Liquefied vs stratified sediment mobilization processes: Insight from the South of the Barbados accretionary prism
This paper discusses the nature and origin of subsurface sediment mobilization processes in deep marine clay-rich environments. In the studied area of the southern Barbados accretionary prism, new geophysical acquisitions have emphasized the spectacular widespread development of mud volcanoes that are well-developed along ramp anticlines and along sigmoidal rises with trends that are oblique to the axes of the main folds of the accretionary wedge. On some active mud volcanoes, heat-flow measurements show high positive anomalies related to high fluxes of mud transfer. The mobilized solid fraction expelled by the mud volcanoes does not originate from a unique source bed but from various formations pierced by the mud conduits and is driven by the water phase. The area studied also exhibits trends of structures corresponding to sub-circular massive local uplifts of deformed but well-preserved stratified sediments (turbidites and hemipelagics). No piercing shale diapirs have been encountered in this area. Some of these local uplift structures are complicated by the development of collapses, calderas, and superimposed mud volcanoes. Mud volcanism corresponds fundamentally to fluid displacement (water and gas), whereas massive sedimentary uplift corresponds to large vertical displacements of stratified solid levels but for which the deep cause could be partly the intrusion of mud plugs. Both are dynamic phenomena controlled by the development of overpressure at depth, contributing to sedimentary mobilizations.
(Tectonophysics. vol. 428, n° 0040-1951, pp. 33–47, 22/02/2026)
IFPEN, BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGCA, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, CNRS, LT, UPMC, INSU - CNRS, UCP, CNRS, GEOSCIENCES, PSL
Metallothionein gene expression and protein levels in triploid and diploid oysters Crassostrea gigas after exposure to cadmium and zinc.
Quantitative real-time polymerase chain reaction (PCR) was used to compare for the first time the differential expression of metallothionein (MT) isoform genes, together with biosynthesis of the total MT proteins, in the gills of triploid and diploid juvenile Pacific oyster Crassostrea gigas in response to cadmium (Cd) and zinc (Zn) exposure. Oysters were exposed to Cd (0.133 mM), Zn (15.3 mM), and Cd1Zn for 14 d. Results showed similar response capacities to metal exposures in the two populations. No significant difference was revealed in terms of MT gene expression, MT protein synthesis, and Cd accumulation. However, triploid oysters bioaccumulated Zn 30% less efficiently than diploid oysters. Among the three MT isoform genes, CgMT2 appeared to be more expressed than CgMT1, whereas CgMT3 appeared to be anecdotal (106 times lower than CgMT2). CgMT2 and CgMT1 gene expression levels were increased sevenfold in the presence of Cd, whereas Zn appeared to have no effect. A twofold increase in MT protein levels occurred in response to Cd exposure. Discrepancies between mRNA and protein levels suggest that in C. gigas MT are regulated at the transcriptional level, as well as at the translational level.
(Environmental Toxicology and Chemistry. vol. 25, n° 0730-7268, pp. 412-418, 22/02/2026)
LEESA, UB, IFP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
3D-fluorescence spectroscopic analysis of HPLC fractionated estuarine fulvic and humic acids
Six estuarine fulvic (FA) and humic acids (HA) were fractionated with reversed-phase high performance liquid chromatography in a water/acetonitrile gradient, with fluorescence detection. Differences between FA and HA chromatograms pointed to a higher incidence of hydrophobic components in the latter. Excitation-emission matrix fluorescence diagrams of most fractions were similar to those of the bulk samples indicating that, in spite of their distinct polarities, the complexity and main spectral characteristics of the materials persisted. A primary group of fluorophores, which are present in most of the fractions, seems to be at the origin of the fluorescence properties of both kinds of HS. A bathochromic shift of the bulk solutions spectra in relation to the fraction emissions was attributed to a greater proximity of these fluorophores, possibly due to the formation of aggregates. Generally, the results reinforced concepts that humic macromolecules consist of assemblages of structurally similar building blocks. \textcopyright 2006 Sociedade Brasileira de Qu\'imica.
(Journal of the Brazilian Chemical Society. vol. 17, n° 0103-5053, pp. 113--124, 22/02/2026)
UCS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Monitoring the maximum turbidity zone and detecting fine-scale turbidity features in the Gironde estuary using high spatial resolution satellite sensor (SPOT HRV, Landsat ETM+) data
This study concerns the quantification of suspended particulate matter in the highly turbid estuarine waters of the Gironde, France, from high spatial resolution remotely sensed data, SPOT (Satellite Pour l'Observation de la Terre) High Resolution Visible (HRV), Landsat Enhanced Thematic Mapper Plus (ETM+). The methodology is based on calibration relationships established between the remote sensing reflectance (R-rs) signal and suspended particulate matter concentration (SPM), from in situ optical measurements. These relationships are valid in the long term as R-rs ratios between near-infrared (NIR) and visible wavebands are relatively independent of the particle grain-size and mineralogy. Consequently, they can be applied to satellite images, even if no simultaneous in situ measurements are carried out concurrently with the satellite overpass. Selected satellite sensor data are corrected for atmospheric effects using radiative transfer code, then converted into surface water SPM concentrations according to the established calibration relationships. Resulting SPM maps are presented for different river flow and tidal conditions. These maps are used to locate the maximum turbidity zone and observe its tidal and seasonal movements. The high spatial resolution of SPOT HRV and Landsat ETM+ satellite sensor data also shows detailed turbidity features in the estuary, resulting from re-suspension phenomena over banks and turbulent currents.
