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Browsing Artikler, rapporter og annet (arktisk og marin biologi) by Issue Date
Now showing items 1-20 of 122
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Nilssen, Eilif J. (Research report; Forskningsrapport, 1996)[+][-]
Abstract: Ti pollendiagram fra syv lokaliteter presenteres. Lokalitetene er gårder eller tidligere gårder med endelsen –stad eller -staðir (gammel flertallsform). Gårdene er i kommunene Bø, Hadsel og Vestvågøy i Nordland fylke, og Namdalseid kommune i Nord-Trøndelag fylke.
Undersøkelsene er en del av prosjektet ” ..-stadirgårder og pollenanalyse” (gårder med endelsen -stadir og pollenanalyse). Formål og resultat av dette prosjektet er publisert i Vorren et al 1990.
I ett av diagrammene fra Vestvågøy, Tangstad 1, starter akkumuleringa av organisk materiale 9700 år før nåtid. Innvandring av bjørk (Betula) er registrert 8900 år før nåtid. Menneskelig innvirkning på vegetasjonen kan registreres fra ca 5000 år før nåtid i diagrammene fra Gimstadbakken og Rystad 2. Jordbruksaktivitet startet omkring 2950 år før nåtid og de første spor etter dyrking av kornsorten bygg (Hordeum), registreres fra ca 2820 år før nåtid. Flere perioder med mindre jordbruksaktivitet og/eller ødeperioder registreres.URI: http://hdl.handle.net/10037/2535 File(s) in this item: 11
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Åsbakk, Kjetil; Nilssen, Arne C.; Oksanen, Antti; Haugerud, Rolf E.; Hemmingsen, Willy (Journal article; Tidsskriftartikkel; Peer reviewed, 1999)[+][-]
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Rædergård, V.B.; Mathiesen, S.D.; Vader, M.A.; Haga, Ø.E.; Norberg, H.J.; Sørmo, W.; Tyler, N.J.C. (Journal article; Peer reviewed, 1999)[+][-]
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Milne, Eric; Gotaas, Geir; Tyler, Nicholas J.C.; Haggarty, Paul (Journal article; Peer reviewed, 2000)[+][-]
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Van Oort, B.E.H.; Tyler, N.J.C.; Reierth, E.; Stokkan, K.-A. (Journal article; Peer reviewed, 2000)[+][-]
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Milne, Eric; Gotaas, Geir; Haggarty, Paul; Tyler, Nicholas J.C. (Journal article; Peer reviewed, 2000)[+][-]
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Nilssen, Arne C.; Hemmingsen, Willy; Haugerud, Rolf E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2002)[+][-]
Abstract: The highly efficient endectocide ivermectin is used to reduce the burden of parasites in many semidomestic reindeer herds in northern Fennoscandia. In the autumn of 1995 and 1996 all reindeer on the island of Silda (42 km2) were treated with ivermectin in an attempt to eradicate the warble fly (Hypoderma (=Oedemagena) tarandi (L.)), the nose bot fly (Cephenemyia trompe (Modeer)) (Diptera: Oestridae) and the sinus worm (Linguatula arctica Riley, Haugerud and Nilssen) (Pentastomida: Linguatulidae). Silda is situated 2-3 km off the mainland of Finnmark, northern Norway, and supports about 475 reindeer in summer. A year after the first treatment, the mean abundance of H. tarandi was reduced from 3.5 to 0.6, but a year after the second treatment the mean abundance unexpectedly had increased to 4.5. After one year without treatment, the mean abundance and prevalence of the three target parasites were at the same level, or higher, than pre-treatment levels. The main hypothesis for the failure to eliminate the parasites is that gravid H. tarandi and C. trompe females originating from untreated reindeer in adjacent mainland areas dispersed to the island during the warm summer of 1997 (possibly also in 1998). As these oestrids are strong flyers, it may not be too difficult for them to cross >2-3 km of oceanic waters. There are no good explanations for the failure to eradicate L. arctica, but the results indicate that there may be elements in its life cycle that are unknown. The conclusion of the study is that it may be difficult or impossible to eradicate these parasites permanently, even locally such as on islands unless adjacent areas on the mainland are also cleared. URI: http://hdl.handle.net/10037/608 File(s) in this item: 1
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Peruzzi, Stefano (Journal article; Tidsskriftartikkel; Peer reviewed, 2003)[+][-]
