Effects of Methylmercury Contained in a Diet Mimicking the Wayana Amerindians Contamination through Fish Consumption: Mercury Accumulation, Metallothionein Induction, Gene Expression Variations, and Role of the Chemokine CCL2
(International Journal of Molecular Sciences. vol. 13, n° 1661-6596, pp. 7710-7738, 01/06/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSERM, CNRS, UPMC, INSERM, CNRS, DC2N, UNIROUEN, NU, INSERM, UPMC, INSERM, IBGC, UB, CNRS
Évènements Rares sur des Séries Temporelles Environnementales
La mesure de l'activité de mollusques bivalves est un moyen d'enregistrer le comportement de bivalves in situ et donc d'évaluer des changements de la qualité de l'eau. Nous proposons une méthode statistique basée sur la théorie des valeurs extrêmes permettant d'estimer des changements globaux (pollution, changement de température) et ainsi d'aider à la surveillance de systèmes aquatiques.
(pp. 1-6, 21/05/2012)
LMBA, UBS, UBO EPE, CNRS, LIMATB, UBS, UBO EPE, IBNM, UBO EPE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Use of passive samplers extracts for toxicity assessment of environmental realistic mixture of pesticides on natural biofilms communities
The objective of this study was to evaluate the potential use of passive samplers extracts in order to highlight effects of representative pesticide mixtures on natural biofilm communities. Chronic and acute impacts of pesticides in mixture were evaluated using POCIS (Polar Organic Chemical Integrative Sampler) extracts on natural biofilm communities. Biofilms were exposed to POCIS extracts (PE+) or placed in clean water (PE-) in order to maintain or to model a removal of a toxic pressure in relation with a realistic pesticide mixture directly isolated from the field. After 13 days of exposure, a significant decrease of DW, AFDM and diatoms density on downstream biofilms exposed to PE compared to non exposed biofilms was observed; moreover mean chla amount was lower for biofilms exposed to PE compared to non exposed biofilms. Acute toxicity tests at day 13 revealed a significant higher tolerance for PE+ compared to PE- biofilms. Moreover a decrease of tolerance of downstream biofilms from day 0 to day 13 was observed for both treatments; with 51±13 and 43±2% of inhibition at day 13 compared to 25±3% of inhibition at day 0 in the highest concentration (d0). This global decrease of tolerance to PE with time could be explained by differences between channel and field conditions (light intensity, PE composition different from real river exposure due to POCIS selectivity, pesticides concentrations lower in channels than in river,…) Nevertheless, tolerance of downstream biofilms at day 13 still be much more higher than tolerance of biofilms originated from upstream site (significant inhibition of Fv/Fm for d0, d1, d2 and d3 for upstream biofilms). Our results underline impacts of pesticides in mixture on both growth (DW, AFDM and diatoms density) and community tolerance of a natural biofilm. In the one hand, removing the toxic pressure stimulates global biofilm growth but in the other hand it leads to a decrease of biofilms tolerance. A global decrease of tolerance over time for both treatments was observed; nevertheless without reaching the tolerance levels of upstream biofilms. This study highlights the potential use of passive sampler extracts combined with acute toxicity tests in order to evaluate effects of more realistic pesticide mixtures on natural biofilms communities, and then the future and likely applications of such approaches for ecological risk assessment.
(pp. 1, 20/05/2012)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Long term effects of an early exposure to PAHs on Zebrafish behavioural responses
Polycyclic aromatic hydrocarbons (PAH) emission in the environment is constantly increasing with human activity. The goal of this study was to assess long term consequences of fish early exposure to PAH on behaviour. Eggs were collected from AB zebrafish strain and were placed at 4 hours post fertilization (hpf) until 96 hpf in a 3 cm diameter Petri dish containing 3 g reference sediment either plain (control) or spiked with a mixture of Benzo[a]pyrene, Pyrene and Phenanthrene at environmental concentrations based on values measured in the Seine Estuary (France), a highly polluted site. Thereafter, larvae were transferred in clean water and raised until adulthood. Behavioural tests such as locomotion during 24-hrs, sudden dark change challenge and T-maze exploration were performed at adults’ stage (F0) and sudden dark change on larvae produced by F0 adults. In adults, during night or dark period, contaminated fish were significantly less active than control fish. A similar observation was made for contaminated F0 in T-maze safe area. Contaminated F1 larvae were more active when light was on than control and less active when the light was off. This study indicates that contamination of zebrafish using environmentally relevant concentration during the very first stage of development with a PAH mixture of 3 molecules induced late behavioural effects measured at the adult stage. Further, effect was transmitted to the next generation and behavioural responses of F1 larvae were different to that of F1 control larvae. Consequences on fish abilities (e.g. predator escape, food search, courtship) will be discussed.
