The "storm of the century" (December 1999) and the incidental escape of Siberian sturgeons (Acipenser baeri) in the Gironde estuary (SW France): an original bioindicator for metal contamination
(Environmental Science and Pollution Research. vol. 15, n° 0944-1344, pp. 89-94, 02/01/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
STABLE OXYGEN AND CARBON ISOTOPES OF LIVE (STAINED) BENTHIC FORAMINIFERA FROM CAP-FERRET CANYON (BAY OF BISCAY)
A 2800-m-deep station (Station I) from the lower part of Cap-Ferret Canyon (Bay of Biscay) was sampled with a multitube corer in January 1999, June 1999 and April 2000. Four cores (with two replicate cores in April 2000) were investigated to study the stable carbon and oxygen isotopes of live (rose-Bengal-stained) foraminiferal taxa. Eight taxa were analyzed: Hoeglundina elegans, Cibicides wuellerstorfi, Uvigerina peregrina, Bulimina inflata, Melonis barleeanus, Pullenia quinqueloba, Chilostomella oolina and Globobulimina affinis. By using the apparent oxygen utilization of the lower Northeastern Atlantic Deep Water (NEADW) in our study area, we calculated the bottom-water d 13 C DIC , which we compared with foraminiferal carbon isotope values. Next, we investigated the relationship between the foraminiferal d 13 C and the microhabitat of investigated species. By using the value of d 18 O (SMOW) for the lower NEADW, we calculated the equilibrium calcite d 18 O of the bottom water, which we compared with the foraminiferal d 18 O. The occurrence of a living holothurian in its deep infaunal burrow from one of two replicate cores collected in April 2000 (core B) allowed us to investigate the impact of macrofaunal activity on foraminiferal isotopes. Our results are finally compared with data from shallower open-slope stations close to our study area. The d 13 C signatures of most foraminiferal taxa are not correlated to the bottom-water d 13 C DIC but seem to be controlled by a microhabitat effect. Only the d 13 C of Cibicides wuellerstorfi is close to the bottom water d 13 C DIC. When investigating oxygen isotopes, there is no obvious relationship between the foraminiferal microhabitat and the offset between the foraminiferal d 18 O and the equilibrium calcite d 18 O. The presence of a living holothurian had no obvious effect on the d 18 O and d 13 C of foraminifera occurring in the bioturbated interval. However, several individuals of Melonis barleeanus collected in the direct vicinity of the holothurian exhibited lower d 13 C values, suggesting a potential influence of macrofaunal activity on the carbon isotopes of some intermediate and deep infaunal taxa calcifying in the deep sediment. The comparison of Dd 13 C between Uvigerina peregrina, M. barleeanus and Globobulimina spp. with values recorded at shallower stations suggests that the focusing of organic matter in an intermediate state of decay, at our canyon station, has a weak impact on the biogeochemical processes deeper in the sediment. The d 13 C of U. peregrina and the Dd 13 C between U. peregrina and Globobulimina affinis appears definitively more sensitive to labile organic matter supplies than to the advection of low-quality, organic matter.
(Journal of Foraminiferal Research. vol. 38, n° 0096-1191, pp. 39-51, 01/01/2008)
BIAF, UA, LPGN, UN, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Activity of the turbidite levees of the Celtic–Armorican margin (Bay of Biscay) during the last 30,000 years: Imprints of the last European deglaciation and Heinrich events
High-resolution sedimentological and micropaleontological studies of several deep-sea cores retrieved from the levees of the Celtic and Armorican turbidite systems (Bay of Biscay - North Atlantic Ocean) allow the detection of the major oscillations of the British-Irish Ice Sheet (BIIS) and 'Fleuve Manche' palaeoriver discharges over the last 30,000 years, which were mainly triggered by climate changes. Between 30 and 20 cal ka, the turbiditic activity on the Celtic-Annorican margin was weak, contrasting with previous stratigraphic models which predicted a substantial increase of sediment supply during low sea-level stands. This low turbidite deposit frequency was most likely the result of a weak activity of the 'Fleuve Manche' palaeoriver and/or of a reduced seaward transfer of sediments from the shelf to the margin. However, two episodes of turbiditic activity increase were detected in the Celtic-Armorican margin, during Heinrich events (HE) 3 and 2. This strengthening of the turbiditic activity was triggered by the meltwater releases from European ice sheets and glaciers favouring the seaward transfer of subglacial material, at least via 'Fleuve Manche' palaeoriver. At around 20 cal ka, a significant increase of turbidite deposit frequency occurred as a response to the onset of the last deglaciation. The retreat of the European ice sheets and glaciers induced a substantial increase of the 'Fleuve Manche' palaeoriver discharges and seaward transfer of continentally-derived material into the Armorican turbidite system. The intensification of the turbiditic activity on the Celtic system was directly sustained by the widespread transport of subglacial sediments from the British-Irish Ice Sheet (BIIS) to the Celtic Sea via the Irish Sea Basin. A sudden reduction of turbiditic activity in the Armorican system, between ca. 19 and 18.3 cal ka, could have been triggered by the first well known abrupt sea-level rise ('meltwater pulse', at around 19 cal ka) favouring the trapping of sediment in the 'Fleuve Manche' palaeoriver valleys and the decrease of the seaward transfer of continentally-derived material. The maximum of turbiditic activity strengthening in the Celtic-Armorican margin, between ca. 18.3 and 17 cal ka, was induced by the decay of European ice sheets and glaciers producing the most extreme episode of the 'Fleuve Manche' palaeoriver runoff and a great seaward transfer of subglacial material into the Bay of Biscay, Between ca. 17.5 and 16 cal ka, the turbiditic activity significantly decreased in both Celtic and Armorican turbidite systems in response to a global re-advance of glaciers and ice sheets in Europe. The last episode of ice sheet retreat, between ca. 16 and 14 cal ka, is well expressed in the Celtic system by a new increase of the turbiditic activity. The major episode of sea-level rise at around 14 cal ka ('Meltwater Pulse 1A'), precluding the seaward transfer of sediments, induced the end of turbiditic activity in both the Celtic and the Armorican system. Although two main phases of global sea-level rise seem to have had an effect on the Celtic-Armorican margin, this work proposes the BUS retreat and associated riverine discharges as the main trigger mechanisms of the turbiditic activity in this region during the last 30,000 years. (c) 2007 Elsevier B.V. All rights reserved.
(Marine Geology. vol. 247, n° 0025-3227, pp. 84-103, 01/01/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana: a model for the mercurial intoxication of the Wayana Amerindians.
Background: In 2005, 84% of Wayana Amerindians living in the upper marshes of the Maroni River in French Guiana presented a hair mercury concentration exceeding the limit set up by the World Health Organization (10 μg/g). To determine whether this mercurial contamination was harmful, mice have been fed diets prepared by incorporation of mercury-polluted fish from French Guiana. Methods: Four diets containing 0, 0.1, 1, and 7.5% fish flesh, representing 0, 5, 62, and 520 ng methylmercury per g, respectively, were given to four groups of mice for a month. The lowest fish regimen led to a mercurial contamination pressure of 1 ng mercury per day per g of body weight, which is precisely that affecting the Wayana Amerindians. Results The expression of several genes was modified with mercury intoxication in liver, kidneys, and hippocampus, even at the lowest tested fish regimen. A net genetic response could be observed for mercury concentrations accumulated within tissues as weak as 0.15 ppm in the liver, 1.4 ppm in the kidneys, and 0.4 ppm in the hippocampus. This last value is in the range of the mercury concentrations found in the brains of chronically exposed patients in the Minamata region or in brains from heavy fish consumers. Mitochondrial respiratory rates showed a 35–40% decrease in respiration for the three contaminated mice groups. In the muscles of mice fed the lightest fish-containing diet, cytochrome c oxidase activity was decreased to 45% of that of the control muscles. When mice behavior was assessed in a cross maze, those fed the lowest and mid-level fish-containing diets developed higher anxiety state behaviors compared to mice fed with control diet. Conclusion We conclude that a vegetarian diet containing as little as 0.1% of mercury-contaminated fish is able to trigger in mice, after only one month of exposure, disorders presenting all the hallmarks of mercurial contamination.
(Environmental Health. vol. 7, n° 1476-069X, pp. 53, 01/01/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, U1211 INSERM/MRGM, UB, INSERM, IBGC, UB, CNRS, CNIC, UB, CNRS
Discovery of a giant deep-sea valley in the Indian Ocean, off eastern Africa: the Tanzania channel
During the Fanindien 2006 cruise of R/V ‘Beautemps-Beaupré’, high resolution multibeam bathymetry, sub-bottom profiling and sediment coring was carried out along the East African margin, offshore Tanzania and Mozambique (Indian Ocean). The newly acquired data reveal the presence of a giant deep-sea valley (the Tanzania channel) that is more than 10 km wide at 4000 m water depth, along the continental rise. The valley remains 70 m deep and 7 km wide at 800 km from the Tanzania coast. Morphological comparison with worldwide submarine channels show that the Tanzania channel is one of the largest known submarine valleys. This discovery brings new light on development of submarine valleys that drain sediments originated from the East African Rift System (EARS) highlands (i.e. the Tanzania channel and its neighbor Zambezi channel located 1000 km southward). Both of the systems have a morphology markedly different to the classical sinuous, V-shaped channels located at similar latitudes (e.g. the Zaire or Amazon channels). Their submarine drainage system consists of a downslope converging tributary canyons joining a central trunk channel in the continental rise. The presence of such giant deep-sea drainage systems is probably linked to a strong structural control on the sediment pathway, associated to a massive sediment transfer towards the Indian Ocean in relation with the tectonic activity of the East African Rift System (i.e. the uplift periods trough mid-Miocene and Plio-Pleistocene times) and its interplay with the East African equatorial climate changes.
