Can host density attenuate parasitism?
Bivalve populations display fluctuating densities resulting in different interactions among them and with their environment. Using the edible cockle (Cerastoderma edule) as a model, we investigated two alternative hypotheses concerning the effect of density on individual infection intensity by trematode parasites. Considering that these parasites infect cockles through filtration activity, our first hypothesis was that high host density will have a dilution effect so that infection intensity decreases with host density. Conversely, high cockle density could attract other hosts used by these trematode parasites to complete their life cycle. A 17-year monthly survey of a cockle population in Arcachon Bay, France, showed a negative correlation between the cockle density and the abundance of parasite larvae in juvenile cockles with a significant threshold when adult cockle density reached 400 ind. m−2. This result was confirmed for the four dominating trematode parasites, independently considered. Additionally, a field experiment was performed during 9 months, with cockles maintained in enclosures with two densities (200 and 800 ind. m−2). Individual cockle mean infection was 1.5 times higher at low cockle density, mainly due to one dominant trematode species (Parvatrema minutum). In conclusion and confirming the first advanced hypothesis, for certain environments, negative consequences of bivalve intraspecific competition at high density can be mitigated by lower parasite pressure.
(Journal of the Marine Biological Association of the United Kingdom. vol. 97, n° 0025-3154, pp. 497-505, 16/08/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Combined effects of temperature changes and metal contamination at different levels of biological organization in yellow perch
(Aquatic Toxicology. vol. 177, n° 0166-445X, pp. 324-332, 01/08/2016)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRS, LECA, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019], INRS - ETE, INRS, IBIS, ULaval
The French initiative for scientific cores virtual curating : a user-oriented integrated approach
Managing scientific data is a crucial issue for modern science. This concerns particularly the conservation of high value geological samples: cores. International scientific programs are leading an intense effort to solve this problem and propose detailed high standard work- and dataflows including core handling and curating. However, there is currently no consensual standard for sample and associated metadata management. The national excellence equipment program CLIMCOR aims at developing French facilities for scientific coring (ice, marine and continental). As part of it, we led a reflexion about cores and associated metada curating. Our aim is to conserve all metadata from fieldwork in an integrated cyber-environment which could evolve toward laboratory-acquired data storage. In that aim, our demarche was conducted through a close relationship with field operators and core curators, in order to propose user-oriented solutions.The national core curating initiative currently proposes a single web portal to store field data. For forthcoming samples, we propose a mobile application to capture technical and scientific metadata on the field or in cruise. This application is linked with a unique coring tools library and is adapted to most coring devices, including multiple sections and holes coring operations.Those field data can be uploaded automatically to the national portal, but also referenced through international standards or persistent identifiers (IGSN - SESAR, ORCID) and INSPIRE schema and displayed in international portals (currently, NOAA IMLGS).In this paper, we present the architecture of the integrated system, future perspectives and the approach we adopted to reach our goals.(1) http://climcor-equipex.dt.insu.cnrs.fr/?lang=en
(01/08/2016)
EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, DTI, INSU - CNRS, CNRS, ISTerre, IFSTTAR, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGGE, INSU - CNRS, CNRS, OSUG, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019], EMBS, iSTeP, UPMC, CNRS, IRSI, IFREMER, INSU - CNRS
Permafrost carbon as a missing link to explain CO2 changes during the last deglaciation
The atmospheric concentration of CO2 increased from 190 to 280 ppm between the last glacial maximum 21,000 years ago and the pre-industrial era1, 2. This CO2 rise and its timing have been linked to changes in the Earth’s orbit, ice sheet configuration and volume, and ocean carbon storage2, 3. The ice-core record of δ13CO2 (refs 2,4) in the atmosphere can help to constrain the source of carbon, but previous modelling studies have failed to capture the evolution of δ13CO2 over this period5. Here we show that simulations of the last deglaciation that include a permafrost carbon component can reproduce the ice core records between 21,000 and 10,000 years ago. We suggest that thawing permafrost, due to increasing summer insolation in the northern hemisphere, is the main source of CO2 rise between 17,500 and 15,000 years ago, a period sometimes referred to as the Mystery Interval6. Together with a fresh water release into the North Atlantic, much of the CO2 variability associated with the Bølling-Allerod/Younger Dryas period ~15,000 to ~12,000 years ago can also be explained. In simulations of future warming we find that the permafrost carbon feedback increases global mean temperature by 10–40% relative to simulations without this feedback, with the magnitude of the increase dependent on the evolution of anthropogenic carbon emissions.
