Cadmium uptake by the European eel: Trophic transfer in field and experimental investigations
(Ecotoxicology and Environmental Safety. vol. 70, n° 0147-6513, pp. 10-19, 01/05/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
Effects of dietary methylmercury on zebrafish skeletal muscle fibres
Mercury and more specifically methylmercury have been reported as hazardous environmental pollutants able to accumulate along the aquatic food chain with severe risk for animal and human health. Adult male zebrafish (Danio rerio) were distributed in two groups: a control group (fed with uncontaminated food) and a MeHg-contaminated group (fed with food containing 13.5μgHgg(-1) (dry wt)). Five fish per condition were removed after 7, 21 and 63 days. Bioaccumulation of mercury was determined and muscle samples from control and exposed groups were fixed for histological and ultrastructural studies. In contaminated muscles were observed a decrease of the inter-bundle surface, mitochondria with variable shapes, sizes and cristae disorganization, also decreasing the surface area and inter-bundle surfaces. Indeed, damage in the endoplasmic reticulum cisternae was observed. For statistical evaluation the damages in mitochondria was quantified by image. According to the current results, methylmercury affects the structure of fibre cells of D. rerio after trophic and low dose exposure.
(Environmental Toxicology and Pharmacology. vol. 25, n° 1382-6689, pp. 304-309, 01/05/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A radiometric chronology for the Iberian margin marine sequence through Termination II: implications for interhemispheric phasing of deglaciation.
(13/04/2008)
PACEA, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AWI, AWI
Shot noise modelling of high frequency valvometry data in oysters
(13/04/2008)
LMBA, UBS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence
We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago a time period centred on Marine Isotope Stage (MIS) 9 and characterised by particular baseline climate states. This study enables to document the vegetation changes in north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appears more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appears related to changes in deep water circulation and likely to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of a pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in southern Europe.
(pp. 375-414, 28/03/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, WHOI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Metazoan parasites in an intermediate host population near its southern border:The common cockle (Cerastoderma edule) and its trematodes in a Moroccan coastal lagoon (Merja Zerga)
The metazoan parasite community of Cerastoderma edule was studied in the southern geographical range of the host (the coastal lagoon Merja Zerga, Morocco). A total of 11 metazoan species was found in cockles. Nine of these were trematodes using cockles as either first intermediate host (three species) or second intermediate host (six species). In addition, two other endo-metazoan species (Pinnotheres pisum and Paravortex cardii) were recorded from cockles in the studied lagoon. All the observed metazoans in cockles from Merja Zerga have previously been recorded at sites north of Africa.Up to 10% of the cockles in the studied size-groups were first intermediate hosts to castrating parasites (Gymnophallus choledochus, Labratrema minimus and Monorchis parvus). Among trematodes having metacercariae in cockles (second intermediate host) Meiogymnophallus minutus was the most widespread as it was observed in all cockles from all the examined habitats in the lagoon and it occurred in record high intensities. Different sub-communities of the trematode fauna using cockles as second intermediate host could be identified (subtidal vs intertidal associations).The richness and species composition of the macroparasite community in cockles from Morocco are discussed in relation to patterns seen in cockles from other sites along their geographical range. Migratory fish and waterbirds (final hosts) are generally responsible for the large scale spread (latitudinal spread) of trematodes. However, the distributional patterns of involved intermediate hosts in the life-cycles of the different trematode species in cockles are determining the richness and species composition patterns seen in cockles at shallow water sites along the east Atlantic shoreline.
(Journal of the Marine Biological Association of the United Kingdom. vol. 88, n° 0025-3154, 01/03/2008)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The relative importance of disturbance and environmental stress at local and regional scales in French coastal sand dunes
Questions: 1. Is there a primary role of disturbance at local scale and of environmental stress at regional scale? 2. Does disturbance increase or decrease environmental stress at local scale? Location: The Atlantic coastal dune system of the Aquitaine Region (France). Methods: Species biomass and 16 environmental variables were sampled in 128 quadrats along a local beach-inland gradient and a regional North-South gradient. Environmental data were analysed with ANOVAs and vegetation-environment relationships with Canonical Correspondence Analysis. Results: At the local scale community composition was primarily driven by disturbance due to sand burial, whereas water and nutrient stress better explained regional differences. However, random biogeographical events are very likely to also affect community composition at the largest scale. The main interaction between environmental stress and disturbance was the mitigation of nutrient stress induced by disturbance at a local scale. This was due to a positive direct effect of sand burial and a positive indirect effect of wind (decrease in VPD by ocean spray). Although wind had also a significant effect on soil conductivity and pH, there was no evidence that these factors had any role in community composition. Conclusions: Our results support the hypothesis that disturbance had a primary role at local scale and environmental stress at regional scale but further research is needed to separate the effect of stress from that of dispersal at regional scale. We also demonstrated that environmental stress in primary succession may not always decline with decreasing disturbance.
(Journal of Vegetation Science. vol. 19, n° 1100-9233, pp. 493-502, 29/01/2008)
ECODIV, UNIROUEN, NU, UNINE, BioGeCo, INRA, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Evidence of former Holocene sea level in the Marennes-Oléron Bay (French Atlantic coast)
Both sedimentological and mollusc death assemblage analyses from a 14C-dated core, coupled with seismic stratigraphical analysis within the Marennes-Oléron Bay (French Atlantic coast), provide a detailed record of environmental changes during the end of the Holocene rapid sea-level rise. Lithofacies and mollusc fauna changes evidence the transition from a former intertidal bare mudflat to a subtidal environment. The newly shown former sea-level record, computed from radiocarbon-dated Scrobicularia plana shell, matches previously published local sea-level curves. This drowned mudflat belongs to an incised valley-fill that provides new insights into valley-fill successions along the French Atlantic coast.
(Comptes Rendus. Géoscience. vol. 340, n° 1631-0713, pp. 306-314, 21/01/2008)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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