Univ., Diss.--Münster, 1999. / Literaturverz. S. 167 - 182. Nebent.: Zum geologischen Aufbau von NW Spitzbergen.

Th.--Lett. et sci. hum.--Paris--EHESS, 1987. / Bibliogr. p. 317-325.

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L’Arctique s’est réchauffé rapidement et il y a urgence d’anticiper les effets que cela pourrait avoir sur les protistes à la base de la chaîne alimentaire. Le phytoplancton de l’Océan Arctique inclut les pico- et nano-eucaryotes (0.45-10 μm diamètre de la cellule) et plusieurs de ceux-ci sont des écotypes retrouvés seulement dans l’Arctique alors que d’autres sont introduits des océans plus méridionaux. Alors que les océans tempérés pénètrent dans l’Arctique, il devient pertinent de savoir si ces communautés microbiennes pourraient être modifiées. L’archipel du Svalbard est une région idéale pour observer la biogéographie des communautés microbiennes sous l’influence de processus polaires et tempérés. Bien qu’ils soient géographiquement proches, les régions côtières entourant le Svalbard sont sujettes à des intrusions alternantes de masses d’eau de l’Arctique et de l’Atlantique en plus des conditions locales. Huit sites ont été échantillonnés en juillet 2013 pour identifier les protistes selon un gradient de profondeur et de masses d’eau autour de l’archipel. En plus des variables océanographiques standards, l’eau a été échantillonnée pour synthétiser des banques d’amplicons ciblant le 18S SSU ARNr et son gène pour ensuite être séquencées à haut débit. Cinq des sites d’étude avaient de faibles concentrations de chlorophylle avec des compositions de communauté post-efflorescence dominée par les dinoflagellés, ciliés, des alvéolés parasites putatifs, chlorophycées et prymnesiophytées. L’intrusion des masses d’eau et les conditions environnementales locales étaient corrélées avec la structure des communautés ; l’origine de la masse d’eau contribuant le plus à la distance phylogénétique des communautés microbiennes. Au sein de trois fjords, de fortes concentrations de chlorophylle sous-entendaient des activités d’efflorescence. Un fjord était dominé par Phaeocystis, un deuxième par un clade arctique identifié comme un Pelagophyceae et un troisième par un assemblage mixte. En général, un signal fort d’écotypes liés à l’Arctique prédominait autour du Svalbard. / The Arctic is warming rapidly and there is an urgent need to anticipate the effect this will have on the microbial eukaryotes at the base of the food chain. Arctic Ocean phytoplankton include pico- and nano-eukaryotes (0.45-10 μm cell size), many of these are unique ecotypes found only in the Arctic, but others are advected in from lower latitude oceans. As temperate oceans waters penetrate further into the Arctic, knowledge of whether microbial communities could be displaced is needed. Svalbard is an ideal region to address questions on microbial communities under the influence of polar and temperate processes. Although geographically close, the fjords and offshore regions surrounding Svalbard are subjected to alternate intrusions of Atlantic and Arctic waters in addition to local conditions. Eight sites were surveyed in July 2013 with the aim of identifying microbial eukaryotes at a range of depths and water masses around Svalbard. In addition to standard oceanographic variables, seawater was collected for targeted amplicon libraries based on the 18S SSU rRNA gene and rRNA using high throughput amplicon sequencing. Five of the sites had low chlorophyll concentrations with typical post bloom summer communities; dinoflagellates, ciliates, putative alveolate parasites, chlorophytes and prymnesiophytes. Intrusive water masses and local environmental conditions correlated to community structure, with the origin of the water mass contributing most to the phylogenetic distance of the microbial communities. In three of the fjords, chlorophyll concentrations were high, consistent with a bloom. One fjord was dominated by Phaeocystis, a second by a putative Arctic clade of Pelagophyceae, and the third by mixed species. Overall, a strong signal of Arctic ecotypes prevailed around Svalbard.

Glacier surges are amongst the most dynamic of glaciological phenomena, but their controlling mechanisms remain incompletely understood. Surging glaciers are characterised by cyclical flow instabilities and the rapid transfer of ice to the ablation area, typically resulting in significant mass loss. The High-Arctic archipelago of Svalbard is one of several regions in the northern hemisphere which contain a high-density of surge-type glaciers, variously estimated to be between 13-90% of the total glacier population across the islands. Developing a better understanding of which of these figures, if either, is most realistic is important in the context of glacier dynamics and related contributions of small glaciers and ice caps to sea level change in the immediate future. This study presents detailed assessments of the margins of several known surge-type glaciers in Svalbard in order to update and improve the existing framework by which they are identified, and to provide a foundation for future reassessments of the surge-type glacier population based on distinct ice-sediment-landform assemblages. A range of techniques is utilised, including geomorphological and structural glaciological mapping, sedimentological analysis, basal ice descriptions, and stable isotope analysis. This work provides further insight into diagnostic indicators of surge behaviour preserved in basal ice sequences; provides links between surge dynamics and basal ice sequences, the glaciological structure and the landform record; and investigates the structural and tectonic development of surge-type glaciers. Based on this, surge landsystems are proposed for: (1) small valley glaciers, (2) large land-terminating glaciers, and (3) large tidewater glaciers. It is suggested that these three landsystems, with some variability, broadly characterise the geomorphology of the vast majority of known Svalbard surge-type glaciers and, in conjunction with structural glaciological and basal ice investigations where relevant, may allow previously unknown surge-type glaciers to be identified in the field, from aerial photographs, and on sea floor imagery. This work adds to the existing repertoire of modern analogues and the breadth of surging glacier landsystems, and provides a holistic basis for assessing possible palaeo-surge behaviour within the Quaternary record.

The study was aimed to obtain basic information about the distribution of intestinal parasites of mammals and birds in Svalbard. Faeces of different species were used to detect intestinal parasites. All samples were collected during two seasons and examined by microscopic methods and molecular diagnostic was used for detection of microsporidia, cryptosporidia, coccidia and giardiae.

Plankton are generally considered good indicators for ocean climate variability, but plankton data from the Arctic are still comparatively scarce. Due to this scarcity of information, the prevalence of vertical migration behaviour at high latitude is still debated. Atlantic inflow is a key process governing biological diversity in the Arctic Ocean, and the location of the Svalbard archipelago makes it an ideal study area to monitor this inflow. Comparing the zooplankton community within the fjords of Svalbard at various latitudes allowed us to assess the influence of Atlantic inflow and any subsequent changes in zooplankton composition that may have implications for higher trophic levels. Using sediment traps deployed on oceanic moorings, Chapter 3 of this thesis analysed long term observations from sea-ice dominated Rijpfjorden for the first time, and compared the zooplankton to Atlantic Water influenced Kongsfjorden. Chapters 4 and 5 investigated the spatial relevance of our moored observations using shipboard observations, and chapters 6 and 7 present observations of vertical migration across a range of conditions. Kongsfjorden was dominated by Calanus copepods associated with Arctic and Atlantic water, and strongly influenced by Atlantic Water advection. Rijpfjorden was largely influenced by sea-ice formation with higher proportional abundances of macrozooplankton species. Advection brought Atlantic associated species into Rijpfjorden during warmer years. Prevailing hydrology and bathymetry were highlighted as factors forcing zooplankton distribution, while advection was identified as responsible for much of the observed small scale spatial variation amongst weaker swimmers. At an aggregation scale of 0.5 nautical miles, zooplankton distribution was highly patchy and moored observations could only be reliably expanded outwards to a maximum of 1 nautical mile. Low amplitude diel vertical migration (especially by younger copepodids) was identified in surface waters when a food source was available. These observations must be considered within the dynamic framework of advection highlighted by this thesis.

Glaciers and ice caps (GIC) are central parts of the hydrological cycle, are key to understanding regional and global climate change, and are important contributors to global sea level rise, regional water resources and local biodiversity. Multispectral (visible and near-infrared) remote sensing has been used for studying GIC and their changing characteristics for several decades. Glacier surfaces can be classified into a range of facies, or zones, which can be used as proxies for annual mass balance and also play a significant role in understanding glacier energy balance. However, multispectral sensors were not designed explicitly for snow and ice observation, so it is not self-evident that they should be optimal for remote sensing of glaciers. There are no universal techniques for glacier surface classification which have been optimized with in situ reflectance spectra. Therefore, the roles that the various spectral, spatial, and radiometric properties of each sensor play in the success and output of resulting classifications remain largely unknown. Therefore, this study approaches the problem from an inverse perspective. Starting with in situ reflectance spectra from the full range of surfaces measured on two glaciers at the end of the melt season in order to capture the largest range of facies (Midtre Lovénbreen, Svalbard & Langjökull, Iceland), optimal wavelengths for glacier facies identification are investigated with principal component analysis. Two linear combinations are produced which capture the vast majority of variance in the data; the first highlights broadband albedo while the second emphasizes the difference in reflectance between blue and near-infrared wavelengths for glacier surface classification. The results confirm previous work which limited distinction to snow, slush, and ice facies. Based on these in situ data, a simple, and more importantly completely transferrable, classification scheme for glacier surfaces is presented for a range of satellite multispectral sensors. Again starting with in situ data, application of relative response functions, scaling factors, and calibration coefficients shows that almost all simulated multispectral sensors (at certain gain settings) are qualified to classify glacier accumulation and ablation areas but confuse classification of partly ash-covered glacier surfaces. In order to consider the spatial as well as the spectral properties of multispectral sensors, airborne data are spatially degraded to emulate satellite imagery; while medium-resolution sensors (~20-60 m) successfully reproduce high-resolution (2 m) observations, low-resolution sensors (i.e. 250 m+) are unable to do so. These results give confidence in results from current sensors such as ASTER and Landsat ETM+ as well as ESA’s upcoming Sentinel-2 and NASA’s recently launched LDCM. In addition, images from the Landsat data archive are used to classify glacier facies and calculate the albedo of glaciers on the Brøgger Peninsula, Svalbard. The time series is used to observe seasonal and interannual trends and investigate the role of melt-albedo feedback in thinning of Svalbard glaciers. The dissertation concludes with recommendations for glacier surface classification over a range of current and future multispectral sensors. Application of the classification schemes suggested should help to improve the understanding of recent and continuing change to GIC around the world.

