Mastergradsoppgaver i biologi: Nye registreringer

Viser treff 281-300 av 380

    • Can ground nesting birds escape predation by breeding in less productive habitats? A large-scale artificial nest study from Finnmark, Northern Norway 

      Jacobsen, Mari (Master thesis; Mastergradsoppgave, 2014-05)
      Predation is known to be one of the most important causes of nest failure in ground nesting birds, and many populations are experiencing a decline in breeding success worldwide. Predator abundance are expected to be highest closer to productive areas (i.e. Ecosystem exploitation hypothesis), and vary according to the availability of other prey (i.e. Alternative prey hypothesis). I hypothesized that ...

    • Sampling site and potential errors in estimating total body water and water turnover rate in fasting hooded seals (Cystophora cristata) 

      Alvira-Iraizoz, Fernando (Master thesis; Mastergradsoppgave, 2014-05-15)
      The purpose of this project is to study in detail the water balance and methodological aspects of the use of the tritiated water method of hooded seals (Cystophora cristata). Following 24 hours of fasting, 5 sub-adult hooded seals aged 1.5 years were injected intravenously with a bolus dose of tritiated water through a catheter inserted into the extradural intravertebral vein (EDV) at the level of ...

    • Parallelism in parasite infections in two populations of polymorphic Arctic charr (Salvelinus alpinus L.) in northern Norway 

      Refsnes, Birgitte (Master thesis; Mastergradsoppgave, 2014-05-15)
      The composition and structure of a component community can vary widely across host populations of the same host species. Revealing the causes and consequences of geographical variation in parasite community composition is of great importance in order to determine parasites role in an ecosystem. Divergence in parasite infections among sympatric polymorphic Arctic charr is commonly associated with ...

    • Recovery potential of Arctic wetland tundra on Svalbard. Long-term impacts of grazing by barnacle geese (Branta leucopsis) within the context of climate change 

      Paquin, Karolina (Master thesis; Mastergradsoppgave, 2014-05-19)
      The substantial increase of the migratory Svalbard population of Barnacle geese Branta leucopsis during the past 50 years has been attributed to a warming climate, changes in agricultural land use, and conservation measures. The geese are likely to continue to forage and reproduce in Arctic wetlands in increasing numbers. This project revisited the experimental plots from an earlier experiment ...

    • Langtidsstudie av næringsøkologi og vekst hos storørret i Pasvikvassdraget - en sammenligning mellom utsatt og vill ørret 

      Haugland, Øyvind (Master thesis; Mastergradsoppgave, 2014-05-15)
      Kraftutbyggingen i Pasvikvassdraget startet i 1964 og det finnes syv kraftverk i vassdraget. Storørretbestanden gikk kraftig tilbake som følge av kraftutbyggingen og i 1979 ble det startet et utsettingsprogram av ørret i elva for å kompensere for reduksjonen i størrelsen av den naturlige populasjonen. I dag settes det årlig ut 5000 ørret større enn 25 cm. Dette langtidsstudiet omhandler diett og ...

    • Seasonal abundance of parasitic Marine Alveolate Group II (MALV II) in an Arctic fjord, Svalbard 

      Thomson, Stuart Daniel (Master thesis; Mastergradsoppgave, 2014-05)
      During the last decade, knowledge has been building of the parasitic dinoflagellate group Marine Alveolate Group II (MALV II, within Syndiniales). While environmental cloning and sequencing approaches have indicated a high abundance of MALV II throughout the world’s oceans, relatively little is known about their seasonality and the significance of their role in the marine ecosystem. No studies to ...

    • Autumn senescence response to a changing climate: effects of snow-depth on High Arctic plants 

      Abbandonato, Holly (Master thesis; Mastergradsoppgave, 2014-05-15)
      Temperature and precipitation in the Arctic are projected to increase over the next century with a changing climate. Understanding how tundra plants respond to this change is still unclear. Little is known about autumn senescence in the Arctic and with a short growing season, timing is critical. If a plant senesces too early, it compromises photosynthetic activity and growth. If a plant senesces ...

    • Samfunnsstruktur og tetthet av bunndyr i littoralsonen av en oligotrof, subarktisk innsjø - variasjoner gjennom dyp og sesong 

      Johansen, Kristin M. Sommerseth (Master thesis; Mastergradsoppgave, 2014-05-15)
      Bentiske makroinvertebrater i littoralsonen av innsjøer utgjør en stor del av innsjøers økosystem, og samfunnsstrukturen av disse dyrene kan være med å påvirke hele økosystemet. Forskjellige arter av bunndyr har forskjellige livssykluser og tilpasninger til habitatene de lever i og det er rimelig å forvente at sammensetningen av arter endrer seg med forskjellige dyp og bunnsubstrat, og også over ...

    • Long-term population dynamics of Diphyllobothrium ditremum and D. dendriticum (Cestoda: Pseudophyllidea) in their salmonid hosts following a fish removal experiment 

      Henriksen, Eirik Haugstvedt (Master thesis; Mastergradsoppgave, 2014-02-15)
      Parasite-host interactions are important in understanding ecosystem processes, for instance by using trophically transmitted parasites as indicators of host ecology. Parasite infections are expected to correlate with host density, habitat choice and feeding behaviour. The importance of long-term data and perturbation experiments has been emphasized for advancing our knowledge of the parasite-host ...

    • The ontogeny of nasalheat exchange structures in Arctic artiodactyles 

      Casado Barroso, Iratxe Lorea (Master thesis; Mastergradsoppgave, 2014-05-15)
      Reindeer (Rangifer tarandus) live in the Arctic and have evolved special adaptations to cope with hard environmental conditions. Nasal heat exchange (NHE), which is an efficient heat and water exchange mechanism to combat loss of energy, is well documented in adult reindeer (e.g. Blix and Johnsen (1983), Johnsen 1988). However, it is not known if this mechanism is fully developed from birth and if ...

