Distance decay of similarity among parasite communities of three marine invertebrate hosts
The similarity in species composition between two communities generally decays as a function of increasing distance between them. Parasite communities in vertebrate definitive hosts follow this pattern but the respective relationship in intermediate invertebrate hosts of parasites with complex life cycles is unknown. In intermediate hosts, parasite communities are affected not only by the varying vagility of their definitive hosts (dispersing infective propagules) but also by the necessary coincidence of all their hosts in environmentally suitable localities. As intermediate hosts often hardly move they do not contribute to parasite dispersal. Hence, their parasite assemblages may decrease faster in similarity with increasing distance than those in highly mobile vertebrate definitive hosts. We use published field survey data to investigate distance decay of similarity in trematode communities from three prominent coastal molluscs of the Eastern North-Atlantic: the gastropods Littorina littorea and Hydrobia ulvae, and the bivalve Cerastoderma edule. We found that the similarity of trematode communities in all three hosts decayed with distance, independently of local sampling effort, and whether or not the parasites used the mollusc as first or second intermediate host in their life cycle. In H. ulvae, the halving distance (i.e. the distance that halves the similarity from its initial similarity at 1 km distance) for the trematode species using birds as definitive hosts was approximately two to three times larger than for species using fish. The initial similarities (estimated at 1 km distance) among trematode communities were relatively higher, whereas mean halving distances were lower, compared to published values for parasite communities in vertebrate hosts. We conclude that the vagility of definitive hosts accounts for a high similarity at the local scale, while the strong decay of similarity across regions is a consequence of the low probability that all necessary hosts and suitable environmental conditions coincide on a large scale.
(Oecologia. vol. 160, n° 0029-8549, pp. 163-173, 01/01/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
At environmental doses, dietary methylmercury inhibits mitochondrial energy metabolism in skeletal muscles of the zebra fish (Danio rerio).
The neurotoxic compound methylmercury (MeHg) is a commonly encountered pollutant in the environment, and constitutes a hazard for human health through fish eating. To study the impact of MeHg on mitochondrial structure and function, we contaminated the model fish species Danio rerio with food containing 13 μg of MeHg per gram, an environmentally relevant dose. Mitochondria from contaminated zebrafish muscles presented structural abnormalities under electron microscopy observation. In permeabilized muscle fibers, we observed, a strong inhibition of both state 3 mitochondrial respiration and functionally isolated maximal cytochrome c oxidase (COX) activity after 49 days of MeHg exposure. However, the state 4 respiratory rate remained essentially unchanged. This suggested a defect at the level of ATP synthesis. Accordingly, we measured a dramatic decrease in the rate of ATP release by skinned muscle fibers using either pyruvate and malate or succinate as respiratory substrates. However, the amount and the assembly of the ATP synthase were identical in both control and contaminated muscle mitochondrial fractions. This suggests that MeHg induced a decoupling of mitochondrial oxidative phosphorylation in the skeletal muscle of zebrafish. Western blot analysis showed a 30% decrease of COX subunit IV levels, a 50% increase of ATP synthase subunit α, and a 40% increase of the succinate dehydrogenase Fe/S protein subunit in the contaminated muscles. This was confirmed by the analysis of gene expression levels, using RT-PCR. Our study provides a basis for further analysis of the deleterious effect of MeHg on fish health via mitochondrial impairment.
(International Journal of Biochemistry and Cell Biology. vol. 41, n° 1357-2725, pp. 791-799, 01/01/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, U1211 INSERM/MRGM, UB, INSERM, IBGC, UB, CNRS
Treatment of topographic and bathymetric data acquired at the Truc-Vert Beach during the ECORS Field Experiment
The aim of this paper is to present the topographic and bathymetric surveys acquired during the international ECORS mission (March-April 2008) at Truc Vert Beach, SW of France. Topographic surveys have been done with an accuracy of about 2.5cm in the horizontal directions and 3cm for the elevation. Using both a GPS kinematics (by foot or implemented on a quad) and a theodolite, an area extending from the dune to the nearshore region was covered. In this paper, we present the methods developed in order to merge the different dataset. The acquisition and treatment of this large dataset was made possible thanks to the coordination of a large work force available on the field comprising numerous international institutions. From this work, together with the lower sample rate topographic data gathered over the last 10 years, Truc Vert Beach is the most documented beach of the French Coast.
