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Author |
Pisanu Benoît, Caut Stéphane, Gutjahr Sylvain, Vernon Philippe, Chapuis Jean-Louis, |
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Title |
Introduced black rats Rattus rattus on Ile de la Possession (Iles Crozet, Subantarctic): diet and trophic position in food webs
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Type |
Journal Article |
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Year |
2011 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol. |
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Volume |
34 |
Issue |
2 |
Pages |
169-180 -180 |
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Keywords |
Biomedical and Life Sciences, |
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Abstract |
Rats introduced on islands can affect ecosystem structure and function by feeding on terrestrial plants and both marine and terrestrial animals. The diet and trophic position of Rattus rattus introduced on Ile de la Possession (Iles Crozet) was assessed from two sites, according to the presence or absence of a king penguin colony. We used three complementary assays: macroanalyses of the stomach, faecal microhistology, and stable isotope analyses of 15N/13C in liver. Near the rookery, spermatophytes contributed on average 50% (confidential interval: 2375) to the diet based on isotopes, mainly consisting in reproductive parts of Poa spp., Agrostis magellanica, and Cerastium fontanum identified in faeces. Terrestrial animal preys were represented by insects that contributed 25% (056) in isotopes, dominated in faeces by caterpillars of Pringleophaga spp. and adult weevils. Bird remains were found in faeces, forming 18% (630) of isotopes. Terrestrial earthworms contributed to 7% (021), with chaetae observed in faeces. On the other site, spermatophytes represented 62% (5173) of assimilated food in rats livers, mainly formed by Poaceae and Acaena magellanica, insects by caterpillars [24% (1039)], and terrestrial earthworms [13% (223)]. Our results suggest that rats, which were found at the top of terrestrial food chains, may have a direct role on a such simplified ecosystem, by preying on the most abundant and largest body-sized terrestrial invertebrates,e.g. the keystone species Pringleophaga spp., and by feeding on both reproductive and vegetative parts of autochthonous and introduced plants. The discrepancies and usefulness of employing both isotopes and faecal analyses are discussed. |
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Programme |
136 |
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Thesis |
Bachelor's thesis |
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Publisher |
Springer Berlin / Heidelberg |
Place of Publication |
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Series Volume  |
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Series Issue |
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Edition |
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ISSN |
0722-4060 |
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Notes |
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yes |
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Call Number |
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Serial |
2671 |
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Author |
International Association of Geomagnetism and Aeronomy Working Group V-MOD Participating members, Finlay C C, Maus S, Beggan C D, Bondar T N, Chambodut A, Chernova T A, Chulliat A, Golovkov V P, Hamilton B, Hamoudi M, Holme R, Hulot G, Kuang W, Langlais B, Lesur V, Lowes F J, Lühr H, Macmillan S, Mandea M, McLean S, Manoj C, Menvielle M, Michaelis I, Olsen N, Rauberg J, Rother M, Sabaka T J, Tangborn A, Tøffner-Clausen L, Thébault E, Thomson A W P, Wardinski I, Wei Z, Zvereva T I, |
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Title |
International Geomagnetic Reference Field: the eleventh generation
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Type |
Journal Article |
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Year |
2010 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
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Volume |
183 |
Issue |
3 |
Pages |
1216 -1230 |
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Keywords |
Magnetic field, Satellite magnetics, |
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Abstract |
SUMMARY The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.02015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.02015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined.
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Programme |
139;905 |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
Blackwell Publishing Ltd |
Place of Publication |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1365-246X |
ISBN |
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Medium |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2683 |
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Author |
Branger Karine, Drillet Yann, Houssais Marie-Nolle, Testor Pierre, Bourdall-Badie Romain, Alhammoud Bahjat, Bozec Alexandra, Mortier Laurent, Bouruet-Aubertot Pascale, Crpon Michel, |
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Title |
Impact of the spatial distribution of the atmospheric forcing on water mass formation in the Mediterranean Sea
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Type |
Journal Article |
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Year |
2010 |
Publication |
J. Geophys. Res. |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
115 |
Issue |
C12 |
Pages |
C12041 - |
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Keywords |
Mediterranean Sea, deep water formation, numerical modeling, atmospheric forcing, 4504 Oceanography: Physical: Air/sea interactions, 4215 Oceanography: General: Climate and interannual variability, 4513 Oceanography: Physical: Decadal ocean variability, 4283 Oceanography: General: Water masses, 4520 Oceanography: Physical: Eddies and mesoscale processes, |
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Abstract |
The impact of the atmospheric forcing on the winter ocean convection in the Mediterranean Sea was studied with a high-resolution ocean general circulation model. The major areas of focus are the Levantine basin, the Aegean-Cretan Sea, the Adriatic Sea, and the Gulf of Lion. Two companion simulations differing by the horizontal resolution of the atmospheric forcing were compared. The first simulation (MED16-ERA40) was forced by air-sea fields from ERA40, which is the ECMWF reanalysis. The second simulation (MED16-ECMWF) was forced by the ECMWF-analyzed surface fields that have a horizontal resolution twice as high as those of ERA40. The analysis of the standard deviations of the atmospheric fields shows that increasing the resolution of the atmospheric forcing leads in all regions to a better channeling of the winds by mountains and to the generation of atmospheric mesoscale patterns. Comparing the companion ocean simulation results with available observations in the Adriatic Sea and in the Gulf of Lion shows that MED16-ECMWF is more realistic than MED16-ERA40. In the eastern Mediterranean, although deep water formation occurs in the two experiments, the depth reached by the convection is deeper in MED16-ECMWF. In the Gulf of Lion, deep water formation occurs only in MED16-ECMWF. This larger sensitivity of the western Mediterranean convection to the forcing resolution is investigated by running a set of sensitivity experiments to analyze the impact of different time-space resolutions of the forcing on the intense winter convection event in winter 1998–1999. The sensitivity to the forcing appears to be mainly related to the effect of wind channeling by the land orography, which can only be reproduced in atmospheric models of sufficient resolution. Thus, well-positioned patterns of enhanced wind stress and ocean surface heat loss are able to maintain a vigorous gyre circulation favoring efficient preconditioning of the area at the beginning of winter and to drive realistic buoyancy loss and mixing responsible for strong convection at the end of winter.
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Programme |
452 |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
AGU |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0148-0227 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2693 |
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Author |
Coco I, Amata E, Marcucci M F, Ambrosino D, Villain J-P, Hanuise C, |
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Title |
The effects of an interplanetary shock on the high-latitude ionospheric convection during an IMF By-dominated period
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Type |
Journal Article |
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Year |
2008 |
Publication |
Ann. Geophys. |
Abbreviated Journal |
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Volume |
26 |
Issue |
9 |
Pages |
2937-2951 |
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Keywords |
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Abstract |
On 6 January 1998 an interplanetary shock hit the magnetosphere around 14:15 UT and caused a reconfiguration of the northern high-latitude ionospheric convection. We use SuperDARN, spacecraft and ground magnetometer data to study such reconfiguration. We find that the shock front was tilted towards the morning flank of the magnetosphere, while the Interplanetary Magnetic Field (IMF) was By-dominated, with By<0, IMF Bz>0 and |By|>>Bz. As expected, the magnetospheric compression started at the first impact point of the shock on the magnetopause causing an increase of the Chapman-Ferraro current from dawn to dusk and yielding an increase of the geomagnetic field at the geostationary orbit and on the ground. Moreover, the high-latitude magnetometer data show vortical structures clearly related to the interaction of the shock with the magnetosphere-ionosphere system. In this context, the SuperDARN convection maps show that at very high latitudes above the northern Cusp and in the morning sector, intense sunward convection fluxes appear, well correlated in time with the SI arrival, having a signature typical for Bz>0 dominated lobe reconnection. We suggest that in this case the dynamic pressure increase associated to the shock plays a role in favouring the setting up of a new lobe merging line albeit |By|>>Bz≥0. |
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Programme |
312;911 |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
Copernicus Publications |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1432-0576 |
ISBN |
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Medium |
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Area |
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Expedition |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2731 |
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| Permanent link to this record |
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Author |
Lukianova R, Hanuise C, Christiansen F, |
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Title |
Asymmetric distribution of the ionospheric electric potential in the opposite hemispheres as inferred from the SuperDARN observations and FAC-based convection model
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Type |
Journal Article |
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Year |
2008 |
Publication |
Journal of Atmospheric and Solar-Terrestrial Physics |
Abbreviated Journal |
1364-6826 |
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Volume |
70 |
Issue |
18 |
Pages |
2324-2335 |
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Keywords |
Ionosphere, Convection, Field-aligned currents, SuperDARN, |
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Abstract |
We compare the SuperDARN convection patterns with the predictions of a new numerical model of the global distribution of ionospheric electric potentials. The model utilizes high-precision statistical maps of field-aligned currents (FAC) derived from measurements made by polar-orbiting low-altitude satellites. Both the solar and auroral precipitation contributions are included in order to derive the ionospheric conductance. Taking into account the electrodynamic coupling of the opposite hemispheres, the model allows one to obtain the convection patterns developed simultaneously in both hemispheres for given input parameters. SuperDARN, with its database containing global northern and southern convection maps, provides the unique opportunity to compare the model predictions of electric fields with observations. In the present study we focus on the effect of significant interhemispheric asymmetry governed by the IMF clock angle and solar zenith angle. We calculate the convection patterns for specific cases caused by the sign of BY and season and demonstrate the capability of the FAC-based model reproduce the radar observations. The simulation confirms that the solar zenith angle should be linked to the IMF clock angle to fully characterize the convection patterns. The model predicts that the cross-polar cap potential drop is regularly larger in the winter hemisphere than in the summer hemisphere. |
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Programme |
312;911 |
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Campaign |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1364-6826 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2743 |
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| Permanent link to this record |
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Author |
Dalton Colleen A, Ekstrm Gran, Dziewoski Adam M, |
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Title |
The global attenuation structure of the upper mantle
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Type |
Journal Article |
| |
Year |
2008 |
Publication |
J. Geophys. Res. |
Abbreviated Journal |
J. Geophys. Res. |
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| |
Volume |
113 |
Issue |
B9 |
Pages |
B09303- |
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Keywords |
Attenuation, surface waves, global seismology, 7270 Seismology: Tomography, 7260 Seismology: Theory, 7208 Seismology: Mantle, 3909 Mineral Physics: Elasticity and anelasticity, 8124 Tectonophysics: Earth's interior: composition and state, |
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Abstract |
A large data set of fundamental mode Rayleigh wave amplitudes is analyzed to derive a new global three-dimensional model of shear wave attenuation in the upper mantle. The amplitude observations span a range of periods between 50 and 250 s and are derived from earthquakes with M W > 6.0 that occurred between 1993 and 2005. Four separate factors may influence an amplitude anomaly: intrinsic attenuation along the raypath, elastic focusing effects along the raypath, uncertainties in the strength of excitation, and uncertainties in the response at the station. In an earlier paper (Dalton and Ekstrm, 2006a), dependence of the retrieved attenuation structure on these terms was shown to be significant and an approach was developed to invert the amplitudes simultaneously for each term. The new three-dimensional attenuation model QRFSI12, which is the subject of this paper, is derived using this method. The model contains large lateral variations in upper-mantle attenuation, 60% to 100%, and exhibits strong agreement with surface tectonic features at depths shallower than 200 km. At greater depth, QRFSI12 is dominated by high attenuation in the southeastern Pacific and eastern Africa and low attenuation along many subduction zones in the western Pacific. Resolution tests confirm that the change in pattern of attenuation above and below 200-km depth can be determined with confidence using the fundamental mode data set. The new model is highly correlated with global models of shear wave velocity, particularly in the uppermost mantle, suggesting that the same factors may control both seismic attenuation and velocity in this depth range. However, forcing the lateral perturbations in attenuation to match those found in global velocity models decreases the data variance reduction, which suggests that subtle differences between patterns of attenuation and velocity are robust.
