Flexibility in Antarctic krill Euphausia superba decouples diet and recruitment from overwinter sea-ice conditions in the northern Antarctic Peninsula

Winter sea-ice conditions are considered important for Antarctic krill Euphausia superba survival and recruitment, yet few broad-scale longitudinal studies have examined the underlying relationships between winter conditions and krill recruitment. We used data from a 4 yr winter study of krill condition (lipid content), diet (stable isotopes and fatty acids), and length distributions around the northern Antarctic Peninsula to examine relationships among environmental variables (annual sea-ice cover, water column chlorophyll a [chl a], and upper mixed-layer water temperature), the condition and diet of krill, and recruitment success the following year. Diet indicators (lipid content, δ15N, δ13C, and the fatty acid ratios 16:1n-7/18:4n-3 and 18:1n-9/18:1n-7) in post-larvae were consistent among years regardless of sea-ice cover, suggesting that post-larval krill do not rely on sea-ice resources for overwinter survival. Diet indicators in larvae were more variable and suggest that larvae may feed on sea-ice resources when they are available but can still persist in the water column when they are not. Principal component analysis between environmental variables and diet indicators showed that water-column chl a was the only variable that significantly affected diet, regardless of annual changes in sea-ice cover. Extensive winter ice in one year did not translate into successful recruitment the following year. Krill demonstrate a high degree of flexibility with respect to overwinter habitat and diet, and the degree to which sea ice is important during different times of year and at different life stages may be more complex than previously thought.

The first steps in the earth aerospace remote sensing in the Institute of Geography RAS

Fifty years ago, in the autumn of 1968, experiments on interpretation of the first Soviet global space image made by ‘Zond-5’ automatic spacecraft and of American space images from Gemini III, IV, V piloted spacecrafts were carried out for the first time in the USSR. The aim of these experiments was the study of possibilities to use satellite images in geomorphology and geography. The first results demonstrated high value of space images for geomorphological research for the studies of morphostructures and morphosculptures of various genesis, the discovery of a 2500 km long lineament in Sahara; real time-related transitive borders of latitudinal landscape zones in Africa were indicated for the first time. It was suggested that satellite images could be applied for the studies of various geological structures, seismicity, volcanic activity, global and regional zones of jointing as well as for thematic mapping. Thanks to these studies a new Department of Satellite-related Geography was established at the Institute of Geography of the USSR Academy of Sciences. Later on, studies were carried out at the Institute’s Department of Satellite-related Geography in order to find application possibilities of TV multispectral scanned and photographic satellite images for thematic research and mapping. The first conclusions were confirmed in the course of further studies in the field of aerospace remote sensing in Russia and abroad; their results were summarized in two fundamental atlases published under the auspices of the Institute of Geography of the Russian Academy of Sciences (IGRAS): “Resources and Environment World Atlas” (1998) and “World Atlas of Snow and Ice Resources” (1997). Up to date, methods of aerospace remote sensing continue to be applied successfully at IGRAS for geomorphological studies and for resolving of environmental problems in physical and human geography.