(Marine Geology. vol. 255, n° 0025-3227, pp. 179-185, 01/01/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM, GM, IFREMER, IFP
Courants induits et dissipation de l'énergie des vagues sur les plages macrotidales de la mer d'Iroise
Several field experiments of both morphological and hydrodynamical measurements occured during springs 2004 and 2005 on four beaches of the Iroise Sea (Finistère). Within these four datasets (sea surface elevation, cross-shore and longshore flow velocities), dissipation of wave energy is investigated through time (accounting with tidal cycle) and space (across the intertidal zone). These results are compared to empirical parametrizations of relative wave height Γs (Raubenheimer et al., 1996 ; Sénéchal et al., 2001), parameter greatly used in hydrodynamic models. Then, the local breaking criteria Γs,b is used to characterize wave-related processes (wave asymetry, breaking-induced undertow) involved in sediment transport in the intertidal zone
(European Journal of Environmental and Civil Engineering. vol. 12, n° 1964-8189, pp. 105-116, 01/01/2008)
LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sea ice seasonality during the Holocene, Adélie Land, East Antarctica
Thin sections of laminated cores from different Antarctic coastal areas have demonstrated the potential of diatom species to document climate change at the seasonal scale. Here we present the relative abundances of four diatom species and species groups (Fragilariopsis curta group as a proxy for yearly sea ice cover, F. kerguelensis as a proxy for summer sea-surface temperature, Chaetoceros Hyalochaete resting spores as a proxy for spring sea ice melting and the Thalassiosira antarctica group as a proxy for autumn sea ice formation) in core MD03-2601 retrieved off Adélie Land on the Antarctic continental shelf. These abundances were compared to surface temperatures and sea ice cover modelled over the last 9000 years. Both the marine records and the simulated climate demonstrated a cooler Early Holocene (9000-7700 years BP), a warmer Mid-Holocene (7700-4000 years BP) and a colder Late Holocene (4000-1000 years BP). Yearly sea ice cover followed an inverse pattern to temperatures with less sea ice during the Mid-Holocene Hypsithermal than during the Late Holocene Neoglacial. However, diatom census counts and model output indicate that sea ice spring melting happened earlier in the season, as expected, but that autumn sea ice formation also occurred earlier in the season during the Hypsithermal than during the colder Neoglacial, thereby following seasonal changes in local insolation.
(Marine Micropaleontology. vol. 66, n° 0377-8398, pp. 222-232, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Identification of a minimal adequate model to describe the biomass dynamics of river epilithon
(River Research and Applications. vol. 24, n° 1535-1459, pp. 36-53, 10/04/2026)
LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The Fetch Campaign, study of the turbulent fluxes, surface waves and remotely sensed parameters in fetch limited situations
description of the Fetch Campaign conducted in the Golfe du Lion in Mediterranéean sea
(10/04/2026)
CETP, UVSQ, INSU - CNRS, CNRS, SA, UVSQ, UPMC, INSU - CNRS, CNRS, IRPHE, AMU, ECM, CNRS, LEPI, UTLN, APL/RSMAS, RSMAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LAERO, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNRS, FIMR, DIROP/MAR, DIROP, IFREMER
Cadmium uptake by the European eel: Trophic transfer in field and experimental investigations
Due to its status of threatened species and being heavily contaminated by metals, the European eel (Anguilla anguilla) was selected to investigate cadmium contamination levels of fish settled along a historically cadmium-contaminated hydrosystem, the GaronneGironde continuum (France), according to its various location sites and fish length. Results have shown an important site effect on cadmium concentrations in liver but not in gills, highlighting the possible predominance of the trophic exposure route. Subsequently, uncontaminated eels were experimentally exposed to cadmium by water uptake and/or trophic route(s). Eels were fed with different preys: white shrimps collected in an unpolluted area in the Gironde estuary, and cadmium-enriched shrimps. Data obtained tend to show that the use of cadmium-enriched food during experimental investigations triggers an underestimation of the metal trophic transfer rate. These two complementary approaches provide some elements to suggest that the trophic route plays an important role in cadmium contamination of wild eels.
(Ecotoxicology and Environmental Safety. vol. 70, n° 0147-6513, pp. 10-19, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, CEMAGREF