| Records |
| Author |
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| Title |
Fine-scale structures as spots of increased fish concentration in the open ocean |
Type |
Journal |
| Year |
2021 |
Publication |
Scientific Reports |
Abbreviated Journal |
|
| Volume |
11 |
Issue |
1 |
Pages |
15805 |
Keywords  |
Fisheries Marine biology Physical oceanography |
| Abstract |
Oceanic frontal zones have been shown to deeply influence the distribution of primary producers and, at the other extreme of the trophic web, top predators. However, the relationship between these structures and intermediate trophic levels is much more obscure. In this paper we address this knowledge gap by comparing acoustic measurements of mesopelagic fish concentrations to satellite-derived fine-scale Lagrangian Coherent Structures in the Indian sector of the Southern Ocean. First, we demonstrate that higher fish concentrations occur more frequently in correspondence with strong Lagrangian Coherent Structures. Secondly, we illustrate that, while increased fish densities are more likely to be observed over these structures, the presence of a fine-scale feature does not imply a concomitant fish accumulation, as other factors affect fish distribution. Thirdly, we show that, when only chlorophyll-rich waters are considered, front intensity modulates significantly more the local fish concentration. Finally, we discuss a model representing fish movement along Lagrangian features, specifically built for mid-trophic levels. Its results, obtained with realistic parameters, are qualitatively consistent with the observations and the spatio-temporal scales analysed. Overall, these findings may help to integrate intermediate trophic levels in trophic models, which can ultimately support management and conservation policies. |
| Programme |
109 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
|
Edition |
|
| ISSN |
2045-2322 |
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 |
|
Approved |
yes |
| Call Number |
|
Serial |
8384 |
| Permanent link to this record |
| |
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| |
| Author |
Anzhou Cao, Zheng Guo, Xiaoyu Qi, Peiliang Li, Hailun He |
| Title |
Seasonal and nodal variations of predominant tidal constituents in the global ocean |
Type |
Journal |
| Year |
2021 |
Publication |
Continental Shelf Research |
Abbreviated Journal |
|
| Volume |
217 |
Issue |
|
Pages |
104372 |
| Keywords |
Fitting Modified two-step harmonic analysis Nodal modulation Seasonal variation Tide gauge Tides |
| Abstract |
Tides are one of the basic types of ocean water motions. Previous studies have reported that the M2 constituent exhibits seasonal variations (annual cycles) in some regions. However, based on the newly proposed method of modified two-step harmonic analysis (HA) and its application at 240 global tide gauges, we find that the M2 constituent as well as the S2 and K1 do not have significant seasonal variations at these tide gauges. The seasonal variations of the M2 constituent reported in previous studies are caused by its satellites, the H1 and H2 constituents, which are not resolved in these studies due to the short time window (one month or three months) used in HA. Because the frequency of the H1 (H2) constituent is equal to that of the M2 minus (plus) the frequency of annual cycles, the superposition of the M2, H1 and H2 constituents with constant amplitudes is equivalent to the M2 constituent with seasonally varying amplitudes. Compared with the new method, some adaptations to traditional HA aiming to capture variations in amplitudes and phase lags of constituents have some limitations, because they either neglect some satellites of the major constitutes or introduce spurious fluctuations resulting from an unreasonably large number of independent points. The nodal modulations of predominant constituents are also explored in this study. On the global scale, the nodal modulations of the M2, K1 and O1 constituents agree with the theoretical predictions, except a cold spot region with reduced nodal modulation in the Gulf of Maine and a hot spot region with enhanced nodal modulation in the South China Sea for the M2. Nodal modulation is also found for the S2 constituent (in theory, the S2 has no nodal modulation), which is 0.8% averaged at 164 tide gauges where the S2 is not too weak. |
| Programme |
688 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
0278-4343 |
ISBN |
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Medium |
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| Area |
|
Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
8032 |
| Permanent link to this record |
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| |
| Author |
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| Title |
Using Reciprocal Transplants to Assess Local Adaptation, Genetic Rescue, and Sexual Selection in Newly Established Populations |
Type |
Journal |
| Year |
2021 |
Publication |
Genes |
Abbreviated Journal |
|
| Volume |
12 |
Issue |
1 |
Pages |
5 |
| Keywords |
gene flow genetic rescue local adaptation mating success small population |
| Abstract |
