Genotoxic damages in zebrafish submitted to a polymetallic gradient displayed by the Lot River (France)
Genotoxic effects of a polymetallic pollution gradient displayed by the Lot River and one of its tributary have been assessed on zebrafish Danio rerio. Three methods were compared: RAPD-PCR, the comet assay, and 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) formation. The fishes were exposed for 14 days to waters collected from three stations: Joanis, a site polluted by cadmium (Cd) and zinc (Zn) (mean concentrations: 15. γg Cd/L and 550. γg Zn/L), Bouillac (mean concentrations: 0.55. γg Cd/L and 80. γg Zn/L), and Boisse-Penchot, a reference station (mean concentrations:<0.05. γg Cd/L and 7. γg Zn/L). The quantitative RAPD-PCR methodology proved to be sensitive enough to unmask metal genotoxicity after 3 and 7 days of exposure to Joanis water and after 14 days to Bouillac water, whereas the comet assay only detected DNA damages at the most contaminated station (Joanis). The 8-oxodG quantification was not sensitive enough to be used in zebrafish under these environmental conditions. © 2011 Elsevier Inc.
(Ecotoxicology and Environmental Safety. vol. 74, n° 0147-6513, pp. 974-983, 01/05/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISM, UB, INC-CNRS, CNRS, IRSN/DEI/SECRE/LRE, IRSN/DEI/SECRE, IRSN
Photodegradation of estrone enhanced by dissolved organic matter under simulated sunlight
In the present work the degradation of estrone (E1) a natural estrogenic hormone has been studied under simulated solar irradiation. The photodegradation of E1 has been investigated in the absence and in the presence of 7.7-8.9 mg L(-1) of dissolved organic carbon (DOC), under solar light simulation with irradiance approximating that of the sun. DOC extracts from different origins have been used. Half-lives ranging between 3.9 h and 7.9 h were observed. Results indicated that E1 was photodegraded even in the absence of DOC. The presence of DOC was found to enhance the degradation of E1. Experiments performed with the addition of reactive species scavengers (azide ions and 2-propanol) have shown that these two species play a significant role in the photodegradation. Some experiments have been performed with a DOC previously submitted to solar irradiation. Changes in optical and physico-chemical properties of DOC strongly affect its photoinductive properties, and hence its efficiency on E1 degradation. A part of the study consisted in the investigation of photoproducts structures. Five photoproducts were shown by chromatographic analysis: one arising from direct photolysis and the four others from DOC photoinduced degradation.
(Water Research. vol. 45, n° 0043-1354, pp. 3341-50, 01/05/2011)
LCEE [Poitiers], UP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCME [Poitiers], UP, INC-CNRS, CNRS, WDRC, KAUST
Tracing cadmium contamination kinetics and pathways in oysters (Crassostrea gigas) by multiple stable Cd isotope spike experiments
Laboratory experiments using stable Cd isotopes (110 Cd and 112 Cd) were conducted to separately and simultaneously characterize Cd accumulation in different tissues of Pacific oysters (Crassostrea gigas) via the (i) trophic and (ii) direct pathways. For this, we exposed juvenile oysters to 110 Cd-spiked seawater (110 Cd: 2 mg l À 1 ; constant level) and 112 Cd-spiked food (Thalassiossera weissflogii, 112 Cd: 2 mg l À 1 in 35 Â 10 3 cells/oyster/L) in four experimental treatment groups, each containing 6 oysters, for 21 days with constant trophic feeding. These Cd contamination levels were $ 10 times lower than those typically used in experimental accumulation studies. Three oysters per treatment group were dissected every 7 days with separate sampling of the gills, digestive gland and the rest of the body. Metallothioneins were analysed in the digestive gland and gills. Cadmium concentrations and isotope ratios were measured in water (daily) and tissues (weekly) by GF-AAS and ICP-MS. The observed time-dependant evolution in Cd concentrations and 110 Cd/ 114 Cd and 112 Cd/ 114 Cd isotope ratios clearly revealed the bio-accumulation short-term kinetics and pathways of Cd contamination in the different tissues. Under the experimental conditions, significantly changed isotope ratios in gills and the digestive gland of oysters suggested rapid and efficient contamination by 110 Cd derived from direct exposure followed by internal Cd transfer between organs. Trophic contamination became measurable after 14 days of exposure corresponding to a trophic transfer rate of 1%. Constant metallothionein levels during the experiment suggested that the initially present metallothionein levels were sufficient to deal with the experimental Cd exposure.
(Ecotoxicology and Environmental Safety. vol. 74, n° 0147-6513, pp. 600-606, 01/05/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The use of Eugenol and electro-narcosis as anaesthetics: Transcriptional impacts on the European eel (Anguilla anguilla L.)
