression non paramétriques : application en valvométrie
La mesure de l'activité de mollusques bivalves est un moyen d'enregistrer le comportement de bivalves in situ et donc d'évaluer des changements de la qualité de l'eau. Nous proposons un modèle de régression non paramétrique et comparons trois estimateurs non paramétriques, récursifs ou non, de la fonction de lien sur les données acquises en Nouvelle Calédonie.
(23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IMB, UB, Bordeaux INP, CNRS
Effects of tidal forcing on biogeochemical processes in intertidal permeable sandy sediments
(23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGN, UN, CNRS
Approche de l’évolution contemporaine (-50 ans à nos jours) de l’estuaire de la Gironde sous modifications des forçages hydro-climatiques et des contraintes anthropiques : Projet 2009-2011 – Réseau de recherche littoral aquitain - Atelier Gironde
Les propositions présentées ci-après pour la période 2009-2011 s'inscrivent dans le prolongement de celles proposées précédemment (2007-2008) et elles constituent ainsi les "briques" d'un projet plus vaste de moyen terme, visant une meilleure compréhension du système girondin : "Fonctionnement, évolution et trajectoire de l'écosystème estuarien sous contraintes naturelles et anthropiques.
(pp. 86, 23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, CEMAGREF
The euthycarcinoid arthropods from Montceau-les-Mines, France: functional morphology and affinities
New three-dimensionally preserved specimens of two euthycarcinoid arthropods, namely Schramixerxes gerem and Sottyxerxes multiplex, allow complete description of both the dorsal and ventral sides of the exoskeleton. The functional morphology is tentatively interpreted for the first time. In S. gerem, the ‘thirteenth somite', or ‘monosomite' is fully described and re-interpreted as the main articulatory process of the body, between the cephalic region and the preabdomen. The morphology and arrangement of the two parts of the process clearly indicate that the anterior cephalic region of the body could move laterally and bend ventrally, while posterior somites could only move ventrally. Unlike several other euthycarcinoid species, the ventral side of the head area exhibits one or two plates instead of mandibles; such distinct morphologies are indicative of different feeding mechanisms and behaviours among euthycarcinoid arthropods. Possible homologies with the labrum of Hexapoda support the hypothesis that euthycarcinoids have hexapod affinities.
(Earth and Environmental Science Transactions of the Royal Society of Edinburgh. vol. 99, n° 1755-6910, pp. 11-25, 02/12/2008)
LDO, INSU - CNRS, UBO EPE, CNRS, PEPS, UCBL, INSU - CNRS, CNRS
Late Quaternary history of the Nouméa lagoon (New Caledonia, South West Pacific) as depicted by seismic stratigraphy and multibeam bathymetry A modern model of tropical rimmed shelf
The barrier reef tract of New Caledonia is the second largest in the world enclosing lagoons of variable width. The Late Quaternary evolution of these barrier reefs and lagoons is poorly known. A recent high resolution seismic and multibeam bathymetry survey was carried out in the south-western lagoon from shoreline to open ocean across the barrier reef pass systems to perform sequence stratigraphy and to better understand the Quaternary evolution of the lagoon. Two depositional sequences bounded by type-1 erosional surfaces can be identified. The bounding surfaces delineate the bottom of two generations of incised valleys. System tracts comprising a complete succession of regressive, lowstand, transgressive and highstand tracts were observed only in the upper sequence. Chronostratigraphic and sedimentological interpretations of the seismic data are based on correlations with the chronology defined in the nearby cores drilled through the reefs and in the gravity cores previously recovered in the inner lagoon. Interpretation of seismic data is also carried out on the basis of correlation with multibeam bathymetric data. Our results indicate that the history of the New Caledonian lagoon probably does not exceed 200ka marked by two or three brief episodes each of immersion of about ten thousand years. The bathymetric data reveal that during successive low sea level stands, the lagoon was dependent upon erosional fluvial networks. The deep fluvial valleys were connected to the continental slope through the passes. Seismic records reveal that upstream palaeo-channels are not connected to the modern coastal rivers. In contrast, many aggrading deposits, including numerous stacking channels, and extending across the proximal part of the outer lagoon, can be identified. Examination of drainage network morphology suggests a progressive tilt of the outer lagoon. Such evolution reveals that the Nouméa lagoon which is one of the widest in the world is an exceptional modern example of a rimmed shelf providing data to analyze the past counterparts.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 270, n° 0031-0182, pp. 29-45, 01/12/2008)
LDO, INSU - CNRS, UBO EPE, CNRS, UEB, PALEOTROPIQUE, IPRA, UPPA, CNRS, LDL, UM2, INSU - CNRS, CNRS, GEOAZUR 6526, IRD, UPMC, UNS, INSU - CNRS, UniCA, CNRS
Production of marine trematode cercariae: A potentially overlooked path of energy flow in benthic systems
Parasites, in particular trematodes, are unseen but ubiquitous components of marine intertidal ecosystems. Although parasites are known to affect population dynamics and food web structure, their potential function as an unrecognized path of energy flow in these ecosystems is yet to be quantified. We use published data on rates at which trematodes produce free-swimming infective larvae (cercariae) that are released from their gastropod intermediate hosts to investigate patterns in cercarial output as a function of different variables, and to calculate the annual production of cercariae in different marine benthic systems. Across 18 trematode species, cercarial output (no. cercariae shed snail–1 d–1) ranged over 4 orders of magnitude and was positively correlated with snail host species size. While cercarial output did not correlate with latitude, it did correlate negatively with the size of cercariae, and was influenced by the type of downstream host sought by cercariae, being highest when this host was a vertebrate. Our estimates of annual cercarial production (kJ m–2 yr–1), which take into account the density of infected snails in the habitat, were within the range of production values reported for free-living invertebrates inhabiting benthic ecosystems. These estimates would be much higher if they included all trematode species in an ecosystem, and not just single-species values. Overall, results suggest that trematode cercariae represent potentially important paths of energy flow in benthic systems as well as a potentially important food supply to benthic organisms.
