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Dragon Anne-Cecile, Monestiez P, Bar-Hen A, Guinet C, . (2010). Linking foraging behaviour to physical oceanographic structures: Southern elephant seals and mesoscale eddies east of Kerguelen Islands
. Progress In Oceanography, 87(14), 61–71.
Abstract: In the Southern Ocean, mesoscale features, such as fronts and eddies, have been shown to have a significant impact in structuring and enhancing primary productivity. They are therefore likely to influence the spatial structure of prey fields and play a key role in the creation of preferred foraging regions for oceanic top-predators. Optimal foraging theory predicts that predators should adjust their movement behaviour in relation to prey density. While crossing areas with sufficient prey density, we expect predators would change their behaviour by, for instance, decreasing their speed and increasing their turning frequency. Diving predators would as well increase the useful part of their dive i.e. increase bottom-time thereby increasing the fraction of time spent capturing prey. Southern elephant seals from the Kerguelen population have several foraging areas: in Antarctic waters, on the Kerguelen Plateau and in the interfrontal zone between the Subtropical and Polar Fronts. This study investigated how the movement and diving behaviour of 22 seals equipped with satellite-relayed data loggers changed in relation to mesoscale structures typical of the interfrontal zone. We studied the links between oceanographic variables including temperature and sea level anomalies, and diving and movement behaviour such as displacement speed, diving duration and bottom-time. Correlation coefficients between each of the time series were calculated and their significance tested with a parametric bootstrap. We focused on oceanographic changes, both temporal and spatial, occurring during behavioural transitions in order to clarify the connections between the behaviour and the marine environment of the animals. We showed that a majority of seals displayed a specific foraging behaviour related to the presence of both cyclonic and anticyclonic eddies. We characterized mesoscale oceanographic zones as either favourable or unfavourable based on the intensity of foraging activity as identified by the behavioural variables. Our findings highlight the importance of mesoscale features for top-predators behaviour and introduce a new approach for evaluating the importance to the seals of the origin and intensity of these features.
Programme: 109
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. (2019). Overcoming deterrent metabolites by gaining essential nutrients: A lichen/snail case study (Vol. 164). Bachelor's thesis, , .
Abstract: Specialised metabolites in lichens are generally considered repellent compounds by consumers. Nevertheless, if the only food available is lichens rich in specialised metabolites, lichenophages must implement strategies to overcome the toxicity of these metabolites. Thus, the balance between phagostimulant nutrients and deterrent metabolites could play a key role in feeding preferences. To further understand lichen-gastropod interactions, we studied the feeding behaviour and consumption in Notodiscus hookeri, the land snail native to sub-Antarctic islands. The lichen Usnea taylorii was used because of its simple chemistry, its richness in usnic acid (specialised metabolite) and arabitol (primary metabolite) and its presence in snail habitats. Choice tests in arenas with intact lichens versus acetone-rinsed lichens were carried out to study the influence of specialised metabolites on snail behaviour and feeding preference. Simultaneously, usnic acid and arabitol were quantified and located within the lichen thallus using HPLC-DAD-MS and in situ imaging by mass spectrometry to assess whether their spatial distribution explained preferential snail grazing. No-choice feeding experiments, with the pure metabolites embedded in an artificial diet, defined a gradual gustatory response, from strong repellence (usnic acid) to high appetence (D-arabitol). This case study demonstrates that the nutritional activity of N. hookeri is governed by the chemical quality of the food and primarily by nutrient availability (arabitol), despite the presence of deterrent metabolite (usnic acid).
Keywords: D-arabitol; Feeding choice; Lichen; Mass spectrometry imaging; Parmeliaceae; Snail; Usnic acid
Programme: 136
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G. Ekstrom, M Nettles, A.M. Dziewonski. (2012). The global CMT project 2004-2010: Centroid-moment tensors for 13,017 earthquakes. Physics of the Earth and Planetary Interiors, 200-201.
Keywords: Centroid-moment tensor; Earthquakes; Global seismicity
Programme: 133
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Okal Emile A, Stein Seth, . (2009). Observations of ultra-long period normal modes from the 2004 SumatraAndaman earthquake
. Physics of the Earth and Planetary Interiors, 175(12), 53–62.
Keywords: Sumatra-Andaman earthquake, Normal modes, Splitting,
Programme: 133
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. (2016). Linking morphometric and genetic divergence with host use in the tick complex, Ornithodoros capensis sensu lato (Vol. 46). Bachelor's thesis, , .
