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Browsing Artikler, rapporter og annet (arktisk og marin biologi) by Author
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Gabrielsen, Tove M; Merkel, Benjamin; Søreide, Janne; Johansson-Karlsson, Emma; Bailey, Allison; Vogedes, Daniel Ludwig; Nygård, Henrik Andreas; Varpe, Øystein; Berge, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: Calanoid copepods of the genus Calanus represent an important, nutrient-rich food source for a multitude of Arctic marine organisms. Although morphologically very similar, their life histories and ecological roles differ. Because the distribution of Calanus glacialis and C. finmarchicus corresponds to Arctic and Atlantic water masses, respectively, they are regularly used as climate indicators. A correct identification of these species is therefore necessary in many ecological, environmental and climatological studies. In this study, we aimed at validating the traditionally used morphological characteristics (combining prosome length and copepodite stage) for separation of species of Calanus by using molecular tools (PCR–RFLP of the 16S mtDNA). A total of 418 specimens of copepodite stages CIV, CV and CVI(af) from three Arctic fjords have been identified both morphologically and genetically. We find that the morphological identification systematically overestimates the abundance of C. finmarchicus at the expense of C. glacialis. Hence, parts of the C. glacialis populations are found to be structurally smaller and the within population size range thus larger than previously assumed. Consequently, using the traditional morphological species delimitation poses a serious problem in the use of these two species as indicators of Atlantic versus Arctic water masses and thus as climatic indicators. Furthermore, it obscures our understanding of the life history differences between the two species and of their relative importance as food for a number of ecologically and economically important species in the Arctic. URI: http://hdl.handle.net/10037/4980 File(s) in this item: 1
article.pdf (439.3Kb) -
Milne, Eric; Gotaas, Geir; Haggarty, Paul; Tyler, Nicholas J.C. (Journal article; Peer reviewed, 2000)[+][-]
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Milne, Eric; Gotaas, Geir; Tyler, Nicholas J.C.; Haggarty, Paul (Journal article; Peer reviewed, 2000)[+][-]
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Haanes, Hallvard; Gulliksen, Bjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: In general, biodiversity and species richness follow the latitudinal diversity gradient and decrease from the tropics towards the poles. Exceptions have however been recorded, as for deep coldwater coral reefs at high latitudes, which comprise biodiversity hotspots. Here we assess and characterise the high-latitude (69 degrees N) species richness and diversity of a local shallow-water fauna associated with small calcareous aggregations of a serpulid polychaete. A dense and very species rich fauna was recorded within aggregations of Filograna implexa Berkeley, 1828. Totally 4663 individuals belonging to 99 species (61 solitary, 38 colonial) were recorded in a total aggregation volume of only 4.4 l covering an area less than 0.05 m2 of a wreck situated in a tidal stream in North Norway. The number of species within each aggregation was positively related to its size, indicating that the high species diversity may be due to structural heterogeneity, which increase with aggregation size and probably creates new microhabitats and protect against predation. We present a species list including abundance and biomass, pin-point common species and describe a method for sampling such faunas associated with calcareous structures. URI: http://hdl.handle.net/10037/3880 File(s) in this item: 1
article.pdf (343.2Kb) -
Hausner, Vera Helene; Fauchald, Per; Jernsletten, Johnny-Leo L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: Abstract Community-based management (CBM) has been implemented in socio-ecological systems (SES) worldwide. CBM has also been the prevailing policy in Sa´mi pastoral SES in Norway, but the outcomes tend to vary extensively among resource groups (‘‘siidas’’). We asked why do some siidas self-organize to manage common pool resources sustainably and others do not? To answer this question we used a mixed methods approach. First, in the statistical analyses we analyzed the relationship between sustainability indicators and structural variables. We found that small winter pastures that are shared by few siidas were managed more sustainably than larger pastures. Seasonal siida stability, i.e., a low turnover of pastoralists working together throughout the year, and equality among herders, also contributed to more sustainable outcomes. Second, interviews were conducted in the five largest pastures to explain the