Abstract: The global climate shift currently underway has significant impacts on both the quality and quantity of snow precipitation. This directly influences the spatial variability of the snowpack as well as cumulative snow height. Contemporary glacier retreat reorganizes periglacial morphology: while the glacier area decreases, the moraine area increases. The latter is becoming a new water storage potential that is almost as important as the glacier itself, but with considerably more complex topography. Hence, this work fills one of the missing variables of the hydrological budget equation of an arctic glacier basin by providing an estimate of the snow water equivalent (SWE) of the moraine contribution. Such a result is achieved by investigating Structure from Motion (SfM) image processing that is applied to pictures collected from an Unmanned Aerial Vehicle (UAV) as a method for producing snow depth maps over the proglacial moraine area. Several UAV campaigns were carried out on a small glacial basin in Spitsbergen (Arctic): the measurements were made at the maximum snow accumulation season (late April), while the reference topography maps were acquired at the end of the hydrological year (late September) when the moraine is mostly free of snow. The snow depth is determined from Digital Surface Model (DSM) subtraction. Utilizing dedicated and natural ground control points for relative positioning of the DSMs, the relative DSM georeferencing with sub-meter accuracy removes the main source of uncertainty when assessing snow depth. For areas where snow is deposited on bare rock surfaces, the correlation between avalanche probe in-situ snow depth measurements and DSM differences is excellent. Differences in ice covered areas between the two measurement techniques are attributed to the different quantities measured: while the former only measures snow accumulation, the latter includes all of the ice accumulation during winter through which the probe cannot penetrate, in addition to the snow cover. When such inconsistencies are observed, icing thicknesses are the source of the discrepancy that is observed between avalanche probe snow cover depth measurements and differences of DSMs.

Abstract: The action of predators, such as diurnal raptors, owls, mammals or humans, influence the nature of small vertebrate fossil assemblages but currently their taphonomic features are still poorly understood. In this study, we investigate the taphonomic signature of the snowy owl (Bubo scandiacus) based on an analysis of pellets collected at breeding sites located in Greenland and the Canadian Arctic. This taxon is widely distributed through the North Hemisphere and was an important predator in Pleistocene times. Taphonomic parameters suggest that, contrary to previous assumptions, B. scandiacus produces, on average, moderate digestion of incisors, molars and post-cranial elements, and should be classed as a Category 3 or Category 3/4 predator according to the terminology established by Andrews. Significant inter-site variability was observed for some of the damage considered (in particular, digestion on incisors), and a key finding is that variability and the associated statistical confidence intervals are crucial notions that should be taken into account when assessing taphonomical features, in order to reliably identify the potential predator(s) responsible for small vertebrate fossil accumulations.

Abstract: Kerguelen Islands harbor a unique, probably very ancient flora with a high rate of endemism. However, the evolutionary history and characteristics of this flora still require investigation. This concerns in particular genome size and ploidy level variation, despite the evolutionary and ecological significance of those traits. Here we report the first assessment of genome size, using flow cytometry, for eight plant species of which two are endemics of Kerguelen Islands and four of the South Indian Ocean Province. The 2C DNA value ranged from 1.08 pg for Pringlea antiscorbutica to 11.88 pg for Ranunculus biternatus. The chromosome numbers of Colobanthus kerguelensis (2n?=?80), Lyallia kerguelensis (2n?=?96) and Poa kerguelensis (2n?=?28) were also reported in this study for the first time. Overall, our data allowed to infer that all Kerguelen studied species are polyploid (from tetra- to octopolyploid). Intra-genus comparisons showed significant differences of 2C DNA values among Poa and among Ranunculus species, despite their identical ploidy level. In addition, our data highlight the existence of an intraspecific variability of genome size for the two octoploid species Colobanthus kerguelensis and Lyallia kerguelensis. Finally, our data also support the hypothesis regarding which polyploidy may have played a major role in the adaptation of flowering plants to high latitudes, as it has been suggested for arctic species.