Ecotoxicological studies aim to assess the potential environmental risks of various products. This implies the use of various biological models and tests on live animals. In case of handling fish and mammals, ethical rules have to be respected. The use of anaesthesia is considered to be the best way to ensure animal welfare. Eugenol and electro-narcosis are among the most popular chemical and physical anaesthetics used in fisheries and by field biologists. In this study, the genetic and endocrine impacts of these anaesthetics were assessed in order to establish whether the use of such methods could skew the results of ecotoxicological studies. Twenty yellow European eels (Anguilla anguilla) were submitted to Eugenol (50mg/L) and electro-narcosis until they reached a level of deep anaesthesia, while 20 other eels were kept aware. Five anaesthetized and five unanaesthetized eels were sacrificed and analysed directly after treatment and after 1, 7 and 21 days of recovery. At the brain level, Eugenol triggered an increase in the transcription level of genes encoding proteins involved in oxidative stress responses (catalase expression 2.5-fold, mitochondrial superoxide dismutase expression 3-fold), probably due to a hypoxic event during anaesthesia. Later impacts were detected in muscles 21 days after anaesthesia (ATP synthase subunit 6 3-fold, NADH deshydrogenase subunit 5 4-fold and mitochondrial superoxide dismutase 3-fold increased) revealing oxidative stress from an accrued mitochondrial respiratory metabolism. Hormone dosages showed that the use of Eugenol reduced the release of plasma cortisol during anaesthesia. However, this impact seemed to be reversible within one day. In case of electro-narcosis, no significant variation in transcriptional levels could be detected between anaesthetized and unanaesthetized eels. Our results suggest that the use of Eugenol as an aesthetic in ecotoxicological studies measuring gene expression or plasma cortisol concentration is not appropriate, while electro-narcosis does not seem to have any impact, at least on the parameters taken into consideration in this study.
(Ecotoxicology and Environmental Safety. vol. 74, n° 0147-6513, pp. 1573-1577, 29/04/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Assessment of Benthic Ecosystem Functioning Through Trophic Web Modelling : The Example of the Eastern Basin of the English Channel and the Southern Bight of the North Sea
Benthic organisms appear to be accurate proxies for assessing coastal ecosystem structures and changes due to climatic and anthropogenic stresses. Functional studies of benthic systems are relatively recent, mainly because of the difficulties in obtaining the basic parameters for each benthic compartment (i.e. detritus, bacteria, meiofauna and macrofauna). Our study focuses on the eastern basin of the English Channel and the Southern Bight of the North Sea. Trophic web modelling was used to assess the functioning of the three main benthic community assemblages. To test and assess the relative importance of factors assumed to influence trophic structure (geographical environment and sedimentary particle size distribution), the study area was subdivided into divisions defined a priori according to the two main structural factors of community distribution; geographic distribution and sedimentary patterns. Then, a steady state trophic model utilising the inverse method was applied to a diagram composed of eight compartments, including detritus, bacteria, meiofauna, macrobenthos and fish. For each compartment, six physiological parameters were assessed, based on our own data, empirical relationships and literature data. This method allowed estimation of the flux of matter and energy within and between the units of the benthic system and assessment of the amount of trophic energy stored in these units (available mostly to fish). Our results showed that suspension-feeders control most of the matter transfer through the macrobenthic food-web, except in the fine sand community, where deposit-feeders play a dominant role. The results also showed that, whatever the geographic area, trophic structure is strongly linked to the sedimentary conditions. As benthic communities are connected through hydrodynamics, a model of the entire eastern basin of the English Channel would appear to be acceptable. However, the main sediment types must be taken into account when establishing relationships between the functional units
(Marine Ecology. vol. 32, n° 0173-9565, pp. 1-15, 04/04/2011)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Evidence for delayed poleward expansion of North Atlantic surface waters during the last interglacial (MIS 5e)
(Quaternary Science Reviews. vol. 30, n° 0277-3791, pp. 934-946, 01/04/2011)
IFM-GEOMAR, CAU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Contrasting sea-surface responses between the western Mediterranean Sea and eastern subtropical latitudes of the North Atlantic during abrupt climatic events of MIS 3
Abstract Dinoflagellate cyst (dinocyst) analysis was conducted on two cores from the SW Iberian margin and central Alboran Sea from which high quality records of Marine Isotope Stage 3 have been previously derived. Our aim in this study is to compare the dinocyst signature between 50 and 25 ka BP with existing datasets of foraminiferal and geochemical proxies related to hydrological parameters. Quantitative reconstructions of sea-surface temperatures (SSTs) and salinities (SSS) based on dinocysts are performed for the first time in this area. The results are compared to SSTs derived from planktonic foraminifera and alkenone measurements, and to SSS calculated from planktonic δ18O and foraminiferal SST. Significant oscillations related to Dansgaard-Oeschger cycles are recorded in both cores. Dinocyst-derived hydrological parameters exhibit synchronous fluctuations and similar values to those derived from the other methods, in particular when considering quantitative reconstructions for February based on foraminifera and dinocysts. Our study shows that the influence of subpolar waters was felt during each Greenland Stadial (GS) off Portugal, and that the amplification of the Heinrich Stadial cooling in the Alboran Sea was related to the penetration of subpolar waters through the Strait of Gibraltar. During Greenland Interstadials (GI), we provide evidence for the occurrence of warm and nutrient-rich sea-surface waters in the Alboran Sea, probably due to gyre-induced upwelling. Finally, the difference between August and February dinocyst SST estimates suggests higher seasonal contrasts during GS compared to GI at the two core sites. Additionally, precession appears to have an imprint on dinocyst-derived long-term seasonality record. However, this observation needs to be confirmed by longer records. Research Highlights ► We provide new dinocyst data on core MD95-2043 (Alboran Sea) during MIS 3. ► Quantitative dinocyst sea-surface parameters (SST, SSS) are reconstructed. ► A multi-proxies compilation (microfossils, alkenones, isotopes) is established. ► This dataset has been compared with the one of a SW Iberian margin core. ► Millennial-scale climatic variability is perfectly apparent from each side of Gibraltar.