relationships between the structural variables and sustainability. The pastoralists expressed a high level of agreement with respect to sustainable policies, but reported a low level of trust and cooperation among the siidas. The pastoralists requested siida tenures or clear rules and sanctioning mechanisms by an impartial authority rather than flexible organization or more autonomy for the siidas. The lack of nestedness in self-organization for managing pastures on larger scales, combined with the past economic policies, could explain why CBM is less sustainable on the largest winter pastures. We conclude that the scale mis-match between selforganization and the formal governance is a key condition for sustainability. URI: http://hdl.handle.net/10037/4934 File(s) in this item: 1
article.pdf (791.1Kb) -
Hausner, Vera Helene; Fauchald, Per; Tveraa, Torkild; Pedersen, Elisabeth; Jernsletten, Johnny-Leo L.; Ulvevadet, Birgitte; Ims, Rolf Anker; Yoccoz, Nigel; Bråthen, Kari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: To ensure economic viability over time, any efforts to meet the Millennium Development Goals need to reconcile conservation with development interventions. Particularly, in marginal and risk prone areas erosion of resilience could make production systems more susceptible to environmental risks that compromise the economic security. By longitudinal analyses of long-term data records we investigated the impacts of big push policies on Saami pastoral ecosystems in Arctic Norway. The big push was accompanied by reindeer herd accumulation and a corresponding degradation of resilience, increasing the susceptibility to herd losses to predators and adverse winters. For the last 20 years the Norwegian government has worked to halt degradation of pasture ecosystems and reduce susceptibility to environmental risks. These intended win-win policies have mainly been based on economic incentives, which have been developed together with Saami pastoralists through negotiated agreements. We argue that the continued degradation of the Saami pastoral ecosystems is a “ghost of the development past”, as the big push policies have resulted in an economic security trap (EST). The gradual reduction of resilience has persisted as the ex post payments of disaster relief and predator compensation have impeded the long-term actions to reduce susceptibility to environmental risks, i.e., ex ante policies, thereby increasing dependency on elevated economic inputs to manage the risks. The transfer of liability for managing risks to the benefactor, both through ex ante and ex post policies, has further discouraged and constrained opportunities for adaptation by the pastoralists. URI: http://hdl.handle.net/10037/4031 File(s) in this item: 1
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Henden, John-André; Ims, Rolf Anker; Yoccoz, Nigel; Sørensen, Raymond; Killengreen, Siw Turid (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: The areal extent and conWguration of thickets of willow shrubs are currently changing in the Arctic both as an eVect of global warming and changed browsing pressure of reindeer. These changes have been predicted to impact the distribution and abundance of wildlife species relying on willow thickets as habitat. We assessed the relation between variables quantifying willow thicket configuration and population dynamics of tundra voles (Microtus oeconomus) in three riparian regions in Finnmark, northern Norway, which were subject to intense browsing by semidomesticated reindeer. The tundra vole, which exhibits 5-year population cycles in Finnmark, is the dominant small rodent species in riparian landscape elements in southern arctic tundra. In the course of a 4-year trapping study, tundra vole populations went through the cyclic phases of increase, peak and crash, however, with distinct differences between the three regions in the population dynamics. Within regions, the occupancy pattern during the increase phase was positively related to willow thicket configuration (in particular edge density and willow height) only in the region attaining the highest abundance and occupancy. However, local abundance was not clearly related to habitat features within any regions. The lack of consistency in the response of tundra vole populations to willow thicket configuration, as well as the positive relation between the degree of thicket shredding and tundra vole habitat occupancy in one of the regions, indicates that tundra voles will not be much aVected by climate or browsing induced changes in the shrubbiness of the tundra in the future. URI: http://hdl.handle.net/10037/3885 File(s) in this item: 1
article.pdf (591.4Kb) -
