Interactive effects of metal contamination and pathogenic organisms on the marine bivalve Cerastoderma edule
The present study evaluated the interactive effects of cadmium contamination and pathogenic organisms (trematodes Himasthla elongata and bacteria Vibrio tapetis) singularly and in combination during 7 days on the bivalve Cerastoderma edule. Some defense-related activities were analyzed such as genetic expression, metallothionein and immune responses. Trematode metacercarial infection, similar whatever the treatment, induced the strongest responses of immune parameters. Particularly, the interaction between cadmium and parasite exposures induced unusual responses on gene expression and immune responses. No effect of bacterial challenge appeared on bivalve responses, nevertheless a strong mortality of V. tapetis infected cockles occured between 7 and 14 days. Cadmium bioaccumulation was significantly modulated by both pathogenic organisms. Furthermore, an antagonistic effect of trematodes and bacteria was shown on metal bioaccumulation of co-infected cockles. These results highlighted the importance of considering the multiplicity of perturbation sources in coastal ecosystems to assess the health status of organisms.
(Marine Pollution Bulletin. vol. 60, n° 0025-326X, pp. 515-525, 27/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Bivalve population health: Multistress to identify hot spots
This study investigated some stress (metals, parasites) and response (immunity, metallothionein) factors in two cockle and two Manila clam populations. Data from eight seasons were averaged to obtain global baseline values. Stress/response characteristics of each population were compared to population health status that was determined through population dynamics parameters. Four different scenarios were discussed: (1) a lightly stressed cockle population with correct population health but with a risk of deterioration (hot spot); (2) a lightly stressed introduced cockle population threatened of extinction. In this case ecological factors were suspected; (3) a moderately stressed clam population with moderate adaptative response. The population was sustainable but the level of stress should not increase (hotspot); and (4) a stressed clam population and unfavourable ecological conditions preventing clam settlement. This monitoring highlighted that the discrepancy between population health and stress levels could be due to insufficient response by bivalves and/or by unfavourable ecological factors.
(Marine Pollution Bulletin. vol. 60, n° 0025-326X, pp. 1307-1318, 27/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Prevalence, intensity, and aneuploidy patterns of disseminated neoplasia in cockles (Cerastoderma edule) from Arcachon Bay: Seasonal variation and position in sediment
The present report presents the first evidence of disseminated neoplasia (DN) in cockles Cerastoderma edule from Arcachon Bay (France). Aneuploidy of neoplastic cells allowed the use of flow cytometry (FCM) to diagnose and stage DN. A 1 year survey (2007) of the prevalence and intensity (% of aneuploid circulating cells in neoplastic cockles) was conducted. Prevalences ranged from 2.2% (June) to 13.6% (May), and disease intensity ranged from 18.7% (June) to 95.5% (September). These percentages were not correlated with seawater temperature, but rather showed unexplained oscillations over the year. Prevalence and intensity of DN were higher in cockles found at the surface of sediment compared to those buried normally (11.8% vs. 6.7% and 53.0% vs. 40.6%, respectively, p < 0.05). DN could thus be one mechanism leading to unexplained presence of cockles at the surface of the sediment in Arcachon Bay. Ploidy characteristics of neoplastic cells were also investigated using FCM, revealing an unusual, broad continuum of ploidy distribution from 1.6 to 9.6n. Ploidy values were not in whole numbers in contrast to the rounded values reported in other studies. Ploidy varied according to DN intensity, with the ploidy distribution of neoplastic cells from lightly-diseased cockles being unimodal (3.7n median). In contrast, highly-diseased cockles showed a bimodal ploidy distribution (3.0n and 4.7n medians). This suggests that, in cockles from Arcachon Bay, mechanisms leading to aneuploidy are complex, developing during disease progression.
