Parasite co-infection of two sympatric bivalves, the Manila clam (Ruditapes philippinarum) and the cockle (Cerastoderma edule) along a latitudinal gradient
Among the potential biotic factors affecting population dynamics, parasitism has received relatively little attention. The purpose of this study was to inventory marine bivalve parasites and to investigate relations between different parasite communities. Five intertidal stations along the French Atlantic shore were studied between Brittany and Arcachon Bay. Two bivalves (the edible cockle, Cerastoderma edule, and the Manila clam, Ruditapes philippinarum) were sampled and examined. The parasites included a bacterium (Vibrio tapetis), a protozoan (Perkinsus sp.), and digenetic trematode metacercariae (10 species). Perkinsus sp. prevalence and density in clams were higher than those measured in cockles (30 250 vs. 36 cells g−1 of gill wet weight, respectively) while digeneans were more common in cockles (46 metacercariae per cockle host vs. 1 per clam host). Distributions of digeneans and Perkinsus sp. were similar along the Atlantic shore. However, at each sampling station and at the individual scale, no correlation between Perkinsus sp. and digenean abundance was detected. These results suggest different ecological niches used by these two parasites within a community of bivalves but a similar response to environmental factors such as temperature and salinity. Vibrio tapetis was found at relatively high prevalence in all stations for both bivalve species (from 17% to 43% in cockles and from 23% to 50% in clams), but was associated with a low prevalence of Brown Ring Disease (BRD), a shell disease caused by this pathogen. No statistically significant relationship of these parasitic bacteria with trematodes and Perkinsus sp. was evidenced in the present study.
(Aquatic Living Resources. vol. 20, n° 0990-7440, pp. 33-42, 26/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Sedimentary processes in the Thau Lagoon (France): From seasonal to century time scales
As a part of the MICROBENT programme, an investigation of the sedimentation framework was carried out at the water-sediment interface in the Thau Lagoon (French Mediterranean coast). Two main sites, C4 in the middle of the lagoon and C5 near oyster farms, were visited six times between December 2001 and May 2003. Interface sediments were studied using classical sedimentology parameters (radiography RX, grain size distribution) and analysis of selected radionuclides (234Th, 7Be, 210Pb, 226Ra). On a century time scale, excess 210Pb (210Pbxs) presents classical profiles with an upper mixed layer, followed by an exponential decrease of activities to undetectable levels below 20 - 30 cm. At the central site, C4, cores seem to register episodic changes in mean grain size, presenting recurrently peaks. The upper 10 cm of 210Pbxs profiles at site C5 exhibit a mixed layer associated with coarser sediments: this could be related to biological activity. Sedimentation rates derived from 210Pbxs varied from 0.15 cm y−1 at the edge of the basin, to 0.25 cm y−1 at the central site. On a seasonal time scale, 234Th and 7Be both show significant variations in activities and in penetration within the sediment. Bioturbation rates derived from both radionuclides agree well and range between 1-10 cm2 y−1 at site C4 and 1-31 cm2 y−1 at site C5. 234Th and 7Be fluxes at the water-sediment interface show too seasonal variations, more pronounced for site C5. This latter site presents especially a higher variability that is well marked with season, probably in relation with its position near oyster farms.
(Estuarine, Coastal and Shelf Science. vol. 72, n° 0272-7714, pp. 534-542, 26/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, LMGEM, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS
Impairment of lipid storage by cadmium in the European eel (Anguilla anguilla)
Because European silver eels (Anguilla anguilla) fast during their reproductive migration to the Sargasso Sea, the successful completion of their unusual life cycle depends on quantity of lipids stored beforehand. These lipids are mainly accumulated during the growth phase stage of the animals, called yellow eel, as triglycerides in muscle. They are then catabolized to provide sufficient energy to enable migration, gonad maturation and spawning. In the laboratory, we investigated the possible impact of cadmium on the lipid storage efficiency of yellow eels in order to evaluate the possible contribution of this pollutant to the reported decline of European eel populations. Eels were exposed to dissolved cadmium at nominal concentrations of 0 and 5 µg.L-1 for one month. Cd toxicity was then examined by studying the activity and expression level of several enzymes involved in liver lipolysis and lipogenesis and by determining lipid content in muscle. Contaminated eels showed a lower body weight growth with a lower efficiency of lipid storage compared to controls. Using two complementary approaches, genetic and enzymatic, it was possible to conclude that this impairment is mainly explained by an increased utilisation of triglycerides since cadmium contamination did not trigger a reduced fatty acid synthesis. These observations suggest an increased fat consumption in presence of cadmium, which could compromise successful reproduction.