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Programme |
133 |
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Campaign |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
AGU |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0148-0227 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2785 |
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| Permanent link to this record |
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Author |
Nettles Meredith, Dziewoski Adam M, |
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Title |
Radially anisotropic shear velocity structure of the upper mantle globally and beneath North America
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Type |
Journal Article |
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Year |
2008 |
Publication |
J. Geophys. Res. |
Abbreviated Journal |
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Volume |
113 |
Issue |
B2 |
Pages |
B02303- |
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Keywords |
North America, seismic velocity, anisotropy, 7208 Seismology: Mantle, 7218 Seismology: Lithosphere, 7270 Seismology: Tomography, 7255 Seismology: Surface waves and free oscillations, |
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Abstract |
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Programme |
133 |
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Campaign |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
AGU |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0148-0227 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2809 |
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| Permanent link to this record |
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Author |
Bascou J, Delpech G, Vauchez A, Moine B N, Cottin J Y, Barruol G, |
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Title |
An integrated study of microstructural, geochemical, and seismic properties of the lithospheric mantle above the Kerguelen plume (Indian Ocean)
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Type |
Journal Article |
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Year |
2008 |
Publication |
Geochem. Geophys. Geosyst. |
Abbreviated Journal |
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Volume |
9 |
Issue |
4 |
Pages |
Q04036- |
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Keywords |
Kerguelen, mantle plume, seismic anisotropy, metasomatism, crystallographic fabric, lithosphere, 8121 Tectonophysics: Dynamics: convection currents, and mantle plumes, 8030 Structural Geology: Microstructures, 7208 Seismology: Mantle, |
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Abstract |
Peridotite xenoliths brought up to the surface by the volcanism of the Kerguelen Islands represent a mantle that has been affected by a high degree of partial melting followed by intense melt percolation above the Kerguelen plume. These xenoliths are therefore particularly suitable to investigate effects of melt-rock interaction on crystallographic fabrics (lattice-preferred orientation (LPO)) of peridotite minerals and on the LPO-induced seismic properties of peridotites above a mantle plume. We have studied a suite of 16 ultramafic samples representative of different degrees of partial melting and magma-rock interaction among which the protogranular harzburgites are the least metasomatised xenoliths and dunites are the ultimate stage of metasomatism. Olivine LPO is characterized by high concentration of [010] axes perpendicular to the foliation and [100] axes close to the lineation or distributed in the foliation plane in harzburgites, whereas the high concentration of [100] axes is parallel to the lineation and [010] axes is perpendicular to the assumed foliation in dunites. Olivine LPO in harzburgites is interpreted as being due to a deformation regime in axial compression or transpression. The fabric strength of olivine decreases progressively from protogranular to poikilitic harzburgites and finally to dunites, for which it remains nevertheless significant (J index $\geq$ 3.8). Seismic properties calculated from LPO of minerals indicate that metasomatism at higher melt/rock ratio lowers the P wave velocities. The most significant difference between harzburgites and dunites corresponds to the distribution of S wave anisotropy. Harzburgites display the maximum of anisotropy within the foliation plane and the minimum of anisotropy perpendicular to the foliation plane, whereas the lowest anisotropy is parallel to the lineation for dunites. These modifications of seismic properties as a result of metasomatic processes may induce seismic heterogeneities in the mantle above the Kerguelen plume. In addition, assuming a lithospheric mantle primarily harzburgitic and structured with a horizontal foliation, the seismic properties calculated for the Kerguelen xenoliths reconcile the rather high anisotropy evidenced by the horizontally propagating surface waves with the apparent isotropy revealed by the absence of splitting of vertically propagating teleseismic SKS waves recorded by the GEOSCOPE Kerguelen station.