(INTERNATIONAL JOURNAL OF REMOTE SENSING. vol. 27, pp. 2303-2321, 22/02/2026)
LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
SYNCARID CRUSTACEANS FROM THE MONTCEAU LAGERSTÄTTE (UPPER CARBONIFEROUS; FRANCE)
Key aspects of the morphology, autecology, systematics and taphonomy of the crustacean syncarids from the Montceau Lagerstätte (Upper Carboniferous, Stephanian B; France) are presented. Palaeocaris secretanae is the most abundant faunal element of the Montceau biota and shows striking morphological similarities with Palaeocaris typus from the Mazon Creek Lagersta¨tte (Westphalian D; Illinois, USA). Palaeocaris secretanae was a shrimp-like animal with a short head (no head shield), large mandibles, 14 trunk segments (the first one being reduced) and a fan-like caudal termination. Both the body and the appendage design indicate abilities for crawling on the substratum (slender endopods) and for escape reaction (uropodal fan, pleonal flexibility), although swimming activities may have been reduced (trunk appendages with small flap-like exopods). Details of the appendages involved in feeding, e.g. mandibles and maxillipeds, indicate poor ability for predation but point to an omnivorous detritus feeding mode. Poorly developed respiratory organs (small cylindrical epipods) suggest a relatively low level of locomotory activity. The field of vision may have been large and panoramic (stalked eyes). Rows of pores on 12 trunk segments are interpreted as possible sensory organs used for current detection. Females were brooding eggs (clusters of eggs preserved along anteroventral trunk). Microprobe analysis indicates that siderite is the major component of the nodules. Four events played a key-role in the three-dimensional preservation of syncarids: (1) rapid burial, (2) minimal decomposition, (3) phosphatic mineralization shortly after the animal's death and (4) nodule formation around the carcass. Palaeocaris secretanae is morphologically close to Recent syncarids such Anaspides tasmaniae (freshwater streams, Australia) in its general body plan and detailed anatomy, e.g. mouth parts, indicating morphological stasis in syncarids over more than 200 million years.
(Paleontology. vol. 49, pp. 647-672, 22/02/2026)
PEPS, UCBL, INSU - CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS
Spatial distribution of zooplankton size spectra on the French continental shelf of the Bay of Biscay during spring 2000 and 2001
During two cruises in springtime (18 March to 13 April 2000 and 27 March to 4 June 2001), the whole French continental shelf of the Bay of Biscay was sampled to obtain an overview on the zooplankton community size structure. A laboratory optical plankton counter (OPC-1L) was used to process plankton net tow samples and estimate abundance, biovolume, and general characteristics of size spectra. In a second step, biomass estimates were extrapolated from size by using a conversion factor. Both biomass and abundance estimates show spatial patterns with a clear coastal-open sea gradient for both years. The coastal area was characterized by the highest biomasses and abundances per volume. A first analysis of the zooplankton community size spectra was made by using the slope of the normalized biomass size spectrum. Different spatial patterns of zooplankton size spectra were highlighted for spring 2000 and 2001. The highest slopes were found for the coastal zone, showing a large ratio of small organisms, although this was less marked in the springtime 2000. Stations characterized by high proportions of large organisms were located in majority in the north of the bay and at the shelf break. A second analysis using the size probability distributions of organisms revealed a nearly permanent nonlinearity of probability distributions. This implied the community structure was not in an equilibrium state during spring and this nonlinearity could be locally related to dominant species dynamics.
(Journal of Geophysical Research. Oceans. vol. 111, n° 2169-9275, 22/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOPB, INSU - CNRS, CNRS
Tsunami Deposits Related to Flank Collapse in Oceanic Volcanoes: The Agaete Valley Evidence, Gran Canaria, Canary Islands
(Marine Geology. vol. 227, pp. 135--149, 22/02/2026)
GEOLAB, UBP, IR SHS UNILIM, UNILIM, UCA [2017-2020], CNRS, UCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGP, UP1, UPEC UP12, CNRS, DIMAR, UFPE
Cytochrome c Oxydase Subunit I Gene is Up-regulated by Cadmium in Freshwater and Marine Bivalves
Inhibition of the mitochondrial electron transfer chain and induction of reactive oxygen species (ROS) production are one of the roots of cadmium (Cd) toxicity. To appreciate the impact of Cd on mitochondria, we focused on the expression of CoxI gene which encodes the subunit I of the Cytochrome c oxidase (complex IV of the respiratory chain). CoxI gene expression was studied by real-time quantitative PCR in three species: two freshwater bivalves (Corbicula fluminea and Dreissena polymorpha) and one marine bivalve (diploid or triploid Crassostrea gigas). Bivalves were exposed for 10 or 14 days to 0.13 μM Cd$^2$$^+$ and 15.3 μM Zn$^2$$^+$ in controlled laboratory conditions. We demonstrate that in the three mollusk species CoxI gene was up-regulated by Cd. Zinc (Zn), which is known to have antioxidant properties, had no effect on CoxI gene expression. In the presence of Cd and Zn, CoxI gene inducibility was lower than after a single Cd exposure, in each species; result that could not be fully explained by a decreased Cd accumulation. CoxI gene induction by Cd was 4.8-fold higher in triploid oysters than in diploid ones, indicating a possible influence of triploidy on animal responses to Cd contamination.
(BioMetals. vol. 19, n° 0966-0844, pp. 237-244, 22/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Metallothionein gene identification and expression in the cockle ( Cerastoderma edule) under parasitism (trematodes) and cadmium contaminations
Among benthic organisms, bivalves are often used as bioindicators of environmental pollution because of their high bioaccumulation capacities for heavy metals leading to metallothioneins (MT) induction. MT are small cytosolic metal-binding proteins involved in metal homeostasis and detoxification in living organisms. These proteins can also be induced by a wide range of factors, such as hormones, physical stress, parasitism. MT quantification in relation to parasitism is rarely reported in literature, while parasites are omnipresent and have deleterious impacts on bivalves. Moreover, only a few number of MT genes have been characterized in molluscs. This study describes the partial sequence of the MT gene (Cemt1) in the edible cockle Cerastoderma edule. The cockle's MT cDNA was sequenced and showed over 80% homology to several other bivalve MT sequences. This sequence was then used to determine MT specific primers which can be used in quantitative real time PCR. MT protein and gene expression levels were quantified for individuals selected under different conditions: free from or infected by the digenean trematode Himasthla elongata, and under cadmium exposure at 15 mu g Cd L-1. Results evidenced that MT concentrations were significantly increased by both treatments; parasite infection and Cd exposure. Moreover, congruent results between MT protein and gene expression levels were obtained.
(Aquatic Living Resources. vol. 20, n° 0990-7440, pp. 43-49, 22/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Temporal variability in phytoplankton pigments, picoplankton and coccolithophores along a transect through the North Atlantic and tropical southwestern Pacific
Biogeochemical processes in the sea are triggered in various ways by chlorophyll-containing phytoplankton groups. While the variability of chlorophyll concentration at sea has been observed from satellites for several years, these groups are known only from cruises which are limited in space and time. The Geochemistry, Phytoplankton and Color of the Ocean programme (GeP&CO) was set up to describe and understand the variability of phytoplankton composition on large spatial scales under a multi-year sampling strategy. It was based on sea-surface sampling along the route of the merchant ship Contship London which travelled four times a year from Le Havre (France) to Noumea (New Caledonia) via New York, Panama and Auckland. Observations included the measurement of photosynthetic pigments, counts of picoplanktonic cells by flow cytometry (Prochlorococcus, Synechococcus, and picoeucaryotes) and counting and identification of coccolithophores. The results confirmed that tropical areas have low seasonal variability and are characterized by relatively high divinyl-chlorophyll a and zeaxanthin concentration and that the variability is strongest at high latitudes-where the phytoplankton biomass and population structure are found to have large seasonal cycles. Thus, the spring bloom in the North Atlantic and an austral winter bloom north of New Zealand are marked by chlorophyll concentrations which are often higher than 0.5 mu g l(-1) and by high concentration of fucoxanthin (a pigment used as an indicator for diatoms), while summer populations are dominated by Prochlorococcus sp. and have low chlorophyll concentrations. Apart from this yearly bloom at temperate latitudes, fucoxanthin is scarce, except in the equatorial upwelling zone in the eastern Pacific Ocean, where it is found in moderate amounts. In this region, relatively high chlorophyll concentrations extend generally as far as 14 degrees S and do not respond to the seasonal strengthening of the equatorial upwelling during the austral winter. Prochlorococcus, which is known to dominate in oligotrophic tropical seas and to disappear in cold conditions, in fact has its minimum during the spring bloom in the North Atlantic, rather than during the winter. Coccolithophores are ubiquitous, showing a succession of species ill response to oceanic conditions and provinces. 19'Hexanoyloxyfucoxanthin, the pigment generally considered as all indicator of coccolithophores, is relatively abundant at all times and in all regions, but its abundance is generally not tightly correlated with that of coccolithophores. The regional differences revealed by these results are in overall agreement with Longhurst's division of the ocean into ecological provinces. (c) 2006 Elsevier Ltd. All rights reserved.
(Deep Sea Research Part I: Oceanographic Research Papers. vol. 53, n° 0967-0637, pp. 689-712, 22/02/2026)
LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, CYROCO, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOBB, OOB, UPMC, CNRS, UPMC, INSU - CNRS, CNRS