(Aquatic Toxicology. vol. 81, n° 0166-445X, pp. 304-311, 26/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IBGC, UB, CNRS, UR EPBX, CEMAGREF
Silicic acid dynamics in the glacial sub-Antarctic: Implications for the silicic acid leakage hypothesis
The silicic acid leakage hypothesis (SALH) purports that changes in silicon and nitrogen depletion ratios in the glacial Antarctic created a large pool of unused silicic acid that was transported to lower latitudes in subantarctic mode water (SAMW) where it enhanced diatom productivity lowering atmospheric pCO 2. However, increased opal accumulation beneath the sub-Antarctic during glacial times implies significant consumption of silicic acid in subantarctic surface waters that may have significantly diminished or eliminated Si leakage. To test how nutrient dynamics in the sub-Antarctic affected the Si(OH) 4 content of SAMW during the last glacial period, we produced d 30 Si opal records for cores from the subantarctic and subtropical zones of the Indian Ocean spanning the last 50,000 years. Comparison with diatom-bound d 15 N records shows that subantarctic surface waters were enriched in Si relative to N during the last glaciation consistent with the SALH. The record from the subtropics does not show this enrichment in Si during the last glacial period suggesting that subantarctic surface waters were mainly incorporated into SAMW rather than being transported across the Subtropical Front. Isotope mass balance calculations were used to test for Si leakage from the sub-Antarctic. The results show that silicic acid concentration in SAMW would more than double during the last glaciation if upwelling and northward Ekman drift in the Antarctic were similar to the present-day circulation. Calculations that assume increased stratification in the glacial Antarctic eliminate Si leakage, but they do not produce the known increase in opal burial in the glacial sub-Antarctic. Reconciling the isotope data and opal burial records with a highly stratified Antarctic requires the addition of a large local source of silicic acid in the glacial sub-Antarctic that is inconsistent with present-day circulation and nutrient distributions. Including such a source in our calculations results in significant opal burial in the sub-Antarctic, but it does not enhance Si leakage over that occurring in the Holocene. Resolving past changes in the circulation of the Southern Ocean is clearly vital to future tests of the SALH.
(Global Biogeochemical Cycles. vol. 21, n° 0886-6236, pp. GB3015, 26/08/2026)
LEMAR, IRD, IFREMER, UBO EPE, CNRS, MSI, UC Santa Barbara - UCSB, UC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Messinian palaeoenvironments and hydrology in Sicily (Italy): The dinoflagellate cyst record
Hydrological conditions prevailing before, during and after the Messinian salinity crisis in Sicily have been approached using dinoflagellate cyst records. The synthetic sequence considered is based on five classical sections from the Caltanissetta Basin. Our interpretations are based on the recognition of autochthonous, allochthonous and reworked population among the dinocyst assemblages. For the first time, sea-surface temperatures and seasonal salinity contrastswere tentatively reconstructed using a ‘‘Mutual Climatic RangeMethod''. Sicilian lateTortonian deposits correspond to marine environment with significant terrestrial inputs favourable to eutrophic dinocyst species. Immediately after the beginning of the Messinian Stage, euryhaline assemblages took place, followed bymeso-hyperhaline taxa,within a general trend to shallowing.At the end of the Tripoli diatomitic Formation, environment appears confined, with regular oceanic inflows. Such marine inflows remain persistent during the deposition of the salt Member, witnessing the probable persistence of nearby normal marine sea-surface water conditions in the Mediterranean Sea but with possible reduced hydrological circulation and/or lownutrient component. Such inflows are slightly decreasing up to the top of the Sicilian Upper Evaporites. At the same time, river inputs appearweak during the salt deposition, as the consequence of a rather dry climatic context.As shown by reworking activity, terrestrial inputs increase progressively fromthe base of the Upper Evaporites.During the Lago Mare period,while climate remains rather dry (absence of freshwater algae inputs, very low amount in trees requiring humid conditions), local deposition environment is confined with mesohaline to hypohaline sea-surfacewaters, in a context with relatively high seasonal sea-surface salinity contrast (up to 6%). The very high reworking observed in the Arenazzolo silts, in addition to slightly increasing water depth, led us to consider the presence of a discontinuity between the Lago Mare and the Arenazzolo Fms.We consider the Arenazzolo Formation as a transgressive facies following a deep downcutting period. The Arenazzolo Formation presents a two-step development. The first one, correlative with the presence of a G. etrusca (a species with Paratethyan affinities), corresponds to a relative high-stand sea-level with oceanic influxes, low seasonal sea-surface salinity contrast and probable more humid context, as revealed by the important freshwater algal inputs. During the second step, salinity becomes much more variable, with a clear increase of seasonal sea-surface salinity contrast, a possible slight mean sea-surface temperature increase (only few degrees) and a clear weakening of the river inputs. Taking the proposed Zanclean position of the Arenazzolo Fm. into consideration, we state that mean sea-surface temperature did not change significantly fromthe base of the Messinian to the earliest Zanclean. At 5.33 Ma, the suddenly achieved flooding restored a fair, deep oceanic environment characterized, at the beginning, by a clear mean sea-surface temperature cooling (up to 6–7°C) and a nutrient depletion, associated with the basins starvation. Sea-surface salinitieswere normal, with very lowseasonal contrast. Hydrodynamics then nutrient supply became then quite normal fromc.a. 5.08 Ma.The status of the SicilianCaltanissettaBasin as amarginal basin although fastly deepening and the stratigraphical location of the Messinian discontinuity at the base of the Arenazzolo is the scenario that best matches our dinocyst record.
(Geobios. vol. 40, n° 0016-6995, pp. 233-250, 26/08/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UM5, PEPS, UCBL, INSU - CNRS, CNRS
Vegetation dynamics in southern France during the last 30 ky BP in the light of marine palynology
The composition of the glacial vegetation of southern French plains has been a matter of debate for several decades. Vegetation is considered as steppic according to French and Spanish lacustrine pollen records whereas cave deposits suggest the presence of mesothermophilous trees through the Last Glacial Maximum. In our paper, we display new palynological records from marine sediments of the Gulf of Lions. They indicate the presence of Abies, Picea and deciduous Quercus in the Gulf of Lions, certainly located in the drainage basins of the Pyreneo-Languedocian rivers. These populations that were sensitive to short climatic events during Marine Isotopic Stage 2 could have been linked to northeastern Spanish and southeastern French relicts already evidenced by phylogenetic data. These trees were absent from the Rhone drainage basin during the deglaciation and certainly also disappeared from the Pyreneo- Languedocian drainage basins from ca 17 to 15 ky cal BP. Finally, the Last Glacial Maximum does not appear as stable, cold and dry as previously thought.
(Quaternary Science Reviews. vol. 26, n° 0277-3791, pp. 1037-1054, 26/08/2026)
PEPS, UCBL, INSU - CNRS, CNRS, SYSU, LDO, INSU - CNRS, UBO EPE, CNRS, GM, IFREMER
Processus sédimentaires et activité de la Veine d'Eau Méditerranéenne au cours du Quaternaire terminal dans le Golfe de Cadix
Cette thèse représente une étude pluridisciplinaire des dépôts actuels et anciens dans la partie orientale du Golfe de Cadix afin d'améliorer la compréhension de la dynamique de la MOW et de caractériser les forçages à l'origine des variations sédimentaires observées depuis le Pléistocène terminal. Le schéma de circulation actuel est parfaitement conforme à la distribution des faciès sédimentaires et montre l'omniprésence des cicatrices de glissement. La morphologie du fond marin et la force de Coriolis exercent un contrôle important sur l'orientation et l'intensité des différentes branches de la MOW. La diminution de la vitesse et de la compétence de cet écoulement vers l'Ouest s'accompagne d'une diminution de la granularité des dépôts. L'étude chronostratigraphique et sismique permet de contraindre dans le temps et l'espace la mise en place des séquences contouritiques. Le climat est un facteur de contrôle majeur de la sédimentation des 50 000 dernières années. Associées aux fluctuations climatiques hautes fréquences, les variations glacio-eustatiques apparaissent responsables du changement important des conditions de sédimentation mis en évidence dès l'entrée dans l'interglaciaire actuel. Enfin, la mise en place polyphasée des systèmes chenal-lobes situés au débouché des chenaux contouritiques montre l'interaction entre les processus contouritiques et les processus gravitaires. L'activité de ces systèmes paraît contrôlée par la MOW, la morphologie du fond et les changements climatiques ayant affecté le Quaternaire terminal.
