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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Cost of migration in moose (Alces alces) with regard to mortality risk and locomotion

Tollefsen, Zandra Margareta January 2011 (has links)
Summary1. Migration is present in all animal taxa and is defined as a periodic movement pattern between given ranges. Migratory individuals generally move more directional and with higher speed than stationary individuals during the migration seasons. It is suggested that migratory individuals in these periods encounter more risk factors, and therefore experience a higher mortality.2. I studied the variation in the speed of movement and the number of times migratory and stationary moose were crossing elements associated with mortality risk, i.e. water bodies, roads and railroads, in Central Norway. This was done by examining the movement pattern of 121 GPS-collared moose. I also examined whether realized mortality differed between the two movement strategies. 3. The results only partly supported my hypothesis that migratory moose experience higher costs of movement and are confronted with more risk elements than stationary moose. As predicted, migratory moose moved faster than stationary moose, particularly during the migratory season. However, stationary moose had higher densities of risk elements within their home ranges, and crossed risk elements more frequently than migratory moose. For a given density of risk elements, migratory moose crossed more frequently, supporting the hypothesis that migratory moose are less risk adverse. This pattern was present throughout the year, suggesting that the behavior is not only related to higher movement during the migratory period. 4. I found no effect of movement strategy on the mortality rates, but the sample size was low. However, the trend of realized mortality was opposite of what I expected, with migratory moose having a lower mortality rate than stationary moose.5. My results suggest that migratory moose experience a higher risk of mortality by their movement strategy compared to stationary moose. However, this varies between individuals. By considering individual differences in costs of migration, it is possible to increase our understanding of partial migration. Increased human induced risks such as roads, will most likely increase the number of road crossings. The differences between the two movement strategies in number of crossings will most likely decrease as risk density increase, resulting in a high crossing frequency of risk factors performed by moose.
202

Variation in recruitment failure of moose (Alces alces) - any effects of population condition and climate?

Markussen, Stine Svalheim January 2011 (has links)
Summary1. Recruitment failure may represent an important demographic response to changes in the environment or in population size. In this study, I examined whether there was a positive relationship between recruitment rates and ovulation rates in year t-1 in eight Norwegian moose populations. Further, I examined how body condition and climate affected the spatiotemporal variation in recruitment rates and ovulation rates. 2. Both recruitment rates and ovulation rates exhibited spatial and temporal variation. The ovulation and twin ovulation rate in yearlings showed more temporal variation than in prime-aged adults. Furthermore, twinning rates varied more than ovulation and calving rates.3. The number of calves per female recruited to the population was positively related to number of eggs per female the previous year. More calves per female were recorded in years with a high June temperature, smaller snow depths and larger yearling body mass, indicating that more egg cells are realised into a calf in years with good living conditions.,4. Additionally, more calves per female were found in regions with higher number of eggs per female, cool June temperatures and low snow depths. The level of recruitment failure varied among regions, and was highest in Vestfold which is associated with low ovulation rates and body masses. This shows that prenatal or neonatal losses of offspring are likely to be an important demographic response in moose to changes in population size or in the environment.
203

Size-dependent habitat use in juvenile Atlantic salmon (Salmo salar L.)

Hamnes, Frøydis Bolme January 2011 (has links)
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204

Plasma melatonin profiles in Common carp (Cyprinus carpio) exposed to indoor photoperiods

