IUEM

Plouzané, France
Plouzané, France
SEARCH FILTERS
Time filter
Source Type

Tarits P.,IUEM | Hautot S.,IMAGIR Sarl | Roach P.,Oyster Oil and Gas Ltd | Magareh H.M.,CERD Djibouti
SEG Technical Program Expanded Abstracts | Year: 2015

We present an application of joint inversion techniques to model gravity data. The intrinsic non uniqueness of gravity fields to retrieve density distribution implies that a priori information be introduced in the modeling or inversion. Here the information is introduced explicitly in the form of geometrical constraints brought by magnetotelluric (MT). While there is no obvious reason to correlate one to one electrical resistivity and density values, there may be geological clues to expect similar resistivity and density features. We used a stochastic correlation technique through cross gradient modeling to provide the required constraints to obtain a distribution of density values associated with resistivity features. The approach is tested on field data from the Republic of Djibouti. © 2015 SEG.


Hooper C.,University of Melbourne | Day R.,University of Melbourne | Slocombe R.,Veterinary Clinical Center | Benkendorff K.,Southern Cross University of Australia | And 2 more authors.
Aquaculture | Year: 2014

High summer temperatures are one of the most stressful environmental problems confronted by the abalone mariculture industry and are commonly associated with outbreaks of infectious disease. We tested the effect of extreme but non-lethal elevated temperatures on abalone immunology, biochemistry and quantitative histology. We subsequently compared the haemolymph results to the histology to gain increased understanding of how heat stress impacts abalone health. Abalone were kept in water that was heated from the ambient 16. °C temperature to 26. °C within 5. h and then held at 26. °C for one week to determine the effects of this acute heat stress on the day of temperature elevation and whether there was acclimatization or deterioration 2 and 7. days later. Antibacterial activity, phenoloxidase activity and neutral red retention times declined significantly with heat and did not recover. The total haemocyte count was elevated significantly during heat stress and was highest on day 1. The phagocytic rate was elevated on day 1 but had recovered by the following day. Acid phosphatase activity, leucine aminopeptidase, haemolymph protein and haemolymph electrolytes (calcium, phosphate, magnesium, sodium, and chloride) were not significantly affected by heat stress. This indicates that severe heat stress causes changes in some, but not all haemolymph parameters. The sublethal immunologic effects seen in haemolymph samples occurred concurrently with histological changes. The digestive gland had significantly increased haemocyte infiltrates in heat stressed abalone. Heat stressed abalone had significantly greater loss of epithelium lining from the gills, with no recovery. The gill goblet cell numbers declined significantly on day 2 and had recovered by day 7. There was no significant change in the volume of fluid or protein concentration of the haemolymph in the gill sinuses between treatment groups. These results indicate that immunosuppression and organ damage are likely to be involved in the increased incidence of bacterial disease reported by abalone farmers during summer. © 2014 Elsevier B.V.


Suquet M.,French Research Institute for Exploitation of the Sea | Le Mercier A.,IUEM | Rimond F.,French Research Institute for Exploitation of the Sea | Mingant C.,French Research Institute for Exploitation of the Sea | And 2 more authors.
Theriogenology | Year: 2012