(pp. 355, 20/05/2012)
BE, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, LRHLR, HGS, IFREMER, LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique
Multi-agent simulations of the trajectory of the LBK Neolithic
(01/05/2012)
DEHIPE, CNRS, GEODE, UT2J, Comue de Toulouse, CNRS, UP1, CNRS, BioArch, MNHN, CNRS, LIVE, UNISTRA, CNRS, EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OCCR, UNIBE, LCE, CNRS, UFC, UBFC, PSL, REEDS, UVSQ
High resolution optical and radar data for mapping intertidal flats and salt marshes
The main objective of this study is to define relevant data to improve land-cover maps of the Arcachon bay. With this aim, the authors introduce the use of radar data by assessing their potential for mapping intertidal flats and salt-marshes. In addition, the potential of using images acquired at different seasons is evaluated in order to derive the wavebands useful to test a multi-temporal classification strategy. For this purpose, hyperspectral field measurements carried out seasonally are analyzed. Then, the most discriminating SAR and optical wavebands are concatenated and the resulting muti-sensor multi-temporal composite images are classified. The validation of the resulting maps is performed on a regularly surveyed site. Image data selection, map production and validation are detailed in the present poster.
(23/04/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR TETIS, Cirad, IRSTEA
Analysis of extreme hydrological events (river and tidal floods) in the Medoc vineyards and consequences on the metal pollution of the Gironde Estuary
The ADAPT’EAU research project (ANR CEP&S) intends to assess the vulnerability of environments and societies to the impacts of Global Change on river-estuarine environments. During the last decades, the Gironde Estuary has been affected by major storm events (e.g. Martin in 1999, Xynthia in 2010), which caused river and tidal floods that temporarily submerged urban and agricultural lands. In the context of regional environmental changes forecast (e.g. sea level rise, urbanization, changing agriculture), there are uncertainties on the frequency of extreme events (storms, floods) and their impacts on metal mobilization from temporarily submerged land surfaces, particularly from copper (Cu) contaminated vineyard soils. Based on an interdisciplinary approach coupling geochemistry, geomatics and geography, our study aims at characterizing extreme events in one of the largest areas of red wine production (Medoc; left bank of the Gironde Estuary) using the prefectural orders on natural catastrophes published in the Official Journal from 1982 to 2011 (database GASPAR; French Ministry of Ecology) associated with a weather events database. In identified flood-stricken sites, vineyard soils were collected and leached by natural waters under laboratory conditions in order to (i) simulate the effects of river floods (soil with freshwater) and tidal floods (soil with estuarine water) and (ii) investigate the physico-chemical processes of metal leaching or adsorption on soils. The parameters of the incubations (duration, temperature, salinity) were determined from the event characteristics. Our first experimentations simulating prolonged river flood (20 days) showed significant Cu desorption increasing Cu levels in freshwater by a factor 5. We discuss the potential impact of water flooding in intra-estuarine watersheds with similar land uses on the water quality of the Gironde Estuary by comparing metal mobilization to metal gross fluxes transported by the Garonne River to the coastal ocean.
(pp. 1, 11/04/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR ADBX, IRSTEA
Effects of uranium on crayfish Procambarus clarkii mitochondria and antioxidants responses after chronic exposure What have we learned?
We examined the impacts of Uranium (U) on mitochondria and on the response of antioxidants in the gills and the hepatopancreas of crayfish Procambarus clarkii after long-term exposure (30 and 60 days) to an environmentally relevant concentration (30 μg. U/L). The expression of mitochondrial genes (12s, atp6, and cox1), as well as the genes involved in oxidative stress responses (sod(Mn) and mt) were evaluated. The activities of antioxidant enzymes (SOD, CAT, GPX and GST) were also studied. U accumulation in organs induced changes in genes' expression. The evolution of these transcriptional responses and differences between gene expression levels at high and low doses of exposure were also discussed. This study demonstrated that, after long-term exposure, U caused a decrease in antioxidant activities and induced oxidative stress. A possible ROS-mediated U cytotoxic mechanism is proposed. Expression levels of the investigated genes can possibly be used as a tool to evaluate U toxicity and seem to be more sensitive than the enzymatic activities. However a multiple biomarker approach is recommended as the perturbed pathways and the mode of action of this pollutant are not completely understood. © 2011.
(Ecotoxicology and Environmental Safety. vol. 78, n° 0147-6513, pp. 218-224, 01/04/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSN/DEI/SECRE/LRE, IRSN/DEI/SECRE, IRSN
Network analysis of the planktonic food web during the spring bloom in a semi-enclosed lagoon (Arcachon, SW France)
The structure and functioning of the food web in Arcachon Bay (Bay of Biscay, Northeast Atlantic Ocean) was analyzed during the spring bloom period to evaluate the sensitivity of this ecologically and economically important ecosystem perturbation. Differences in the timing of the peaks in phytoplankton and zooplankton populations occur due to a mismatch between primary production and grazing. Using an inverse approach based on in situ experimental data, an ecological network analysis was carried out to characterize emergent properties of the food web and to estimate carbon flows. The data set was composed of rate measurements for net primary production, import and export of dissolved organic carbon, and grazing of heterotrophic nanoflagellates and ciliates by metazoan micro- and mesozooplankton. Ecological network analysis indices were calculated on the estimated fluxes and compared to values from plankton models built with exactly the same method. The largest activities in the resulting model came from the nano- and microphytoplankton. The detritivory/herbivory ratio, the recycling rates and the relative redundancy of the system were very low compared to other planktonic systems, even in similar periods of bloom. These values indicate a transitional system with poor resilience that exports a large quantity of carbon either to the benthos where it is consumed by non-planktonic consumers such as oysters, or else to systems outside of the bay (outwelling).
(Acta Oecologica. vol. 40, n° 1146-609X, pp. 40-50, 01/04/2012)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Cleaning of marine sediment samples for large diatom stable isotope analysis
Diatom stable isotope analysis offers considerable potential in palaeoceanography, particularly where carbonate material is scarce or absent. However, extracting pure diatom frustules free of external labile organic matter from marine sediments is an essential requirement for their applications as paleoenvironmental proxies. Here, based largely on previous work, we developed a method including physical separation and chemical oxidation steps to concentrate and clean pure large diatoms from laminated diatom mat and diatomaceous clay sediment samples for their stable isotope analysis. Using the physical separation techniques consisting of the removal of carbonate and excess organic matter, sieving, differential settling, and heavy liquid floatation, pure diatoms can be successfully isolated from the sediment samples with opal concentration more than 10%. Subsequent time oxidation experiment shows that labile organic matter coating pure diatom valves can be effectively removed with 30% H 2 O 2 at 65 ℃ for 2 h. Measurements of δ 13 C after every step of physical separation demonstrate that contaminants and lost diatoms can influence the original diatom stable isotope signal, highlighting the importance of a visual check for dominant diatom size in the initial sample and purity in the final sample. Although the protocol described here was only applied to diatom mats or diatom oozes containing large diatoms (Ethmodiscus rex), we believe that this method can be adapted to common dia-toms of general marine sediment samples. KEY WORDS: large diatom, stable isotope, physical separation, chemical oxidation, Parece Vela basin, palaeoceanography.
(Journal of Earth Science. vol. 23, n° 1674-487X, pp. 161-172, 01/04/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS