Development of a multimetric approach to assess perturbation of benthic macrofauna in Zostera noltii beds
Biotic indices based on soft-bottom macrozoobenthic communities are currently used throughout Europe to assess the ecological quality of coastal and transitional water bodies according to the European Water Framework Directive. However, the performance of the currently available biotic indices still has to be tested against a variety of different impact sources. In particular, physical perturbations have received much less attention than other kind of disturbances. This study consisted in testing the capacity of currently available uni- (BOPA, AMBI and BENTIX) and multivariate (M-AMBI) Biotic Indices to assess the ecological impact of the destruction of a Zostera noltii seagrass bed in Arcachon Bay (France) following sediment deposits. Changes of habitat after this physical perturbation were hardly assessed by any of these Biotic Indices whereas analysis of the benthic community showed drastic changes of structure following the perturbation and no recovery after 15 months. This study demonstrates that these Biotic Indices must be integrated into a multimetric approach which describes better the biological integrity of the benthic community by including a complementary set of metrics. A new multimetric approach, named MISS (Macrobenthic Index of Sheltered Systems) is proposed. MISS correctly highlighted the destruction of the seagrass beds, by using 16 metrics describing the biological integrity of the macrofauna.
(Journal of Experimental Marine Biology and Ecology. vol. 368, n° 0022-0981, pp. 101-112, 31/01/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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
Sediment transport particular events and beach profile response
A field campaign was carried out as part of the ECORS project on the macro-tidal beach of Truc Vert (France, March-April 2008). Velocities, sediment concentrations and bed evolutins recorded at the mid intertidal zone are presented, covering calm (Hs~0.5m)and energetic (Hs~1m) conditions. Cross-shore transport rates were estimated using the BAILARD (1981) model for the total load transport, beach profile changes for the net transport and suspended sediment fluxes. Under energetic wave forcing the undertow was large and sediment transport was directed offshore whereas under calm conditions the undertow was weaker and sediment transport was directed onshore.
(Journal of Coastal Research, n° 0749-0208, pp. pp 1766-1770, 01/01/2009)
LCPC/EAU, LCPC, UNAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, 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
Consequences of a recent flood event on the biogeochemistry of the Rhône Delta
(10/04/2026)
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
Non parametric regression estimator: application in valvometry
(10/04/2026)
LMBA, UBS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Comparaison d'estimateurs de régression non paramétriques : application en valvométrie,
(10/04/2026)
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, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS, UPPA
Etude expérimentale de la célérité des vagues en zone de surf
L'estimation de la célérité des vagues en zone de surf est une étape essentielle dans la modélisation de la circulation littorale. Nous présentons une étude de ce paramètre basée sur les données de la campagne de mesure internationale ECORS 2008. En particulier, nous analysons, pour des houles très energétiques, l'influence des non-linéarités et évaluons plusieurs modèles prédictifs de célérité. Enfin, nous discutons l'influence des pulsations très basse-fréquence de la circulation sur la célérité.
(10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS