Snow and ice surfaces on King George Island (Antarctic Peninsula) with high-resolution TerraSAR-X time series, with links to shapfiles and GeoTIFFs

Changes of glaciers and snow cover in polar regions affect a wide range of physical and ecosystem processes on land and in the adjacent marine environment. In this study, we investigate the potential of 11-day repeat high-resolution satellite image time series from the TerraSAR-X mission to derive glaciological and hydrological parameters on King George Island, Antarctica during the period Oct/25/2010 to Apr/19/2011. The spatial pattern and temporal evolution of snow cover extent on ice-free areas can be monitored using multi-temporal coherence images. SAR coherence is used to map glacier extent of land terminating glaciers with an average accuracy of 25 m. Multi-temporal SAR color composites identify the position of the late summer snow line at about 220 m above sea level. Glacier surface velocities are obtained from intensity feature-tracking. Surface velocities near the calving front of Fourcade Glacier were up to 1.8 ± 0.01 m/d. Using an intercept theorem based on fundamental geometric principles together with differential GPS field measurements, the ice discharge of Fourcade Glacier was estimated to 20700 ± 5500 m**3/d (corresponding to ~19 ± 5 kt/d). The rapidly changing surface conditions on King George Island and the lack of high-resolution digital elevation models for the region remain restrictions for the applicability of SAR data and the precision of derived products.

Retreat of top cliff of Kurungnakh Island, Lena Delta, Siberia, Russia, 2010-2014, with links to shapefiles

Thawing-induced cliff top retreat in permafrost landscapes is mainly due to thermo-erosion. Ground-ice-rich permafrost landscapes are specifically vulnerable to thermo-erosion and may show high degradation rates. Within the HGF Alliance Remote Sensing and the FP7 PAGE21 permafrost programs we investigated how SAR and optical remote sensing can contribute to the monitoring of erosion rates of ice-rich cliffs in Arctic Siberia (Lena Delta, Russia). We produced two different vector products: i) Intra-annual cliff top retreat based on TerraSAR-X (TSX) satellite data (2012-2014): High-temporal resolution time series of TSX satellite data allow the inter-annual and intra-annual monitoring of the upper cliff-line retreat also under bad weather conditions and continuous cloud coverage. This published SAR product contains the retreating upper cliff lines of a 1.5 km long part of eroding ice-rich coast of Kurungnakh Island in the central Lena Delta. The upper cliff line was mapped using a thresholding approach for images acquired in the years 2012, 2013 and 2014 for the months June (2013, 2014), July (2013, 2014), August (2012, 2013, 2014) and September (2013, 2014). The cliff top retreat vector product is called 'upper_cliff_TerraSAR-X'. While the 2014 cliff lines show a clear retreat of 2 to 3 m/month, the cliff top lines for 2012 and 2013 are not chronologically ordered. However, lines from the end of the season of a year are always close to the lines from the beginning of the next summer season, indicating low cliff retreat in winter. ii) 4-year cliff top retreat based on optical satellite data (2010-2014): Long-term cliff top retreat could be assessed with two high-spatial resolution optical satellite images (GeoEye-1, 2010-08-05 and Worldview-1, 2014-08-19). The cliff top retreat vector product is called 'upper_cliff_optical'. Results: The long-term cliff top retreat derived from optical satellite data are 35 m cliff retreat within 4 years. The higher-temporal resolution SAR data equivalently show long-term rates of 18 m within 2 years and nearly now degradation activities in winter but maximum erosion rates in summer months.The Intra-seasonal cliff top retreat lines from 2014 show a rate of 2 to 3 m per month.

Images and animation of a complex microboring (Pyrodendrina cupra n. igen. and isp.) from the early Paleozoic of Anticosti Island, Canada

Three complementary imaging techniques were used to describe a complex rosette-shaped microboring that penetrates the shells of brachiopods from the Ordovician–Silurian shallow marine limestones of Anticosti Island, Canada. Pyrodendrina cupra n. igen. and isp. is among the oldest dendrinid microborings and consists of shallow and deep penetrating canals that radiate from a central polygonal chamber. The affinity of the tracemaker is unknown, but a foraminiferal origin, as proposed for some dendrinid borings, is rejected. Combining microCT with traditional stereomicroscopy and SEM helped distinguish and quantify fine morphological features while maintaining contextual information of the microboring within the shell substrate. Different imaging techniques inherently bias the description of microborings. These biases must be accounted for as new methods in ichnotaxonomy are integrated with past research based on different methods.