(Nature Geoscience. vol. 9, n° 1752-0894, pp. 683–686, 01/08/2016)
UGA [2016-2019], LGGE, INSU - CNRS, CNRS, OSUG, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, VU
Sedimentary processes determining the modern carbonate periplatform drift of Little Bahama Bank
This paper presents an analysis of the combined influence of along-slope sediment transport and off-bank sediment export from the Little Bahama Bank (LBB) to the periplatform sediment wedge of the northwestern part of the slope over the last 424 ka. The LBB northwestern slope is divided in (i) a plateau-like structure (margin) at similar to 40 m water depth over at least 4 km parallel to the edge of the LBB; (ii) the uppermost slope with a mean slope angle of similar to 1.15 degrees from 40 to 300 m water depth; (iii) the upper, slope with slope angle of similar to 0.7 from 300 to 650 m water depth, (iv) the middle slope with slope angle of similar to 1.2, from 650 to 800 m water depth, and (v) the lower slope with slope angle of -6 m) that occurred during interglacial periods, the highest sedimentation rates (10-30 cm/ka) and the finest sediment fades were found on the slope. During interglacial periods when RSL < -6 m, LBB was emerged but bank margins were still flooded and correspond to intermediate sedimentation rates (a few to 10 cm/ka) on the slope. Finally, during glacial periods (RSL < -90 m), LBB was emerged (including its margins), sedimentation rates on the slope dropped to a few mm/ka associated to coarser sediment facies. Off-bank-transported sediment is the main sediment supply during sea-level highstands, occurring preferentially during three major periods of LBB flooding over the last 424 ka: marine isotopic stages 1, 5e and 11. During sea level lowstands, shallow carbonate production was very low but could develop over a 4 km-wide plateau-like structure when RSL was above -40 m. The regional Antilles Current affected the sea floor along the northwestern LBB slope and influenced coral mound distribution as well as sediment facies and sequences along the upper and middle slopes (300-800 m). During glacial periods, the stronger influence of the Antilles Current upon the along-slope sedimentation promoted diagenesis via the development of indurated nodules in the upper slope (similar to 400 m water depth). It also encouraged bi-gradational sequences showing a coarsening-up unit followed by a fining-up unit along the middle slope (similar to 800 m water depth) that is thoroughly bioturbated. The characteristics of these contourite sequences were similar to those described in siliciclastic environments, but in contrast were condensed with low sedimentation rates over long (glacial) periods. (C) 2015 Elsevier B.V. All rights reserved.
(Marine Geology. vol. 378, n° 0025-3227, pp. 213-229, 01/08/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, KFUPM, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, [Total Energies. Anciennement : Total, TotalFina, TotalFinaElf]
Effects of disc asymmetries on astrometric measurements
(Astronomy & Astrophysics - A&A. vol. 592, n° 0004-6361, pp. A39, 01/08/2016)
LESIA (UMR_8109), INSU - CNRS, CNRS, PSL, UPD7, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LUTH (UMR_8102), INSU - CNRS, CNRS, PSL, UPD7, CNRS, SYRTE, INSU - CNRS, CNRS, PSL, SU, CNRS
On the use of the Radon transform to estimate longshore currents from video imagery
(Coastal Engineering. vol. 114, n° 0378-3839, pp. 301-308, 01/08/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LAAS, UT Capitole, Comue de Toulouse, INSA Toulouse, INSA, Comue de Toulouse, UT2J, Comue de Toulouse, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, LGO, UBS, IFREMER, UBO EPE, CNRS
An integrated chemical-biological study using caged mussels (Mytilus trossulus) along a pollution gradient in the Archipelago Sea (SW Finland, Baltic Sea)
Mussels (Mytilus trossulus) were caged along a known pollution gradient in the inner Archipelago Sea (northern Baltic Sea) and retrieved after 71 and 121 d for the measurement of selected chemical contaminants in tissues and biological endpoints including biochemical biomarkers and growth. Additional samples were collected during the growth season from a native mussel population at an alleged reference site. Elevated concentrations of numerous contaminants (e.g., PAH) were observed in spring, apparently due to the loss of tissue mass during the winter, while also the levels of many biomarkers (e.g., glutathione S-transferase activity) were elevated. Spatial and temporal changes in the accumulation of contaminants and biological parameters were observed with some of them (e.g., growth) linked to seasonal changes in environmental factors. The results underline the importance of understanding the effects of seasonal natural factors on the growth dynamics and general condition of mussels when assessing tissue concentrations of contaminants and biological effects.