Henden, John-André; Ims, Rolf Anker; Yoccoz, Nigel; Killengreen, Siw Turid (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: The recent range contractions and population declines of many grouse species worldwide have been attributed to loss and fragmentation of their habitats, although the empirical evidence for the actual drivers is often weak. In case of the willow ptarmigan Lagopus lagopus in Fennoscandia, ungulate overbrowsing of willows has been hypothesized to exert such negative habitat-related impacts. Moreover, a steep population decline of willow ptarmigan in southern Fennoscandia has recently been attributed to community interactions linking the fate of the willow ptarmigan to a change in keystone tundra rodent populations. Community and habitat factors may also interact in their impact on willow ptarmigan abundance. Here we assess whether willow thicket structural characteristics sensitive to ungulate browsing impacted willow ptarmigan habitat occupancy and whether such impacts depended on small rodent population dynamics. We employed an extensive survey approach spatially encompassing three riparian tundra regions and covering the phases of increase, peak and crash of the small rodent cycle. Willow ptarmigan habitat occupancy increased with the areal extent of willow thickets, whereas it decreased with increasing degree of thicket fragmentation (i.e. habitat shredding). Both of these effects were consistent with ungulate over-browsing impacting willow ptarmigan abundance negatively. Over the 4-year study period, willow ptarmigan habitat occupancy declined steeply independently of spatial variation in willow thicket areal extent and fragmentation. Moreover, the expected increase in ptarmigan populations during the increase/peak phase of the rodent cycle was not observed. Thus although our study provides support for the hypothesis that intense ungulate browsing negatively impacts willow ptarmigan, our study also suggests that causes of the current steep decline of ptarmigan populations in northern Fennoscandia should be sought in factors other than habitat fragmentation and changed rodent population dynamics URI: http://hdl.handle.net/10037/4214 File(s) in this item: 1
article.pdf (891.2Kb) -
Hodal, helene; Kristiansen, Svein; Hop, Haakon; Falk-Petersen, Stig; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: The marine ecosystem in Kongsfjorden (79 N), a glacial fjord in Svalbard, is to a large extent well known with regard to hydrography, mesozooplankton and higher trophic levels. Research on primary production and lower trophic levels is still scare and especially investigations from winter and spring periods. The spring bloom dynamics in Kongsfjordenwere investigated in 2002. The development in nutrient conditions, phytoplankton, protozoans and primary production were followed from 15 April until 22 May. The winter/ spring in 2002was categorized as a cold yearwith sea ice cover and water masses dominated by local winter-cooled water. The spring bloom started around 18 April and lasted until the middle ofMay. The bloom probably peaked in late April, but break-up of sea ice made it impossible to sample frequently in this period. Diatoms dominated the phytoplankton assemblage. We estimated the total primary production during the spring bloom in 2002 to range 27–35 g C m-2. There was a mismatch situation between the mesozooplankton and the phytoplankton spring bloom in 2002. URI: http://hdl.handle.net/10037/4982 File(s) in this item: 1
article.pdf (838.0Kb) -
Ims, Rolf Anker; Henden, John-André (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: Rapid, but contrasting, changes in the extent of erect thicket-forming shrubs is presently seen in the Arctic, either resulting from a warmer climate (increasing extent) or intensified herbivory (decreasing extent). We investigated the impact of loss of willow shrubs on a bird community in arctic riparian sediment plains in northern Norway subject to varying intensities of reindeer browsing. In riparian habitats where willow thickets had been lost, bird species richness was more than halved compared to habitats where some patches of thickets were still present. As could be expected species previously suggested to use erect woody vegetation as nesting places and/or foraging habitats were most consistently impacted. However, even some open ground habitat specialists appeared to be negatively impacted, possibly due to loss of spatial spill-over effects of insects from willow thickets. To preserve low-arctic avian biodiversity in a warming climate, management should strive to identify levels of ungulate browsing that strike the balance between shrub-encroached and shrub-denuded arctic tundra URI: http://hdl.handle.net/10037/4821 File(s) in this item: 1
article.pdf (693.4Kb) -
Ims, Rolf Anker; Knutsen, Kjartan; Mørk, T.; Killengreen, Siw Turid; Yoccoz, Nigel Gilles; Sarre, Arne Petter; Ørjebu, Alfred; Henden, John-André (Research report; Forskningsrapport, 2008)[+][-]
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Ims, Rolf Anker; Killengreen, Siw Turid; Henden, John-André; Yoccoz, Nigel Gilles (Research report; Forskningsrapport, 2007)[+][-]
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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
report.pdf (950.2Kb) -
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
report.pdf (856.4Kb) -
Mørk, Torill; Ims, Rolf Anker; Sarre, Arne Petter; Killengreen, Siw Turid; Jensvoll, Ingrid; Knutsen, Kjartan; Ørjebu, Alfred; Yoccoz, Nigel Gilles; Henden, John-André (Research report; Forskningsrapport, 2009)[+][-]
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Isemer, Rena; Krause, Kirsten; Grabe, Nils; Kitahata, Nobutaka; Asami, Tadao; Krupinska, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: WHIRLY1 is a protein that can be translocated from the plastids to the nucleus, making it an ideal candidate for communicating information between these two compartments. Mutants of Arabidopsis thaliana lacking WHIRLY1 (why1) were shown to have a reduced sensitivity toward salicylic acid (SA) and abscisic acid (ABA) during germination. Germination assays in the presence of abamine, an inhibitor of ABA biosynthesis, revealed that the effect of SA on germination was in fact caused by a concomitant stimulation of ABA biosynthesis. In order to distinguish whether the plastid or the nuclear isoform of WHIRLY1 is adjusting the responsiveness toward ABA, sequences encoding either the complete WHIRLY1 protein or a truncated form lacking the plastid transit peptide were overexpressed in the why1 mutant background. In plants overexpressing the full-length sequence, WHIRLY1 accumulated in both plastids and the nucleus, whereas in plants overexpressing the truncated sequence, WHIRLY1 accumulated exclusively in the nucleus. Seedlings containing recombinant WHIRLY1 in both compartments were hypersensitive toward ABA. In contrast, seedlings possessing only the nuclear form of WHIRLY1 were as insensitive toward ABA as the why1 mutants. ABA was furthermore shown to lower the rate of germination of wildtype seeds even in the presence of abamine which is known to inhibit the formation of xanthoxin, the plastid located precursor of ABA. From this we conclude that plastid located WHIRLY1 enhances the responsiveness of seeds toward ABA even when ABA is supplied exogenously. URI: http://hdl.handle.net/10037/5002 File(s) in this item: 1
article.pdf (1.218Mb) -
Iversen, Kriss Wenche Rokkan; Seuthe, Lena (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: Temporal dynamics of the microbial food web in the Barents Sea and adjacent water masses in the European Arctic are to a large extent unknown. Seasonal variation in stocks and production rates of heterotrophic bacteria and phototrophic and heterotrophic picoplankton and nanoflagellates was investigated in the upper 50 m of the highlatitude Kongsfjorden, Svalbard, during six field campaigns between March and December 2006. Heterotrophic bacteria, picoplankton and nanoflagellates contributed to ecosystem structure and function in all seasons. Activity within the microbial food web peaked during spring bloom in April, parallel to low abundances of mesozooplankton. In the nutrient-limited post-bloom scenario, an efficient microbial loop, fuelled by dissolved organic carbon from abundant mesozooplankton feeding on phytoplankton and protozooplankton, facilitated maximum integrated primary production rates. A tight microbial food web consisting of heterotrophic bacteria and phototrophic and heterotrophic picoplankton and nanoflagellates was found in the stratified water masses encountered in July and September. Microbial stocks and rates were low but persistent under winter conditions. Seasonal comparisons of microbial biomass and production revealed that structure and function of the microbial food web were fundamentally different during the spring bloom when compared with other seasons. While the microbial food web was in a regenerative mode most of the time, during the spring bloom, a microbial transfer mode represented a trophic link for organic carbon in time and space. The microbial food web’s ability to fill different functional roles in periods dominated by new and regenerated production may enhance the ecological flexibility of pelagic ecosystems in the present era of climate change. Description: This article is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777 URI: http://hdl.handle.net/10037/3779 File(s) in this item: 1
article.pdf (1.196Mb) -
Janhunen, Matti; Rudolfsen, Geir; Kekäläinen, Jukka; Figenschou, Lars; Peuhkuri, Nina; Kortet, Raine (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)[+][-]
Abstract: The modern theories of sexual selection predict that male sexual ornaments may have evolved as reliable signals of male fertilization efficiency. However, among the studies of fishes with external fertilization, the results have yielded ambiguous evidence. In the present study, we present data on the phenotypic relationships between red spawning coloration and ejaculate quality (spermatocrit, sperm motility) from Arctic charr, Salvelinus alpinus. We studied two generations (F1 and F2) of males from a large lake population, reared in a standardized hatchery environment, to determine whether differential hatchery history, or duration of hatchery selection, affected the variation in ejaculate characteristics or abdominal coloration. After controlling for body length, there was no difference between the hatchery generations in these traits. However, the degree of redness increased with fish size. We found a positive correlation between sperm velocity and sperm longevity, indicating a functional integration between these sperm features across generations. Sperm velocity was also positively correlated with male redness. Therefore, the finding obtained in the present study suggests that the carotenoid-based ornamentation in Arctic charr may provide information about differences between males in their fertilization potential URI: http://hdl.handle.net/10037/4791 File(s) in this item: 1
article.pdf (330.6Kb) -
Jensen, Louise Kiel; Jæger, Iris; Honkanen, Jani O.; Caroll, JoLynn (Journal article; Tidsskriftartikkel, 2011)[+][-]
Abstract: With petroleum exploration and development expanding in the Arctic (AMAP, 2007) there is a need to obtain additional information on the ecotoxicology of Arctic organisms. Here we perform 192 hr laboratory exposure experiments on the keystone Arctic zooplankton species, Calanus finmarchicus. We trace the accumulation and depuration of two polycyclic aromatic hydrocarbons (PAHs): phenanthrene and benzo[a]pyrene (B[a]P) using 14C labeled PAH compounds. Copepods were not fed during the experiment, limiting uptake to diffusion processes alone. The lighter PAH compound, phenanthrene, accumulated rapidly in C. finmarchicus, reaching steady state within 96 h. The heavier PAH compound, B[a]P, accumulated more slowly and steady state was not reached within the 192 h exposure period. As expected, the bioconcentration factor (BCF) for B[a]P was higher than for phenanthrene in accordance with a higher octanol/water partition coefficient for B[a]P (log Kow = 6.04) compared to phenanthrene (log Kow = 4.53). However, for both compounds, log BCF was lower than log Kow that may indicate active biotransformation and excretion of the selected PAH compounds. These findings on the bio-uptake kinetics for petroleum hydrocarbons are essential for evaluating the potential consequences of an oil spill in the Arctic. Description: This is the submitted manuscript version of the paper. This paper is part of Louise Kiel Jensen's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3794 URI: http://hdl.handle.net/10037/3802 File(s) in this item: 1
article.pdf (161.7Kb) -
Jensen, Louise Kiel; Carroll, Jolynn (Journal article; Tidsskriftartikkel; Peer reviewed, 30-Sep-2010)[+][-]
Abstract: Copepods of the genus Calanus are keystone species in the transfer of energy from lower to higher trophic levels of the Arctic/sub-Arctic food web. We performed experimental tests on the reproduction and feeding of Calanus spp. exposed to the water-soluble fraction (WSF) of crude oil. Fecal pellet and egg production were examined for females of C. glacialis exposed to WSF (16 EPA) concentrations of 10.4 μg l–1 (high treatment; HT), 3.6 μg l–1 (low treatment; LT) and 0 μg l–1 (control treatment; CT). We observed no significant difference in cumulative egg or fecal pellet production. Egg hatching success was examined for 2 d after transferring eggs from treatment solutions to uncontaminated seawater. Hatching success was significantly lower in the HT compared to the CT. In a second experiment, feeding of C. finmarchicus was examined after exposure for 11 and 18 d to 7.0 (HT), 3.4 (LT) or 0 (CT) μg l–1 of WSF (16-EPA). Using algae cell concentrations as a proxy for feeding success, feeding was inhibited for C. finmarchicus specimens exposed to the HT of WSF compared to the CT. Our findings indicate that adult females of C. glacialis may withstand some exposure to crude oil components but the survival of offspring is negatively affected. Reduced feeding efficiency in C. finmarchicus exposed to high concentrations of WSF provides evidence that adult specimens are sensitive to exposure to crude oil. The study expands on the limited body of knowledge of potential changes to key life history traits of Arctic Calanus species resulting from exposure to chemical compounds in crude oil. Description: This paper is part of Louise Kiel Jensen's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3794 URI: http://hdl.handle.net/10037/2839 File(s) in this item: 1
article.pdf (274.0Kb)
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