(Journal of Coastal Research. vol. II, n° 0749-0208, pp. 1786-1790, 01/01/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGEM, UPVD, UPVD, SHOM, BRGM, LAB, UB, INSU - CNRS, CNRS
Morphodynamic response of a meso- to macro-tidal intermediate beach based on a long-term data set
Four years of bi-monthly topographic surveys have been conducted on a 350 m stretch of the meso- to macro-tidal Truc Vert beach, France. Here we study the dynamics of both the inner bar and the upper part of the beach where a berm can develop in the presence of fair weather conditions. For the inner bar, the occurrences of the different states within the intermediate classification, following that of Wright and Short (Wright, L.D., Short, A.D. 1984. Morphodynamic variability of surf zones and beaches: a synthesis. Marine Geology 56, 93–118), are presented and compared to other sites in both micro- and meso-tidal environments. The results show a similar frequency of occurrence of the Transverse Bar and Rip (TBR) state, while the more dissipative states, Rhythmic Bar and Beach (RBB) and Longshore Bar and Trough (LBT), are less regularly observed despite the high wave energy levels. The LBT and RBB states are also observed in the presence of fair weather conditions and the TBR state can persist during very energetic events. Similar results are also observed with the upper beach dynamics. Very energetic events are not necessarily associated with erosion while and low-energy events are not necessarily accompanied by accretion. The conditions given here indicate, that berm development occurs preferentially when the beach morphology exhibits a TBR or a LTT state. Apart from the control exerted by offshore wave conditions, the beach state and berm development patterns exhibited by Truc Vert beach are also discussed within the framework of possible morphological (morphodynamic) feedback and of the influence of the meso- to macrotidal range which modulates the type, intensity and duration of the wave processes operating on the cross-shore profile.
(Geomorphology. vol. 107, n° 0169-555X, pp. 263 - 274, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGN, UN, CNRS
Very Low Frequency motions of a rip current system: observations and modeling
(Journal of Coastal Research, n° 0749-0208, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Holocene glacier and deep water dynamics, Adélie Land region, East Antarctica
This study presents a high-resolution multi-proxy investigation of sediment core MD03-2601 and documents major glacier oscillations and deep water activity during the Holocene in the Ade ´lie Land region, East Antarctica. A comparison with surface ocean conditions reveals synchronous changes of glaciers, sea ice and deep water formation at Milankovitch and sub-Milankovitch time scales. We report (1) a deglaciation of the Ade ´lie Land continental shelf from 11 to 8.5 cal ka BP, which occurred in two phases of effective glacier grounding-line retreat at 10.6 and 9 cal ka BP, associated with active deep water formation; (2) a rapid glacier and sea ice readvance centred around 7.7 cal ka BP; and (3) five rapid expansions of the glacier-sea ice systems, during the Mid to Late Holocene, associated to a long-term increase of deep water formation. At Milankovich time scales, we show that the precessionnal component of insolation at high and low latitudes explains the major trend of the glacier-sea ice-ocean system throughout the Holocene, in the Ade ´lie Land region. In addition, the orbitally-forced seasonality seems to control the coastal deep water formation via the sea ice-ocean coupling, which could lead to opposite patterns between north and south high latitudes during the Mid to Late Holocene. At sub-Milankovitch time scales, there are eight events of glacier-sea ice retreat and expansion that occurred during atmospheric cooling events over East Antarctica. Comparisons of our results with other peri-Antarctic records and model simulations from high southern latitudes may suggest that our interpretation on glacier-sea ice-ocean interactions and their Holocene evolutions reflect a more global Antarctic Holocene pattern.
(Quaternary Science Reviews. vol. 28, n° 0277-3791, pp. 1291 - 1303, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VU, FRE 2255
Non parametric regression estimator: application in valvometry
(28/05/2026)
LMBA, UBS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Comparaison d'estimateurs de régression non paramétriques : application en valvométrie,
(28/05/2026)
LMBA, UBS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Impact of cadmium on aquatic bird Cairina moschata
The impact on palmiped Cairina moschata of two levels of dietary cadmium (Cd) contamination (C1: 1 mg kg-1 and C10: 10 mg kg-1) was investigated on liver gene expression by real-time PCR. Genes involved in mitochondrial metabolism, in antioxidant defences, detoxification and in DNA damage repair were studied. Metallothionein (MT) protein levels and Cd bioaccumulation were also investigated in liver, kidneys and muscle. Male ducks were subjected to three periods of exposure: 10, 20 and 40 days. Cd was mainly bioaccumulated in kidneys first and in liver. The concentrations in liver and kidneys appeared to reach a stable level at 20 days of contamination even if the concentrations in muscle still increased. Cd triggered the enhancement of mitochon-drial metabolism, the establishment of antioxidant defences (superoxide dismutase Mn and Cu/Zn; catalase) and of DNA repair from 20 days of contamination. Discrepancies were observed in liver between MT protein levels and MT gene up-regulation. MT gene expression appeared to be a late hour biomarker.
(BioMetals. vol. 22, n° 0966-0844, pp. 843-853, 28/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS, UPPA
Consequences of a recent flood event on the biogeochemistry of the Rhône Delta
(28/05/2026)
EDF R&D STEP, EDF R&D, EDF [E.D.F.], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGN, UN, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS