Mastergradsoppgaver i biologi

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Mastergradsoppgaver i biologi

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• Adaptive radiation of the European whitefish Coregonus lavaretus (L.) in the Pasvik watercourse: the genetic description of a new morph

  Couton, Marjorie (Master thesis; Mastergradsoppgave, 26-Nov-2012)

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  Abstract:

  Sympatric occurring fish morphs in postglacial lakes usually exhibit differences in morphology and physiology driven by adaptations to differential trophic niches. The European whitefish (Coregonus lavaretus (L.)) is a highly variable fish species, with more than 200 intraspecific forms described in Europe. The morphs usually differ in their number of gill-rakers, therefore this trait has been traditionally used for whitefish classification. According to this taxonomy, three different morphs can be distinguished in northern Fennoscandia: the large sparsely rakered (LSR), the densely rakered (DR), and the small sparsely rakerd (SSR) morphs. They all exhibit differences in morphology, diet, habitat, and physiology. Recently, a new morph has been discovered in several lakes of the Pasvik watercourse which displays densely rakered gills and an external morphology similar to the LSR whitefish, and was called large densely rakered (LDR). In this study, genetic data from 18 microsatellites markers were used to evaluate the genetic differentiation and the possible origin of this new morph in three Finnish lakes of the Pasvik watercourse. The LDR morph in each lake was found to be genetically different from the three other morphs. Several possible origins were suggested, but the sympatric speciation from either the LSR or the DR morphs was the hypothesis that gained the most support from the results. Moreover, the three different LDR populations were found to have a common origin, suggesting that the divergence occurred only once after the last ice retreat and the same population divided into three when the different lakes were formed.

  URI:

  http://hdl.handle.net/10037/5171

  File(s) in this item: 1

  thesis.pdf   (1.404Mb)
• Populasjonsstruktur, kjønnsmodning og variasjon i fekunditet hos kongekrabbe (Paralithodes camtschaticus) i Porsangerfjorden, Finnmark : et litteratur- og feltbasert studium

  Lindberg, Ken Ståle J. (Master thesis; Mastergradsoppgave, 22-Nov-2012)

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  Abstract:

  Russiske forskere introduserte kongekrabben, Paralithodes camtschaticus, til Barentshavet på 1960 og 1970-tallet for å gi lokale fiskere en ny art å høste av. Det var antatt at spredning til norske farvann var lite sannsynlig. Artens etablering ble en suksess sett fra russisk side. Kongekrabben har nå spredt seg over hele kysten av Finnmark fylke, og Porsangerfjorden er den siste av fjordene som arten hittil har kolonisert. På norsk side har krabbens invasjon skapt store utfordringer, som har bidratt til at det i dag er etablert et todelt fangstregime. Dette regimet fungerer slik at vest for 26°Ø er det fri fangst og et ønske om å begrense mer spredning, mens øst for denne grensen er fangsten regulert av kvoter og er blitt en ressurs for fiskerinæringen. Porsangerfjorden ligger i grenseområdet for dette todelte fangstregimet, men innenfor det kvoteregulerte området. For å kunne forvalte kongekrabben bærekraftig må man ha kunnskap om bestandssammensetning, kjønnsmodning, fekunditet og rekruttering, og det er disse temaene jeg skal belyse i denne avhandlingen. Innsamlingen av data ble foretatt i mai og oktober 2011, hvor til sammen 4 105 krabber ble målt og veid. I tillegg ble det tatt 160 eggprøver som ble videre behandlet på laboratoriet ved Universitetet i Tromsø. Jeg har sett på størrelsessammensetningen og kjønnsfordeling, størrelse ved kjønnsmodning, individuell eggvekt, fekunditet og eggtap hos kongekrabber i Porsangerfjorden. Størrelse ved kjønnsmodning er bestemt ved bruk av to metoder: 1. OL50, som er et estimat på hvilken ryggskjoldlengde (RL) 50 % av hunnkrabbene er eggbærende, og 2. Knekkpunktanalyse som estimerer hvor krabbene kjønnsmodnes, basert på at ulike kroppsdeler har ulik veksthastighet før og etter kjønnsmodning. Dataene viser at det er en overvekt av hunner i Porsangerfjorden, at det er en god rekruttering av mange små (< 100 mm RL) krabber og at det er få store krabber (> 130 mm RL). Krabbene kjønnsmodnes ved en relativ høy RL sammenlignet med andre områder, knekkpunkthann= 115.5 mm RL, knekkpunkthunn= 110.5 mm RL og OL50 = 111.3 mm RL. Den gjennomsnittlige individuelle tørre eggvekten var 0.228 mg per egg og viser ikke tendens til å endre seg vesentlig ved forskjellige RL eller ved ulike tidspunkt på året det måles. Det medfører at man kan lage fekunditetsestimat for et system som Porsangerfjorden ved hjelp av relativt få eggprøver. Fekunditeten var høyere enn i de nærliggende fjordene, og var estimert til 170 000 egg for en standardisert hunn på 125 mm RL. I området mellom 120 – 126 mm RL investerer kongekrabben mest i eggproduksjon i Porsangerfjorden 2011. Det ble ikke funnet statistisk bevist at kongekrabben i Porsangerfjorden 2011 hadde et eggtap, men av målinger så vises en tendens til at så kan være tilfelle da beregnet tap lå på omtrent 10 – 12 % av totalt antall egg hos en hunn på 125 mm RL.

  URI:

  http://hdl.handle.net/10037/5170

  File(s) in this item: 1

  thesis.pdf   (3.248Mb)
• Seawater consumption in dehydrated hooded seals (Cystophora cristata)

  Verlo, Are (Master thesis; Mastergradsoppgave, Mar-2012)

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  Abstract:

  Studies based on satellite-tracking show that hooded seals (Cystophora cristata) spend many months out in the open sea each year. When the seals are out in the open sea they have no access to fresh water. Experimental studies have showed that hooded seals drink seawater and that they have the capacity to produce urine with Na+ and cl- concentrations equal to or higher than that of seawater. They may also produce urine with an osmolality twice that of seawater. This indicates that the hooded seal may use seawater to restore water balance and maintain homeostasis. The purpose of this study is to quantify the amount of seawater drunk as a result of a controlled experimental dehydration and to monitor the endocrine response to dehydration and seawater drinking. Following 24 hrs of fasting five subadult hooded seal males were dehydrated using the diuretic mannitol. They were then given al lib access to seawater for 48 hrs. For the duration of the experiment total body water and the turnover rates of water was estimated by tritiated water injections and subsequently isotope dilution. Plasma parameters such as Na+, Cl- were monitored and all seals maintained relatively stable plasma concentrations of the electrolytes for the duration of the entire experiment, while urinary excretion of Na+ and cl- increased after ad lib access to seawater. Plasma osmolality and hematocrit values indicated seawater intake. The amount of seawater drunk by the seals were calculated as the difference between total influx and water influx from respiration and endogenous reserves. The hooded seals drank on average 1900 ml of seawater each day. The role of the hormones ,ADH and aldoesterone ,in the osmoregualtion of hooded seals still remain somewhat unclear.

  URI:

  http://hdl.handle.net/10037/5169

  File(s) in this item: 1

  thesis.pdf   (765.0Kb)
• Population dynamics, diet and trophic positioning of three small demersal fish species within Porsangerfjord, Norway

  Källgren, Emma Katarina (Master thesis; Mastergradsoppgave, 15-Nov-2012)

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  Abstract:

  In today’s society, one often stumbles over the quote “you are what you eat”. Diet is closely related to fish size and physical conditions, so in order to understand the food web one must first understand the population dynamics of the fish. Three demersal species in the northern hemisphere are; Artediellus atlanticus, Myoxocephalus scorpius and Leptagonus decagonus. The study was undertaken in 2009-2011, within the inner basin of Porsangerfjord (70oN 25oE) through the project ‘Ecological Processes and Impacts Governing the Resilience and Alternations in the Porsangerfjord and Hardangerfjord’. The study objectives were to provide basic information about these species population dynamics and feeding ecology. The length distribution varied between both sex and species, whereas the age structure was the same. The growth were different for L. decagonus but not for A. atlanticus and M. scorpius. The dominant prey found in A. atlanticus was Polychaeta, whereas M. scorpius fed on fish, and L. decagonus had fed on Copepoda. Correlations were found within the species diets, but not between any of these species. The stable isotope analysis showed that L. decagonus had a pelagic related diet whereas the A. atlanticus had a benthic related diet and M. scorpius demonstrated a mixed benthic-pelagic diet signature. The study found that the three species had different diets but similar trophic positions. Thus, indicating that they had individual food chains within the food web of inner Porsangerfjord.

  URI:

  http://hdl.handle.net/10037/5166

  File(s) in this item: 1

  thesis.pdf   (2.002Mb)
• Effects of various early life history temperature regimes on development and metamorphosis of Atlantic cod (Gadus morhua) larvae

  Bashan, Tolga (Master thesis; Mastergradsoppgave, 13-Dec-2012)

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  Abstract:

  The growth and important structures development in different temperature regime histories were studied during mid-metamorphosis stage of Atlantic cod (Gadus morhua) larvae. In order to see the growth and the organ development differentiation due to different temperatures at a given stage, we exposed the larvae into 4 different temperature regimes; L-L (low temperature at incubation, low temperature after hatching), L-H (low temperature at incubation, high temperature after hatching), H-L (high temperature at incubation, low temperature after hatching) and H-H (high temperature at incubation, high temperature after hatching) (low 4±0.2°C and high 9±0.2°C). The sampling was done according to the expected stage at a given sampling stage. Samples were fixed and studied under light microscope. Standard length and myotome height were measured for growth, swim bladder size, alimentary tract and fin differentiation were studied for organ development. The L-H group fish showed the best growth but had the highest variation in myotome heights. There was a lot of variation in organ developments at the given stages among the temperature groups, yet the groups with high temperatures after hatching period showed better organ development, postulating that besides the age is the key factor for fish to reach a given stage, also temperature is an extrinsic factor in organ development.

  URI:

  http://hdl.handle.net/10037/5165

  File(s) in this item: 1

  thesis.pdf   (4.677Mb)

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