Small populations establishing on colonization fronts have to adapt to novel environments with limited genetic variation. The pace at which they can adapt, and the influence of genetic variation on their success, are key questions for understanding intraspecific diversity. To investigate these topics, we performed a reciprocal transplant experiment between two recently founded populations of brown trout in the sub-Antarctic Kerguelen Islands. Using individual tagging and genetic assignment methods, we tracked the fitness of local and foreign individuals, as well as the fitness of their offspring over two generations. In both populations, although not to the same extent, gene flow occurred between local and foreign gene pools. In both cases, however, we failed to detect obvious footprints of local adaptation (which should limit gene flow) and only weak support for genetic rescue (which should enhance gene flow). In the population where gene flow from foreign individuals was low, no clear differences were observed between the fitness of local, foreign, and F1 hybrid individuals. In the population where gene flow was high, foreign individuals were successful due to high mating success rather than high survival, and F1 hybrids had the same fitness as pure local offspring. These results suggest the importance of considering sexual selection, rather than just local adaptation and genetic rescue, when evaluating the determinants of success in small and recently founded populations. |
| Programme |
1041 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
|
ISBN |
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Medium |
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| Area |
|
Expedition |
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Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
|
Serial |
8179 |
| Permanent link to this record |
| |
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| |
| Author |
|
| Title |
Comparison of interferometer calibration techniques for improved SuperDARN elevation angles |
Type |
Journal |
| Year |
2021 |
Publication |
Polar Science |
Abbreviated Journal |
|
| Volume |
28 |
Issue |
|
Pages |
100638 |
| Keywords |
Geolocation HF radar Interferometer calibration Ionosphere SuperDARN |
| 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. |
| Programme |
312 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
|
Edition |
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| ISSN |
1873-9652 |
ISBN |
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Medium |
|
| Area |
|
Expedition |
|
Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
|
Serial |
8088 |
| Permanent link to this record |
| |
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| |
| Author |
|
| Title |
Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field |
Type |
Journal |
| Year |
2021 |
Publication |
Earth, Planets and Space |
Abbreviated Journal |
|
| Volume |
73 |
Issue |
1 |
Pages |
48 |
| Keywords |
Geomagnetism IGRF Magnetic field modeling |
| Abstract |
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| Programme |
139 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Summary Language |
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Original Title |
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| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
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| ISSN |
1880-5981 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
|
Serial |
7937 |
| Permanent link to this record |
| |
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| |
| Author |
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| Title |
International Geomagnetic Reference Field: the thirteenth generation |
Type |
Journal |
| Year |
2021 |
Publication |
Earth, Planets and Space |
Abbreviated Journal |
|
| Volume |
73 |
Issue |
1 |
Pages |
49 |
| Keywords |
Geomagnetism IGRF Magnetic field modeling |
| Abstract |
In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted the thirteenth generation of the International Geomagnetic Reference Field (IGRF). This IGRF updates the previous generation with a definitive main field model for epoch 2015.0, a main field model for epoch 2020.0, and a predictive linear secular variation for 2020.0 to 2025.0. This letter provides the equations defining the IGRF, the spherical harmonic coefficients for this thirteenth generation model, maps of magnetic declination, inclination and total field intensity for the epoch 2020.0, and maps of their predicted rate of change for the 2020.0 to 2025.0 time period. |
| Programme |
139 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
1880-5981 |
ISBN |
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Medium |
|
| Area |
|
Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
|
Serial |
8085 |
| Permanent link to this record |
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| |
| Author |
O. Alemany, P. Talalay, P. Boissonneau, J. Chappellaz, J. F. Chemin, R. Duphil, E. Lefebvre, L. Piard, P. Possenti, J. Triest |
| Title |
The SUBGLACIOR drilling probe: hydraulic considerations |
Type |
Journal |
| Year |
2021 |
Publication |
Annals of Glaciology |
Abbreviated Journal |
|
| Volume |
62 |
Issue |
84 |
Pages |
131-142 |
| Keywords |
Glaciological instruments and methods ice coring ice engineering paleoclimate |
| Abstract |
Using significant technological breakthroughs and unconventional approaches, the goal of the in situ probing of glacier ice for a better understanding of the orbital response of climate (SUBGLACIOR) project is to advance ice core research by inventing, constructing and testing an in situ probe to evaluate if a target site is suitable for recovering ice as old as 1.5 million years. Embedding a laser spectrometer, the probe is intended to make its own way down into the ice and to measure, in real time and down to the bedrock, the depth profiles of the ice ?D water isotopes as well as the trapped CH4 gas concentration and dust concentration. The probe descent is achieved through electromechanical drilling combined with continuous meltwater sample production using a central melting finger in the drill head. A key aspect of the project lies in the design and implementation of an efficient method to continuously transfer to the surface the ice chips being produced by the drill head and from the refreezed water expulsed downstream from the melting finger, into the borehole. This paper presents a detailed calculation and analysis of the flow rates and pressure conditions required to overcome friction losses of the drilling fluid and to effectively transport ice chips to the surface. |
| Programme |
119 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
0260-3055, 1727-5644 |
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 |
|
Approved |
yes |
| Call Number |
|
Serial |
8234 |
| Permanent link to this record |
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| |
| Author |
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| Title |
Impact of extreme environmental conditions: Foraging behaviour and trophic ecology responses of a diving seabird, the common diving petrel |
Type |
Journal |
| Year |
2021 |
Publication |
Progress in Oceanography |
Abbreviated Journal |
|
| Volume |
198 |
Issue |
|
Pages |
102676 |
| Keywords |
GPS tracking Habitat modelling Inter-annual variation Marine heatwave Stable isotopes |
| Abstract |
The reproductive success of birds is strongly driven by environmental conditions at different time scales. Thus, during periods of low food availability, breeding success is constrained by the ability of adults to adapt their foraging effort and feeding behaviour to maintain regular incubation shifts and chick provisioning. However, while large seabirds can buffer disruptions in prey availability, the ecophysiological constraints of smaller species may limit their behavioural flexibility. By combining information on at-sea movements, foraging habitat, trophic niche, and breeding success, this study evaluated the effects of intense variability in oceanographic conditions on common diving petrels (Pelecanoides urinatrix) at the northern extent of their range in south-eastern Australia during four consecutive breeding seasons. Unusually low breeding success (6 and 0%) was observed during two years with intense heatwave events, which were associated with higher foraging effort (foraging trips twice longer) and a substantial shift in trophic niche (lower blood ?15N values). These findings suggest that common diving petrels in Bass Strait may have reached a critical threshold above which buffering the effects of environmental variability on their reproductive output is not possible. The clear cascading impacts that marine heatwaves have on zooplankton feeders illustrate the profound bottom-up effect induced by such extreme environmental variations, and suggest strong impact on higher-trophic levels. The wide, circumpolar breeding distribution of the common diving petrel, and its high sensitivity to variations in oceanographic conditions, suggest that this species may be a suitable model to study short-term and long-term behavioural responses to the effects of climate change throughout the Southern Ocean. |
| Programme |
109 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Summary Language |
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Original Title |
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| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
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| ISSN |
0079-6611 |
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 |
|
Approved |
yes |
| Call Number |
|
Serial |
8374 |
| Permanent link to this record |
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| |
| Author |
|
| Title |
Individual migration strategy fidelity but no habitat specialization in two congeneric seabirds |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Biogeography |
Abbreviated Journal |
|
| Volume |
48 |
Issue |
2 |
Pages |
263-275 |
| Keywords |
guillemots light-level geolocation murres Uria aalge Uria lomvia |
| Abstract |
|
| Programme |
388 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Summary Language |
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Original Title |
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| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1365-2699 |
ISBN |
1365-2699 |
Medium |
|
| Area |
|
Expedition |
|
Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
|
Serial |
8025 |
| Permanent link to this record |
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| |
| Author |
|
| Title |
Scouring by rafted ice and cryogenic patterned ground preserved in a Palaeoproterozoic equatorial proglacial lagoon succession, eastern India, Nuna supercontinent |
Type |
Journal |
| Year |
2021 |
Publication |
Marine and Petroleum Geology |
Abbreviated Journal |
|
| Volume |
123 |
Issue |
|
Pages |
104766 |
| Keywords |
Ice-rafted debris Iceberg scouring India Palaeoproterozoic Permafrost Proglacial Reticulate ice |
| Abstract |
|
| Programme |
316 |
| Campaign |
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| Address |
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| Corporate Author |
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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 |
|
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 |
0264-8172 |
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 |
|
Approved |
yes |
| Call Number |
|
Serial |
6471 |
| Permanent link to this record |