(Table 1) Stage of the lemming cycle and nesting parameters of the greater snow geese between 1996-2005, Bylot Island

Resource pulses are common in various ecosystems and often have large impacts on ecosystem functioning. Many animals hoard food during resource pulses, yet how this behaviour affects pulse diffusion through trophic levels is poorly known because of a lack of individual-based studies. Our objective was to examine how the hoarding behaviour of arctic foxes (Alopex lagopus) preying on a seasonal pulsed resource (goose eggs) was affected by annual and seasonal changes in resource availability. We monitored foraging behaviour of foxes in a greater snow goose (Chen caerulescens atlanticus) colony during 8 nesting seasons that covered 2 lemming cycles. The number of goose eggs taken and cached per hour by foxes declined 6-fold from laying to hatching, while the proportion of eggs cached remained constant. In contrast, the proportion of eggs cached by foxes fluctuated in response to the annual lemming cycle independently of the seasonal pulse of goose eggs. Foxes cached the majority of eggs taken (> 90%) when lemming abundance was high or moderate but only 40% during the low phase of the cycle. This likely occurred because foxes consumed a greater proportion of goose eggs to fulfill their energy requirement at low lemming abundance. Our study clearly illustrates a behavioural mechanism that extends the energetic benefits of a resource pulse. The hoarding behaviour of the main predator enhances the allochthonous nutrients input brought by migrating birds from the south into the arctic terrestrial ecosystem. This could increase average predator density and promote indirect interactions among prey.

At surface behaviour of adult male southern elephant seals from King George Island from expedition JUB2000

Adult male southern elephant seals instrumented in 2000 on King George Island (n = 13), travelled both to the north (doi:10.1594/PANGAEA.231580, doi:10.1594/PANGAEA.231585) and to the east (doi:10.1594/PANGAEA.231571, doi:10.1594/PANGAEA.231579, doi:10.1594/PANGAEA.261708, doi:10.1594/PANGAEA.261709, doi:10.1594/PANGAEA.261710, doi:10.1594/PANGAEA.261711) of the Antarctic Peninsula. Five males (doi:10.1594/PANGAEA.231571, doi:10.1594/PANGAEA.231579, doi:10.1594/PANGAEA.231580, doi:10.1594/PANGAEA.261710, doi:10.1594/PANGAEA.231585) remained within 500 km of the island and focusing movements in the Bransfield Strait and around the Antarctic Peninsula. Sea-surface temperatures encountered by these animals showed little variation and they seemed to move about irrespective of sea ice cover, but frequented areas of shallow bathymetry. Three males (doi:10.1594/PANGAEA.261708, doi:10.1594/PANGAEA.261709, doi:10.1594/PANGAEA.261711) moved as far as 75°S to the east of the peninsula, into the Weddell Sea, with maximum distances of more than 1500 km from King George Island. They travelled into the Weddell Sea along the western continental shelf break until they reached the region of the Filchner Trough outflow. Here the bathymetry consists of canyons and ridges which support the intensive mixing between the warm saline waters of the Weddell Gyre and the very cold outflow waters with Ice Shelf water ingredients at the Antarctic Slope Front. Another five data sets were shorter then 40 days, and excluded from analyses (doi:10.1594/PANGAEA.231568, doi:10.1594/PANGAEA.231576, doi:10.1594/PANGAEA.231572, doi:10.1594/PANGAEA.231577, doi:10.1594/PANGAEA.264710). A computer animation was developed to visualize the animal movements in relation to the extent and concentration of sea ice (doi:10.1594/PANGAEA.509404). The need for re-instrumentation of adult males from King George Island is highlighted to investigate whether males continue to travel to similar areas and to obtain higher resolution data.

Dive depth and dive duration data of subadult and adult, male and female southern elephant seals from Marion Island between 2004 and 2008 with links to datasets

Sexual segregation in habitat use occurs in a number of animal species, including southern elephant seals, where differences in migration localities and dive behaviour between sexes have been recorded. Due to the extreme sexual size dimorphism exhibited by southern elephant seals, it is unclear whether observed differences in dive behaviour are due to increased physiological capacity of males, compared to females, or differences in activity budgets and foraging behaviour. Here we use a mixed-effects modelling approach to investigate the effects of sex, size, age and individual variation on a number of dive parameters measured on southern elephant seals from Marion Island. Although individual variation accounted for substantial portions of total model variance for many response variables, differences in maximum and targeted dive depths were always influenced by sex, and only partly by body length. Conversely, dive durations were always influenced by body length, while sex was not identified as a significant influence. These results support hypotheses that physiological capability associated with body size is a limiting factor on dive durations. However, differences in vertical depth use appear to be the result of differences in forage selection between sexes, rather than a by-product of the size dimorphism displayed by this species. This provides further support for resource partitioning and possible avoidance of inter-sexual competition in southern elephant seals.