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Browsing Doktorgradsavhandlinger (BFE-fak) by Author

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Anglerfish Lophius piscatorius L. in Faroese waters. Life history, ecological importance and stock status

Ofstad, Lise Helen (Doctoral thesis; Doktorgradsavhandling, 16-Apr-2013)

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Abstract:	Anglerfish Lophius piscatorius has during the last two decades become a highly exploited resource and is now one of the five most economically important demersal fish species in the Faroese fishery. Despite this, there is at present little information available on the population status of anglerfish in Faroese waters. The main aim of this study is to increase the biological knowledge of anglerfish and to perform an assessment of the stock in order to evaluate the sustainability of the anglerfish fishery and to investigate trophic interactions between anglerfish and other commercially important demersal fish species. Anglerfish illicia, the first fin ray, were used for age reading. The age determinations were validated and concluded to be useful in an age-based assessment because the growth rates were consistent with length frequency and mark-recapture analyses. Anglerfish have a very high growth rate during their first year of life, compared with the older ages. Males mature at a lower length and younger age than females. The L50 for males and females was 58 cm and 84 cm, respectively, corresponding to an age of around four years for males and seven years for females. Observations of spawning males and females, egg-ribbons and pelagic anglerfish larvae revealed that anglerfish have a prolonged spawning season, which peaks from February to April. In addition, observations showed that there are at least two local spawning areas, one southwest of the Faroe Plateau and one in the Faroe Bank area. Large anglerfish tagged with data storage tags and conventional tags showed a seasonal offshore-onshore migration. They migrated to shallow depths in summer to feed and to deeper waters in winter, presumably to spawn. Anglerfish performed vertical movements up into the water column, and were most active in these vertical movements during the winter time and during the nights, and light intensity seemed to trigger the migrations. Anglerfish distribution was temperature dependent, since anglerfish generally preferred temperatures warmer than 4ºC, usually between 6.5–11ºC. This may explain why anglerfish were distributed deeper west of the Faroe Bank area compared to the Faroe Plateau, which is surrounded by cold water deeper than approximately 500 m. Anglerfish in Faroese waters preyed on a variety of food items. They were generally eating fish and the most important prey species in terms of numbers were Norway pout and blue whiting, whereas cod and haddock contributed most in weight. Annual consumption by anglerfish on commercially important demersal species, such as cod, haddock and saithe, was estimated to correspond to 33, 19 and 2% of the landings and to 75, 20 and 2% of biomass losses due to natural mortality, respectively. Even with this high cod consumption by anglerfish, cod cannibalism and fishing mortality still have greater impact on the cod stock dynamics than predation by anglerfish. The annual biomass loss of anglerfish due to cannibalism was estimated to nearly 15% of the annual loss due to natural mortality. Anglerfish in Faroese waters may be regarded as a separate stock because all life stages are found in the area, local spawning area, seasonal offshore-onshore migration on the Faroe Plateau, together with insignificant emigration/immigration (< 5%). An age-based stock assessment of anglerfish in Faroese waters for the period 1999–2011 showed that the stock biomass ranged between 9000 and 19000 t with a peak in 2004–2005 and the fishing mortality for age 3–8 varied between 0.2 and 0.5 year-1. The yield per recruit curve indicated that the stock was slightly growth overfished. Decreasing the fishing mortality could potentially increase the yield per recruit by around 10% leading to a 50% higher equilibrium biomass of anglerfish. No clear stock-recruitment relationship was found. On the other hand, anglerfish year-class strength was correlated with environmental variables, such as sandeel abundance. Hence, the rather short time series of anglerfish year-class strength provides little or no evidence of recruitment overfishing. It is recommended that stock assessments should be performed on an annual basis, allowing managers to react timely when there are signs of overfishing or recruitment failure due to natural or fishery causes.
Description:	The papers of this thesis are not available in Munin: 1. Ofstad, L.H., Pedersen, T., Angus, C.H., and Steingrund, P.: 'Age and growth of anglerfish (Lophius piscatorius) in Faroese waters', Fisheries Research (2013), vol.139:51–60. Available at http://dx.doi.org/10.1016/j.fishres.2012.05.011 2. Ofstad, L.H., Pedersen, T., and Steingrund, P.: 'Maturation, reproduction and early life history of anglerfish Lophius piscatorius in Faroese waters' (manuscript) 3. Ofstad, L.H., Steingrund, P., and Pedersen, T.: 'Seasonal offshore-onshore migration and distribution of anglerfish Lophius piscatorius in Faroese waters' (manuscript) 4. Ofstad, L.H., Steingrund, P., and Pedersen, T.: 'Feeding ecology of anglerfish Lophius piscatorius in Faroese waters' (manuscript)
URI:	http://hdl.handle.net/10037/5070

File(s) in this item: 1

thesis.pdf (5.639Mb)

Some methodological issues in economic evaluation in health care

Olsen, Jan Abel (Doctoral thesis; Doktorgradsavhandling, 1993)

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URI: http://hdl.handle.net/10037/3375

File(s) in this item: 1

thesis.pdf (13.38Mb)

Quantification and characterisation of residual blood in fish muscle : impact of slaughtering methods

Olsen, Stein Harris (Doctoral thesis; Doktorgradsavhandling, 17-Jun-2011)

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Abstract:	Omorganisering i oppdrettsnæringen har ført til større og mer mekaniserte anlegg med høy slaktekapasitet. I dag kontrolleres normalt restblod i fiskefilet ved visuell inspeksjon. Dette er arbeidskrevende og innebærer subjektive evalueringer som muliggjør høy grad av unøyaktighet. Fargen på fiskemuskelen er også et viktig kriterium når kunder vurderer kvalitet, og disse fargeforandringene skyldes ofte restblod. Oppgaven belyser, i første omgang, de ulike enhetsoperasjonene ved slakting av fisk og hvilke effekter de har på selve utblødningen. I tillegg belyser den muligheten for å bruke en objektiv og hurtig målemetode for restblod i fiskemuskel, som er basert på visuell- og nærinfrarød spektroskopi. Restblod fører til store økonomiske tap for fiskeindustrien som følge av nedklassifisering. Området er lite belyst, og denne oppgaven søker å bidra med ny kunnskap rundt hvilke faktorer som påvirker mengden restblod i fiskemuskel. En kjemisk målemetode ble brukt som referanse og sammenlignet opp mot dagens visuelle inspeksjon samt en visuell- og nærinfrarød (VIS/NIR) spektroskopi metode. Sistnevnte innebærer måling av absorbsjon/refleksjon av lys fra bl.a. fargepigmentet hemoglobin, og metoden benyttes allerede i annen næringsmiddelindustri. Oppgaven viser at mengden blod i fiskemuskel påvirkes av stress før slakting, avlivingsmetoder, kjøling og lagring. Spesielt ble det funnet at bedøving ved bruk av slag før bløgging er optimalt med hensyn til restblod. Bruk av karbondioksid anbefales derimot ikke. VIS/NIR metoden anbefales ikke brukt industrielt, men metoden kan forbedres og automatiseres. Det foreslås å anvende avbildende VIS/NIR spektroskopi for å vurdere restblod i fiskefilet, med spektra fra fiske hemoglobin som referanse.
Description:	The papers of this thesis are not available in Munin: 1. Olsen, S.H., Sørensen, N.K., Stormo, S.K. and Elvevoll, E.O.: 'Effect of slaughter methods on blood spotting and residual blood in fillets of Atlantic salmon (Salmo salar)', Aquaculture (2006) 258, 462-469. Available at http://dx.doi.org/10.1016/j.aquaculture.2006.04.047 2. Olsen, S.H., Sørensen, N.K., Larsen, R., Elvevoll, E.O. and Nilsen, H.: 'Impact of pre-slaughter stress on residual blood in fillet portions of farmed Atlantic cod (Gadus morhua) - Measured chemically and by Visible and Near-infrared spectroscopy', Aquaculture (2008) 284, 90-97. Available at http://dx.doi.org/10.1016/j.aquaculture.2008.07.042 3. Olsen, S.H. and Elvevoll, E.O.: 'A pH induced shift in the haemoglobin spectra – A spectrophotometeric comparison of fish (Gadus morhua) and mammalian haemoglobin', Journal of Agriculture and Food Chemistry (2011) 59 (4), pp 1415–1422. Available at http://dx.doi.org/10.1021/jf1036273
URI:	http://hdl.handle.net/10037/3590

File(s) in this item: 1

thesis.pdf (748.0Kb)

Poverty in Small-Scale Fisheries : Governance Challenges in Lake Victoria Fishing Communities, Tanzania

Onyango, Paul Ochieng (Doctoral thesis; Doktorgradsavhandling, 23-Aug-2011)

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Abstract:	The pursuit of a world without poverty is without doubt among the leading global challenges not only for governments but also the poor themselves. This challenge is also in small-scale fishing communities where poverty is persistent and has become a thorny issue to the poor as well as governing actors. Strategies have been formulated and implemented but the results have not been up to the expectations. Why haven’t these strategies yielded expected results? This is the central question of this thesis. This study seeks to understand why poverty persists despite the good instruments that have been directed at its alleviation. It examines poverty through studying the underlying factors that determine relationships between and among the many variables that make poverty a multidimensional problem. It argues that the persistent poverty in small-scale fishing communities in Lake Victoria Tanzania finds explanation in the manner in which poverty and its challenges have been understood and addressed. By using Kooiman’s and Jentoft’s (2009) ‘meta-governance’ perspective, the study discusses how differences in, what people consider as important (values), what they believe is morally mandatory to do (norms) and what should direct behaviour or action (principles), explain the persistent poverty in fishing communities. The study shows that there is inconsistency in the way poor fishers’, riparian to the Lake and governing actors in Tanzania understand poverty in the fishing communities and how to confront it. This inconsistency exists at the meta-governance level i.e. with regards to values, norms and principles. The study proposes that to alleviate poverty, a solution to this difference should be sought from a governance mechanism that addresses the dissimilarity. This must be a process which provides governing actors and the poor opportunities to interact in order to influence policy.
Description:	Papers 1,3,4 and 5 of the thesis are not available in Munin: 1. Onyango, P. O.: 'Re-configuring Poverty: The Wickedness Perspective', African Journal of Tropical Hydrobiology and Fisheries (2009), 12, 37-46. Available at http://www.ajol.info/index.php/ajthf/article/view/58032 3. Onyango, P. O. and S. Jentoft: 'Assessing poverty in small-scale fisheries in Lake Victoria, Tanzania', Fish and Fisheries (2010), 11, 250-263. Available at http://dx.doi.org/10.1111/j.1467-2979.2010.00378.x 4. Onyango, P. O.: 'Occupation of last resort? Small-scale fishing in Lake Victoria, Tanzania', In Jentoft S. and A. Eide (Eds.). Poverty Mosaics: Realities and Prospects in Small-Scale Fisheries (2011) Springer Verlag. Available at http://dx.doi.org/10.1007/978-94-007-1582-0_6 5. Onyango, P. O. and S. Jentoft.: 'Climbing the Hill: Poverty Alleviation, Gender Relationships, and Women’s Social Entrepreneurship in Lake Victoria, Tanzania' (accepted paper in Maritime studies)
URI:	http://hdl.handle.net/10037/3551

File(s) in this item: 2

paper_2.pdf (159.8Kb)

thesis.pdf (1.466Mb)

Converting sub-Arctic birch forests to spruce plantations : responses of predators and prey

Pedersen, Åshild Ønvik (Doctoral thesis; Doktorgradsavhandling, 20-Apr-2010)

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Abstract:	In northern Norway large areas of sub-Arctic coastal birch forests have gradually been replaced by non-native spruce plantations during the last century. Spruce planting changes the forest floor vegetation and soil conditions, increase the amount of artificial edges and alter the forest landscape mosaics. Such tree species conversions are likely to reduce or increase suitable wildlife habitat, alter animal space use patterns, habitat selection and population and community dynamics. In a spatially extensive study design using live-trapping, snow tracking and baited track boards, I studied responses of individual predator species (red fox, pine marten, stoat, least weasel, lynx and corvids) and prey species (mountain hare, voles, common shrew and gallinaceous birds) and their interactions at three spatial scales ranging from within forest stands to landscape mosaics. I also included a study along the birch forest – alpine tundra ecotone to compare nest predation in native landscapes with those impacted by tree species conversion. In a 10 year observational trapping study of small mammals, I found much lower abundances of common shrew, red vole and field vole in spruce plantations compared to four birch forest types at stand scale. Autumn abundances were most impacted indicating that growth rates in the reproductive season were more influenced than winter declines. Species associated with productive forest habitats were most negatively impacted. Prevalence of endoparasites (helminths) in common shrew was highest in the rich birch forests and lowest in spruce plantations. In a 3 year observational study of an assemblage of ground dwelling vertebrates in winter, scale- and time dependent responses to spruce plantations were documented for the dominating species (red fox, stoat, mountain hare and voles). Small-scale affinity to plantation edges was found for most species. Habitat selection for and against spruce plantations at stand scale alternated profoundly among the years and species, however, in qualitatively similar patterns among the dominant species. At landscape scale only red fox was negatively related to amount of spruce plantations, while mountain hares exhibited annual shifts in occurrence relative to the amount of spruce. Predators and prey were related in time and space at the two smallest scales which may be explained by year- and stand-specific snow conditions affecting the predator-prey interactions within the community. In two experimental nest predation studies of 1 and 3 years, respectively, the omnipresent corvids were the dominant predators. The effects of spruce plantation edges and stands on predator prevalence were consistent with those of Einarsen et al. (2008), who concluded that edges and stand types had limited influence on spatial distribution of nest predators (Paper IV). Predator prevalence along the birch forest – II alpine tundra ecotone was remarkably consistent among locations and habitats. These results suggest that man-made and natural edges were not able to explain the overall high levels of predation observed. A decade of research on different wildlife species has documented clear responses to spruce plantations. Among the strongest effects is the pervasive negative impact on small mammal abundances and passerine bird communities in the studies of Hausner et al. (2002; 2003). Common for these species are their responses to habitat qualities at small spatial scales and they serve as prey for the predator communities. Reduction in abundance of key functional species, in particular the small mammals, is expected to influence the overall community structure and dynamics of vertebrates in this boreal forest ecosystem. The relatively weak responses documented at landscape scale (except for red fox) might change when young spruce plantations matures into old closed canopy monocultures. The findings emphasise the importance of maintaining a mix of tree species and high spatial heterogeneity of forest stands to prevent negative impacts on prey species abundances. The studies in this thesis have also shown that modern forestry can reinforce the effects of climate change. Changes in winter climate may modify snow conditions which in turn alter the role of forest stand mosaics in determining the structure of vertebrate communities. Moreover, the most probable cause of long-term declines in small mammal populations is changes in winter climate (Ims and Fuglei, 2005). These results comply with other studies reporting that modern forestry contribute to longterm declines of small mammal populations (Christensen and Hörnfeldt, 2006; Hörnfeldt et al., 2006; Christensen et al., 2008).
Description:	The papers of this thesis are not available in Munin: 1. Pedersen, Å.Ø., Yoccoz, N.G., Ims, R.A. and Sigurdsen, T.: 'Effects of non-native spruce plantations on small mammal communities in sub-Arctic birch forests', Forest Ecology and Management (2010) vol. 260, no. 3, pp. 331-338. Available at http://dx.doi.org/10.1016/j.foreco.2010.04.020 2. Sigurdsen, T., Pedersen, Å.Ø., Yoccoz, N.G., Haukisalmi, V. and Ims, R.A.: 'Are endoparasites of common shrew indicators of tree species conversion from sub-Arctic birch forest to spruce plantations?', manuscript, later published in European journal of forest research, Volume 131, Number 2 (2012), 389-400, available at http://dx.doi.org/10.1007/s10342-011-0511-7 3. Pedersen, Å.Ø., Ims, R.A., Yoccoz, N.G., Hausner V.H. and Juell, K.H.: 'Scale-dependent responses of predators and their prey to spruce plantations in sub-Arctic birch forests in winter', Ecoscience (2010) 17(2):123-136. Available at http://dx.doi.org/10.2980/17-2-3333 4. Pedersen, Å.Ø., Yoccoz, N.G. and Ims, R.A.: 'Spatial and temporal patterns of artificial nest predation in mountain birch forests', European Journal of Wildlife Research (2009) vol.55: 371-384. Available at http://dx.doi.org/10.1007/s10344-009-0253-8 5. Klausen, K.B., Pedersen, Å.Ø., Yoccoz, N.G. and Ims, R.A.: 'Prevalence of nest predators in a sub-Arctic ecosystem', European journal of wildlife research (2010) vol. no.56:221–232. Available at http://dx.doi.org/10.1007/s10344-009-0304-1
URI:	http://hdl.handle.net/10037/3643

File(s) in this item: 1

thesis.pdf (4.950Mb)

Trophic relationships and the role of Calanus in the oceanic ecosystems south and north of Iceland

Pétursdóttir, Hildur (Doctoral thesis; Doktorgradsavhandling, 03-Dec-2012)

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Abstract:	The waters south and north of Iceland vary greatly both oceanographically and biologically with the rather stable and warm Atlantic waters south and west of Iceland and the more variable and cold Arctic and sub-Arctic waters, north and east of Iceland. The aim of this study was to increase the knowledge on the role of Calanus copepods and trophic relations of the key components of the oceanic ecosystems south-west (over the Reykjanes Ridge) and north (in the Iceland Sea) of Iceland. The trophic relationships and energy transfer to higher trophic levels were estimated by using fatty acid trophic markers, by comparing fatty acid profiles among species and by applying stable isotopes of carbon and nitrogen. The inter-annual variability in abundance and community composition of zooplankton on the shelves south and north of Iceland in relation to environmental condition in spring were also observed. The energy rich Calanus species are key links between primary producers and higher trophic levels in the Icelandic waters. The Calanus species dominate the zooplankton biomass around Iceland and their markers (20:1n9 and 22:1n11) are found in high amount in animals at higher trophic levels. Calanus finmarchicus plays important role as a forage species in the Atlantic water south-west of Iceland while its high importance is replaced by the larger lipid rich C. hyperboreus in the Arctic and sub-Arctic waters north of Iceland. Even though Calanus based food-web is the main driver in both areas, there exist a pathway where Calanus species are of less importance and the energy is channeled via euphausiids to higher trophic levels. Around four trophic levels were observed in the two oceanic ecosystems where adult fish occupied the highest trophic levels. Over the Reykjanes Ridge vertically migrating mesopelagic fish, in pronounced deep-scattering layers, are actively bringing energy to deeper layers by feeding on C. finmarchicus in the upper layers. In the Iceland Sea comparable deep-scattering layers were not observed. Epipelagic schools of capelin (Mallotus villosus) are important component of the pelagic ecosystem in the Iceland Sea. After feeding intensively in the Iceland Sea, they migrate and thus transfer the energy to adjacent ecosystems. The ecosystem around Iceland is extremely sensitive to climate variations. Increase in sea temperature has been related to shift in distribution and feeding migrations of capelin in the Iceland Sea with the result of diet switch of older capelin. The importance of the Arctic amphipod Themisto libellula in the diet of adult capelin increased in their new distribution area in the colder western part of the Iceland Sea. A shift in distribution of species may thus influence the whole ecosystem structure and food web interactions in larger area. This study presents novel important knowledge on the food web structures and carbon flow in Icelandic waters.
Description:	The papers of this thesis are not available in Munin: 1. Petursdottir, H., Gislason, A., Falk-Petersen, S., Hop, H., and Svavarsson, J.: 'Trophic interactions of the pelagic ecosystem over the Reykjanes Ridge as evaluated by fatty acid and stable isotope analyses', Deep-Sea Research Part II (2008), 55:83-93. Available at http://dx.doi.org/10.1016/j.dsr2.2007.09.003 2. Petursdottir, H., Gislason, A., and Falk-Petersen, S.: 'Lipid classes and fatty acid compositions of muscle, liver and skull oil in deep-sea redfish Sebastes mentella over the Reykjanes Ridge', Journal of Fish Biology (2008), 73:2485–2496. Available at http://dx.doi.org/10.1111/j.1095-8649.2008.02100.x 3. Petursdottir, H., Falk-Petersen, S. and Gislason, A.: 'Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis', ICES Journal of Marine Science (2012), 69:1277-1288. Available at http://dx.doi.org/10.1093/icesjms/fss125 4. Pálsson, Ó.K., Gislason, A., Guðfinnsson, H.G., Gunnarsson, B., Ólafsdóttir, S.R., Petursdottir, H., Sveinbjörnsson, S., Thorisson, K. and Valdimarsson, H.: 'Ecosystem structure in the Iceland Sea and recent changes to the capelin (Mallotus villosus) population', ICES Journal of Marine Science (2012), 69:1242-1254. Available at http://dx.doi.org/10.1093/icesjms/fss071 5. Gislason, A., Petursdottir, H., Astthorsson, O.S., Gudmundsson, K. and Valdimarsson, H.: 'Inter-annual variability in abundance and community structure of zooplankton south and north of Iceland in relation to environmental conditions in spring 1990-2007', Journal of Plankton Research (2009), vol.31, no.5:541-551. Available at http://dx.doi.org/10.1093/plankt/fbp007
URI:	http://hdl.handle.net/10037/4661

File(s) in this item: 1

thesis.pdf (1.998Mb)

Essays on the economics of marine protected areas and fisheries management

Quach, Thi Khanh Ngoc (Doctoral thesis; Doktorgradsavhandling, 20-Nov-2009)

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Abstract:	Even though the oceans occupy more than 70% of the earth’s surface and 95% of the biosphere (National Research Council, 2001), marine habitats have undergone a substantial decline over the last few decades, and most of which is attributable to fishing. In this regard, marine reserves or marine protected areas (MPAs) are proposed as tools to relieve stresses on marine resources and ecosystems. Despite the advantages of MPAs compared to traditional management tools, some concerns have been expressed about the effectiveness of the creation of MPAs when there are links between MPAs and outside areas as a result of the dispersal process. If the open access regime is applied outside the MPAs, it can attract more fishermen to exploit benefits resulting from the migration process and this can reduce the effectiveness of the MPAs. The problem, thus, to be analysed in this dissertation is how MPAs can benefit for fisheries management, and the conditions under which they are beneficial. With the analyses in different contexts, this dissertation investigates following research questions how the efficiency of fishing vessels in an open access fisheries affected by the creation of a marine protected area, how managers can use compensation payment as a tool to get the support from fishermen for biodiversity conservation and is it possible to use protected areas for conflicts resolving and management of recreational and commercial fisheries. Dynamic bioeconomic model, stochastic frontier analysis and principal agent theory are applied in this dissertation as innovative approaches for studying MPAs. The implication from this dissertation is that MPAs are not a cure-all for fisheries management; however, MPAs may be valuable tools for biodiversity conservation and fisheries management if we apply them under appropriate conditions.
Description:	Papers number 1 and 2 of the thesis are not available in Munin due to publishers' restrictions: 1. Quach Thi Khanh Ngoc, Ola Flaaten and Nguyen Thi Kim Anh: «Efficiency of Fishing Vessels Affected by a Marine Protected Area – The Case of Small-Scale Trawlers and The Marine Protected Area in Nha Trang Bay, Vietnam», chapter 15 in Moksness, Dahl and Støttrup (eds.): «Integrated Coastal Zone Management», Wiley-Blackwell, 2009. Check availablility 2. Quach Thi Khanh Ngoc: «Creation of Marine Reserves and Incentives for Biodiversity Conservation» Natural Resource Modeling, Volume 23, Number 2, May 2010 (Wiley). Available at http://dx.doi.org/10.1111/j.1939-7445.2009.00060.x
URI:	http://hdl.handle.net/10037/2600

File(s) in this item: 2

paper_3.pdf (165.6Kb)

thesis.pdf (330.3Kb)

Seabirds, climate and prey. A population study of two seabird species.

Reiertsen, Tone Kristin (Doctoral thesis; Doktorgradsavhandling, 30-May-2013)

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Abstract:	Many seabird populations have declined dramatically over recent decades, and studying the demography and population dynamic in seabird populations is important to gaining a better understanding of causes and mechanisms lying behind such changes and to identify targets for conservation and management. Climate and prey availability are known to affect demography and population dynamics of seabirds. Climate is now changing and a warming of the ocean may lead to changed availability of prey species and will affect seabirds through their demographic traits and ultimately their abundance and distribution. The main aim of this thesis was to study the impact of climate and prey abundance on seabird demography and population dynamics, using two seabird populations; the black-legged kittiwake Rissa tridactyla and the Common guillemot Uria aalge breeding on Hornøya in NE Norway whose populations are declining in Norway. The first question addressed in the thesis was how environmental conditions affect the demography and population variability of kittiwakes and guillemots. The non-breeding distribution of the kittiwakes has recently been documented using year-round light-based geolocators, and we investigated the relationship between environmental conditions in these non-breeding areas and the adult survival of kittiwakes breeding on Hornøya. We found for the kittiwakes that Thecosomata, a group of pteropods (also called sea butterflies), in the Grand Banks/Labrador Sea area in winter and the capelin Mallotus villosus stock in Barents Sea in the pre-breeding season together explained as much as 52 % of the yearly variation in adult survival rate. Further we found that the availability of 0-group cod Gadus morhua was a much more important factor affecting demography and determining the population dynamics of the common guillemot in the Barents Sea than previously considered. The second question was which demographic trait drives the population dynamics of the steeply declining kittiwake population on Hornøya. We showed, by using demographic matrix modeling and LTRE analyses, that both the variability in breeding success (and hence the recruitment to the population) and adult survival rate contributed to the steep decline in the kittiwake population on Hornøya. The strong reduction in breeding success (and hence a decline in recruitment to the population) had, however, the highest impact. The final question was whether populations can adapt to environmental changes through micro-evolutionary processes. This study found that adult survival of the two different genetic colour morphs (bridled and non-bridled morph) of the common guillemot responded differently to yearly variability in sea surface temperatures. Colour dimorphism may, in this case serve as a genetic marker in the guillemot population, and can potentially visualize the direction of selection and micro-evolutionary processes driven by climate. The studies in this thesis contribute to the understanding of the population dynamic of two declining seabird species which are both on the Norwegian Red List, and to the directions of future studies and conservation targets of both species.
Description:	Papers 1, 2 and 4 of this thesis are not available in Munin: 1. Reiertsen, T.K., Erikstad, K.E., Anker-Nilssen, T., Barrett, R.T., Boulinier, T., Frederiksen, M., González-Solís, J., Gremillet, D., Johns, D., Moe, B., Ponchon, A., Sandvik, H., Skern-Mauritzen, M. and Yoccoz, N.G.: 'Prey density in non-breeding areas affects adult survival of black-legged kittiwakes Rissa tridactyla breeding in the southern Barents Sea' (manuscript). 2. Reiertsen, T.K., Barrett, R.T. and Erikstad, K.E.: 'Kittiwakes on the cliff edge: a demographic analysis of a steeply declining arctic kittiwake population' (manuscript). 4. Reiertsen, T.K., Erikstad, K.., Barrett, R.obert T., Sandvik, H. and Yoccoz, N.: 'Climate fluctuations and differential survival of bridled and non-bridled Common Guillemots Uria aalge', Ecosphere (2013), vol. 3(6). Available at http://dx.doi.org/10.1890/ES12-00031R
URI:	http://hdl.handle.net/10037/5158

File(s) in this item: 2

paper_3.pdf (943.5Kb)

thesis.pdf (1.264Mb)

Consideration set size and choice in fish consumption : the influence of attitude, knowledge, convenience, and category presentation

Rørtveit, Asbjørn Warvik (Doctoral thesis; Doktorgradsavhandling, 11-Jun-2010)

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Abstract:	Purpose – Three main objectives are defined in this thesis: 1) To determine the extent to which the nature of a consideration set affects consumer choice; 2) To investigate how consumer attitudes, knowledge, and convenience motivations affect the formation of a consideration set; and 3) To investigate how category presentation moderates the relationship between convenience motivations and consideration set composition. Design/methodology/approach – Different research designs, several data sources, and different analytical procedures are employed in four papers. Papers #1, #2, and #3 use survey designs and are based on two large (n > 1000) cross-sectional datasets. Data in these papers are analyzed using structural equation modeling in LISREL 8.72. Paper #4 is based on two laboratory experiments (n = 150) with 2 × 2 between-subject factorial designs. Data in Paper #4 are analyzed using a two-way ANOVA in SPSS. Findings and contribution – This dissertation shows that consideration set size is important in explaining a consumer's choice and consumption of food, and is influenced by individual consumer variables such as attitude, knowledge, perceived inconvenience, and convenience orientation. Procedural knowledge is shown to be especially important for the number of food alternatives considered. In addition, the research in this dissertation demonstrates how situational and occasional factors such as availability and the urge to save time or effort (convenience) can affect aspects of consideration set attributes: stability, variety, and size. Importantly, the studies in this dissertation show that these relationships are moderated by the ways food is presented to the consumer (category presentation). While the overall findings are in accordance with previous research on consideration sets, this dissertation builds on and extends the past research by exploring the relationship between convenience and consideration set characteristics. The moderating influence of category presentation on the relationship between convenience motivations and consideration set characteristics is an especially important contribution of this dissertation research. Practical implications – Because the likelihood of being chosen is affected by the size of the consideration set, food producers should advocate that consumers should consider preparing their products in as many ways and in as many combinations with side ingredients as is reasonable. Furthermore, food marketers should focus on activities that enhance the consumer’s direct product experience through testing, trials, tasting, and samples, since procedural knowledge is shown to be of major importance for the number of considered alternatives. If marketers can identify cut-off values of salient attributes such as the time and effort spent on dinner preparation for a particular segment, they will have the ability to position products in accordance with these factors and thereby enhance the possibility of being considered. Furthermore, the moderating effect of category presentation on the relationship between the urge to save time and consideration set (stability, variety, and size) has several practical implications for marketing issues, such as advertising, placement in the retail store, shelf labeling, product development, and package labeling. Research limitations – A limitation of this study is that the relationship between the consideration set and choice was only tested for size dimensions of the consideration set. Future research may focus on the relationship between all the different dimensions of the consideration set (stability, variety, preference dispersion, and size) and choice, at both taxonomic and script category level. In addition, in future research the relationship between knowledge and consideration set (stability, variety, and preference dispersion) should be investigated, because of the close relationship between knowledge and consideration set size shown in this dissertation. Finally, the moderating effect of category presentation is one of the major contributions of this dissertation. These findings should be validated in similar and alternative empirical settings and designs in future research. Originality/value – The findings of this dissertation are in accordance with previous research in the field. The findings also have implications for future theory development and research, as well as practical implications and benefits for the marketing strategy decisions of producers and businesses.
Description:	The papers of the thesis are not available in Munin: 1. Rortveit, A. W. & Olsen, S. O.: «The role of consideration set size in explaining fish consumption», Appetite, 49(1)(2007): 214–222 (Elsevier - publisher's restrictions). Available at http://dx.doi.org/10.1016/j.appet.2007.02.005 2. Rortveit, A. W. & Olsen, S. O.: «Combining the role of convenience and consideration set size in explaining fish consumption in Norway», Appetite, 52(2)(2009): 313–317 (Elsevier - publisher's restrictions). Available at http://dx.doi.org/10.1016/j.appet.2008.11.001 3. Rortveit, A. W. & Olsen, S. O.: «The effects of consumer knowledge on consideration set size» (manuscript) 4. Rortveit, A. W., Haugtvedt, C. P., & Olsen, S. O.: «Goal-derived categories and convenience: Influences on consideration set formation» (manuscript)
URI:	http://hdl.handle.net/10037/2698

File(s) in this item: 1

thesis.pdf (612.2Kb)

Determinants and effects of moth population dynamics in altitudinal gradients in northern Fennoscandia

Schott, Tino (Doctoral thesis; Doktorgradsavhandling, 21-May-2013)

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Abstract:	The aim of this PhD-project has been to increase our knowledge of trophic interactions along altitudinal gradients in a system of sympatric, cyclically outbreaking geometrid moth species in sub-arctic, coastal birch forest in northern Norway. The project resulted in four scientific publications; two sub-studies focused on the causal effect of natural enemies on the observed complex spatio-temporal dynamics of the moth species (Papers 1 & 2). The other two sub-studies investigated the ecological effects of variable moth larvae densities as a resource for predators in the sub-Arctic ecosystem (Papers 3 & 4). In paper 1, we rejected the hypothesis that larval parasitoids might terminate moth population peaks, one of the most important hypotheses on insect population regulation. We, however, found that larval parasitoids can influence local spatial variation in moth population density. Hence, we concluded that spatial replication of sampling sites is crucial to arrive at non-biased estimates for the temporal effect of larval parasitoids on host populations. The long enduring debate on the regulation potential of parasitoids on insect populations in the scientific literature may be viewed in light of our findings. Similarly, in Paper 2, we tested if the often-observed spatial outbreak patterns of moth populations might be a result of release from invertebrate predators. Along mountain slopes, moth outbreaks in northern Fennoscandia often occur close to the tree line, and we tested if the abundance of ground dwelling invertebrate predators was inversely correlated with altitude, testing the assumption that moth outbreaks may be a result of reduced predation impact at high altitudes. As our analyses could not reveal this predicted pattern, we rejected the hypothesis. Consequently, the first two sub-studies delimitated the number of candidate factors that might shape Fennoscandian moth dynamics by reevaluating the role of larval parasitoids and ground-dwelling invertebrate predators. In paper 3, we reanalyzed the data from Paper 1 from the parasitoid's perspective by determining the dependencies of individual parasitoid species to host densities. For comparison, we also estimated the strength of effects hidden in the spatial and temporal attributes of altitude and year on parasitoid prevalence rates. We found that altitude and year, rather than host density, explained by far most of the extra-binomial variation in the parasitoid prevalence data. Hence, we concluded that unknown factors, which co-vary with altitude and year, dominate the prevalence dynamics of the larval parasitoids in our study and, consequently, act to decouple parasitoid dynamics from the dynamics of their hosts. Moth larvae as a resource for predators were also the focal issue in Paper 4, which focused on the importance of prey availability and forest phenology for breeding parameters in the two passerine birds great tit and pied flycatcher. The study was based on the phenological conflict that spring arrives in mountain slopes first at low altitude, while the bird's main food resource during the breeding season (i.e. moth larvae) often dominates forest habitat at higher altitude. Thus, we tested if passerine birds select breeding habitat according to the onset of spring or the availability of moth larvae and if the two bird species differed in this respect. We found that the phenological timing was the main driving force for both species when selecting breeding habitat lowest in the gradients where spring arrived first. However, also the positive correlations with moth larvae density appeared to be significant in our analyses. The main difference between the two species was found in the timing strategy for egg laying and size of clutches, which might make the great tit more prone to mismatch during springs of lower temperature. In addition, while nest box occupancy decreased with altitude in both species, the same relationship with respect to clutch size was only found for pied flycatchers, but not for great tits. Finally, great tits were more prone to fail during their breeding attempt and we concluded that the pied flycatcher, by laying eggs up to two weeks after great tits, appears to be the better adapted species with respect to breedig at sub-arctic conditions. This PhD-thesis strengthens the view that so-called top-down interactions in the ecological moth system in northern Fennoscandia cannot explain complex moth population dynamics, but that moth larvae can be regarded as a valuable resource for species at other trophic levels. The consistent dominance of altitude and year in all our analyses, on the other hand, suggests that explanations for the complex spatio-temporal moth population dynamics ought to be looked for in mechanisms ruled by environmentally governed processes such as phenology.
Description:	The papers of this thesis are not available in Munin: 1. Schott T., Hagen S.B., Ims R.A. & Yoccoz N.G.: 'Are population outbreaks in sub-arctic geometrids terminated by larval parasitoids?', Journal of Animal Ecology (2010), vol.79:701-708. Available at http://dx.doi.org/10.1111/j.1365-2656.2010.01673.x 2. Schott T., Kapari L., Hagen S.B., Vindstad O.P.L., Jepsen J.U. & Ims R.A.: 'Predator release from invertebrate generalists does not explain geometrid moth outbreaks at high altitudes', The Canadian Entomologist (2013), vol.145:184-192. Available at http://dx.doi.org/10.4039/tce.2012.109 3. Schott T., Ims R.A., Hagen S.B. & Yoccoz N.G.: 'Sources of variation in larval parasitism of two symmetrically outbreaking birch forest defoliators', Ecological Entomology (2012), vol. 37:471-479. Available at http://dx.doi.org/10.1111/j.1365-2311.2012.01386.x 4. Schott T., Svavarsdottir S., Hagen S.B., Kapari L., Vindstad O.P.L., Biuw M., Jepsen J.U. & Ims R.A.: 'Coping with variation in prey abundance and phenology: Comparative breeding performance of two passerines at the northern limit of their geographic range' (manuscript).
URI:	http://hdl.handle.net/10037/5159

File(s) in this item: 1

thesis.pdf (3.351Mb)

Planktonic food webs in the Arctic Ocean : structure and function in contrasting seasons and physical settings across Fram Strait

Seuthe, Lena (Doctoral thesis; Doktorgradsavhandling, 08-Dec-2011)

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Abstract:	This thesis investigates the structure and function of planktonic food webs at two sites between Greenland and the Svalbard Archipelago, covering a coastal ecosystem influenced by Atlantic water masses (Kongsfjorden, 78º N) and a more oceanic system off the East Greenlandic shelf, influenced by the outflow of Arctic water and sea ice from the Arctic Ocean (northwest Fram Strait, 75 - 80º N). In Kongsfjorden, a seasonal study was conducted with sampling at six occasions between March and December 2006. Logistical constrains prohibited a similar extensive seasonal investigation in the ice-covered waters of northwest Fram Strait. Sampling fell into the onset (April-May 2008) and end (September 2006/2007) of the productive season. All four studies investigated the stocks of pico- to micro-sized autotrophs and heterotrophs, i.e. heterotrophic bacteria, proto- and metazooplankton. Production rates of autotrophs and heterotrophic bacteria were measured in Kongsfjorden. Ratios of heterotrophic and autotrophic biomass (H:A) and of specific bacterial and primary production (µBac:µPhyto) allowed to asses the overall structure and function of the investigated planktonic food webs and to compare them to published data from other Arctic regions. The emerging picture provides three distinct food web modes, where mode A is characterized by H:A < 1 and µBac:µPhyto > 1, new production, and large-celled phytoplankton. Mode B and C are characterized by dominance of heterotrophs (H:A > 1), more regenerated production, and small-celled phytoplankton. The difference between mode B and C is a difference in the specific production ratio, with µBac:µPhyto smaller and larger 1, respectively. According to this scheme, Arctic plankton communities appear to prevail under mode B and C most of the year. In Kongsfjorden, e.g. five of the six months sampled fell under mode B and C, with mode C being typical for light-limited winter communities. From own and literature data, it is suggested that the food web mode controlling physical factors are the amount of incident photosynthetically active radiation (PAR), ice cover, nutrient concentration, and water column stability. Due to an approximately latitudinal change in these physical settings, the relative prevalence of the three food web modes changes from the marginal seas to the central Arctic Ocean, with mode A most likely being absent from the highest latitude waters. In general, Arctic plankton communities appear to sustain on average a 3-fold higher H:A biomass ratio for a given phytoplankton stock than the world’s coastal oceans, which may mainly be due to extensive import of long-lived copepods from sub-Arctic European seas through advection. It is argued that the large stock of heterotrophs plays a crucial role in structuring Arctic plankton communities, with the potential to prohibit phytoplankton bloom formation (mode A) through extensive grazing.
Description:	Paper 3 and 4 of this thesis are not available in Munin: 3. Seuthe L, Töpper B, Reigstad M, Thyrhaug R and Vaquer-Sunyer R: 'Microbial communities and processes in ice-covered Arctic waters of the northwestern Fram Strait (75 – 80ºN) during the vernal pre-bloom phase', Aquatic Microbial Ecology (2011) 64:253-266. Available at http://dx.doi.org/10.3354/ame01525 4. Svensen C, Seuthe L, Vasilyeva Y, Pasternak A and Hansen E: 'Zooplankton communities across Fram Strait in autumn : are small copepods and protozooplankton important? (in press in Progress in Oceanography).
URI:	http://hdl.handle.net/10037/3777

File(s) in this item: 3

paper_1.pdf (1.039Mb)

paper_2.pdf (966.8Kb)

thesis.pdf (2.535Mb)

Green sea urchin (Strongylocentrotus droebachiensis,Müller) in aquaculture: the effects of environmental factors on gonad growth.

Siikavuopio, Sten Ivar (Doctoral thesis; Doktorgradsavhandling, 30-Oct-2009)

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Abstract:	Ved hjelp av eksperimentelle studier har en undersøkt effekten av ulike miljøfaktorer på gonadevekst hos Drøbak-kråkebolle i oppdrett. Dette inkluderer effekten av temperatur, størrelse, sesong, individtetthet og forskjellige vannkvalitetsparametre (O2, CO2, nitritt, ammoniakk) og håndtering på overlevelse, gonadevekst, fôrinntak og fôrutnyttelse. Optimal temperatur for gonadevekst hos voksne kråkeboller ligger mellom 10 og 12 ºC om sommeren og ca 8 ºC om vinteren. Temperaturer over 12 ºC gir redusert vekst og fôrutnyttelse. Studiene viser at Drøbak-kråkebollen har lav toleranse for CO2, nitritt og ammoniakk sammenliknet med laksefisk. Forhøyede nivåer av disse stoffene medfører redusert gonadevekst, mens fôrinntaket blir lite påvirket. Dette resulterer i svært dårlig fôrutnyttelse. Kråkebollene har lavt oksygenforbruk, men er likevel svært følsomme for reduksjoner i vannets oksygeninnhold. Disse forholdene tilsier at kråkeboller i oppdrett krever stor vannutskifting for å opprettholde maksimal gonadevekst. For høy individtetthet i oppdrett medfører også nedsatt gonadevekst. Arbeidet omfatter en kartlegging av akseptabel tetthet for kråkebolle i oppdrett.
Description:	Papers number 1, 2, 3, 5, 6, 7, 8, 9 and 10 of the thesis are not available in Munin due to publishers' restrictions: 1. Siikavuopio, S. I., Mortensen. A., Christiansen, J. S.: "Effects of body weight and temperature on feeding, gonad growth and oxygen consumption in green sea urchin, Strongylocentrotus droebachiensis." Aquaculture 2008; 281, 77-82 (Elsevier). Available at http://dx.doi.org/http://dx.doi.org/10.1016j.aquaculture.2008.05.033> 2. Siikavuopio, S. I., Christiansen, J.S., Dale, T.: "Effects of temperature and season on gonad growth and feed intake in the green sea urchin (Strongylocentrotus droebachiensis)." Aquaculture 2006; 255, 389-394 (Elsevier). Available at http://dx.doi.org/http://dx.doi.org10.1016j.aquaculture.2005.12.021 3. Siikavuopio, S. I., Christiansen, J. S., Sæther, B-S., Dale, T.: "Seasonal variation in feed intake under constant temperature and natural photoperiod in the green sea urchin (Strongylocentrotus droebachiensis)." Aquaculture 2006; 272, 328-334 (Elsevier). Available at http://dx.doi.org/http://dx.doi.org/10.1016/j.aquaculture.2007.09.003 5. Siikavuopio, S. I., Dale, T., Foss, A., Mortensen, A.: "Effects of chronic ammonia exposure on gonad growth and survival in green sea urchin, Strongylocentrotus droebachiensis." Aquaculture 2004; 242, 313-320 (Elsevier). Available at http://dx.doi.org/10.1016j.aquaculture.2004.08.042 6. Siikavuopio, S. I., Dale, T., Christiansen, J. S., Nevermo, I.: " Effects of chronic nitrite exposure on gonad growth in green sea urchin, Strongylocentrotus droebachiensis." Aquaculture 2004; 242, 357-363 (Elsevier). Available at http://dx.doi.org/10.1016/j.aquaculture.2004.09.007 7. Siikavuopio, S. I., Dale, T., Mortensen, A., Foss, A.: " Effects of hypoxia on feed intake and gonad growth in the green sea urchin (Strongylocentrotus droebachiensis)." Aquaculture 2007; 266, 112-116 (Elsevier). Available at http://dx.doi.org/10.1016j.aquaculture.2007.02.028 8. Siikavuopio, S. I., Mortensen, A., Dale, T., Foss, A.: " Effects of carbon dioxide exposure on feed intake and gonad growth in green sea urchin (Strongylocentrotus droebachiensis)." Aquaculture 2007; 266, 97-101 (Elsevier).Available at http://dx.doi.org/10.1016/j.aquaculture.2007.02.044 9. Siikavuopio, S. I., Dale, T., Mortensen, A.: " The effects of stocking density on gonad growth, survival and feed intake of adult green sea urchin (Strongylocentrotus droebachiensis)." Aquaculture 2007; 262, 78-85 (Elsevier). Available at http://dx.doi.org/10.1016/j.aquaculture.2006.09.045 10. Christiansen, J. S., Siikavuopio, S. I.: "The relationship between feed intake and gonad growth of single and stocked green sea urchin (Strongylocentrotus droebachiensis) in a raceway culture." Aquaculture 2007; 262, 163-167 (Elsevier). Available at http://dx.doi.org/10.1016/j.aquaculture.2006.09.043
URI:	http://hdl.handle.net/10037/2263

File(s) in this item: 2

paper_4.pdf (248.9Kb)

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Animal-habitat relationships in high altitude rangelands

Singh, Navinder J. (Doctoral thesis; Doktorgradsavhandling, 18-Sep-2008)

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Abstract:	This study conducted in the high altitude rangelands of Indian Transhimalaya, deals with basic questions regarding the ecology of an endangered species, the wildsheep Tibetan argali (Ovis ammon hodgsoni) and applied issues related to its conservation and potential conflict with the local nomadic pastoralists. The basic questions on ecology are aimed at delineating the habitat and resource selection processes, identifying factors causing sexual segregation and efficient surveying and sampling. The applied aspect focuses on the changing face of pastoralism and the potential impacts of modernising livestock husbandry on argali. Overall, the study provides a general framework towards the understanding of argali-habitat relationships at different spatio-temporal scales. The spatial determinant associated with altitude in the area, predicts argali habitat and resource selection in this relatively homogenous landscape. These determine the range of other topographic variables and forage characteristics selected by argali. The selection of feeding patches in the selected range of altitude and topography is mainly characterised by their greenness and the quality of plant groups. Adjusting to changing forage quality, argali display an opportunistic feeding strategy, selecting grasses in early spring and switching to forbs later in summer. Nevertheless, the habitat selection process did not appear to differ among the sexes to drive sexual segregation. There was, however, strong segregation among the sexes as well as between lactating and non lactating females. The reasons for segregation appeared to be predominantly social, but driven ultimately by predation and concomitantly by resources. The habitat selection information was used to design a stratified random sampling strategy that led to i) a significant reduction in survey effort in sampling these sparsely distributed species and ii) reduction in sampling bias. The applied aspect of the study outlines and evaluates the dramatic changes in the nomadic pastoralism that have occurred in the past five decades in the study area. These have led to a loss of pastures (-25 to -33%) of the nomads, consequent readjustment in traditional patterns of pasture use, intensified grazing pressures (25 to 70%) and rangeland degradation in the area. Such changes may have serious consequences on the survival of local wildlife, as tested with a study of the effects on argali of livestock presence and resource exploitation. Hence, a successful conservation and recovery strategy should focus on: minimising the impacts of livestock on argali, identifying the factors affecting the persistence of the current populations, increasing local sub populations of this species to prevent extinction due to stochastic events, prevent loss of genetic diversity and excessive fragmentation and thus ensuring gene flow. Ecological Niche Factor Analyses (ENFA), bias-reduced logistic regression and Fuzzy correspondence analyses (FCA) were used to answer habitat and resource selection questions. A sexual segregation and aggregation statistic (SSAS) was used to estimate the components of sexual segregation and test segregation. SSAS combined with canonical correspondence analyses (CCA) allowed the estimation of segregation based on habitat variables. Logistic regression models were formulated to estimate models on which the stratified random sampling strategy was based. The Animal - Habitat relationships in high altitude rangelands overall study also included surveys, interviews and literature reviews to understand the nomads’ movement and pasture use patterns of their livestock. Kernel density estimations (KDE) were used to estimate extent of range overlaps between livestock and argali.
Description:	The papers of the thesis are not available in Munin: 1. Navinder J Singh, Nigel G Yoccoz, Nicolas Lecomte, Steeve D Côté and Joseph L Fox: «Scale and selection of habitat and resources: Tibetan argali in high altitude rangelands» (manuscript). Published version, Can. J. Zool. 88: 436-447 (2010), available at http://dx.doi.org/10.1139/Z10-015 2. Navinder J Singh, Christophe Bonenfant, Nigel G Yoccoz and Steeve D Côté: «Proximate and ultimate causes of sexual segregation in eurasian wildsheep, the Tibetan argali (Ovis ammon hodgsoni)» (manuscript). Later published (with altered title) in Behavioral Ecology, 2010, 21(2):410-418, available at http://dx.doi.org/10.1093/beheco/arp205 3. Navinder J Singh, Nigel G Yoccoz, Yash Veer Bhatnagar and Joseph L Fox: «Using resource selection functions to sample rare species in high-altitude ecosystems: a case study with Tibetan argali» (manuscript). Later published (with altered title) in Biodiversity and Conservation, Volume 18, Number 11, October 2009, available at http://dx.doi.org/10.1007/s10531-009-9615-5 4. Navinder J Singh, Joseph L Fox, Yash Veer Bhatnagar, Nicolas Lecomte and Nigel G Yoccoz: «Changing nomadic pastorialism in transhimalyan rangelands of India - causes and consequences» (manuscript). 5. Singh, N.J., Bhatnagar, Y.V., Yoccoz, N.G. and Fox, J L: «Assessing wildlife-livestock interaction in Indian transhimalya: Tibetan argali as a case study» (manuscript) 6. Navinder J. Singh, Joseph L. Fox and Yash Veer Bhatnagar: «Tibetan argali in India, Nepal and the western Tibet autonomous region, China», chapter in Richard P Reading (Ed): «Argali biology and conservation», Denver Zoological Foundation (In press).
URI:	http://hdl.handle.net/10037/2574

File(s) in this item: 1

thesis.pdf (9.332Mb)

Diversity along a speciation continuum : ecology and morphology of northern European whitefish (Coregonus lavaretus)

Siwertsson, Anna (Doctoral thesis; Doktorgradsavhandling, 24-Aug-2012)

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Abstract:	How new species are formed is still a major question in evolutionary biology. In ecological speciation, natural selection drives the evolution of slight distinctions between individuals into extensive differences between species. In this thesis, early stages of an ecologically driven speciation process are addressed using ecological and morphological data from a large number of European whitefish (Coregonus lavaretus) populations in northern Fennoscandia. Northern Fennoscandia is an area scattered with lakes created during the glacial retreat (~10-12 kyr BP). Many of these lakes are inhabited by one or up to three different morphs of whitefish. As many other temperate freshwater fishes, whitefish typically diverge into pelagic and littoral resource specialists, the densely rakered (DR) and the large sparsely rakered (LSR) morph, respectively. Parallel within-lake divergence is the most probable origin of these sympatric morphs. In addition, a third whitefish morph (the small sparsely rakered; SSR), specializing on profundal resources, was recently described in a few lakes in the area. The aims of this thesis were to explore and document the phenotypic diversity of whitefish in northern Fennoscandia, and to investigate some of the factors limiting the level of diversity reached within each lake. Further, the ability of LSR whitefish morphs to utilize profundal resources was explored, as this is a probable origin of profundal specialist SSR morphs. Based on the distribution of gill raker number, a temporally stable morphological trait in the studied populations, I have documented a continuum of increasing diversity in northern Fennoscandian whitefish. This whitefish diversity comprises mono (only LSR), di- (LSR and DR), and tri-morphic (LSR, DR and SSR) populations, in addition to intermediate stages between them. Within three different lakes with dimorphic whitefish populations, some individuals of the LSR morph were specialized to exploit profundal resources. This could indicate an incipient evolution towards a profundal specialist morph (SSR) in some dimorphic lakes. Ecological opportunity (lake size and productivity) is likely a prerequisite for whitefish to diverge, although limitations related to the colonization history also were present. In conclusion, there is astonishing parallel divergence in ecology, morphology and genetics along a continuum of increasing diversity in whitefish. Thus, ecologically-based natural selection is likely driving the divergence, promoting reproductive isolation and incipient ecological speciation in northern Fennoscandian whitefish populations.
Description:	Papers 1,3 and 4 of this thesis are not available in Munin: 1. Anna Siwertsson, Rune Knudsen and Per-Arne Amundsen: 'Temporal stability in gill raker numbers of subarctic European whitefish populations', Advances in Limnology (2012), vol. 63:229-240. Available at http://www.schweizerbart.de/papers/adv_limnology/detail/63/77932/Temporal_stability_ingill_raker_numbers_of_subarct 3. Anna Siwertsson, Rune Knudsen, Kim Præbel, Colin E. Adams, Jason Newton and Per-Arne Amundsen: 'Discrete foraging niches promote ecological, phenotypic, and genetic divergence in sympatric whitefish (Coregonus lavaretus)', (accepted manuscrip) 4. Anna Siwertsson, Rune Knudsen, Colin Adams and Per-Arne Amundsen: 'Replicated morphological divergence supports incipient ecological morph formation in European whitefish (Coregonus lavaretus)', (manuscript)
URI:	http://hdl.handle.net/10037/4566

File(s) in this item: 2

paper_2.pdf (1.450Mb)

thesis.pdf (4.188Mb)

Studies of infectious pancreatic necrosis virus (IPNV) and immune evasion strategies

Skjesol, Astrid (Doctoral thesis; Doktorgradsavhandling, 23-Oct-2009)

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Abstract:	Infectious pancreatic necrosis (IPN) is a highly contagious disease which causes huge economic loss to the salmon farming industry world wide. The causative agent, the IPN virus (IPNV), is a dsRNA, non-enveloped virus with two genomic segments encoding five viral proteins, VP1-VP5. Available vaccines against this disease give only partial protection. In order to optimize vaccine efficacies, properties of the virus and virus-host interactions during an infection need to be elucidated. In this thesis, interactions between the individual viral proteins are described and functional analyses of the interactions performed. VP3 was found to be a key organizer in the viral particle, as it binds both to other VP3 proteins, to the VP1 RNA-dependent RNA-polymerase and to the viral genome. The different binding domains were mapped. Elucidation of fish defense against virus infections is also essential. Interferons (IFNs) act as “alarm” proteins and are produced upon viral infections. Most viruses have evolved strategies to avoid host defense. This is also true for IPNV. Treatment of uninfected cells with IFN makes the cells resistant to IPNV infection, whereas addition of IFN after the onset of viral replication enables the IPN virus to overcome host defense, and reduce the antiviral activity. Thus, IPNV has an antagonistic effect on the IFN-signaling pathway (JAK/STAT pathway). We suggest the viral proteins VP4 and VP5 to be implicated in this effect. STAT1 is a central molecule that is being activated by IFN and participates in up-regulation of antiviral genes. In this work STAT1 from Atlantic salmon has been cloned and found to have properties similar to mammalian STAT1; salmon STAT1 was activated by phosphorylation and translocated from cytoplasm to the nucleus upon stimulation with IFNs.
Description:	Papers number 1 and 2 of the thesis are not available in Munin due to publishers' restrictions: 1. Torunn Pedersen, Astrid Skjesol and Jorunn B. Jørgensen: «VP3, a structural protein of the infectious pancreatic necrosis virus, interacts with the RNA-dependent RNA polymerase VP1 and with double-stranded RNA», Journal of virology; 2007, 81(12), 6652-6663 (American Society for Microbiology). Available at http://dx.doi.org/10.1128/JVI.02831-06 2. Astrid Skjesol, Toril Aamo, Marit Nøst Hegseth, Børre Robertsen and Jorunn B. Jørgensen: «The interplay between infectious pancreatic necrosis virus (IPNV) and the IFN system: IFN signaling is inhibited by IPNV infection», Virus Research; 2009, 143, 53-60 (Elsevier). Available at http://dx.doi.org/10.1016/j.virusres.2009.03.004
URI:	http://hdl.handle.net/10037/2589

File(s) in this item: 2

paper_3.pdf (4.055Mb)

thesis.pdf (1.078Mb)

Interactions between small rodents and their food plants in tundra habitats

Soininen, Eeva Marjatta (Doctoral thesis; Doktorgradsavhandling, 19-Oct-2012)

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Abstract:	Small rodents are key herbivores of arctic ecosystems, where their cyclic population dynamics have important implications for vegetation dynamics. The role of vegetation for shaping small rodent population dynamics remains, however, unclear. Evaluation of this interaction has been greatly hampered by the rather fragmentary knowledge of small rodents feeding ecology, which in turn is due to methodological challenges in studying small rodent diets. In this thesis, I investigated interactions between small rodents and vegetation, focusing on variability of both diets and plant defences induced by rodent herbivory. In order to overcome limitations set by methods, I have evaluated the use of two recently developed methods and one traditionally used method for studying small rodent diets. I found that novel DNA metabarcoding methods give the best taxonomic resolution whereas traditional microhistological methods may still be useful to elucidate which plant parts have been eaten. Moreover, use of stable isotope analysis in research of small rodent feeding habits can be useful when evaluating the temporal persistence of diets. In three observational studies, I described diets of small rodents in tundra habitats and assessed sources of variability in them. I found that diets of my study species were more diverse than previously believed, suggesting that diversity is an important but previously underrated trait of small rodent diets. Nutritional quality seems to determine which food items are preferred, as small rodents selected in general for most palatable food items. In addition to nutritional drivers, my results suggest that various ecological drivers, such as food availability, competition and predation risk avoidance, are important determinants of for small rodent diets in the wild. A better incorporation of ecological and nutritional drivers into a common framework is therefore needed to understand what shapes diets of small rodents, and herbivores in general, in natural habitats. I evaluated the impact of herbivory on grass silica defences in an experimental study. I found that levels of such defences vary between locations, probably due to heritable differences among grass populations in the response to herbivory and differences in local growth conditions. Based on such spatial variation and the large proportion of other food items included in the diets of the focal small rodent populations, it is unlikely that silica-based defences would have a strong direct role in shaping small rodent population dynamics in Finnmark. However, increased levels of silica in grasses reduce grass palatability for rodents, and hence probably impact rodent diet quality indirectly, through a shift to diets with less grasses. I therefore suggest that availability of alternative food items is likely to be an important factor shaping the interaction between small rodents and grasses. Variability in both small rodent diets and plant defences suggests that interaction between vegetation and a small rodent species may show pronounced spatial variation. This, together with my findings on the diversity of diets and its increase during high population densities, indicates that a single plant defence mechanism is unlikely to shape rodent-vegetation interactions. I suggest that deeper understanding of the role of food for small rodent population dynamics could rather be gained by focusing on the compensatory nutritional effects of different food items as well as diet diversity.
Description:	Papers 2, 3, 4 and 5 are not available in Munin: 2. Soininen E.M., Zinger L., Gielly L., Bellemain, E., Br athen, K.A., Brochmann, C., Epp, L.S., Gussarova, G., Hassel, K., Henden, J.-A., Killengreen, S.T., R am a, T., Sten ien, H.K., Yoccoz, N.G. and Ims, R.A.: 'Shedding new light on the diet of Norwegian lemmings : metabarcoding of stomach DNA' (manuscript) 3. Soininen E.M., Ravolainen V.T., Br athen K.A., Yoccoz N.G., Gielly, L. and Ims R.A.: 'Arctic small rodents have diverse diets and exible food preferences' (manuscript) 4. Soininen E.M., Ehrich D., Lecomte N., Yoccoz N.G., Tarroux A., Berteaux D., Gauthier G., Gielly L. and Ims R.A.: 'Sources of variation in small rodent trophic niche : new insights from DNA metabarcoding and stable isotope analysis' (manuscript) 5. Soininen E.M., Br athen, K.A., Jusdado J.G.H, Reidinger S., Hartley S.E.: 'More than herbivory : levels of silica-based plant defences in grasses varies with genotype, species and location', Oikos (2012), Online before print. Available at http://dx.doi.org/10.1111/j.1600-0706.2012.20689.x
URI:	http://hdl.handle.net/10037/4574

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Antimicrobial natural products from Arctic and sub-Arcticmarine invertebrates

Tadesse, Margey (Doctoral thesis; Doktorgradsavhandling, 17-Sep-2010)

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Abstract:	Infectious diseases are a leading cause of death world-wide and there is a growing need for new anti-infective agents to combat multi-resistant strains of bacteria and fungi. Marine natural products are promising sources of novel antimicrobial compounds. In the present thesis, an investigation into the antimicrobial metabolites of Arctic and sub-Arctic marine invertebrate species is presented. Extracts of seven ascidian species, six sponge species, a soft-alcyonid coral and a bryozoan species, were screened for their antimicrobial activities. The extracts were pre-fractionated by solid phase extraction (SPE) and purified by reversephase high-performance liquid chromatography (RP-HPLC). Active metabolites were characterized by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) techniques. The antibacterial tyrosine-derived guanidines, 3-dihydroxy-tubastrine and tubastrine, have been isolated from the ascidian Dendrodoa aggregata. This is the first report on the isolation of active metabolites from D. aggregata. 3-dihydroxy-tubastrine has previously been isolated from the Australian sponge species Spongosorites sp. The compound was present in high concentrations in extracts of the ascidian and could serve as a chemotaxonomic marker for the species. Extracts of the ascidian Synoicum pulmonaria displayed the highest antimicrobial activities in our assays. Bio-guided fractionation of the extract, revealed the presence of three novel compounds, named synoxazolidinones A, B and C. The structures of the compounds were elucidated by spectroscopic methods including 1D and 2D NMR techniques, and analysis of mass spectrometric data. The absolute configuration of the compounds was also established by computational methods. The synoxazolidinones contain a unique 4-oxazolidinone core rarely encountered in natural products. Biogenetically, the compounds appear to be derived from arginine and tyrosine. This is the first report on the chemistry of S. pulmonaria. Synoxazolidinones also displayed anticancer activities and provide novel chemical scaffolds for structure-activity relationship studies which are currently being carried out. The dibrominated tryptophan-derived metabolite, eusynstyelamide B, and three new derivatives, eusynstyelamides D, E and F, have been isolated from the bryozoan Tegella cf. spitzbergensis. The structures of the compounds were elucidated by mass spectrometry and, 1D and 2D NMR techniques. All four compounds displayed potent antibacterial activities in our assays. This is the first report of bioactive metabolites from T. spitzbergensis. Eusynstyelamide B has previously been isolated from the Australian ascidian Eusynstyela latericius. The presence of the same metabolites in different organisms and environments, suggests biosynthesis by symbiotic microorganisms. In addition, this thesis provides background information on natural product research and current antimicrobial investigations of marine invertebrate species. The potential of Arctic and sub-Arctic marine invertebrates as sources of structurally novel, bioactive metabolites is demonstrated.
Description:	The papers of the thesis are not available in Munin due to publisher's restrictions: 1. Margey Tadesse, Bjørn Gulliksen, Morten B. Strøm, Olaf B. Styrvold, Tor Haug: «Screening for antibacterial and antifungal activities in marine benthic invertebrates from northern Norway», Journal of Invertebrate Pathology, 99(2008), 286-293 (Elsevier). Available at http://dx.doi.org/10.1016/j.jip.2008.06.009 The accepted version of the article is avalable in Munin at http://hdl.handle.net/10037/2728 2. Margey Tadesse, Veronika Tørfoss, Morten B. Strøm, Espen Hansen, Jeanette Hammer Andersen, Klara Stensvåg, Tor Haug: «Isolation and biological activity of (E)-1-(4-hydroxystyryl)guanidine from the sub-Arctic ascidian, Dendrodoa aggregata», Biochemical Systematics and Ecology (2010) - in press-version (Elsevier). Available at http://dx.doi.org/10.1016/j.bse.2010.04.002 3. Margey Tadesse, Morten B. Strøm, Johan Svenson, Marcel Jaspars, Bruce F. Milne, Veronika Tørfoss, Jeanette H. Andersen, Espen Hansen, Klara Stensvåg and Tor Haug: «Synoxazolidinones A, B, and C; novel bioactive alkaloids from the ascidian Synoicum pulmonaria». Manuscript, published version available in Organic Letters at http://dx.doi.org/10.1021/ol101707u 4. Margey Tadesse, Jioji N. Tabudravu, Marcel Jaspars, Morten B. Strøm, Espen Hansen, Jeanette H. Andersen and Tor Haug: «The antibacterial eusynstelamides B, D, E and F, from the Arctic bryozoan Tegella cf. spitzbergensis» (manuscript)
URI:	http://hdl.handle.net/10037/2702

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