Present deep-submarine canyons activity in the Bay of Biscay (NE Atlantic)
Present sedimentation in three canyons of the Bay of Biscay (Audierne, Blackmud and Capbreton) is studied by the combined analysis of cores and current meter data collected over a 7 month period. At the current meter mooring locations, interface cores were collected to characterize the recent sedimentation processes. In the two canyons located in the Northern part of the Bay of Biscay (Audierne and Blackmud), there is no evidence of recent sedimentary deposits. Canyons are by-passing or erosive areas. In the southern part of the Bay of Biscay (Capbreton), recent turbidite are deposited. In the three canyons, current meters recorded energetic currents with velocities showing alternating upslope and downslope motions, and a period corresponding to the semi-diurnal component M2. These currents are supposed to be related to deep internal tides. The high speed of the current (1 m/s) in Audierne and Blackmud is consistent with the lack of preservation of recent sediments on the canyon floors. In Capbreton Canyon, the magnitude of currents is less and recent turbidites are preserved. In addition to periodical current motion, small magnitude gravity event corresponding to a low-concentration turbulent surge or a high-concentration nepheloid layer initiated during a storm was recorded during the mooring period. These results suggest that deep-sea canyons in the Bay of Biscay have behaviour at present varying between by passing or erosion areas and sediment trapping. These examples suggest that sediments are moved up and down by low-energy, tide-initiated hydrodynamic events during most of the time. During higher magnitude, short-duration gravity events, the sediments are transferred down canyon towards the deep sea.
(Marine Geology. vol. 295-298, n° 0025-3227, pp. 113-127, 15/02/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM, LDO, INSU - CNRS, UBO EPE, CNRS
EVOLUTION OF HARD X-RAY SOURCES AND ULTRAVIOLET SOLAR FLARE RIBBONS FOR A CONFINED ERUPTION OF A MAGNETIC FLUX ROPE
(The Astrophysical Journal. vol. 746, n° 0004-637X, pp. 17, 10/02/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LESIA, UPMC, INSU - CNRS, CNRS, PSL, UPD7, CNRS, ULiège
Behavioural indicators of welfare in farmed fish.
Behaviour represents a reaction to the environment as fish perceive it and is therefore a key element of fish welfare. This review summarises the main findings on how behavioural changes have been used to assess welfare in farmed fish, using both functional and feeling-based approaches. Changes in foraging behaviour, ventilatory activity, aggression, individual and group swimming behaviour, stereotypic and abnormal behaviour have been linked with acute and chronic stressors in aquaculture and can therefore be regarded as likely indicators of poor welfare. On the contrary, measurements of exploratory behaviour, feed anticipatory activity and reward-related operant behaviour are beginning to be considered as indicators of positive emotions and welfare in fish. Despite the lack of scientific agreement about the existence of sentience in fish, the possibility that they are capable of both positive and negative emotions may contribute to the development of new strategies (e.g. environmental enrichment) to promote good welfare. Numerous studies that use behavioural indicators of welfare show that behavioural changes can be interpreted as either good or poor welfare depending on the fish species. It is therefore essential to understand the species-specific biology before drawing any conclusions in relation to welfare. In addition, different individuals within the same species may exhibit divergent coping strategies towards stressors, and what is tolerated by some individuals may be detrimental to others. Therefore, the assessment of welfare in a few individuals may not represent the average welfare of a group and vice versa. This underlines the need to develop on-farm, operational behavioural welfare indicators that can be easily used to assess not only the individual welfare but also the welfare of the whole group (e.g. spatial distribution). With the ongoing development of video technology and image processing, the on-farm surveillance of behaviour may in the near future represent a low-cost, noninvasive tool to assess the welfare of farmed fish.
(Fish Physiology and Biochemistry. vol. 38, n° 0920-1742, pp. 17-41, 04/02/2012)
CCMAR, UAlg, NOFIMA, Tecnologia & Ricerca, CNPS, UP11, CNRS, IO-PAN, PAN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ARU, UAB, IMR, UiB
Calage de la sorption et de la biodégradation de micropolluants dans un modèle biocinétique : nouveau protocole expérimental et premiers résultats
An innovative experimental strategy is proposed to calibrate sorption and biodegradation modelling parameters. The protocol was based on batch experiments simulating the different conditions occurring in a full-scale activated sludge reactor. The studied conditions were the redox condition (aerobic, anoxic) and the substrate condition (no other substrate, carbon and nitrogne substrate, only nitrogen substrate). Thanks to the monitoring of dissolved and sorbed concentrations of micropollutant, robust mass balances could be performed. We succeeded in determining easily modelling parameter values associated to each condition. An application of the strategy is presented for a beta blocker (atenolol). We will apply this procedure to the other studied substances (other pharmaceuticals, alkylphenols, polycyclic aromatic hydrocarbons and pesticides).
(pp. 1, 01/02/2012)
UR MALY, IRSTEA, UM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Simulation of future Geostationnary Ocean Color Images
no abstract
(IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. vol. 5, n° 1939-1404, pp. 173-182, 01/02/2012)
Le2i, UB, ENSAM, CNRS, LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TAS
Mapping coastal habitats over the Arcachon Lagoon using high-resolution optical and SAR
This study explores the potential of high-resolution spaceborne Synthetic Aperture Radar data for mapping intertidal coastal areas as a complement of high-resolution optical imagery (e.g. SPOT, Formosat-2). Classification algorithms based on optical imagery alone fail to accurately discriminate a series of relevant habitats, in particular seabeds of benthic fauna (oysters), low-density Zostera noltii seabed and salt-marsh vegetation species. Firstly, the benefits from TerraSAR-X data by investigating SAR signatures over intertidal wetlands which have been poorly described in the literature were addressed. Secondly, a supervised classification algorithm is run based on the fused SAR-optical bands. A statement of the mapping performance is finally carried out using field observations.