Glaciologer har under en längre tid observerat förändringar av glaciärer på Svalbard, att några minskar i storlek och att vissa växer. Avsmältning med ökade havsnivåer och potentiellt ändrad havscirkulation till följd är ett scenario som berör människor över hela värden. Dessa förändringar kan eventuellt förklaras genom att koppla de meteorologiska förhållandena i området till större cirkulationsförändringar. De meteorologiska förhållandena över Svalbard har simulerats med en regional klimatmodell, WRF (Weather Research Forecasting), för tre domäner med upplösningarna 24 km, 8 km och 2,7 km. Modellen har testats i två versioner, standard-WRF med förvalda processbeskrivningar och WRF med processbeskrivningar anpassade för polärt klimat och har drivits med ERA-Interim data, som är en återanalys av de globala väderförhållandena framtagen av ECMWF. Resultaten från WRF har verifierats mot observationer uppmätta av AWS-stationer (Automatic Weather Station). Följande parametrar ingår i studien: temperatur, vindhastighet, specifik fuktighet, kortvågig in och utstrålning samt långvågig instrålning.  Simulationer med standard-WRF underskattar samtliga strålningsparametrar. En felaktig strålningsbalans leder till att standard-WRF simulerar för låga temperaturer. Att mängden kortvågig och långvågig instrålning är för liten beror förmodligen på att standard-WRF simulerar för stor mängd höga moln och för liten mängd låga moln. För vindhastigheten och den långvågiga instrålningen ökar respektive minskar korrelationen när resultaten från nedskalning från 24 km till 8 km med standard-WRF analyseras. Bäst korrelation för vindsimuleringar fås med standard-WRF i upplösningen 8 km. För temperaturen ger ERA-Interim bättre korrelation mot observationer än simuleringar med standard-WRF. Ett test av polaroptimerade WRF visar att detta utförande av modellen bättre förutsäger strålningsbalansen över glaciärerna och som en följd av detta fås en mer överensstämmande temperaturmodellering. Polaroptimerade WRF simulerar en mindre mängd höga moln och en strörre mängd låga moln jämfört med standard-WRF. Bättre molnmodelleringarna i kombination med ett mer passande schema som beskriver mängden kortvågig strålning ger en förbättrad energibalans. Vindmodelleringar i upplösningen 2,7 km utförda av standard-WRF och polaroptimerade WRF ger minskad korrelation och ökad spridning jämfört med simuleringar i upplösningen 8 km. Denna rapport visar på att polaroptimerade WRF är ett bättre alternativ än standard-WRF när Svalbards meteorologiska parametrar ska simuleras.

The purple sandpipers (Calidris maritima) are the most common waders in the high arctic archipelago of Svalbard, Norway. There they have to cope with a very short summer season and high metabolic costs of migrating far north and breeding in an arctic environment. The food on land is usually scarce, whereas there are rich feeding grounds in the littoral zone, such as in the intertidal zone of river flats. These feeding grounds are though only available to the purple sandpipers during low tide and as long as the estuary is not covered by sea ice. One of these intertidal flats was used as the fieldwork area in this study. To study when the birds are coming to this intertidal flat for feeding, a count study was performed during the entire stay of the purple sandpipers in Svalbard in summer 2010. Point counts were performed at low tide during 118 different days. Additionally, point counts were performed at twenty days during the six hours of the entire low tide period, to study when during the tidal cycle most sandpipers were feeding at the estuary. Most sandpipers were counted at the intertidal flat at the beginning of June with the highest number, 921 individuals, on 8th June. When the tundra was free of snow and the birds could start breeding, numbers where rapidly declining with very few sandpipers left in the estuary in July and the first part of August. From the end of August numbers were increasing again with a second but lower peak in the end of September and beginning of October. By the end of October all sandpipers had left the estuary. The study on the appearance of purple sandpipers at the estuary at the different periods of low tide showed that there were significantly more sandpipers between low tide and half an hour later than at the rest of the low tide period. This might be due to better access to their prey at that time. This knowledge could be used in future studies aiming at recording the maximum numbers. The result of the phenologic study could be included in a long term monitoring to see if the numbers and the timing of purple sandpipers are stable in this area or not: Are the peak numbers differing significantly? Is the timing of the arrival, the stay on the tundra and the timing of leaving the archipelago in the fall changing? Long-term monitoring would be especially interesting in the view of possible influences of the climate change on the purple sandpipers. Rising sea level as a result of the climate change would change the morphology of the estuaries and thereby influence the food resources available for sandpipers.