(Marine Ecology Progress Series. vol. 372, n° 0171-8630, pp. 147-155, 01/12/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UTPA
Impact of hypoxia on hemolymph contamination by uranium in an aquatic animal, the freshwater clam Corbicula fluminea
Multi-stress situations are a major question and low-oxygenated waters (hypoxia) are a growing problem. Importantly, hypoxia stimulates the ventilatory flow rate in aquatic animals and this increases gill exposure to contaminants. Surprisingly, in the freshwater clam Corbicula fluminea, this is associated with increased bioaccumulation of uranium in gills but not in deep tissues. We searched for an explanation by analyzing hemolymph U-transport in Corbicula exposed to 0.36 μM dissolved uranium at various O2-levels for 10 days. In hypoxia, one observed an increased U concentration in the arterial hemolymph flowing from gills to tissues but this was not associated with an increased U concentration in the venous hemolymph nor in the other tissues. We conclude that the cardiac flow rate must have decreased to explain this absence of over-accumulation. In addition to its already known deleterious effects, uranium can thus deeply impair cardiac flow rate in exposed aquatic animals during multi-stress exposures. © 2008 Elsevier Ltd. All rights reserved.
(Environmental Pollution. vol. 156, n° 0269-7491, pp. 821-826, 01/12/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSN/DEI/SECRE/LRE, IRSN/DEI/SECRE, IRSN
Live foraminifera from the open slope between Grand Rhône and Petit Rhône Canyons (Gulf of Lions, NW Mediterranean)
(Deep Sea Research Part I: Oceanographic Research Papers. vol. 55, n° 0967-0637, pp. 1532-1553, 01/11/2008)
UA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, OCEANIS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, HCL, HCL, HIFIH, UA
Ocean color measurements onboard a jet-ski: consistency for calval exercise of high-resolution satellite imagery?
An original data set has been acquired on the 5th of April 2008 during the international field experiment ECORS-Truc Vert 2008 (SW France) in the nearshore zone over a complex bathymetry and in moderate turbid waters (SPM <10 mg/l). This data set synchronizes in-situ reflectance measurements onboard a jet-ski, bathymetric surveys and a Formosat-2 high-resolution satellite acquisition. The jet-ski provides an interesting mean to gather optical data in shallow waters and in environments hard to sample with traditional coastal ships. An experimental device has been implemented on the jet-ski, equipped with two TRIOS RAMSES sensors which measure simultaneous atmospheric downwelling irradiances Ed and in-water upwelling radiances Lu in the 350-950nm range. Water samples have also been collected at different stages of the jet-ski trajectory (3-25m water depth) in order to assess the concentrations of the ocean constituents (SPM and Chl-a). In the current study we present a methodology to validate FORMOSAT-2 high-resolution ocean color data using “jetski” reflectance measurements, which first require a detailed analysis. The reflectance spectra measurements are shown to be consistent : (i) they are typical of the presence of mineral particles with light absorption at short wavelengths ; (ii) their shape and magnitude depend on the depth and the water type (turbidity) ; (iii) some of them, especially in low turbid waters, are similar to other reflectance spectra measured northward from a ship (Gironde mouth). Thus, the use of “jet-ski” ocean color measurements appears to be adequate for remote sensing calval activities in shallow case-2 waters.
(pp. 10 p, 01/11/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The Virtual Fields Method for Extracting Constitutive Parameters From Full‐Field Measurements: a Review
ABSTRACT: The virtual fields method has been developed for extracting constitutive parameters from full‐field measurements provided by optical non‐contact techniques for instance. It is based on the principle of virtual work written with some particular virtual fields. This paper can be regarded as a general review summarising some 15 years of developments of this method. The main aspects of the method are first recalled in the case of both linear and non‐linear constitutive equations. They are then illustrated by some recent relevant examples. Some studies underway as well as relevant issues to be addressed in the near future are eventually discussed.
(Strain. vol. 42, n° 0039-2103, pp. 233-253, 29/10/2008)
IUT d'Allier, UBP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TECH ECO (ex-ITESE), CEA-DES (ex-DEN), CEA, IP, CNRS, UCA, INP Clermont Auvergne, UCA, IP, UBP, SIGMA Clermont, CNRS