Holtan, Marte Berg January 2011 (has links)
An intervention against extreme poverty and hunger was introduced in year 2000, when all members of the United Nations agreed on the Millennium Development Goals (MDG). Today, 1.4 billion people live in poverty and hunger, with poor prospects for increased living standards. Nepal is one of the world’s poorest countries with most of its population living ruraly on low-income agriculture. Due to ongoing climatic changes and financial instability, the international food security is threatened. Inexpensive and low water consuming food production will therefore be an important development for times to come. In line with the MDGs, the NTNU initiated programme Sustainable Poverty Reduction in Nepal (SPRN) have started to utilize Nepal’s rich freshwater resources to develop fish farms in tandem with eco-friendly hydropower projects. The main target is to develop year-round delivery of carp fingerlings in hilly rural areas.Fish are seasonally breeding animals that use environmental signals to coordinate and control their biological rhythms. Photoperiod represents an accurate indicator of time of day and season, and may be translated into a chemical body signal, melatonin, by the pineal gland. Pineal melatonin is released during night and the secretory pattern – which reflects the environmental light/dark cycle – may exhibit one of three known patterns. A daily and annual rhythmic production of melatonin may provide the fish with a physiological capacity to anticipate and prepare for upcoming seasonal changes. Manipulation of the photoperiodic control of pineal melatonin release has been successfully used to initiate biorhythms like spawning in cultured finfish species at mid and high latitudes. The current study was performed to describe the day/night plasma melatonin levels in Common carp (Cyprinus carpio) during November at mid-hills Nepal (28 ºN). It represents the first part of possible development of a maturation control system for low latitude carps. Plasma melatonin levels exhibited a single peak profile during late darkphase and decreased to low daytime levels before the onset of light. When subjected to an extended night period, carp plasma melatonin rhythm appeared to repeat this profile from natural photoperiod, which may indicate a circadian clock system at work. Blood plasma cortisol levels were elevated during these experiments but are not expected to have stimulated the melatonin release. These results demonstrate a possible complex melatonin control system of type B in the Common carp kept at low latitude (Nepal).
205

Oksygenforbruk, stressrespons og stress under Aqui-S sedasjon hos bergnebb (Ctenolabrus rupestris) i transportrelaterte forsøk / Oxygen Consumtion, Stress Response and Stress During Aqui-S Sedation in Goldsinny Wrasse (Ctenolabrus Rupestris) in Transport Related Experiments

Freland, John-Are January 2011 (has links)
Dagens problem med lakselus på atlantisk laks (Salmo salar) er betydelig, og bakgrunn for store økonomiske tap. Fiskeridirektoratet anslår at 80 % av tap i matproduksjon av atlantisk laks er forårsaket av lakselus. Nasjonalpolitiske bestemmelser tydeliggjør satsningen på bekjempelse av lakselus i Norge. Biologisk avlusning med bruk av leppefisk er i sterk fokus for flere aktører i laskeoppdrettsnæringen, og det er et stort behov for økologisk og biologisk kunnskap om leppefisk. Leppefiskfamilien (Labridae) er svært artsrik med mer enn 500 arter globalt, hvor få naturlige leppefiskarter er å finne i Norge. Tre av dem har vist sin nytteverdi som lusepisere. Bergnebb (Ctenolabrus rupestris) er en av disse, og har størst forekomst langs norskekysten. Tilgang på leppefisk for bruk i lakseoppdrett er i dag basert på villfangst og biltransport. Sykdom og dødelighet er imidlertid et stort problem relatert til de påvirkninger som fisken blir utsatt for ved disse prosessene. Metabolisme og stressrespons hos bergnebb er tema for denne oppgaven, hvor det nærmere undersøkes betydningen av Aqui-S sedasjon for bergnebb i simulert transport. En næringsrettet tilnærming med spesielt fokus på transport av leppefisk er bakgrunn for målinger i småskala oppsett som tillater fri bevegelse hos bergnebb under forsøk.Oksygenforbruk hos villfanget bergnebb viste stor spredning for individer i forhold til vekt og temperaturendring. Vinterakklimert fisk viste samlet redusert oksygenforbruk sammenlignet med sommerakklimerte. Stress ved plasma kortisol viste uendrede verdier for 10- og 30 minutter post lufteksponering som kontrollverdier og indikerer ukjente stresseffektorer for bergnebb i fangenskap. Stressrespons antydes redusert ved Aqui-S sedasjon ved 2,5-7,5 ppm, og gir ingen endring i løpet av 20 min. for oksygenforbruk ved introduksjon.
206

Physiological Characterization of Protocerebral Neurons in the Olfactory Network of the Moth, Heliothis virescens

Kirkerud, Nicholas Hagen January 2011 (has links)
In the sensory systems of insects, the primary olfactory centre in the antennal lobe has been one of the major areas of interest for the last two decades. Considerable progress has been made in understanding this earlier part of the olfactory network, whereas very little is known about the odour processing of the higher order centres within the protocerebrum. In this study, the olfactory system of the moth Heliothis virescens was employed as a model. Intracellular recordings and stainings of neurons in the higher order olfactory centre in the lateral protocerebrum (LP) were performed during stimulation with identified primary plant odorants and multicomponent blends. Neurons were visualized by scanning with confocal laser microscope and 3-dimensional reconstructions. In order to morphologically identify and characterize neurons in the LP, recontructed neurons were registered into a standard brain atlas that has been developed for this species. Two different analyses were performed on the obtained physiology. First, a cluster analysis revealed clear divitions with respect to different neurons interspike interval (ISI) distributions, thus indicating groups of neurons with different functional properties within the higher order olfactory network. Secondly, a novel method in which to quantify complex temporal response patterns was introduced. A t-test used to compare the quantified reponses to single odorants versus blends showed that the majority of neurons ( ~70%) in the LP responded stronger to multicomponent blends. This indicated a predominant synergistic interaction of plant odours in the higher order olfactory centre of H. virescens.
207

GABA Immunostaining of the Olfactory Pathway in the Heliothine Moth Brain

Jacobsen, Bente January 2012 (has links)
γ-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in all known nervous systems, and it is widely distributed in the olfactory circuit as well as other parts of the invertebrate brain. In order to further understand the GABAergic olfactory circuitry, the distribution of GABA in the brain of a nuctoid moth, Heliothis virescens, was investigated. Immunohistochemical experiments with an antibody against GABA were performed in order to visualize GABAergic structures and neurons. The stainings revealed strong immunoreactivity in the antennal lobes, the lateral protocerebrum, and the mushroom bodies, all of which are areas involved in olfactory information processing. The dense immunostaining in the lateral protocerebrum included a brightly immunoreactive cell cluster linked to processes innervating the mushroom bodies; this likely corresponds to the protocerebral calycal tract described in other species. Of the main antenno-protocerebral tracts, fibers in the medio-lateral showed strong immunoreactivity. However, double labeling of two intracellularly pre-stained projection neurons passing in this tract showed that not all fibers therein are GABAergic. Looking at the projection pattern of these neurons, it seems likely that they belong to a different morphological class of projection neurons than the GABAergic ones.Some methodologically important issues were also discovered in the study, the most significant being that the identity of not only the primary but also of the secondary antibody is of great importance to the quality of the results.
208

Morphological Characterization of Descending Neurons and Determination of Output areas in the Brain of the Moth Heliothis virescens

Børø, Siri January 2012 (has links)
Knowledge on how an insect’s behavior changes in response to chemical substances in the environment can ultimately contribute to the development of biologically harmless pest controls. One of the links between sensory processing systems in the brain and motoric output is thought to be the neurons mediating the pre-processed information from the brain to act on motor circuits in the ganglia of insects. In the present study, the noctuid moth Heliothis virescens was the insect of study, and the thoracic ganglion of in total 88 preparations was stained with fluorescent dye to systematically study the descending neurons mediating information out of their brains. Performing mass-staining of the thoracic ganglion have contributed to knowledge on the areas where these neurons originates or projects. Visualizing the stained neurons in a confocal microscope showed condensed staining of dendrites of descending neurons in the anterior-ventral part of the lateral protocerebrum and in the lateral accessory lobes. Knowing that processing of chemosensory information might result in activities of behavioral relevance, it was especially interesting to see whether projection neurons making up the olfactory axis in the lateral protocerebrum overlapped spatially with dendrites of descending neurons eventually terminating in motor systems in the thoracic ganglia. Double staining of both the antennal lobe and the thoracic ganglion were therefore performed in the same individual, in 31 preparations. Three dimensional reconstruction and registration of descending neurons into the digital standard brain atlas (SBA) of H.virescens supported the spatial position of descending neurons in the anterior-ventral part of the lateral protocerebrum. The SBA containing the descending neurons was visually compared to a separate SBA containing the olfactory axis in the lateral protocerebrum, indicating no or minimal spatial overlap between the olfactory axis and the dendrites of descending neurons. This highlights the need for a detailed examination to discover if sensory information can be transferred to motor systems via 3rd order neurons local to the protocerebrum.
209

Effects of different live feed on larval growth and development in ballan wrasse (Labrus bergylta Ascanius, 1767) : - A metabolomics study

Almli, Martin January 2012 (has links)
The use of ballan wrasse (Labrus bergylta) for the treatment of salmon lice (Lepeophtheirus samonis) in salmon farming is rapidly growing due to resistance to chemical treatments. The demand for high quality and large amounts of ballan wrasse has thus led to the development of ballan wrasse farming. Due to the small size of the newly hatched larvae, the first-feeding of the larvae has become a bottleneck area. The size and nutritional properties of the live feed chosen can greatly affect both growth and development. Using copepods as live feed in the first part of the feeding regime should give a positive effect on the larval growth and development as they are the natural prey of marine fish larvae and are nutritional superior to rotifers.The aim of this study was to use 1H-NMR to examine the differences in larval metabolic composition as a function of the different types of live feed, as well as to find the most suited method for preparation of ballan wrasse samples for metabolic analysis. To examine this, ballan wrasse larvae was fed using four different feeding regimes. The live feed used was different between the four groups for the first 30 days post hatch. After this all groups were fed the same diet. Larvae in the Copepod group were fed only the copepod Acartia tonsa. The Cop7 was fed copepods the first 7 days, then enriched rotifers. The RotMG group was fed enriched rotifers, and the RotChl group was fed unenriched rotifers. After 30 days post hatch, all treatments was fed enriched Artemia before weaning to formulated feed. Results from the present study indicate that the use of copepods in first-feeding of ballan wrasse resulted in an increase in growth compared to larvae fed rotifer diets. Metabolic analysis of the larvae show that changes in the levels of certain metabolites can be used as biomarkers for growth and development. Differences seem to be correlated to feed composition, with TMAO and taurine standing out as reliable biomarkers for growth differences
210

Plasma melatonin profiles in silver carp (Hypophthalmichthys molitrix) during natural and manipulated photoperiods

Prestrud, Marit January 2012 (has links)
Photoperiodic manipulation of reproductive events in fish is suggested to secure all-year supply of fish fry in the Nepalese aquaculture. This could significantly improve food security and decrease poverty in Nepal. In order to achieve this, knowledge about the teleost melatonin system and reproduction is needed. The present study examined blood plasma profiles of the hormone melatonin in silver carp (Hypophthalmichthys molitrix) in Nepal during natural and manipulated photoperiods. Plasma melatonin levels throughout the natural 24-hour light-dark cycle were low during the light period, and increased several folds during the dark period. Peak level was reached early in the dark period, 2.5 hours after onset of darkness. Thereafter levels decreased prior to sunrise. When the silver carps were exposed to continuous darkness, the diurnal rhythmical melatonin levels observed during natural light-dark cycle were sustained. The melatonin levels during the time of the natural light period were low, and increased significantly during the time of the natural dark period, even if the fish were deprived of time signals in the light-dark cycle. In another experiment, silver carps were subjected to a period of two hours darkness at different times during the natural light period. Darkness at morning and midday did not increase plasma melatonin levels, whereas darkness during late light-phase gave a significant increase in plasma melatonin levels. The findings in this study suggest that melatonin synthesis from the pineal gland in silver carp is controlled by an endogenous biological clock. Plasma cortisol levels were measured, and were relatively high. However, it is suggested that cortisol may not have influenced the plasma melatonin levels and fluctuations in the silver carps in the present study significantly.

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