Abstract: A preliminary study on tetraploid gynogenetic induction in the European sea bass was performed by pressure-blocking the second polar body release and the first cleavage in eggs fertilized with ultraviolet-irradiated sperm. Fertilization of eggs with genetically inactivated sperm produced only haploid development that terminated around hatching. Pressure treatments (8.500 psi for 2 min) applied at 6 and 65 min after fertilization (a.f.) produced variable levels (7–95%) of tetraploid larvae at hatching. A small proportion of mosaics (3.8n/4.2n) was also recorded. URI: http://hdl.handle.net/10037/5084 File(s) in this item: 1
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Langeland, K.; Ims, Rolf Anker; Skog, E.; Killengreen, Siw Turid; Scheie, J.O.; Yoccoz, Nigel Gilles; Bråthen, Kari Anne (Research report; Forskningsrapport, 2004)[+][-]
Description: Faglig årsrapport for 2004 til DN. URI: http://hdl.handle.net/10037/2516 File(s) in this item: 1
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Næss, Marius W.; Lhagyal, Dondrup; Yangzom, Drolma; Mathiesen, Per; Fox, Joseph L.; Bårdsen, Bård J. (Journal article; Peer reviewed, 2004)[+][-]
Abstract: Nomadic pastoralists live at the northern extent of human habitation within the ca. 5000 m elevation Aru basin, in the nortwestern part of the Chang Tang Nature Preserve, Tibet. These nomads herd primarily sheep and goats, a lesser number of yaks, and a few horses. Goats are increasing in importance because of the value of cashmere wool in national and international markets. Although sheep wool production is greater per animal than for the cashmere goats, the price obtained for its wool is much lower. Still, households keep more sheep than goats, primarily because sheep meat is preferred for consumption and sheep wool is important for the nomads’ own use. The Aru nomads have traditionally depended on hunting to compensate for livestock lost to predators and unpredictable climatic phenomena such as blizzards. The prohibition of hunting in the reserve from 1993 has apparently resulted in a lowering of their standard of living, even with an overall rise in cashmere prices. According to the nomads, without hunting they have thus lost a safety measure important during years with heavy livestock losses. Conservation related development initiatives in the reserve should address this issue. URI: http://hdl.handle.net/10037/591 File(s) in this item: 1
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Yangzom, Drolma; Fox, Joseph L.; Mathiesen, Per; Binrong, Xu; Næss, Marius W. (Journal article; Peer reviewed, 2004)[+][-]
Abstract: In 1993 the Tibet Autonomous Region (TAR) of China established the 300 000 km2 Chang Tang Nature Preserve on the northwestern Tibetan plateau, an action precipitated by rapidly diminishing populations of chiru (Tibetan antelope) and wild yak. Some 30 000 nomadic pastoralists use areas within this reserve for livestock grazing, with many having traditionally depended in part on hunting for supplementary subsistence and trade. Following a 1997 request from TAR leaders for international assistance in addressing the conservation issues associated with the creation of this reserve, the TAR Forestry Bureau and the Network for University Co-operation Tibet – Norway began a 3-year research collaboration program in 2000 to outline human-wildlife interactions and conservation priorities in the western part of the reserve. To date, four excursions (2-6 weeks each) have been made to the western Chang Tang region, and investigations of interactions between pastoralists and wildlife conservation objectives have been initiated in an area of about 5000 km2, including the 2300 km2 Aru basin located at 5000 m elevation at the northern edge of pastoralist inhabitation. The Aru site is unique in that nomads have only recently returned to this previously off-limits basin. But, as in surrounding areas, the people’s lives are undergoing changes recently influenced by the introduction of permanent winter houses, changing international trade in shahtoosh and cashmere wool, and a move towards stricter hunting regulations. The northwestern Chang Tang, with the Aru basin as a prime site, represents one of the last strongholds of the endangered chiru and wild yak, as well as home to Tibetan gazelle, kiang, Tibetan argali, blue sheep, wolf, snow leopard and brown bear. In autumn 2000, for example, with approximately 12 000 of the wild ungulates (mostly the migratory chiru) within the Aru basin along with some 8000 domestic livestock, issues of land use overlap and possible grazing competition are clear to both local nomads and reserve managers. Whereas livestock development actions elsewhere on the Tibetan plateau are promoting increased livestock production, they are doing so at the expense of wildlife, and such an approach will not be appropriate in areas where wildlife conservation is a major priority. Although some of the ongoing livestock development programs may be adapted to the western TAR, new approaches to pastoral development will have to be developed in the reserve. The ultimate goal of enhancing the nomads’ standard of living, while conserving this truly unique array of biodiversity, presents a daunting challenge. URI: http://hdl.handle.net/10037/597 File(s) in this item: 1
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Menu, B; Peruzzi, Stefano; Vergnet, A; Vidal, MO; Chatain, B (Journal article; Tidsskriftartikkel; Peer reviewed, 2005)[+][-]
Abstract: The objective of this study was to develop a rapid and effective method of sexing juvenile sea bass with minimum labour and material.To this end, the gonad squash mount technique was applied along with macroscopic techniques for sexing a large number of experimental fish at the age of 215-275 days post fertilization (p.f.). At this age, 90% of the 3894 fish could be unambiguously sexed by macroscopic examination of their gonads, whereas the remaining proportion was identified using squash mount preparations (10%). The accuracy of the observations was measured up to classical histology procedures. Undifferentiated gonads accounted for 0.1% of the total population only.The application of the squashmount technique holds out the prospect of considerable improvement in the efficiency and rapidity of current sexing techniques in sea bass. URI: http://hdl.handle.net/10037/5088 File(s) in this item: 1
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Peruzzi, Stefano; Varsamos, S; Chatain, B; Fauvel, C; Menu, B; Falguiere, JC; Severe, A; Flik, G (Journal article; Tidsskriftartikkel; Peer reviewed, 2005)[+][-]
Abstract: The purpose of this study was to determine whether diploid and triploid sea bass differed in terms of main haematological and physiological characteristics. Diploid and triploid fish were produced by sub-optimal pressure treatments and held in communal environments under standard rearing conditions. Total red blood cell count (RBCC), haemoglobin concentration (Hb), hematocrit (Hct), mean cell volume (MCV), mean cellular haemoglobin content (MCH), mean cell haemoglobin concentration (MCHC), plasma metabolites, osmotic pressure, gill Na+/K+-ATPase activity, electrolytes, cortisol, and 3,5,3′-triiodo-l-thyronine (T3), were measured and compared. Triploidisation in sea bass led to an increase in erythrocyte size (32% in cytoplasm surface area, and 50% in nucleus) and a decrease in erythrocyte number (∼34%). Haemoglobin and basal plasma cortisol levels were significantly lower in triploid sea bass than in diploids. There were also differences between ploidies in the plasma concentrations of some electrolytes, with triploids showing lower concentrations of K, Fe, Zn, S, and Cu than their diploid counterparts. URI: http://hdl.handle.net/10037/5086 File(s) in this item: 1
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Skog, E.; Ims, Rolf Anker; Killengreen, Siw Turid; Scheie, J. O.; Yoccoz, Nigel Gilles; Mørk, T.; Henden, John-André; Langeland, K.; Ravolainen, Virve (Research report; Forskningsrapport, 2005)[+][-]
Description: Faglig årsrapport for 2005 til DN. URI: http://hdl.handle.net/10037/2517 File(s) in this item: 1
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Junttila, Olavi; Olsen, Jorunn Elisabeth; Tsegay, Berhanu Abraha (Journal article; Tidsskriftartikkel; Peer reviewed, 2005)[+][-]
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Wassmann, Paul (Chapter; Bokkapittel, 06-Jan-2005)[+][-]
Abstract: History of cultural eutrophication. Cultural eutrophication is old as Homo sapiens. In particular after the introduction of agriculture and larger settlements eutrophication has been mans faithful companion. During the pre-agricultural hunting and picking stage only probably a couple million humans inhabited the world and cultural eutrophication was negligible. The 3 orders of magnitude increase in population has changed this considerably. Human population growth and mans present existence is entirely based upon the development and efficiency of agriculture. Seafood delivers only a small percentage of human food word wide (see Chapter 15). A consequence of the increased population (based on agriculture) has been large-scale cultural eutrophication. This process has accompanied all major civilisations. Mesopotamia, the Golden Crescent, the Mediterranean cultures, central Europe, North America and China all have been affected/suffered from the effects of cultural eutrophication. Some of us may dream about the good old times of the Middle ages when man lived closer to nature, when the word appeared to be ‘greener’ than today and when life was more ‘natural’. This view is based on a misunderstanding. The present eutrophication of the Baltic and North Sea was preceded by similar or even worse eutrophication periods caused by logging and the introduction of large-scale agriculture in Europe. Medieval cities were probably not only unsanitary, but contaminated by organic wastes, nutrients and heavy metals. The cultural eutrophication in major cities must have been immense, far beyond today’s imagination. A good example of the ambience of Paris in medieval times is portrayed in Patrick Suesskinds novel ‘Perfume’. Cultural eutrophication is thus not a recent phenomenon. It has continuously accompanied mans existence in variable degrees. Locally cultural eutrophication can have been far more significant than today. URI: http://hdl.handle.net/10037/2391 File(s) in this item: 1
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Wassmann, Paul (Chapter; Bokkapittel, 06-Jan-2005)[+][-]
Abstract: Quantitative estimates of the fluxes and dynamics in the nutrient load on marine environments, their distribution and channelling through the food web and the effect on the increase of new production, are fundamental and constitute a prerequisite for the planning of actions for water protection measures. The Gulf of Riga is no exception. The Gulf is a semi-enclosed part of the eastern Baltic Sea, surrounded by Estonia and Latvia and has one major outlet, the Irbe Straight Sound, and one minor one, the Muhu Sound. The Gulf of Riga has a surface area of 19,000 km2, is up to 67 m deep, has a relatively simple topography and a volume of 420 km3 (Figure 19.1). The Gulf is eutrophicated and most of the pollution loads in the Gulf can be attributed to human activities in the drainage basin, which covers 135,700 km2, or more than seven times the surface area of the Gulf itself. In pelagic environments the fate of organic matter produced by an increased supply of nutrients, the regulation of vertical flux and in particular the pelagicbenthic coupling are not well known in general, let alone in the Gulf of Riga. Since the beginning of this century Estonian, Latvian, Lithuanian and Russian scientists have already carried out a substantial body of work in various disciplines in the Gulf of Riga and its drainage area (summarised by Ojaveer 1995). From 1993–1997 Nordic and Baltic scientists joined forces in an international project, the ‘Environmental Research in the Baltic Sea’, also referred to as the ‘Gulf of Riga Project’ (GoR). The objective was to study environmental problems in the Gulf and its drainage area, and to determine their impact on the rest of the Baltic Sea in general and the Baltic Proper in particular (Figure 19.2). The investigations reviewed here aim at to understand the Gulf of Riga as an ecosystem by analysing 1. the dynamics of the runoff of nutrients and their supply to the Gulf, 2. the distribution of nutrients in the Gulf, 3. the production and distribution of plankton and organic matter and 4. the processes involved in settling and the vertical export of organic matter. This chapter rests upon 14 publications from the project ‘Pelagic eutrophication and sedimentation’ (Wassmann & Tamminen, 1999); see also J. Mar. Syst, Vol 23. URI: http://hdl.handle.net/10037/2388 File(s) in this item: 1
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Wassmann, Paul; Olli, Kalle (Chapter; Bokkapittel, 06-Jan-2005)[+][-]
Abstract: Ingress Eutrophication is an increase in primary production due to increased nutrient supply and its consequences. In its widest sense eutrophication means any increase of nutrient availability that increases primary production. Frequently, however, eutrophication is understood exclusively as the consequence of nutrient input by anthropogenic activities. The primary consequence of eutrophication in aquatic environments is an enhancement of algal productivity and accumulation of algal biomass. Secondary consequences are changes in community structure of plankton and benthos. Man-induced eutrophication or changes in biodiversity are nothing new: they are a well-known consequence of human culture. Eutrophication phenomena accompanied all human settlements. Even in the early days of mankind human activities resulted in ecosystem changes. Several large animals such as the mammoth survived the glacial periods, but not the last one. It has been suggested that Neolithic hunters decimated this species to extinction. Similar suggestions have also been made regarding other large mammals that did not continue to exist after the last glacial. The main sewage canal in the city of Rome, ‘cloaca’, has given rise to a number of expression regarding sewage pathways in numerous languages. Since classical and medieval times there have been ‘clean-ups’ of unsanitary, plague-ridden cities. Eutrophication is thus the oldest environmental problem of human civilization and not a recent phenomenon. However, with the significant increase of human population over recent decades, eutrophication has developed from a more or less local to a global issue. Due to changes in human living conditions and the declining number of people employed in agriculture, the population in the coastal zone increases steadily. The nutrient concentration increases continually from small streams over rivers and larger lakes to the estuaries. The consequences of this, such as discoloured waters, ‘rotten’ bottom water, odour and reduced fishing yields are obvious to even a casual observer. The combined effect of increasing human population and movement to the coastal zone, the environmental pressure on rivers, estuaries and shelf regions results in an ever-increasing pressure on the entire coastal zone (Figure 1). Consequently, eutrophication turns into an escalating global phenomenon as long as the human population increases. Homo sapiens has thus a vital impacton nature that is part of its culture. As a consequence of that we have to distinguish between natural and cultural eutrophication. In most of this text the term eutrophication stands for cultural eutrophication. URI: http://hdl.handle.net/10037/2371 File(s) in this item: 1
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Wassmann, Paul (Chapter; Bokkapittel, 06-Jan-2005)[+][-]
Abstract: Introduction. The effects of global and local changes are most prominent at the land-sea margins where presently population growth is greatest. For example, the population of coastal counties of the USA has roughly doubled since 1960 (Eos, 1992). This gives rise to increased pressure on natural resources and a large number of disturbances to coastal regions. Presently, eutrophication of coastal waters is probably the most important environmental effect (Gesamp, 1991). The effects of nutrient enrichment thoroughly change coastal ecosystems and occur virtually worldwide. Nutrients move across the land-sea margins at such high rates that coastal waters and estuaries are the most fertilized ecosystems on earth (Figure 9.1). URI: http://hdl.handle.net/10037/2390 File(s) in this item: 1
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Msomphora, Mbachi Ruth (Chapter; Bokkapittel, 06-Jan-2005)[+][-]
Abstract: Several of the African Great Lakes are distinctive for their very long water residence time >100 years. Incoming nutrients will be retained within the lakes and recovery will be slow even if inputs are reduced. While changes in chemistry and plankton composition of Lake Malawi have not been extreme to date, strong eutrophication is already happening in Lake Victoria, where damage has reduced its biological wealth and human misery may follow (Baskin, 1992). It could be advisable to prevent this happening to Lake Malawi and Tanganyika. Description: This is chapter 21 of the book "Drainage basin nutrient inputs and eutrophication: an integrated approach." URI: http://hdl.handle.net/10037/2387 File(s) in this item: 1
article.pdf (1.058Mb)
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