Cadmium toxicity and bioaccumulation in freshwater biofilms
A microcosm study was undertaken to examine the effects of dissolved cadmium at various concentrations (0, 10, and 100 μg · L−1) on biofilm accumulation and diatom assemblages. A natural biofilm sampled from the Riou-Mort River (Southwest France) was inoculated into three experimental systems, where biofilm settled on glass slides. Samples collected after 1, 2, 4, and 6 weeks of colonization were analyzed for metal accumulation (total metal content and intracellular metal content in the biofilm), biomass (as measured through dry weight and ash-free dry matter), and quantitative as well as qualitative analysis of diatom assemblages. There was a positive correlation between cadmium accumulation and dissolved cadmium concentrations and duration of exposure: a linear relationship was found between concentration factors (CFs) of growing biofilms and time (CFs/day = 0.25 and 0.38 under contaminations of 10 and 100 μgCd · L−1, respectively). Biofilm settlement, more than photosynthetic activity, was affected by high cadmium concentrations: we observed for all stages of settlement a drastic and significant (p < 0.05) reduction in biofilm biomass and in diatom densities in the highest cadmium contamination, compared to control and low cadmium concentration units.
(Archives of Environmental Contamination and Toxicology. vol. 54, n° 0090-4341, pp. 173-186, 23/02/2026)
UR REBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
In-Water Reflectance Spectra Measured On Board a Jet-Ski Across a Complex Nearshore Zone of Case-2 Waters during the ECORS Experiment
(pp. CDrom, 23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CRC, UB, CNRS
Les micropolluants sont-ils responsables des déformations observées chez les crevettes blanches de l'estuaire de la Gironde ? Description du phénomène et recherches en cours
Présentation et analyse des déformations observées sur la crevette blanche dans l'estuaire de la Gironde.
(pp. 11, 23/02/2026)
UR EPBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Neanderthal Extinction by Competitive Exclusion
Background: Despite a long history of investigation, considerable debate revolves around whether Neanderthals became extinct because of climate change or competition with anatomically modern humans (AMH). Methodology/Principal Findings: We apply a new methodology integrating archaeological and chronological data with high-resolution paleoclimatic simulations to define eco-cultural niches associated with Neanderthal and AMH adaptive systems during alternating cold and mild phases of Marine Isotope Stage 3. Our results indicate that Neanderthals and AMH exploited similar niches, and may have continued to do so in the absence of contact. Conclusions/Significance: The southerly contraction of Neanderthal range in southwestern Europe during Greenland Interstadial 8 was not due to climate change or a change in adaptation, but rather concurrent AMH geographic expansion appears to have produced competition that led to Neanderthal extinction.
(PLoS ONE. vol. 3, n° 1932-6203, pp. e3972, 23/02/2026)
PACEA, UB, CNRS, KU, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Live and Dead Foraminiferal Faunas from Saint-Tropez Canyon (bay of Fréjus): Observations Based on in Situ and Incubated Cores
The impact of sedimentary processes on the live (rose-Bengal-stained) foraminiferal faunas and on the composition of dead assemblages was investigated at a 373-m-deep station in Saint-Tropez Canyon (Bay of Fréjus, France). For the >150-μm fraction, biocoenoses and thanatocoenoses were investigated in two 10-cm-long cores collected with a classical Barnett multi-corer. In the 63- to 150-μm size fraction, living faunas were investigated in the first centimeter of the sediment. The first core was fixed with ethanol and rose-Bengal at the time of the sampling (the in situ core) whereas the second core was stored in a culture room during a 2.5-year-long incubation before its fauna was investigated.Both cores present similar thanatocoenoses (>150-μm size fraction) that are substantially contaminated by neritic foraminifera presumably transported from adjacent shelves. The sedimentological analysis of a third core reveals neither graded sediments nor erosional surfaces. Abundant organic remains are detected downcore in the muddy silt sediment. All these observations preclude the idea of deposition by a recent turbidite. Therefore, our canyon environment seems to behave at present as a depocenter for a rather continuous flux of fine sediment and resuspended organic matter originating from shallower areas. The living in situ faunas in the 63- to 150-μm and >150-μm size fractions are quite diverse with a moderate evenness. In the >150-μm size fraction, the high abundance of intermediate and deep infaunal taxa (Uvigerina elongatastriata, Bolivina alata, Melonis barleeanus, Globobulimina spp. and Chilostomella oolina) underlines the importance of organic matter focusing (and the related redox conditions) in this submarine canyon environment. The dominance of M. barleeanus and bolivinids in the 63- to 150-μm size fraction confirms the eutrophic aspect of our study area. Because of logistical problems, the incubated core suffered important salinity changes throughout the 2.5 years of incubation. Salinity ranged between 35 and 62 psu. Oxygen concentration was almost zero at the sediment-water interface at the end of incubation. In the larger size fraction (>150 μm), only one taxon, Rosalina bradyi (Cushman, 1915), survived these adverse experimental conditions. Its density (516 ind/100 cm2) is two orders of magnitude higher than that of the in situ core (3 ind/100 cm2). No living foraminifera were found in the first centimeter of the 63- to 150-μm size fraction. Rosalina bradyi was obviously the last species able to reproduce and grow in the incubated core. Our results show that this taxon is capable of tolerating extreme salinity changes.
(Journal of Foraminiferal Research. vol. 38, n° 0096-1191, pp. 137 - 156, 23/02/2026)
LPGN, UN, CNRS, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Effects of seasonal dynamics in a Zostera noltiimeadow on phosphorus and iron cycles in a tidalmudflat (Arcachon Bay, France)
A study was conducted in Arcachon Bay, France, to determine the effect of seasonal dynamics in a Zostera noltii meadow on P and Fe cycles in the superficial sediments of a tidal mudflat. The redox-sensitive Fe particulate pool and associated P in the root zone showed a seasonal variation following the growth and decay of Z. noltii biomass, with a maximum content during the growth period. In comparison, the bare sediments did not show significant seasonal changes. A dissolved inorganic phosphorus (DIP) uptake was measured from the water column to the sediment in vegetated sediments, whereas a net DIP efflux was observed in the unvegetated sediments. During the growth period, the formation of an iron oxihydroxide-rich zone occurred and acted as a trap for dissolved phosphorus, constituting a reserve of available P for eelgrass growth. At the periphery of the rhizosphere, a strong reduction of the sediment occurred during the growth phase, probably due to increasing organic matter inputs via the roots. The iron oxihydroxide dissolution releases Fe(II) and the recently bound phosphorus to the pore water, making it available for assimilation by the eelgrass roots for growth metabolism. Fe(II) is re-oxidized to solid Fe(III) forms depleted in P into the root zone, or re-precipitated below as sulphur forms. The highest P uptake occurs by this process, and the seasonal variations in redox-sensitive P stock are sufficient to support the annual Z. noltii P requirement. During the decline period, as the P plant demand and the oxic layer thickness drop, the unused released DIP pool supplies large amounts of DIP to the pore water and water column.
(Marine Ecology Progress Series. vol. 355, n° 0171-8630, pp. 59-71, 23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Fixed point strategies for elastostatic frictional contact problems
Several fixed point strategies and Uzawa algorithms (for classical and augmented Lagrangian formulations) are presented to solve the unilateral contact problem with Coulomb friction. These methods are analyzed, without introducing any regularization, and a theoretical comparison is performed. Thanks to a formalism coming from convex analysis, some new fixed point strategies are presented and compared to known methods. The analysis is first performed on continuous Tresca problem and then on the finite dimensional Coulomb problem derived from an arbitrary finite element method.
(Mathematical Methods in the Applied Sciences. vol. 31, n° 0170-4214, pp. 415-441, 23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICJ, ECL, UCBL, INSA Lyon, INSA, UJM, CNRS
TRAITEMENT DES DONNEES TOPOGRAPHIQUES ET BATHYMETRIQUES ACQUISES SUR LE LITTORAL AQUITAIN : OPTIMISATION DES MESURES EFFECTUEES EN QUAD ET AU THEODOLITE
Dans cette communication, nous présenterons les méthodes originales développées pour le traitement des données topographiques et bathymétriques acquises sur le littoral aquitain, afin d'aboutir à une cohérence centimétrique sur les jeux de données d'origine très différentes. Ce programme de traitement est soutenu par l'ANR VULSACO et par le projet ECORS (SHOM/EPOC)
(23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, L3AB, UB, INSU - CNRS, CNRS, LAB, UB, INSU - CNRS, CNRS
Diatoms preserved in surface sediments of the northeastern Kerguelen Plateau
An ''island mass effect'' was observed from the sedimentary distribution of diatoms on the northeastern Kerguelen Plateau. Five new samples placed in context to species distributions previously reported from the Permanently Open Ocean Zone (POOZ) revealed a plateau community dominated by three species/taxa: Fragilariopsis kerguelensis, Thalassionema nitzschioides f. nitzschioides and Chaetoceros Hyalochaete resting spores. Intermediate abundances of Thalassiosira antarctica were unique to the plateau sediment signature as were increased abundances of Eucampia antarctica v. antarctica. The off-plateau sediment sample contained typical POOZ sediment distributions dominated by F. kerguelensis, Thalassiosira lentiginosa and Thalassiothrix antarctica. The role of deposition from the surface waters to the sediments was investigated by comparison to the diatom thanatocoenose observed in surface waters. These results suggest that the use of sediment abundances of C. Hyalochaete resting spores and F. kerguelensis to determine past productivity events (such as wind-sourced iron enrichment of the Southern Ocean at the Last Glacial Maximum) is not straightforward. The elevated abundance of T. nitzschioides f. nitzschioides on the plateau did not indicate an iron-deplete regime but the converse. For the evaluation of paleo-productivity hypotheses for the open Southern Ocean, we suggest caution in the use of Subantarctic and Kerguelen Plateau sediment signatures, and emphasize that there is a need to also study Antarctic coastal and especially sea-ice melt-water stimulated blooms. r
(Deep Sea Research Part II: Topical Studies in Oceanography. vol. 55, n° 0967-0645, pp. 677-692, 23/02/2026)
LOB, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, LMGEM, CNRS
Analysis of the Flavobacterium psychrophilum outer-membrane subproteome and identification of new antigenic targets for vaccine by immunomics
Flavobacterium psychrophilum is an important infectious Gram-negative bacterium causing cold-water disease (CWD) and rainbow trout fry syndrome. Outer-membrane proteins (OMPs) are key molecules with regard to the interface between the cell and its environment. Therefore, we sought to define the outer-membrane (OM) subproteome of F. psychrophilum in order to gain insight into the biology and pathogenesis of this bacterium and to identify the dominant antigens targeted by the rainbow trout (Oncorhynchus mykiss) immune system during infection. First, OMs were prepared from a cell-envelope suspension by differential Sarkosyl (sodium lauryl sarcosinate) solubility. We then isolated the OMPs and identified 36 proteins from 34 spots resolved by two-dimensional electrophoresis and LC-MS/MS. An immunoproteomic approach using antibodies from CWD-convalescent rainbow trout was then used to identify 25 immunoreactive F. psychrophilum antigens that may be relevant in pathogenesis and diagnosis. These included the previously characterized surface-exposed OMPs OmpA, OmpH/P18 and FspA, as well as newly described antigenic proteins. This study provides a number of novel candidate proteins for developing vaccine(s) against flavobacteriosis infection in aquaculture.
(Microbiology. vol. 154, n° 1350-0872, pp. 1793-1801, 23/02/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VIM (UR 0892), INRA, PGFB