(Journal of Invertebrate Pathology. vol. 104, n° 0022-2011, pp. 110-118, 27/08/2026)
CEMCA, UBO EPE, INC-CNRS, CNRS, IBSAM, UBO EPE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Testing the Hypothesis of Fire Use for Ecosystem Management by Neanderthal and Upper Palaeolithic Modern Human Populations
Background: It has been proposed that a greater control and more extensive use of fire was one of the behavioral innovations that emerged in Africa among early Modern Humans, favouring their spread throughout the world and determining their eventual evolutionary success. We would expect, if extensive fire use for ecosystem management were a component of the modern human technical and cognitive package, as suggested for Australia, to find major disturbances in the natural biomass burning variability associated with the colonisation of Europe by Modern Humans. Methodology/Principal Findings: Analyses of microcharcoal preserved in two deep-sea cores located off Iberia and France were used to reconstruct changes in biomass burning between 70 and 10 kyr cal BP. Results indicate that fire regime follows the Dansgaard-Oeschger climatic variability and its impacts on fuel load. No major disturbance in natural fire regime variability is observed at the time of the arrival of Modern Humans in Europe or during the remainder of the Upper Palaeolithic (40-10 kyr cal BP). Conclusions/Significance: Results indicate that either Neanderthals and Modern humans did not influence fire regime or that, if they did, their respective influence was comparable at a regional scale, and not as pronounced as that observed in the biomass burning history of Southeast Asia.
(PLoS ONE. vol. 5, n° 1932-6203, pp. e9157, 27/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PACEA, UB, CNRS, WITS
Experimental toxicity and bioaccumulation of cadmium in freshwater periphytic diatoms in relation with biofilm maturity
A study was undertaken to examine cadmium accumulation in freshwater biofilm, its effects on biofilm development and on diatom community structure in laboratory experimental conditions. A suspension of a biofilm originated from the Riou-Mort River (South West France) was inoculated into three experimental units containing clean glass substrates under laboratory conditions. Settling and already developed biofilms were exposed to a Cd concentration of 100 μgL−1. Metal accumulation (total and intracellular metal content) in biofilms, dry weight and ash-free dry mass, diatom cell density and diatom community composition were analyzed. Both total and intracellular Cd accumulated by the biofilm throughout the experiment increased with duration of metal exposure. Biofilms in the course of maturation were showed higher Cd content and less effective development than settled biofilms. However diatom communities in younger biofilms exposed to Cd increased their tolerance to Cd by a highly significant development of Nitzschia palea. In contrast, Cd exposure had different effect in installed biofilm and taxonomic composition. These results indicate that mature biofilm may limit Cd accumulation into its architecture and protect diatom communities from the effects of metals.
(Science of the Total Environment. vol. 408, n° 0048-9697, pp. 552-562, 27/08/2026)
IRSTEA, UR REBX, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Viability of differentiated epilithic bacterial communities in the River Garonne (SW France)
Epilithic bacterial community viability was assessed on natural biofilm assemblages from environmentally contrasting locations over a 17-months period to determine if it reflects environmental conditions or conditions within the biofilm assemblage. Vital state was assessed by membrane integrity using LIVE/DEAD® BacLight staining kit. Samples were regularly collected in a large river, up and downstream of a large urban centre. Epilithic biomasses were similar between sites irrespective of the distinct water quality but varied temporarily, peaking up to 48 g AFDM m−2. Bacterial community composition assessed by 16S rDNA based PCR-DGGE significantly differed between sites. Bacterial densities (median of 2.5 × 1011 cell g AFDM−1) were stable whatever the sample origin or biomass. Viable bacterial fractions ranged between 13 and 83% of the total bacterial densities and were correlated with hydrological stability indicators (average of 41.9% during stable water periods, 62.4% during intermediate flow regimes and 50.0% during flow instability) and seasonal parameters. At the river section and epilithic community scales, consistent bacterial densities per unit of biomass could reflect a biofilm assemblage carrying capacity while variable membrane integrity likely integrates changes in the vital state of the community under changing environmental conditions.