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Programme |
133;444 |
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Campaign |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
AGU |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1525-2027 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2814 |
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| Permanent link to this record |
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Author |
Mazzei F, Ghigliotti L, Coutanceau Jean-Pierre, Detrich H, Prirodina V, Ozouf-Costaz C, Pisano E, |
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Title |
Chromosomal characteristics of the temperate notothenioid fish Eleginops maclovinus (Cuvier)
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Type |
Journal Article |
| |
Year |
2008 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol. |
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Volume |
31 |
Issue |
5 |
Pages |
629-634 |
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Keywords |
Biomedical and Life Sciences, |
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Abstract |
The Falklands mullet, Eleginops maclovinus , is the only modern representative of the Sub-Antarctic family Eleginopidae, suborder Notothenioidei. Based on specimens from the Falkland Islands/Islas Malvinas, the Magellan Straits, and the southern coast of Chile, we have established the specific karyotype by conventional cytogenetic methods and have mapped the chromosomal loci of the ribosomal genes by fluorescence in situ hybridization (FISH). With respect to the basal notothenioid family Bovichtidae and to the hypothetical basal condition of the suborder (diploid number = 48, fundamental number = 48), E. maclovinus displays a slightly derived karyotype (diploid number = 48, fundamental number = 54). In contrast to the bovichtids, the 45S and 5S ribosomal DNAs are co-localized to a single chromosome pair. Condensation of the ribosomal genes to a single locus is likely to represent an intermediate stage in the evolution of notothenioid karyology. Features unique to E. maclovinus (e.g., morphology of its large, rDNA-bearing chromosome pair) probably result from divergence during the long evolutionary isolation of the family. |
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Programme |
1124 |
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Campaign |
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Address |
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Corporate Author |
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Thesis |
Bachelor's thesis |
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Publisher |
Springer Berlin / Heidelberg |
Place of Publication |
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Editor |
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Language |
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Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0722-4060 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
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Approved |
yes |
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Call Number |
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Serial |
2824 |
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| Permanent link to this record |
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Author |
Gilg Olivier, Sittler Benoît, Hanski Ilkka |
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Title |
Climate change and cyclic predatorprey population dynamics in the high Arctic
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Type |
Journal Article |
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Year |
2009 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob Chang Biol |
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Volume |
15 |
Issue |
11 |
Pages |
2634-2652 |
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Keywords |
Alopex lagopus, Arctic community, climate change, cyclic dynamics, Dicrostonyx groenlandicus, Greenland, Mustela erminea, Nyctea scandiaca, predatorprey interaction, Stercorarius longicaudus, |
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Abstract |
The high Arctic has the world's simplest terrestrial vertebrate predatorprey community, with the collared lemming being the single main prey of four predators, the snowy owl, the Arctic fox, the long-tailed skua, and the stoat. Using a 20-year-long time series of population densities for the five species and a dynamic model that has been previously parameterized for northeast Greenland, we analyzed the population and community level consequences of the ongoing and predicted climate change. Species' responses to climate change are complex, because in addition to the direct effects of climate change, which vary depending on species' life histories, species are also affected indirectly due to, e.g., predatorprey interactions. The lemmingpredator community exemplifies these complications, yet a robust conclusion emerges from our modeling: in practically all likely scenarios of how climate change may influence the demography of the species, climate change increases the length of the lemming population cycle and decreases the maximum population densities. The latter change in particular is detrimental to the populations of the predators, which are adapted to make use of the years of the greatest prey abundance. Therefore, climate change will indirectly reduce the predators' reproductive success and population densities, and may ultimately lead to local extinction of some of the predator species. Based on these results, we conclude that the recent anomalous observations about lack of cyclic lemming dynamics in eastern Greenland may well be the first signs of a severe impact of climate change on the lemmingpredator communities in Greenland and elsewhere in the high Arctic.
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1036 |
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Bachelor's thesis |
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Blackwell Publishing Ltd |
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1365-2486 |
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yes |
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2841 |
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