(17/01/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR TETIS, Cirad, IRSTEA
Biodiversity and bio-evaluation methods in transitional waters: a theoretical challenge
1 - This paper addresses the question of the weaknesses of the methodologies developed based on the analysis of the composition of benthic invertebrate communities in transitional waters.2 - Benthic communities are an important element of the bio-evaluation methodologies suggested for the Ecological Quality status of the European transitional and coastal waters in the context of the Water Framework Directive. It is argued that the assessment of Ecological Quality status requires both fundamental and applied science.3 - The lack of performance of many biotic indices under varying and highly fluctuating environmental conditions may well be related to weakness in theory supporting marine biodiversity.4 - We propose some possible approaches for future development in the field of biotic indices and marine biodiversity theory.
(Transitional Waters Bulletin, 01/01/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition
A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0-0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ 18 O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass 2 δ 13 C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ 13 C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ 13 C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ 18 O and δ 13 C values of deep waters.
(Quaternary Research. vol. 77, n° 0033-5894, pp. 182-191, 01/01/2012)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOPS, UP11, CNRS, CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], CNRS
A 2500 year record of natural and anthropogenic soil erosion in South Greenland
The environmental impact of the Norse landnám (colonization) in Greenland has been studied extensively. But to date, no study has quantified the soil erosion that Norse agricultural practices are believed to have caused. To resolve this problem, a high resolution sedimentary record from Lake Igaliku in South Greenland is used to quantitatively reconstruct 2500 years of soil erosion driven by climate and historical land use. An accurate chronology, established on 18 AMS 14C, and 201Pb and 137Cs dates, allows for the estimation of detritic fluxes and their uncertainties. Land clearance and the introduction of grazing livestock by the Norse around 1010 AD caused an acceleration of soil erosion up to ∼8 mm century-1 in 1180 AD which is two-fold higher than the natural pre-landnám background. From 1335 AD to the end of the Norse Eastern Settlement (in the mid-fifteenth century), the vegetation began to recover from initial disturbance and soil erosion decreased. After an initial phase of modern sheep breeding similar to the medieval one, the mechanization of agriculture in the 1980s caused an unprecedented soil erosion rate of up to ∼21 mm century-1, five times the pre-anthropogenic levels. Independently, a suite of biological and geochemical proxies (including Ti and diatom concentrations, C:N ratio, δ13C and δ15N of organic matter) confirm that the medieval and modern anthropogenic erosion far exceeds any natural erosion over the last 2500 years. Our findings question the veracity of the catastrophic scenario of overgrazing and land degradation considered to have been the major factor responsible for Norse settlement demise. They also shed light on the sustainability of modern practices and their consequences for the future of agriculture in Greenland.
(Quaternary Science Reviews. vol. 32, n° 0277-3791, pp. 119 - 130, 01/01/2012)
LCE, CNRS, UFC, UBFC, BGS, UB, CNRS, ArScAn, UP1, UP8, UPN, MCC, CNRS, ARTeHiS, MCC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LISA (UMR_7583), INSU - CNRS, UPEC UP12, CNRS, UPCité
The chemokine CCL2 protects against methylmercury neurotoxicity.
Industrial pollution due to heavy metals such as mercury is a major concern for the environment and public health. Mercury, in particular methylmercury (MeHg), primarily affects brain development and neuronal activity, resulting in neurotoxic effects. Because chemokines can modulate brain functions and are involved in neuroinflammatory and neurodegenerative diseases, we tested the possibility that the neurotoxic effect of MeHg may interfere with the chemokine CCL2. We have used an original protocol in young mice using a MeHg-contaminated fish-based diet for 3 months relevant to human MeHg contamination. We observed that MeHg induced in the mice cortex a decrease in CCL2 concentrations, neuronal cell death, and microglial activation. Knock-out (KO) CCL2 mice fed with a vegetal control food already presented a decrease in cortical neuronal cell density in comparison with wild-type animals under similar diet conditions, suggesting that the presence of CCL2 is required for normal neuronal survival. Moreover, KO CCL2 mice showed a pronounced neuronal cell death in response to MeHg. Using in vitro experiments on pure rat cortical neurons in culture, we observed by blockade of the CCL2/CCR2 neurotransmission an increased neuronal cell death in response to MeHg neurotoxicity. Furthermore, we showed that sod genes are upregulated in brain of wild-type mice fed with MeHg in contrast to KO CCL2 mice and that CCL2 can blunt in vitro the decrease in glutathione levels induced by MeHg. These original findings demonstrate that CCL2 may act as a neuroprotective alarm system in brain deficits due to MeHg intoxication.
(Review of Economic Dynamics. vol. 125, n° 1094-2025, pp. 209-18, 01/01/2012)
UPMC, INSERM, CNRS, UNIL, UPMC, INSERM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SU, CRICM, UPMC, INSERM, CNRS