Parameters used to assess the survival of larvae after cryopreservation generally misestimate the damages that prevent larval development. The objectives of the present study were to 1) define the reliability of the survival rate, assessed at 2 and 7 days post fertilization, to estimate Pacific oyster larval quality after thawing, and 2) select complementary tools allowing an early and reliable estimation of their quality. Oyster larvae were reared for 25 h after fertilization at 19 °C and cryopreserved at early D-stage. Then, thawed larvae were incubated in 2-L beakers. At 2 days post fertilization, the survival rate of thawed Pacific oyster larvae was lower than that of fresh larvae for only one experiment (Experiment 3) among the four identical experiments carried out in this work (Experiments 1-4). By contrast, the survival of thawed larvae, as assessed 7 days after fertilization, was lower than that of fresh larvae for the four experiments. These results confirm that the quality of thawed larvae is lower than that of fresh larvae and that the survival rate, estimated 2 days post fertilization, is not adapted to a reliable estimation of the subsequent development ability of thawed larvae. Then, complementary parameters were tested at 2 days: the movement characteristics (Experiments 1 and 2) and the morphologic features (Experiments 3 and 4) of thawed larvae. Compared to values observed on fresh larvae, the percentage of thawed motile larvae was different for only one experiment (Experiment 2) of the two. Compared to control, a reduced Average Path Velocity (VAP) of larvae (determined at the D-larval stage using a CASA-Computer Assisted Sperm Analysis-system) was observed after thawing for both experiments (Experiments 1 and 2), suggesting the ability of larval movement velocity to assess the decrease of the quality of thawed oyster larvae. Using an ASMA (Automated Sperm Morphology Analysis) device, a lower area of thawed larvae was observed, compared to control and for the two experiments (Experiments 3 and 4). By contrast, the Crofton perimeter of thawed larvae was lower than that of control larvae for only one experiment (Experiment 3) and no significant difference of circularity between fresh and thawed larvae was recorded for Experiments 3 and 4. In conclusion, changes in the movement velocity (assessed by CASA) and in the area (measured by ASMA) of D-larvae allow an early and reliable estimation of the quality of thawed Pacific oyster larvae. © 2012 Elsevier Inc.


Trinkler N.,IUEM | Labonne M.,Center Bretagne | Marin F.,University of Burgundy | Jolivet A.,French Research Institute for Exploitation of the Sea | And 4 more authors.
Analytical and Bioanalytical Chemistry | Year: 2010

Since 1987, the Manila clam Ruditapes philippinarum has been regularly affected by the brown ring disease (BRD), an epizootic caused by the bacterium Vibrio tapetis. This disease is characterized by the development of a brown deposit on the inner face of valves. While most of the clams die from the BRD infection, some of them are able to recover by mineralizing a new repair shell layer, which covers the brown deposit by a process of encapsulation. The purpose of this work was to study the organic matrix of the shells of Manila clams in the inner shell layer before, during and after the brown deposit and during the shell repair process by confocal Raman micro-spectrometry and wavelength dispersive spectrometry (WDS) microprobe. In addition, the organic matrix of the repaired shell layer was extracted and quantified, by using standard biochemical shell matrix extractions protocols. The brown deposit exhibited high luminescence intensity in Raman spectra, and an increase of S, C, Sr (forming two peaks) and a decrease of Ca, Na concentrations (% w/w), using WDS microprobe mapping and cross-sectional transects. The signature of these trace elements was similar to that recorded on periostracal lamina (% w/w). The high S concentration likely corresponds to the presence of a high amount of sulfated organic compounds. Interestingly, on cross-sectional transects, before the brown deposit, a thin layer of the shell showed also a high luminescence, which may suggest that this layer is modified by bacteria. After the brown deposit, at the beginning of the shell repair process, the luminescence and the S concentration remain high, before declining the level found in non-BRD-affected shells. Quantification of the organic matrix shows that the shell repair layer zone is significantly different from non-BRD-affected shell layer, in particular with a much higher amount of insoluble matrix. © 2009 Springer-Verlag.


Hamelin C.,I.U.E.M. | Dosso L.,CNRS Oceanic Domains Laboratory | Hanan B.B.,San Diego State University | Moreira M.,CNRS Paris Institute of Global Physics | And 2 more authors.
Earth and Planetary Science Letters | Year: 2011

Samples collected during the PACANTARCTIC 2 cruise fill a sampling gap from 53° to 41° S along the Pacific Antarctic Ridge (PAR). Analysis of Sr, Nd, Pb, Hf, and He isotope compositions of these new samples is shown together with published data from 66°S to 53°S and from the EPR. The recent advance in analytical mass spectrometry techniques generates a spectacular increase in the number of multidimensional isotopic data for oceanic basalts. Working with such multidimensional datasets generates a new approach for the data interpretation, preferably based on statistical analysis techniques.Principal Component Analysis (PCA) is a powerful mathematical tool to study this type of datasets. The purpose of PCA is to reduce the number of dimensions by keeping only those characteristics that contribute most to its variance. Using this technique, it becomes possible to have a statistical picture of the geochemical variations along the entire Pacific Ridge from 70°S to 10°S. The incomplete sampling of the ridge led previously to the identification of a large-scale division of the south Pacific mantle at the latitude of Easter Island. The PCA method applied here to the completed dataset reveals a different geochemical profile. Along the Pacific Ridge, a large-scale bell-shaped variation with an extremum at about 38°S of latitude is interpreted as a progressive change in the geochemical characteristics of the depleted matrix of the mantle. This Pacific Isotopic Bump (PIB) is also noticeable in the He isotopic ratio along-axis variation. The linear correlation observed between He and heavy radiogenic isotopes, together with the result of the PCA calculation, suggests that the large-scale variation is unrelated to the plume-ridge interactions in the area and should rather be attributed to the partial melting of a marble-cake assemblage. © 2010 Elsevier B.V.


Paquet F.,University of Southern Brittany | Paquet F.,Bureau de Recherches Géologiques et Minières | Menier D.,University of Southern Brittany | Estournes G.,University of Southern Brittany | And 3 more authors.
Marine Geology | Year: 2010

High-resolution seismic data have been acquired in June 2008 on the Armorican Shelf (AS), in the northern Bay of Biscay, in order to reassess its stratigraphic architecture in detail and to study the impact of eustasy, tectonic and sediment delivery on the margin sedimentary record. Several profiles show fluvial-type incisions of several tens of meters (up to 54 m) associated to a widespread erosion surface. Several hypotheses are proposed for the stratigraphic position of this surface and incisions. We suggest Middle to Late Miocene age. Considering the relatively quiescent tectonic activity of the margin, we infer that the relative sea-level fall responsible of aerial incision on the Miocene shelf is eustasy-related. We propose the attested Serravallian-Tortonian eustatic lowstand (c. 11.6 Ma) as the key event responsible of such erosion and incision. This event marks the early beginning of the high-amplitude sea-level fluctuations that culminated during the Pleistocene and significantly controlled the present day AS morphology. The variability of vertical incision observed along single reaches can be explained by the confluence of several tributaries, the sinuosity of the channel and can be amplified by the unconsolidated nature of the Miocene substratum. The main pathways of the fluvial network corresponding to these buried valleys have been reconstructed and connections to other existing networks are proposed. © 2009 Elsevier B.V. All rights reserved.


Ritt B.,Institute Carnot Ifremer EDROME | Ritt B.,Temple University | Desbruyeres D.,Institute Carnot Ifremer EDROME | Caprais J.-C.,Institute Carnot Ifremer EDROME | And 5 more authors.
Marine Ecology Progress Series | Year: 2012

The Mediterranean Sea constitutes a unique environment to study cold-seep ecosystems due to the presence of different geodynamic settings, from an active margin along the Mediterranean Ridge (MR) to a passive margin in the Nile Deep-Sea Fan (NDSF). We attempted to identify the structure of benthic communities associated with the Napoli and Amsterdam mud volcanoes (MVs) located on the MR and to establish the links between faunal distribution and environmental conditions at different spatial scales. Comparison between the 2 MVs revealed that the faunal distribution seemed to be mainly controlled by the characteristics of the microhabitats. On both geological structures, the variability between the different microhabitats was higher than the variability observed between replicates of the same microhabitat, and the distribution of macrofauna was apparently linked to gradients in physico-chemical conditions. The peripheral sites from Napoli were generally more oxygenated and harboured lower species richness than the active sites. The reduced sediment microhabitat from Amsterdam presented the highest methane concentrations and was mainly colonised by symbiont-bearing vesicomyid bivalves and heterotrophic dorvilleid polychaetes. Overall, a higher taxonomic diversity was observed on Napoli. Substratum type was hypothesised to be the second factor influencing faunal distribution. The results of this study highlight the high heterogeneity of faunal communities associated with seep ecosystems within this region and the need to pursue investigations at various spatial and temporal scales. © Inter-Research 2012.


Hautot S.,IMAGIR sarl | Tarits P.,IUEM
1st EAGE Eastern Africa Petroleum Geoscience Forum - Sharing Lessons Learned: What's Next? | Year: 2015

The East African Rift region has a strong potential in oil&gas resources and is being under exploration in several areas. Complex geology, large volcanic provinces and remoteness make the exploration difficult and expensive. In the EAR, the basins are generally complicated geological structures because of active magmatism and control by tectonic directions inherited from syn-rifting and Precambrian faults. 3-D magnetotelluric (MT) can be used for preliminary investigations in order to provide an accurate geological background of possible prospects prior extensive seismic surveys. We report on results of 3-D inversion of MT data in the Turkana and Northern Tanzania. The method developed provides accurate models of the sharp resisitivity boundaries observed in these regions. Such a good resolution is necessary to obtain geological models able to help understand the nowadays structuration of the sedimentary basins by the active rifting and volcanism.


Schaeffer J.,IUEM | Casanova A.G.,CC IN2P3
Journal of Physics: Conference Series | Year: 2011

TReqS is a new layer in the storage infrastructure at CCIN2P3 controlling the read operations for data stored on tapes in HPSS (a HSM) by centralizing all requests. The development and deployment of TReqS at CCIN2P3 has brought major advances in data access services on several aspects. First, by sorting and scheduling tape mounts, we radically reduce the waiting time due to media movements in the tape library. Second, in a mutualised environment where tape drives are globally available to all users, TReqS ensures the fair share of the drives. Finaly, TReqS softens the impact of unpredictable grid jobs and transfers on the actual tape library and efficiently masks the data access complexity to the end user.


PubMed | French Research Institute for Exploitation of the Sea and IUEM
Type: | Journal: General and comparative endocrinology | Year: 2016

Most publications devoted to the cryopreservation of mollusc sperm have focused on the definition of technical protocols, avoiding the description of sperm quality after thawing. The present study investigated the effects of cryopreservation on sperm quality in the great scallop. Wild scallop were fished during the natural spawning period and conditioned in the hatchery before use. Sperm samples were obtained after intragonadal injection of serotonin and cryopreserved using a previously published protocol. Sperm quality was assessed using a panel of four parameters: sperm motility characteristics, using a computer assisted sperm analysis plugin with Image J, intracellular ATP content using an ATP-Lite kit, sperm integrity, using flow cytometry and sperm morphology, using transmission electron microscopy. For each parameter, fresh (control) and thawed spermatozoa were compared. A significant decrease of both the percentage of motile spermatozoa (reduction: 75%) and sperm swimming speed (86%) were observed for thawed sperm compared with fresh sperm. The percentage of living spermatozoa, as assessed using flow cytometry, was significantly lower for thawed sperm (72.42.5%) compared with fresh sperm (86.41.1). However, no significant difference of intracellular sperm ATP content was observed between fresh and thawed sperm. Post thawing, while some spermatozoa showed little or no morphological differences compared with fresh sperm, others had undergone drastic changes, including swelling of the plasma membrane, structural alterations of the chromatin and damage to mitochondria. In conclusion, the descriptive parameters studied in the present work showed that the quality of thawed great scallop sperm was lower than that of fresh cells but was still sufficient for use in aquaculture programs and sperm cryobanking for this species.

Loading IUEM collaborators
Loading IUEM collaborators