(Marine Environmental Research. vol. 119, n° 0141-1136, pp. 207-221, 01/08/2016)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sedimentary response to sea ice and atmospheric variability over the instrumental period off Adélie Land, East Antarctica
Diatoms account for a large proportion of primary productivity in Antarctic coastal and continental shelf zones. Diatoms, which have been used for a long time to infer past sea surface conditions in the Southern Ocean, have recently been associated with diatom-specific biomark-ers (highly branched isoprenoids, HBI). Our study is one of the few sedimentary research projects on diatom ecology and associated biomarkers in the Antarctic seasonal sea ice zone. To date, the Adélie Land region has received little attention, despite evidence for the presence of high accumulation of laminated sediment, allowing for finer climate reconstructions and sedimentary process studies. Here we provide a sequence of seasonally to annually laminated diatomaceous sediment from a 72.5 cm interface core retrieved on the continental shelf off Adélie Land, covering the 1970–2010 CE period. Investigations through statistical analyses of diatom communities, diatom-specific biomarkers and major element abundances document the relationships between these proxies at an unprecedented resolution. Additionally, comparison of sedimentary records to meteorological data monitored by automatic weather station and satellite derived sea ice concentrations help to refine the relationships between our proxies and environmental conditions over the last decades. Our results suggest a coupled interaction of the atmospheric and sea surface variability on sea ice seasonality, which acts as the proximal forcing of siliceous productivity at that scale.
(Biogeosciences. vol. 13, n° 1726-4170, pp. 4205-4218, 25/07/2016)
LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, ULaval, INSU - CNRS, CNRS, ULaval, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, VOG, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS
Enhanced development of lacustrine microbialites on gravity flow deposits, Great Salt Lake, Utah, USA.
The Great Salt Lake, Utah, USA is a shallow, hypersaline, intracontinental lake hosting extensive microbial deposits. At a large spatial scale, the distribution of these deposits is driven by environmental and geodynamical factors (i.e. water-level fluctuations and a fault-related framework). A detailed mapping of the Buffalo Point area, in the north-western part of Antelope Island, indicates the presence of an anomalous concentration of microbial deposits dated ca. 5.8 ka BP and distributed along a lobe-shaped geometry. This uncommon microbial deposit geometry results from an extensive colonization of a conglomerate substrate exhibiting an accumulation of m-sized rounded Cambrian quartzite boulders. We suggest that this conglomerate substrate provides a stable nucleation point that promotes the development and preservation of the lobe-shaped microbial deposits. Microbial deposits may also have protected the conglomerate substrate from erosional processes and thereby increased the preservation potential of the lobe-shaped structure. Based on the characteristics of the conglomerate (e.g. grain size, texture) and its location (i.e. 200 m beyond the average shoreline), this lobe-shaped structure likely results from subaqueous debris or a hyperconcentrated density flow that transports sedimentary material from the Buffalo Point slopes downward to the shore. We estimate the age of the conglomerate deposition to be between 21 and 12 ka BP. The initiation of the flow may have been triggered by various mechanisms, but the existence of a major active normal fault in the vicinity of these deposits suggests that an earthquake could have destabilized the accumulated sediments and resulted in conglomerate emplacement. The catastrophic 15 ka BP Bonneville Flood, which led to a drop in the lake level (approximately 110 m), may also provide an explanation for the initiation of the flow.
(Sedimentary Geology. vol. 341, n° 0037-0738, pp. 1-12, 15/07/2016)
BGS, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Bordeaux INP, UBM, UAM, UAM, CRIGEN, GDF Suez, UCONN