(Hydrobiologia. vol. 637, n° 0018-8158, pp. 207-218, 27/08/2026)
CNRS, UR MALY, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Rapid climatic variability in the western Mediterranean during the last 25,000 years from the high resolution pollen record ODP 976
(14/12/2009)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UMLP, UBFC, UHH
Sonochemical Disproportionation of Carbon Monoxide in Water: Evidence for Treanor Effect during Multibubble Cavitation
(Angewandte Chemie International Edition. vol. 48, n° 1433-7851, pp. 9529-9532, 07/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSFC, ICSM - UMR 5257, CEA, ENSCM, INC-CNRS, UM, CNRS
Caractérisation de l'activité hydrosédimentaire dans le Système Turbiditique du Var (NO Méditerranée) et de son enregistrement dans l'archive sédimentaire
Le système turbiditique du Var présente la particularité d'être fréquemment parcouru par des écoulements gravitaires. Cela en fait un endroit privilégié pour étudier simultanément les facteurs déclenchant des courants de turbidité, leurs caractéristiques hydrodynamiques, leur contenu particulaire et les dépôts associés. Dans le cadre du projet Européen HERMES (6ème Programme Cadre), nous avons acquis pendant 2 ans dans le canyon du Var et dans la vallée turbiditique (1) des séries temporelles dans la colonne d'eau (30 m et 400 m au dessus du fond) sur la vitesse des courants, la température et le flux particulaire, et (2) des prélèvements répétés par carottage du sédiment de surface. Nos résultats mettent en évidence deux types de transport sédimentaire: (1) des écoulements gravitaires, et (2) des remises en suspension sur le fond par le Courant Nord. L'étude des caractéristiques hydrodynamiques des courants gravitaires permet de préciser nos connaissances sur leur mécanisme de formation. Les courants gravitaires peuvent être initiés par des déstabilisations dans le canyon ou par le plongement en mer de l'eau turbide du fleuve (courant de turbidité hyperpycnal). Ces derniers peuvent être générés lorsque le débit liquide du fleuve franchit un seuil de 306 m3.s-1 à l'embouchure, et à condition que la crue soit étendue à l'ensemble du réseau hydrographique. L'étude combinée des mesures sur les deux années et des faciès sédimentaires dans les dépôts du siècle dernier souligne la prépondérance des courants de turbidité hyperpycnaux, qui représentent 80 % des écoulements gravitaires. De plus, cette étude combinée montre que les écoulements de faible magnitude (résultant de petites instabilités ou de crues annuelles du fleuve) s'arrêtent généralement au débouché de la vallée supérieure et ne déposent du sédiment que sur une terrasse située à 70 m au dessus du fond de la vallée. Les courants gravitaires de grande magnitude (résultant de larges instabilités ou de crues majeures du fleuve) sont fortement érosifs dans la partie du système située avant le pied de pente, et déposent des séquences sédimentaires sur les terrasses, la levée, et localement dans le chenal. Le cadre chrono-stratigraphique établi pour l'étude des séquences sédimentaires permet de mieux contraindre la manière dont ces courants gravitaires sont enregistrés et préservés, à plusieurs échelles de temps.
(07/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, DRO-EP, IFREMER
A new conceptual model for the deposition process of homogenite: Application to a cretaceous megaturbidite of the western Pyrenees (Basque region, SW France)
The north Pyrenean megaturbidite is a 19–63m exceptional thick bed deposited during the Late Turonian and extending over more than 90km in the Basque region Country (SW France). Its thickness varies from more than 63m to about 19m from east (Mauléon area) to west (Basque coast). It represents a total compacted volume of about 90km3 of carbonates. On the field, rare sedimentary structures are visible in the turbidite bed. They consist of laminar planar lamination and rare cross laminations in the eastern region and antidune-like structures in the western region. Five sites have been sampled with a vertical step of 50cm to 1m. Thin sections have been quantitatively analyzed for counting the terrigeneous fraction, the quartz grain size and the mineral orientation. The deposits fine westward, which suggests a source located in the east of the Mauléon Basin. This is consistent with the quartz grain orientation in the lower part of the megaturbidite. The deposits fine upward from medium sand to clayey-silt. This is consistent with the classical definition of homogenites and suggests that these kinds of deposits are turbidites. These observations also suggest that the term “megaturbidite” is appropriated for these deposits. The sedimentary analysis indicates that the deposit results from a single event. The volume of sediment involved in the process, as well as the quartz grain orientation indicating flow motion in the opposite direction of the initial flow and the antidune-like structure suggest the formation of reflected flows and the formation of standing waves over the complete water column in the Basque flysch sub-basins corresponding to a “Seiche effect”. The origin of the megaturbidite is probably an earthquake-generated collapse on the carbonate platform. This example allows providing a new conceptual model for the process of homogenite deposition. This model explains the deposition of thick, fine-grained, crudely-graded megaturbidites.
(Sedimentary Geology. vol. 222, n° 0037-0738, pp. 263-273, 01/12/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EGID