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Title  |
Contribution of toothfish depredated on fishing lines to the energy intake of killer whales off the Crozet Islands: a multi-scale bioenergetic approach |
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Journal |
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Year |
2021 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
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Volume |
668 |
Issue |
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Pages |
149-161 |
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Keywords |
Bioenergetic model Depredation Dissostichus eleginoides Ecosystem-based management Fisheries interaction Marine mammals Orcinus orca Top predator conservation |
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Abstract |
Fisheries modify prey availability for marine predators by extracting resources but also by providing them with new feeding opportunities. Among these, depredation, which occurs when predators feed on fish caught on fishing gear, is a behavior developed by many species as a way to acquire food through limited foraging effort. However, the extent to which depredated resources from fisheries contribute to the energetic requirements and affect the demography of depredating individuals is unknown. We investigated the contribution of Patagonian toothfish Dissostichus eleginoides depredated on longlines to the energetic requirements of killer whales Orcinus orca around the Crozet Islands (southern Indian Ocean) over the period 2007-2018. Our results indicate that during days when depredation occurred, depredating individuals fulfilled on average 94.1% of their daily energetic requirements with depredated toothfish. However, the contribution varied from 1.2 to 13.3% of the monthly energetic requirements and from 2.4 to 8.8% of the yearly energetic requirements of the total population. Together, these findings suggest that intake of depredated toothfish can be substantial at a fine scale (daily and individually), potentially leading to temporary provisioning effects and changes in predation pressures. These effects become minor (<10%), however, when considering the full population over a whole year. The contribution of depredated fish to the annual energetic requirements of the population has increased in recent years, likely due to larger fishing quotas and greater opportunities for whales to depredate, which stresses the importance of accounting for depredation in ecosystem-based management of fishing activity. |
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109 |
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0171-8630, 1616-1599 |
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yes |
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8335 |
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Title |
Contrasting Spatial and Seasonal Trends of Methylmercury Exposure Pathways of Arctic Seabirds: Combination of Large-Scale Tracking and Stable Isotopic Approaches |
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Journal |
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Year |
2021 |
Publication |
Environmental Science & Technology |
Abbreviated Journal |
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Volume |
54 |
Issue |
21 |
Pages |
13619-13629 |
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388 |
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0013-936X |
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yes |
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8023 |
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Title |
Contrasting Manual and Automated Assessment of Thermal Stress Responses and Larval Body Size in Black Soldier Flies and Houseflies |
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Journal |
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Year |
2021 |
Publication |
Insects |
Abbreviated Journal |
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Volume |
12 |
Issue |
5 |
Pages |
380 |
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Keywords |
Hermetia illucens Musca domestica acclimation automated phenotyping heat and cold tolerance |
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Abstract |
Within ecophysiological and genetic studies on insects, morphological and physiological traits are commonly assessed and phenotypes are typically obtained from manual measurements on numerous individuals. Manual observations are, however, time consuming, can introduce observer bias and are prone to human error. Here, we contrast results obtained from manual assessment of larval size and thermal tolerance traits in black soldier flies (Hermetia illucens) and houseflies (Musca domestica) that have been acclimated under three different temperature regimes with those obtained automatically using an image analysis software (Noldus EthoVision XT). We found that (i) larval size estimates of both species, obtained by manual weighing or by using the software, were highly correlated, (ii) measures of heat and cold tolerance using manual and automated approaches provided qualitatively similar results, and (iii) by using the software we obtained quantifiable information on stress responses and acclimation effects of potentially higher ecological relevance than the endpoint traits that are typically assessed when manual assessments are used. Based on these findings, we argue that automated assessment of insect stress responses and largescale phenotyping of morphological traits such as size will provide new opportunities within many disciplines where accurate and largescale phenotyping of insects is required. |
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136 |
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2075-4450 |
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yes |
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Serial |
8299 |
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Author |
Guillaume Hubert |
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Title |
Continuously Measurements of Energy Spectra of Cosmic-Ray-induced-neutrons on the Concordia Antarctic Station for the period 2015-2021 |
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Journal |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Volume |
395 |
Issue |
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Pages |
1263 |
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Abstract |
The CHINSTRAP (Continuous High-altitude Investigation of the Neutron Spectra for Terrestrial Radiation Antarctic Project) supported by the French Polar Agency (IPEV) aims at recording cosmic-ray (CR) induced-neutron spectra at the Concordia station since December 2015. The neutron spectrometer measures the neutron spectrum over a wide energy range from meV up to tens of GeV with a short time resolution. Several parameters can influence the measurement, including systematic and environmental effects such as the atmospheric pressure, the hydrometric environment close to the instrument and the atmospheric water vapor. This paper presents CR induced neutrons measurements analyses from 2015 to 2021 in Concordia, integrating corrections to take into account environmental and systematic effects. Long-term and short-term analyses are proposed, applied to count rate, fluxes and spectra. A last part investigates the contribution of modelling to data analyses and the ability to deduce the solar modulation from neutron spectra and the radiation field extrapolation using nuclear transport in atmosphere. An underlying objective is also to improve physical models allowing analyses of continuous and simultaneously measurements of CR induced neutrons spectra. |
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1112 |
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yes |
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Call Number |
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Serial |
8516 |
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Title |
Contextual variations in calls of two nonoscine birds: the blue petrel Halobaena caerulea and the Antarctic prion Pachyptila desolata |
Type |
Journal |
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Year |
2021 |
Publication |
Behavioral Ecology |
Abbreviated Journal |
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Volume |
32 |
Issue |
4 |
Pages |
769-779 |
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Abstract |
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Programme |
354 |
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ISSN |
1045-2249 |
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yes |
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Call Number |
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Serial |
8259 |
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Author |
Chastel O., Blévin P., Humann?Guilleminot S., Helfenstein F., Tartu S., Angelier F., Sebastiano M., Costantini D., Shaffer S., Bustamante P., Labadie P., Budzinski H., Herzke D., Moe B., Bustnes J.O., Gabrielsen G.W. |
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Title |
Contaminants of growing concern: Poly- and Perfluoroalkylated Substances (PFAS) and their physiological consequences in seabirds |
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Peer-reviewed symposium |
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Year |
2021 |
Publication |
World seabird conference virtual meeting, October 4-8, 2021 |
Abbreviated Journal |
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Programme |
330 |
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yes |
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Call Number |
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Serial |
8334 |
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Title |
Constraining 20th-Century Sea-Level Rise in the South Atlantic Ocean |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JC016970 |
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Keywords |
data rescue salt-marsh proxies sea-level changes South Atlantic tide gauges |
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Abstract |
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Programme |
688 |
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ISSN |
2169-9291 |
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yes |
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Call Number |
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Serial |
8603 |
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Author |
Hajo Eicken, Finn Danielsen, Josephine-Mary Sam, Maryann Fidel, Noor Johnson, Michael K Poulsen, Olivia A Lee, Katie V Spellman, Lisbeth Iversen, Peter Pulsifer, Martin Enghoff |
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Title |
Connecting Top-Down and Bottom-Up Approaches in Environmental Observing |
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Journal |
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Year |
2021 |
Publication |
BioScience |
Abbreviated Journal |
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Volume |
71 |
Issue |
5 |
Pages |
467-483 |
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Programme |
1090,1206 |
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Thesis |
Bachelor's thesis |
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ISSN |
0006-3568 |
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yes |
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Call Number |
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Serial |
8249 |
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Author |
Steven Franke, Daniela Jansen, Sebastian Beyer, Niklas Neckel, Tobias Binder, John Paden, Olaf Eisen |
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Title |
Complex Basal Conditions and Their Influence on Ice Flow at the Onset of the Northeast Greenland Ice Stream |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Earth Surface |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JF005689 |
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Keywords |
basal roughness bed conditions Greenland Ice Sheet ice stream Northeast Greenland Ice Stream radio-echo sounding |
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Abstract |
Abstract The ice stream geometry and large ice surface velocities at the onset region of the Northeast Greenland Ice Stream (NEGIS) are not yet well reproduced by ice sheet models. The quantification of basal sliding and a parametrization of basal conditions remains a major gap. In this study, we assess the basal conditions of the onset region of the NEGIS in a systematic analysis of airborne ultra-wideband radar data. We evaluate basal roughness and basal return echoes in the context of the current ice stream geometry and ice surface velocity. We observe a change from a smooth to a rougher bed where the ice stream widens, and a distinct roughness anisotropy, indicating a preferred orientation of subglacial structures. In the upstream region, the excess ice mass flux through the shear margins is evacuated by ice flow acceleration and along-flow stretching of the ice. At the downstream part, the generally rougher bed topography correlates with a decrease in flow acceleration and lateral variations in ice surface velocity. Together with basal water routing pathways, this hints to two different zones in this part of the NEGIS: the upstream region collecting water, with a reduced basal traction, and downstream, where the ice stream is slowing down and is widening on a rougher bed, with a distribution of basal water toward the shear margins. Our findings support the hypothesis that the NEGIS is strongly interconnected to the subglacial water system in its onset region, but also to the subglacial substrate and morphology. |
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Programme |
1180 |
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ISSN |
2169-9003 |
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yes |
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Serial |
7272 |
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Title |
Comparison of interferometer calibration techniques for improved SuperDARN elevation angles |
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Journal |
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Year |
2021 |
Publication |
Polar Science |
Abbreviated Journal |
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Volume |
28 |
Issue |
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Pages |
100638 |
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Keywords |
Geolocation HF radar Interferometer calibration Ionosphere SuperDARN |
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Abstract |
The high frequency radars in the Super Dual Auroral Radar Network (SuperDARN) estimate the elevation angles of returned backscatter using interferometric techniques. These elevation angles allow the ground range to the scattering point to be estimated, which is crucial for the accurate geolocation of ionospheric measurements. For elevation angles to be accurately estimated, it is important to calibrate the interferometer measurements by determining the difference in the signal time delays caused by the difference in the electrical path lengths from the main array and the interferometer array to the point at which the signals are correlated. This time delay is known as tdiff. Several methods have been proposed to estimate tdiff using historical observations; these methods are summarised in this paper. Comparisons of the tdiff estimates from the different calibration methods are presented and sources of uncertainty discussed. The effect of errors in the estimated tdiff value on the accuracy of geolocation is evaluated and discussed. The paper concludes with a series of recommendations for both scientific SuperDARN data users and SuperDARN radar operators. |
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312 |
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ISSN |
1873-9652 |
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yes |
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Call Number |
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Serial |
8088 |
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