    • Effect of body condition on tissue distribution of perfluoroalkylated substances (PFASs) in Arctic fox (Vulpes lagopus) 

      Aas, Camilla Bakken (Master thesis; Mastergradsoppgave, 2014)
      The effect of body condition on the distribution and composition of 16 perfluoroalkylated substances (PFASs) in liver, blood, kidney, adipose tissue and muscle of Arctic fox (Vulpes lagopus) from Svalbard was investigated. Quantifiable concentrations of the PFASs were found in all samples (n=18). Overall, PFASs concentrations were highest in liver, followed by blood and kidney, while lowest ...

    • Short term effects of clear cutting on the regeneration of sub-arctic birch forest following severe outbreaks by geometrid moths 

      Klinghardt, Moritz (Master thesis; Mastergradsoppgave, 2013-11-08)
      Birch forests in northern Fennoscandia experience re-occurring mass outbreaks of pest insects often resulting in severe defoliation. Here I test whether systematic clear cutting can accelerate the forest regeneration after outbreaks with uncut control plots as comparison. Basal shoot abundance was used as a main indicator for recovery but comprehensive data sampling also included the abundance of ...

    • Isolation of Fungal Endophytes from Grasses by Laser Micro Dissection & Pressure Catapulting 

      Jahiri, Xhevahire (Master thesis; Mastergradsoppgave, 2013-12-12)
      A very diverse group of fungi capable of forming endophytic associations may have profound consequences for natural ecosystems as well as for cultivated plants. Fungal endophytes may benefit their host plants by producing secondary metabolites, and may be an important source for bioactive antimicrobial compounds, used in agriculture, commercial industry, and in medicine. Earlier studies on endophytes ...

    • Temporal trends of POPs in arctic foxes from Svalbard in light of a changing climate 

      Andersen, Martin Solhøi (Master thesis; Mastergradsoppgave, 2013-11-15)
      The present study investigates concentrations and temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard, Norway, adjusted for sex, age, body condition, diet, reindeer mortality and sea ice coverage. Number of reindeer carcasses in Adventdalen and sea ice coverage of Isfjorden in the spring preceding the trapping season were used as indexes for climate ...

    • Alternative prey choice in the pteropod Clione limacina (Gastropoda) studied by DNA-based methods 

      Kallevik, Ida Helene Funderud (Master thesis; Mastergradsoppgave, 2013-11-15)
      The gymnosome pteropod Clione limacina is regarded as a monophagous predator, feeding exclusively on the thecosome pteropod Limacina helicina in Arctic waters. C. limacina is adapted to survive periods of low food availability by long-term starvation. Although L. helicina is absent from the water, a number of other zooplankton species are present during this time. It may therefore seem surprising ...

    • Morphological divergence in a trimorphic population of Arctic charr (Salvelinus alpinus (L.)) in Skogsfjordvatn, northern Norway. 

      Skoglund, Sigrid Østrem (Master thesis; Mastergradsoppgave, 2013-09-30)
      Sympatric polymorphisms are found in many freshwater fish taxa, including the salmonid Arctic charr (Salvelinus alpinus (L.)). Polymorphism is often expressed as differences in morphology, behaviour and life-history strategies, and may be driven by alternative phenotypic adaptations to resource use such as habitat and prey preferences. Morphological divergence is usually linked to different functions ...

    • The world's northern most harbour seal population - How many are there? 

      Merkel, Benjamin (Master thesis; Mastergradsoppgave, 2012-11-15)
      This study presents the first abundance estimate for the world's northernmost harbour seal (Phoca vitulina) population, which resides in Svalbard, Norway, based on three digital stereoscopic photographic surveys conducted in 2009 and 2010. The counts from these high resolution 3D images were combined with a novel method for estimating correction factors for animals that were in the water at the time ...

    • Relation between habitat characteristics and abundance, diet and condition of 0-group cod in two northern Norwegian fjords 

      Heggland, Kristin Nymark (Master thesis; Mastergradsoppgave, 2013-05)
      There is a correlation between the vegetation coverage and the abundance of 0-group cod. The highest abundance was found between 50 – 70 %, which is consistent with previous studied and imply that there is a nonlinear relationship between vegetation coverage and abundance of 0-group cod. There was found a difference in diet between the three habitats, with the intertidal zones of Balsfjord and ...

    • Carbon source and trophic structure along a depth gradient in Isfjorden, Svalbard 

      Løkken, Therese Smelror (Master thesis; Mastergradsoppgave, 2013-08-29)
      Stable isotope analysis has been used to examine marine food webs since the 1980s and has become a valuable tool for studying carbon sources and trophic structures in benthic food chains in the Arctic. Prior to the present study, no one has used stabile isotope analysis to test for a difference in the main carbon source or trophic structure along a depth gradient in the Arctic. Carbon sources (pelagic ...

    • Ernæringsbasert metanproduksjon hos sau 

      Nilsen, Marte (Master thesis; Mastergradsoppgave, 2013-05-21)
      Drøvtyggere er plantespisere og avhengig av symbiotisk mikrobiell fordøyelse i vom og baktarm for å kunne utnytte cellulose, hemicellulose og lignin som finnes i plantecelleveggen til plantene. I drøvtyggervomma finnes ulike bakterier, ciliater, anaerob sopp og metanogene arker i høye konsentrasjoner. Metanogenene produserer metan ved at de bruker hydrogen til å redusere karbondioksid (Sirohi et al, ...