(Marine Micropaleontology. vol. 80, n° 0377-8398, pp. 1-17, 11/03/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS
The mid-Pleistocene transition in the subtropical southwest Pacific
Reconstructions of subtropical southwest Pacific climate variability over the Pleistocene were derived from coupled planktic foraminiferal δ18O-Mg/Ca measurements taken from a southern Coral Sea sediment core. A clear shift from ˜40 kyr to ˜100 kyr modes of reconstructed glacial-interglacial sea surface temperature (SST) variability is seen over the mid-Pleistocene transition, and these fluctuations are shown to have remained coherent with the orbital obliquity cycle across the transition. The likely origin of this strong obliquity signal in subtropical southwest Pacific SST is shown to be the southern high latitudes, and comparison with existing SST reconstructions from the equatorial Pacific is consistent with the communication of the signal occurring principally by greenhouse gas forcing. In contrast to the SST reconstruction, regional hydrological cycle variability (based on the calculated local component of δ18Osw change) does not show significant coherence with obliquity after ˜1000 ka. The decoupling of the SST and hydrological cycle responses over the mid-Pleistocene transition allows constraints to be placed on the evolution and extent of orbitally paced fluctuations within the coupled low-latitude ocean-atmosphere system.
(Paleoceanography. vol. 26, n° 0883-8305, pp. 1211, 01/03/2011)
LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Field Chronobiology of a Molluscan Bivalve: How the Moon and Sun Cycles Interact to Drive Oyster Activity Rhythms
The present study reports new insights into the complexity of environmental drivers in aquatic animals. The focus of this study was to determine the main forces that drive mollusc bivalve behavior in situ. To answer this question, the authors continuously studied the valve movements of permanently immersed oysters, Crassostrea gigas, during a 1-year-long in situ study. Valve behavior was monitored with a specially build valvometer, which allows continuously recording of up to 16 bivalves at high frequency (10 Hz). The results highlight a strong relationship between the rhythms of valve behavior and the complex association of the sun-earth-moon orbital positions. Permanently immersed C. gigas follows a robust and strong behavior primarily driven by the tidal cycle. The intensity of this tidal driving force is modulated by the neap-spring tides (i.e., synodic moon cycle), which themselves depend of the earth-moon distance (i.e., anomalistic moon cycle). Light is a significant driver of the oysters' biological rhythm, although its power is limited by the tides, which remain the predominant driver. More globally, depending where in the world the bivalves reside, the results suggest their biological rhythms should vary according to the relative importance of the solar cycle and different lunar cycles associated with tide generation. These results highlight the high plasticity of these oysters to adapt to their changing environment.
(Chronobiology International. vol. 28, n° 0742-0528, pp. 307-317, 15/02/2011)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
Mercury and methylmercury concentrations in high altitude lakes and fish (Arctic charr) from the French Alps related to watershed characteristics
Total mercury (THg) andmethylmercury (MeHg) concentrations were measured in the muscle of Arctic charr (Salvelinus alpinus) and in the water column of 4 lakes that are located in the French Alps. Watershed characteristics were determined (6 coverage classes) for each lake in order to evaluate the influence of watershed composition on mercury and methylmercury concentrations in fish muscle and in the water column. THg and MeHg concentrations in surface water were relatively low and similar among lakes and watershed characteristics play a major role in determining water column Hg and MeHg levels. THg muscle concentrations for fish with either a standardized length of 220 mm, a standardized age of 5 years or for individualuals did not exceed the 0.5 mg kg−1 fish consumption advisory limit established for Hg by the World Health Organization (WHO, 1990). These relatively low THg concentrations can be explained by watershed characteristics, which lead to short Hg residence time in the water column, and also by the short trophic chain that is characteristic of mountain lakes. Growth rate did not seem to influence THg concentrations in fish muscles of these lakes and we observed no relationship between fish Hg concentrations and altitude. This study shows that in the French Alps, high altitude lakes have relatively low THg and MeHg concentrations in both the water column and in Arctic charr populations. Therefore, Hg does not appear to present a danger for local populations and the fishermen of these lakes.
(Science of the Total Environment, n° 0048-9697, pp. 1909-1915, 11/02/2011)
LGGE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, INSU - CNRS, CNRS, PACTE, UPMF, UJF, IEPG, CNRS, LAPM, UJF, CNRS, GEOTOP, EPM, UdeM, UQAT, UQAR, UQAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS