Doktorgradsavhandlinger (BFE-fak): Recent submissions
Now showing items 81-100 of 277
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The spread of salmon lice (Lepeophtheirus salmonis Krøyer) from Norwegian fish farms and their impact on sea trout (Salmo trutta L.)
(Doctoral thesis; Doktorgradsavhandling, 2020-10-09)<p>The transmission of salmon lice (<i>Lepeophtheirus salmonis</i> Krøyer) from farm salmon to wild salmonids and the impact on wild populations are sources of intense debate in all salmon producing countries, and it is currently an issue of high political and economic relevance in Norway. Solid science-based evidence is therefore needed by decision makers to apply sound management strategies. Given ... -
Bioactive secondary metabolites from bacteria. Natural products from marine and terrestrial bacteria, dereplication, isolation and investigation of bacterial secondary metabolites
(Doctoral thesis; Doktorgradsavhandling, 2020-09-29)The thesis gives an introduction to natural product drug discovery and the underlying chemical principles that make natural products privileged structures for drug discovery. Paper I deals with the isolation of Lipid 430 from cultures of two <i>Algibacter</i> sp. isolates and the investigation of their anti-proliferative and anti-bacterial effect. Paper II describes the isolation of Serratiochelin ... -
Short-term tundra plant-community nutrient responses to herbivory and warming: New insights from Near infrared-reflectance spectroscopy methodology
(Doctoral thesis; Doktorgradsavhandling, 2020-09-22)In the long-term, herbivores and climate warming have been shown to alter nutrient levels in tundra plant communities by changing the functional composition of the vegetation. Here, I asked the extent to which they affect tundra plant-community nutrient levels in the short-term by directly modifying the chemistry of plants. I first developed a time- and cost-effective method that allowed me to ... -
Mapping nature’s contribution to people: Opportunities and limitations of crowdsourced data to identify place-based values and conservation concerns
(Doctoral thesis; Doktorgradsavhandling, 2020-06-16)Nature provides people with a wide range of benefits, also known as nature’s contributions to people (NCP). The NCP framework evolved from the Ecosystem services (ES) concept as a response to the critiques and misconceptions associated with ES over the last years. Broadening ES valuations that have been dominated by economic valuations, the NCP framework emphasizes a pluralistic approach to valuation ... -
Polar Cod in a Changing Arctic. Toxicity of crude oil on sensitive life history stages of a key Arctic species
(Doctoral thesis; Doktorgradsavhandling, 2020-06-12)Environmental change in the Arctic is occurring at an unprecedented rate with a loss of sea ice and warmer sea temperatures, simultaneously as increased human activity in the Arctic poses a risk of petroleum pollution. The potential future of a key Arctic forage fish, polar cod (<i>Boreogadus saida</i>), was investigated using laboratory simulations of oil spills during sensitive life-history stages: ... -
The challenges of understanding the biogeography of commercially important crustacean species of the Southwestern Indian Ocean — Separating what we know from what we think we know.
(Doctoral thesis; Doktorgradsavhandling, 2020-05-25)Demersal trawl fisheries play an important role in providing income and protein to the people of the Southwestern Indian Ocean (SWIO). These fisheries are very destructive to the habitats in which they operate and have an impact on the associated biodiversity. Three crustacean species, knife prawn (<i>Haliporoides triarthrus</i>), African langoustine (<i>Metanephrops mozambicus</i>) and pink geryon ... -
Atlantic salmon B cells- local and systemic responses to intraperitoneally administered salmonid alphavirus
(Doctoral thesis; Doktorgradsavhandling, 2020-03-04)Viral diseases represent one of the major threats for salmonid aquaculture. Disease prevention by vaccination relies on the induction of protective antibody responses mediated by B-cells. Upon binding to a specific antigen during vaccination or infection, the B-cells become activated and mature into antibody secreting cells (ASC). The antibodies protect against re-infection and prevent spreading of ... -
Sedimentary ancient DNA: Exploring methods of ancient DNA analysis for different taxonomic groups
(Doctoral thesis; Doktorgradsavhandling, 2020-02-28)This thesis explores the potential of sedimentary ancient DNA (sedaDNA) from lakes as a tool for studying past communities. First it sets out to determine what taxa in the environment are most likely to be detected in lake sediments. For this, vegetation surveys were carried out around eleven different lakes in Norway and the taxa detected based on plant metabarcoding of the lake sediments were ... -
Sjarkfiske og ressursforvaltning
(Doctoral thesis; Doktorgradsavhandling, 1997-11-07)<p>Med utgangspunkt i feltarbeid fra fiskevær i Troms, samt intervjuer med flere fiskere i Troms og Finnmark, drøfter jeg det nordnorske sjarkfisket i lys av to motstridende teorier om ressurshøsting og -regulering. Den ene sier at små enheter er mer ressursvennlige enn store. I småskalaproduksjon finnes innebygde begrensninger i produksjonsmåten, dels fordi vi står ovenfor husholdsbasert produksjon ... -
Bycatch Reduction in Eastern North Pacific Trawl Fisheries
(Doctoral thesis; Doktorgradsavhandling, 2019-12-20)<p>This thesis provides an overview of recent selectivity studies conducted in eastern North Pacific trawl fisheries (e.g., West Coast groundfish bottom trawl fishery, Pacific hake [<i>Merluccius productus</i>] fishery, and ocean shrimp [<i>Pandalus jordani</i>] fishery). Collectively, these fisheries play a significant role in supporting fishing jobs, income, and coastal communities. However, bycatch ... -
Reproductive biology of the calanoid copepod, Eudiaptomus graciliodes (Lilljeborg): Polyandry, Phenology and Life Cycle Strategies
(Doctoral thesis; Doktorgradsavhandling, 2007-12-19) -
The speciation landscape of European whitefish in Northern Fennoscandia – the importance of deglaciation history, standing genetic variation and natural selection
(Doctoral thesis; Doktorgradsavhandling, 2019-12-10)<p>During the last deglaciation, one clade of European whitefish (<i>Coregonus lavaretus</i> L.) colonized the lakes in the three contemporary watercourses of northern Fennoscandia (Pasvik, Tana and Alta) and diverged thereafter in sympatry. This thesis investigates the interplay between evolutionary processes and standing genetic variation in shaping phenotypic and genetic divergence, and how ... -
The impact of entrepreneurship education on students' career reflections
(Doctoral thesis; Doktorgradsavhandling, 2019-11-25)The thesis aims to explore the impact entrepreneurship education (EE) has on students’ career reflections. EE has developed significantly in both scope and importance over recent decades and is now being taught worldwide at all education levels. Major stakeholders, such as educators, education institutions, funders, governments and policymakers, are investing heavily in terms of human and/or financial ... -
Isolation and Charecterization of New secondary metabolites from the Arctic Bryozoans Securiflustra securifrons and Dendrobeania murrayana
(Doctoral thesis; Doktorgradsavhandling, 2019-08-30)Marine bryozoans is a prolific source of structurally diverse bioactive secondary metabolites. However, the total number of natural products isolated from marine bryozoans is limited, The present study was focused on isolation and characterization of new compounds from Arctic marine bryozoans. The novel compounds were isolated by using two different approaches. For bioassay-guided isolation, fractions ... -
Life history and distribution of the edible crab (Cancer pagurus) in Norway - Effect of temperature and other environmental parameters at high latitudes
(Doctoral thesis; Doktorgradsavhandling, 2019-06-25)The overall aim of this study has been to provide information on how environmental conditions in Norway might affect the life history and distribution of the edible crab (<i>Cancer pagurus</i>). The results show that the size at which female crabs reach physiological maturity vary little, and just randomly, across northern Europe, and among latitudinally separated areas within Norway. Analysis of ... -
Food traceability in theory and in practice
(Doctoral thesis; Doktorgradsavhandling, 2018-01-12)The thesis consists of five papers and a synopsis, and outlines theoretical concepts and practical considerations when implementing traceability in food supply chains. The term traceability and the components of a traceability system are discussed and defined, a method for describing and analysing material flow, information flow, and information loss is outlined, and numerous practical implementations ... -
Migration in seabirds: seasonal structure in space and environment across species, populations and individuals
(Doctoral thesis; Doktorgradsavhandling, 2019-05-21)Identifying drivers of population trends in migratory species is difficult, as they can face many stressors while moving through different areas and environments during the annual cycle. Their population response to environmental change may in addition be affected by consistent differences in individual behaviour, which are widespread in free-living populations. An understanding of the structure of ... -
Towards a framework to guide and facilitate interdisciplinary social-ecological system research in practice.
(Doctoral thesis; Doktorgradsavhandling, 2019-06-27)Social-ecological systems (SES) consist of a social and an ecological system that are linked through a complex interplay of social and ecological processes. SES can be studied through SES research, which has become increasingly important because it is thought that it can potentially address and solve many societal challenges, such as climate change, resource scarcity, and habitat degradation. SES ... -
Ecophysiological Responses of Sea Ice Algae and Phytoplankton to a Changing Arctic
(Doctoral thesis; Doktorgradsavhandling, 2019-03-29)The ice-covered seas of the Arctic have two major types of primary producers; phytoplankton growing in open waters and sea ice algae growing within and on the underside of the sea ice. This thesis investigates the controlling role of light availability on Arctic pelagic and sympagic (i.e. ice-associated) algae, and how light-induced responses are modulated by NO3 and pCO2 levels. A combination of ... -
Implementation of ecosystem-based ocean management
(Doctoral thesis; Doktorgradsavhandling, 2019-03-29)Ecosystem-based management (EBM) is a holistic approach for nature management that aims at achieving the good health and sustainable use of ecosystems. It is a complex and challenging concept: understanding ecosystems and human impacts upon them is complicated, there are demanding needs for collaboration and harmonisation of approaches and policies, and many conflicting interests must be balanced. ...