Abstract: Host specific adaptations in parasites can lead to the divergence of conspecific populations. However, this divergence can be difficult to measure because morphological changes may not be expressed or because obvious changes may simply reflect phenotypic plasticity. Combining both genetic and phenotypic information can enable a better understanding of the divergence process and help identify the underlying selective forces, particularly in closely-related species groups. Here, we link genetic and morphometric data to understand divergence patterns within the Ornithodoros (Carios) capensis complex, a group of soft ticks (Argasidae) exploiting colonial seabirds across the globe. Species designations in this complex were historically based on larval morphology and geographic location. However, recent work has suggested that divergence within the group may be at least partially linked to host specificity. We therefore first examined population genetic structure of ticks in relation to host use and geography. These analyses revealed strong structure in relation to host use, both when populations were sympatric and widely allopatric, with a secondary effect of geography. They also demonstrated the presence of several novel and presumably undescribed species exploiting these seabird hosts. We then used geometric morphometrics (landmark and outline analyses) to test whether host-associated genetic divergence is always accompanied by the same phenotypic changes. We found that morphological variation (size and shape) correlated well with genetic structure; tick size and shape varied strongly in relation to host type, and weakly with geography. These results support the hypothesis that speciation in this tick group has been more strongly shaped by host use than by geographic barriers per se. The revealed phenetic patterns now require detailed investigation to link them with host-specific selective forces.
Keywords: Adaptation Ectoparasite Host specificity Morphometry Population genetic structure Tropical seabirds
Programme: 109,1151
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. (2021). (Vol. 169). Bachelor's thesis, , .
Keywords: At-sea survey Frontal system Garbage patch Plastic litter Southern Indian Ocean
Programme: 109
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. (2014). Areas of importance for seabirds tracked from French southern territories, and recommendations for conservation
. Marine Policy, 48, 1–13.
Keywords: High Sea, Key areas, Marine Important Bird Area, Seabirds, Southern Ocean, Tracking,
Programme: 109;394
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. (2012). Comparative phylogeography of three trematomid fishes reveals contrasting genetic structure patterns in benthic and pelagic species
. Marine Genomics, 8, 23–34.
Abstract: Population genetics patterns of marine fish in general and of Southern Ocean fish in particular range from virtual panmixia over ocean-wide scale to deeply fragmented populations. However the causes underlying these different patterns are not properly understood. In this paper, we tested the hypotheses that population connectivity is positively related to a combination of life history traits, namely duration of pelagic larval period and the tendency towards pelagic life style in the adulthood. To do so, we analysed the variability of six microsatellite and one mitochondrial marker (cytochrome b) in three Southern Ocean fish species (Trematomus newnesi, Trematomus hansoni and Trematomus bernacchii). They share a recent common ancestor but notably differ in their duration of pelagic larval period as well as pelagic versus benthic lifestyle. We sampled over a range of more than 5000 km for all three species and used a number of population genetics tools to investigate past and contemporary levels of connectivity. All species experienced population fluctuations, but coalescent simulations suggested that contemporary populations are in migration-drift equilibrium. Although global FST values were rather low, a significant population structure separated the High-Antarctic from the Peninsular regions in all species. The level of genetic differentiation was much lower in the pelagic versus benthic species. Present data suggest that past and present genetic structuring in the Southern Ocean are indeed related with the ecological traits of Antarctic fish, however the relative importance of individual factors remains unclear.
Keywords: Microsatellite markers, Mitochondrial, Larval duration, Glaciations, Notothenioidei, Life history,
Programme: 1142
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. (2012). Specific pathways for the incorporation of dissolved barium and molybdenum into the bivalve shell: An isotopic tracer approach in the juvenile Great Scallop (Pecten maximus)
. Mar. Environ. Res., 78, 15–25.
Keywords: Isotopes, Femtosecond laser ablation, Scallop shell, Barium, Molybdenum, Pecten maximus, Tracers, Biogeochemical cycle,
Programme: 1090
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. (2018). Ediacaran to lower Cambrian basement in eastern George V Land (Antarctica): Evidence from U-Pb dating of gneiss xenoliths and implications for the South Australia-East Antarctica connection (Vol. 318-319). Bachelor's thesis, , .
Keywords: Antarctica-Australia connection George V Land; Gondwana margin; Ross orogeny; Zircon and monazite UPb dating
Programme: 1003
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