Mastergradsoppgaver i biologi: Nye registreringer
Viser treff 261-280 av 427
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Body composition changes of hooded seal (Cystophora cristata) pups during extreme lactation
(Master thesis; Mastergradsoppgave, 2018-05-15)Among phocids, the hooded seal has the most extreme lactation period. It lasts, for most pups, four days, making it also the shortest lactation period of any mammal. During the lactation period, there is a high energy transfer, which affects and changes the body of the pup in preparation for the following post-weaning fast period. With regard to the decline of the West Ice population, the main purpose ... -
Predator aversion in resident generalist birds. A ghost of evolutionary past?
(Master thesis; Mastergradsoppgave, 2018-05-14)Predator aversion is an important adaptation that can significantly lower the mortality rate among prey animals, but avoiding a predator requires knowing and recognizing them. The predator aversion of Common gulls and Mallard ducks at Prestvannet Lake, Tromsø, Northern Norway was tested in an experiment by placing differing objects resembling snakes next to bread during the summer and autumn of 2017. ... -
Climate-induced range expansions of marine fauna into the Arctic – what is the most likely colonisation route?
(Master thesis; Mastergradsoppgave, 2018-05-14)As a result of climate change, the Arctic faunas of the Northeast Atlantic have begun to shift in an Atlantic direction. One system exposed to such a change is the Northeast Greenland (NEG) Shelf. However, the colonisation route taken by boreal fauna to the NEG shelf is unknown. This knowledge is essential to predict to what extent boreal fauna will dominate Arctic habitats, and alter ecosystems in ... -
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 ... -
Life-history strategies in two subarctic lakes with polymorphic Arctic charr Salvelinus alpinus L. populations. High across lakes stability in evolution of life-history strategies
(Master thesis; Mastergradsoppgave, 2018-05-13)Life history strategies of polymorphic Arctic charr in two sub-arctic lakes (Tårnvatn and Skøvatn) with similar environmental- and physiochemical conditions were studied. Disparities in life history traits may reflect ecological adaptations and is suggested an important factor in the incipient speciation process. In this region several lakes have polymorphic charr, and the designation of a fish to ... -
Calving site characteristics and habitat use in Svalbard reindeer
(Master thesis; Mastergradsoppgave, 2018-05-15)Migrating reindeer and caribou tend to return to traditional calving locations every spring with specific environmental conditions and protection of calving grounds is a central part of Rangifer conservation. In contrast, the non-migratory Svalbard reindeer inhabit an environment free of predators during calving season making them ideal as a reference population. Little is known about habitat ... -
Parasites of Northeast Arctic cod (Gadus morhua) in the Barents Sea: effects on reproduction
(Master thesis; Mastergradsoppgave, 2017-07-15)Parasites play a key role in the biodiversity and dynamics of an ecosystem, either by affecting host mortality and/or host reproduction. Spawning comes with a great cost in time and energy, and in times of poor conditions this time and energy is better directed into growth and survival to increase future success. The phenomenon of skipped spawning, where sexually mature fish skip a reproductive ... -
Diving behaviour of humpback whales feeding on overwintering herring in North-Norwegian fjords
(Master thesis; Mastergradsoppgave, 2017-07-06)Since 2011, large numbers of humpback whales have aggregated to feed on Norwegian spring-spawning herring overwintering from late October to February within the fjords of the Troms county in Northern Norway. Whale aggregations are new in this region and little information on the whales’ behaviour is available. How whales dive and forage and how they adjust to the extreme light regime at this latitude ... -
Gjenfangst av laks (Salmo salar L.) etter fang og slipp-praksis i norske elver
(Master thesis; Mastergradsoppgave, 2017-05-18)Som følge av at norske laksebestander har blitt redusert i løpet av de siste tiårene har det blitt vanligere å gjenutsette laks i forbindelse med sportsfiske. Noen av disse gjenutsatte laksene er rapportert å gjenfanges, men omfanget av dette har hittil ikke vært dokumentert i detalj i norske elver. Slik gjenfangst kan tenkes å beskatte forskjellige deler av en populasjon ulikt, være problematisk i ... -
Haul-out behaviour of walruses (Odobenus rosmarus) monitored by camera stations - potential impacts of tourist visitations
(Master thesis; Mastergradsoppgave, 2017-05-16)The rapid growth of tourism in Polar Regions stimulates a need for investigating potential impacts on targeted species and sensitive areas, such as walrus (Odobenus rosmarus) haul-out sites. This study examines effects of tourist visitations on haul-out dynamics and site use by walruses in Svalbard, Norway. Camera stations were established at five traditional walrus haul-out sites that experience ... -
Spawning behavior of Arctic charr (Salvelinus alpinus): spawning synchrony, vibrational communication and mate guarding.
(Master thesis; Mastergradsoppgave, 2017-05-15)A mismatch between male and female gamete release can result in reduced or failed fertilization in external fertilizers, sperm competition and reduced paternity. Here, I video monitored spawning behavior of free living Arctic charr (Salvelinus alpinus), and analyzed details of their reproductive biology. In total, 157 spawnings were recorded. Females clearly preferred spawning with the dominant male, ... -
Strategies for timing of nest departure in the common guillemot Uria aalge
(Master thesis; Mastergradsoppgave, 2017-05-15)Duration of parental care in avian species varies widely, from altricial to precocial species. The seabird family Alcidae is unique among birds in the variation of mass and age at nest departure. The common guillemot Uria aalge exhibits an intermediate nest departure, where chicks leave the nest flightless and only at a quarter of adult body size. The aim of this study was to examine factors controlling ... -
Estimating population trends of a riparian bird community in low-Arctic tundra.
(Master thesis; Mastergradsoppgave, 2018-02-15)In the Northern Norway tundra, willow thicket along river valleys create a more productive environment than the surrounding open tundra and host a rich community of bird species by providing food, shelter from predators and nesting site. The state of Arctic ecosystem is expected to undergo long-term changes due to opposite effects of climate change and herbivory pressure. It is also the background ... -
Estimating survival rate in Brünnich's guillemot (Uria lomvia) chicks. A study of mark-recapture methods using photo series data
(Master thesis; Mastergradsoppgave, 2008-05)Three different mark-recapture models were applied to resighting data for Brünnich's guillemot (Uria lomvia) chicks obtained from photo series. Performances of the various models as potential tools for estimating chick survival over the breeding season were assessed. Of particular interest was Pradel’s multievent model, estimating state transition probabilities while accounting for uncertainty of ... -
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 ... -
Shared predation and its impact on two sympatric rodent species. Adding to nature’s complexity
(Master thesis; Mastergradsoppgave, 2017-09-03)I used a theoretical model with different predatory preference relationships but with no direct competition. Simulated time series were statistically analysed to evaluate changes in rodent dynamics, with respect to periodicity, synchrony, amplitude and symmetry. The study found that shared predation could mediate a relationship between the two rodents to some extent. Periodicity increased on average ... -
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, ... -
Epibenthic fauna in Balsfjord. Potential food for the invasive red king crab (Paralithodes camtschaticus) with special attention to the deposit-feeding sea star Ctenodiscus crispatus
(Master thesis; Mastergradsoppgave, 2017-05-12)After its introduction to the Barents Sea in the 1960’s, the red king crab Paralithodes camtschaticus has become an invasive species in northern Norwegian fjords and it is continuing to spread southward along the coast. Due to its negative effects on native benthic fauna through predation, establishing baseline studies in undisturbed fjords is important. In this study, the soft-bottom epibenthic ... -
Do diet of long rough dab (Hippoglossoides platessoides) differ between fjords with and without red king crab (Paralithodes camtschaticus)? A study of summer diet
(Master thesis; Mastergradsoppgave, 2017-05-15)The purpose of this study is to describe the diet of long rough dab in three different fjords with and without red king crab. The hypothesis is that red king crab are influencing the diet and possible also growth of long rough dab. By the applying objectives it is assumed to give an answer to if red king crab is influencing different aspects of the diet and growth in long rough dab. By the ... -
An assessment of three survey methods on common bird species in low Arctic tundra.Comparing line transect distance sampling, repeated point counts and double observer point counts
(Master thesis; Mastergradsoppgave, 2017-05-15)Long-term studies of bird communities in Arctic regions are rare in comparison to studies performed in temperate regions, particularly studies that takes detectability into consideration. Finding a suitable and robust method for long-term monitoring of bird populations in the low Arctic which includes a correction of imperfect detection, can contribute to increased ecological understanding and easier ...