(19/12/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Shoreface migrations at the shelf edge and sea-level changes around the Last Glacial Maximum (Gulf of Lions, NW Mediterranean)
The Bourcart–Hérault canyon interfluve in the Gulf of Lions (NW Mediterranean) was the site of very high sedimentation (up to 2.5 m/kyr) around the Last Glacial Maximum, due to the vicinity of major fluvial systems that fed the shelf edge. Shoreface deposits and offshore muds deposited during each glacial/interglacial 100 kyr-cycle, created a repeated motif with high-angle and low-angle clinoforms on seismic profiles. New detailed morphological, sedimentological and paleo-environmental data, constrained by 14C dating, allow us to propose a scenario for the evolution of this critical area between 46 and 15 cal. kyr BP. The major seismic sequence (S5), formed as a forced regression during the overall sea-level fall between MIS-3 and MIS-2, can be sub-divided into several prograding units, which indicate that relative sea-level changes were punctuated by intervals of increased fall or slow-down, or even stillstand. Similarly, the onset of sea-level rise was marked by steps, during which wave-cut terraces formed, and can be tracked all around the Gulf of Lions. Three stillstands or slow-downs of sea-level change are identified and dated by deposits found at 90 m relative sea-level (21 cal. kyr BP), 110–115 m rsl (18–17 cal. kyr BP), and 98–105 m rsl (before 15.9 cal. kyr BP). Cementation of beach rocks, that now form eroded pinnacles culminating at 90 m, occurred during the 21 kyr stillstand. The position of relative sea-level during the maximum lowstand is not known, but should be deeper than 115 m. Periods of increased northwesterly winds favoured transport of coarser sediment at the shelf edge, in relation with deep water cascading: this created a distinct sandy interval during the period of Heinrich event 2 (around 24 cal. kyr BP), at the origin of amplitude anomaly on very high-resolution seismic data. The increased sea-level rise, around 15 cal. kyr BP, resulted in an abrupt decrease of sedimentation.
(Marine Geology. vol. 234, n° 0025-3227, pp. 21-42, 06/12/2006)
LDO, INSU - CNRS, UBO EPE, CNRS, GM, IFREMER, PEPS, UCBL, INSU - CNRS, CNRS, ISMAR, ISMAR, CNR
The impact of the last European deglaciation on the deep-sea turbidite systems of the Celtic-Armorican margin (Bay of Biscay)
(Geo-Marine Letters. vol. 26, n° 0276-0460, pp. 317-329, 22/11/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
The genome of the sea urchin Strongylocentrotus purpuratus.
We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
(Science. vol. 314, n° 0036-8075, pp. 941-52, 10/11/2006)
SBU, SUNY, AU, QMUL, CSIRO, CSIRO Energy Technology, CSIRO, MI, CATS, LSE, Jefferson Lab, LEMTA, UL, CNRS, LEGS, CNRS, UIUC, ECE, PSU, IAH, BBSRC, CAS, Ipsen, UC Berkeley, UC, ICAS, SEE, CAU, ACE-CRC, AER, TUM, MS, SBR, UPMC, CNRS, UPMC, CNRS, NPL, IRI, CAM, PCU, IMM, CNR, LAUM, UM, CNRS, ISL, CMU, DICP, CAS, ALCHEMY, LRI, UP11, CNRS, Inria, CATF, ISRO, CERAG, UPMF, CNRS, SQU, EMBL, UMich, Radonc, UMich, UVIC, LPL, AMU, CNRS, ISCR, UR, INSA Rennes, INSA, ENSCR, INC-CNRS, CNRS, SIE, USTB, LASP, SoMaS, LML, CNRS, CSD, UCLA, UC, DE, UP11, CNRS, LBDV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, CNRS, LPA, FRDPENS, ENS-PSL, PSL, CNRS, UPMC, UPD7, CNRS, CRUB, UNCOMA, BECP, UJF, CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IJM (UMR_7592), UPD7, CNRS, LNS, INFN, UAB, UAB, IOCAS, CAS, NCTU, HWR, SKL-NPT, ARC, DICORA, HUFS, RAL Space, RAL, STFC, IBCP, UCBL, CNRS, HMNAO, RAL, STFC, UCL, UCLA, UC, SEES, SNU, MMC, NTU, RQMP, EPM, UdeS, UdeM, FQRNT, UdeM, SEE, UKCEH, NERC, NIVA