Blar i tittel Mastergradsoppgaver i biologi
Viser treff 336-355 av 355
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Uncovering the foraging strategies in two pelagic diving seabird species outside their breeding season using coupled feather stable isotopes and light-based geolocators
(Master thesis; Mastergradsoppgave, 2022-02-16)The critical endangered Common and Brünnich guillemot are exhibiting contrasting population trends in the Barents Sea region, where the Common guillemots are increasing, while Brünnich guillemots are declining. The non-breeding season is regarded as the main mortality period among seabirds, especially in winter, as climate conditions may be harsh and prey availability rather limited. The contrasting ... -
Uncovering the secrets they keep – the role of parasites in food web ecology
(Master thesis; Mastergradsoppgave, 2022-06-01)Interactions involving parasites often account for large proportions of links within aquatic food webs, yet few studies integrate parasites into their food web analyses. This analysis compares three sets of highly resolved food webs that differ in taxa composition, space, and time for a subarctic lake system. Key topological food web metrics, including connectance, linkage density, and mean generality ... -
Under-ice plankton abundance and lipid dynamics in a subarctic lake.
(Master thesis; Mastergradsoppgave, 2022-05-16)Shortening winters and changing ice and snow cover conditions are examples of the many shifts expected in subarctic lakes due to climate change. Well-documented changes in ice and snow cover conditions highlight the need to understand under-ice ecosystems and the consequences a changing climate brings to the freshwater biota. This study investigated the impact of under-ice environmental conditions ... -
Unexpected feeding behaviour inferred by DNA metabarcoding of Barents Sea skates
(Master thesis; Mastergradsoppgave, 2022-05-18)Feeding studies give an indication about the role and position of species within ecosystems and provide crucial knowledge for management. Traditional methods are based on morphological identification of prey. DNA metabarcoding is a promising tool that allow for identification of specific prey items, also when highly digested. A total of 63 stomachs from three skate species caught in the Barents Sea ... -
Ungulate population monitoring in a tundra landscape: evaluating total counts and distance sampling accuracy
(Master thesis; Mastergradsoppgave, 2014-05-19)Researchers and managers are constantly working towards decreasing monitoring uncertainties in order to improve inferences in population ecology. The solitary and sedentary Svalbard reindeer (Rangifer tarandus platyrhynchus) inhabit a high-Arctic tundra landscape highly suitable to compare accuracy (precision and bias) of population monitoring methods in the wild. The flexible Bayesian state-space ... -
Use of bubble flotation to improve copepod fisheries: laboratory studies on the physical and behavioural interactions of Calanus finmarchicus and air bubbles
(Master thesis; Mastergradsoppgave, 2008-11-15)The current study presents a novel approach to zooplankton harvest in the ocean, where copepods are lifted through the water column and concentrate them at the ocean surface. There they are harvested with a surface skimmer or shallow trawl. The method can potentially reduce fuel costs and unwanted by-catch compared to a conventional plankton trawl. The optimal bubble size for attachment to Calanus ... -
Using food web structure based on stable nitrogen and carbon isotopes to investigate pelagic-benthic coupling in different areas of the Barents Sea
(Master thesis; Mastergradsoppgave, 2017-11-15)Pelagic-benthic coupling is generally assumed to be tighter on Arctic shelves than in lower latitudes, due to for example pronounced seasonal cycles of sunlight and primary production and a potential mismatch between the bloom and its pelagic consumers. Pelagic-benthic coupling is also often stronger in shallower areas compared to deeper areas, due to the shorter distance between the productive, ... -
The utility of in vitro Precision-Cut Liver Slices to investigate toxicity pathways of contaminants in polar cod (Boreogadus saida)
(Master thesis; Mastergradsoppgave, 2015-06-12)The development of in vitro methodologies has contributed significantly in elucidating mechanisms of xenobiotic toxicity in aquatic organisms. The present study aimed to develop the in vitro methodology Precision-Cut Liver Slices (PCLS) and to investigate the effects of model compounds (WY-14,643 [WY] and benzo(a)pyrene [BaP]) and two mixtures of 2- and 3-4-ring polycyclic aromatic hydrocarbons ... -
Validating the Tritiated Water Method in Adult Harp Seal
(Master thesis; Mastergradsoppgave, 2022-05-16)As one of the top predators in the northeast Atlantic, and most numerous, the harp seal (Pagophilus groenlandicus), has a significant role in the higher trophic levels in the ecosystem. Their condition can be an indicator of changes in prey availability, competition with other species or even climate. It can also be a useful tool in predicting the pup production and breeding success. The ... -
Variation in abundance, diet, otolith zone patterns and black spot disease (Cryptocotyle lingua) of 0-group coastal cod (Gadus morhua L.) in northern Norway
(Master thesis; Mastergradsoppgave, 2006-12-11)Knowledge of the early life-history and habitat requirements of coastal cod is very sparse. Young of the year cod juveniles from three different locations in northern Norway were collected monthly from August to November 2005 using beach seine. Diet analyses based on stomach contents showed that 0-group cod mainly ate copepods, gammarids, polychaetes, mysids, shrimps and isopods. The three ... -
Variation in egg size, fecundity and size structure in female red king crab (Paralithodes camtschaticus, Tilesius 1815) from Varangerfjorden over time.
(Master thesis; Mastergradsoppgave, 2018-05-14)The introduced red king crab (Paralithodes camtschaticus) has successfully established in Norwegian waters since its release to the Barents Sea in the 1960’s. It has become an important commercial resource contributing to the local coastal society in the eastern region of Finnmark. The fishery consists of one quota regulated area east of 26° (North Cape) and an open fishery west of 26°E. During the ... -
Variation in epiphytic vegetation in spruce plantations and adjacent native birch forests in North Norway
(Master thesis; Mastergradsoppgave, 2007-05)Epiphytic vegetation can contribute to increased knowledge on how planting of spruce in areas where spruce does not occur naturally in the landscape can affect the environment. In the current study, 31 spruce plantations in Troms and Vesterålen in North Norway were investigated, with emphasis on species abundance of macrolichens on tree trunks and branches. The main assumption was that planting of ... -
Vegetation-environment analysis of areas with peat accumulation and hummock formation in the context of NiN (Natur i Norge). A study from Laggu, Gamvik municipality, Troms and Finnmark county.
(Master thesis; Mastergradsoppgave, 2021-05-18)A conspicuous type of heath and forest with peat accumulation and hummock formation in terrestrial systems has been investigated in Laggu, Gamvik municipality in northern Norway. The aim was to describe vegetational composition, soil depth and hummock distribution, and identify environmental factors that cause terrestrial peat accumulation. Vascular plants, bryophytes and lichens were registered ... -
Vertical distributions of zooplankton using the Video Plankton Recorder in two high-latitude fjords. “A case study on diel migration in Billefjorden, Svalbard, and seasonal migration in Porsangerfjord, northern Norway”
(Master thesis; Mastergradsoppgave, 2015-08-17)Zooplankton is the link between primary producers and higher trophic levels, so it is of vital importance for the food chain. The strong seasonality in the Arctic affects the vertical distribution of zooplankton in the water column. Predators can also affect the vertical distributions of their prey in the water column due to avoidance adaptations. The importance of these differences between prey and ... -
Vertikalt habitatbruk, næringsvalg og vekst hos en innsjølevende bestand av ørret (Salmo trutta L.) i Pasvikvassdraget
(Master thesis; Mastergradsoppgave, 2007-10-16)En av våre nordligste fiskespisende ørretbestander finnes i Pasvikvassdraget i Finnmark. Omfattende regulering av vassdraget har virket negativt på bestanden, og den blir nå opprettholdt gjennom årlige utsettinger. På 1990-tallet innvandret lagesild fra Enare-sjøen, og den ser ut til å ha hatt positiv effekt på ørreten. Denne undersøkelsen omhandler habitatbruk, næringsvalg og vekst hos innsjølevende ... -
Winter behaviour of riverine anadromous Arctic charr and sea trout in northern Norway
(Master thesis; Mastergradsoppgave, 2008-05)Based on earlier migration studies of lake-dwelling anadromous Arctic charr Salvelinus alpinus (L.) and sea trout Salmo trutta L. in northern Norway, both species are believed to solely overwinter in fresh water and spend only one to three months in the sea during summer. This is an assumption upon which all current management of the species in the area is based, although no studies have focused on ... -
Within-Season Trends in Abundance and Distribution of Humpback Whales (Megaptera novaeangliae) in the Antarctic Peninsula Region
(Master thesis; Mastergradsoppgave, 2020-12-15)Fine-scale knowledge of cetacean abundance and distribution throughout the Antarctic Peninsula (AP) is lacking yet essential for effective ecosystem-based fisheries management (EBFM). We investigated an important area both for migratory humpback whales (Megaptera novaeangliae) and Antarctic krill (Euphausia superba) fisheries to assess potential spatio-temporal interactions, for use in adaptive EBFM ... -
The world's northern most harbour seal population - How many are there?
(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 ... -
Yearly variation in allelopathic compound production along a climatic gradient. A case of study of Empetrum nigrum
(Master thesis; Mastergradsoppgave, 2017-11-15)Empetrum nigrum is a plant common in northern ecosystems with capacity to produce allelopathic compounds, which among other effects inhibit seed establishment and germination of other plants. Some of the most studied compounds regarding this effect are batatasin-III and phenolic acids, among them caffeic acid, which account for a large proportion of the leaf’s biomass. 5 random sites were established ... -
Zooplankton communities on the Northeast coast of Greenland. How can we explain vertical and regional distribution?
(Master thesis; Mastergradsoppgave, 2019-05-16)Most studies on zooplankton investigate the famous, and omnipresent, Calanoid copepods Calanus spp., because they are abundant, and constitute the major trophic link in marine ecosystems. Indeed, Northeast Greenland is located on the crossroad of Arctic and Atlantic waters which, potentially, can lead to a high biodiversity originating from different domains of marine life. However, there are very ...