| 1. |
- Al-Handal, Adil Y, 1952, et al.
(författare)
-
Observations on diatoms inhabiting natural and artificial substrates in Kongsfjorden, Svalbard, the Arctic
- 2016
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 39:11, s. 1913-1932
-
Tidskriftsartikel (refereegranskat)abstract
- The most dramatic effects of global climate change are predicted for the Arctic, and there is a raising concern about the lack of baseline information on microalgal biodiversity. The present study was motivated by the general lack of information on species distribution of Arctic benthic diatoms and particularly studies providing photographs to facilitate morphological species identification. Diatoms were studied in samples collected from Ny lesund, Spitsbergen, Svalbard, during summer 2006 and spring 2008. Two types of samples were examined: diatoms scraped from ceramic tiles, immersed at 0.5 m depth (2006), and diatoms extracted from surface sediment, collected at 0.5 to 3 m depth (2008). A total number of 75 taxa belonging to 45 genera were encountered. Sixty-eight species were found in the sediment samples and 48 on the ceramic tiles, of which 41 species were found on both substrata. Common species of the tile assemblages were Fragilariopsis spp., Licmophora spp., Odontella aurita, Synedropsis hyperborea and Trachyneis aspera, while Thalassiosira spp., Diploneis spp. and Navicula spp. were common in the sediment samples. Twenty-five percent of the observed diatom species belonged to freshwater taxa brought to the fjord from surrounding meltwater and river discharges. ELMANN A, 1992, DEEP-SEA RESEARCH PART A-OCEANOGRAPHIC RESEARCH PAPERS, V39, PS525
|
|
| 2. |
- Arcalis-planas, A., et al.
(författare)
-
Limited use of sea ice by the Ross seal (Ommatophoca rossii), in Amundsen Sea, Antarctica, using telemetry and remote sensing data
- 2015
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 38:4, s. 445-461
-
Tidskriftsartikel (refereegranskat)abstract
- To understand the use and importance of the Antarctic sea ice to the Ross seal (Ommatophoca rossii), four adult females were tagged with Argos satellite transmitters in the Amundsen Sea, Antarctica. The Ross seal is the least studied of the Antarctic seal species and nothing was previously known about their behaviour in the Amundsen Sea. During almost 1 year, their movements, haul out behaviour and time spent at different temperatures were logged. By comparing their movements with daily ice maps, distances to the ice edge were calculated, and seals dependence on sea ice for resting, breeding and moulting was analysed. The tagged seals spent on average 70.8 % (range 66.8–77.8 %) of their time in the water and hauled out mainly during the moult in December–January, and in late October–mid-November during breeding. During the pelagic period, they were on average 837.5 km (range 587–1,282 km) from the ice edge indicating a fully pelagic life during several months. Their pelagic behaviour suggests that Ross seals, although being an ice obligate species, may adapt comparatively easy to climate change involving ice melting and recession and thereby potentially being less sensitive to the reduction of sea ice than other Antarctic seal species. Although nothing is known about their mating behaviour, they appear to be relatively stationary during moulting and breeding, hence requiring a small ice surface. Although previous studies in other parts of Antarctica have found similar results, still many questions remain about this peculiar species.
|
|
| 3. |
|
|
| 4. |
- Barrio, Isabel C., et al.
(författare)
-
Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome
- 2017
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 40:11, s. 2265-2278
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6-7% over the current levels with a 1 degrees C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.
|
|
| 5. |
- Barrio, Isabel C., et al.
(författare)
-
Publisher Correction to : Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome (vol 40, pg 2265, 2017)
- 2018
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 41:8, s. 1653-1654
-
Tidskriftsartikel (refereegranskat)abstract
- The above mentioned article was originally scheduled for publication in the special issue on Ecology of Tundra Arthropods with guest editors Toke T. Hoye . Lauren E. Culler. Erroneously, the article was published in Polar Biology, Volume 40, Issue 11, November, 2017. The publisher sincerely apologizes to the guest editors and the authors for the inconvenience caused.
|
|
| 6. |
- Barthelemy, Hélène, et al.
(författare)
-
Short- and long-term plant and microbial uptake of 15N-labelled urea in a mesic tundra heath, West Greenland
- 2024
-
Ingår i: Polar Biology. - : Springer Nature. - 0722-4060 .- 1432-2056. ; 47:1, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- Terrestrial animals are key elements in the cycling of elements in the Arctic where nutrient availability is low. Waste production by herbivores, in particular urine deposition, has a crucial role for nitrogen (N) recycling, still, it remains largely unexplored. Also, experimental evidence is biased toward short-term studies and Arctic regions under high herbivore pressure. In this study, we aimed to examine the fate of N derived from urine in a nutrient poor tundra heath in West Greenland, with historical low level of herbivory. We performed a pulse labelling with 15N-urea over the plant canopy and explored ecosystem N partition and retention in the short-term (2 weeks and 1 year) and longer-term (5 years). We found that all vascular plants, irrespective of their traits, could rapidly take up N-urea, but mosses and lichens were even more efficient. Total 15N enrichment was severely reduced for all plants 5 years after tracer addition, with the exception of cryptogams, indicating that non-vascular plants constituted a long-term sink of 15N-urea. The 15N recovery was also high in the litter suggesting high N immobilization in this layer, potentially delaying the nutrients from urine entering the soil compartment. Long-term 15N recovery in soil microbial biomass was minimal, but as much as 30% of added 15N remained in the non-microbial fraction after 5 years. Our results demonstrate that tundra plants that have evolved under low herbivory pressure are well adapted to quickly take advantage of labile urea, with urine having only a transient effect on soil nutrient availability.
|
|
| 7. |
- Becher, Marina, 1983-, et al.
(författare)
-
Decreased cryogenic disturbance : one of the potential mechanisms behind the vegetation change in the Arctic
- 2018
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 41:1, s. 101-110
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- During the last few decades, the Arctic has experienced large-scale vegetation changes. Understanding the mechanisms behind this vegetation change is crucial for our ability to predict future changes. This study tested the hypothesis that decreased cryogenic disturbances cause vegetation change in patterned ground study fields (non-sorted circles) in Abisko, Sweden during the last few decades. The hypothesis was tested by surveying the composition of plant communities across a gradient in cryogenic disturbance and by reinvestigating plant communities previously surveyed in the 1980s to scrutinise how these communities changed in response to reduced cryogenic disturbance. Whereas the historical changes in species occurrence associated with decreased cryogenic disturbances were relatively consistent with the changes along the contemporary gradient of cryogenic disturbances, the species abundance revealed important transient changes highly dependent on the initial plant community composition. Our results suggest that altered cryogenic disturbances cause temporal changes in vegetation dynamics, but the net effects on vegetation communities depend on the composition of initial plant species.
|
|
| 8. |
- Beyens, L., et al.
(författare)
-
Are soil biota buffered against climatic extremes? An experimental test on testate amoebae in arctic tundra (Qeqertarsuaq, West Greenland)
- 2009
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 32, s. 453-462
-
Tidskriftsartikel (refereegranskat)abstract
- Climate warming is likely to have pronounced impacts on soil biota in arctic ecosystems. In a warmer climate, heatwaves are more frequent and intense, but it is unclear to what extent soil communities are buffered against this. We studied the effects of an artificially induced heatwave on the structure of testate amoebae communities in dry heath tundra in Qeqertarsuaq (Disko Island, West Greenland) during the summer of 2003. While the heatwave was severe enough to induce significant leaf mortality in the aboveground vegetation, overall testate amoebae abundance did not react to the difference in temperature. However, in the heated plots transient shifts in species populations occurred during the exposure, followed by increases in species richness weeks after the heatwave had ended. The most important taxa appearing after the heating period belonged to bacterivorous genera, in agreement with a transient peak in bacterial colony forming units, caused by the heatwave. Lobose testate amoebae resisted the heating and its associated desiccation better than their filose counterparts.
|
|
| 9. |
|
|
| 10. |
- Bonnedahl, Jonas, 1970-, et al.
(författare)
-
Antibiotic susceptibility of faecal bacteria in Antarctic penguins
- 2008
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 31:6, s. 759-763
-
Tidskriftsartikel (refereegranskat)abstract
- Faecal bacteria from 49 Gentoo penguins on the Antarctic Peninsula were identified by biochemical methods and sequencing, and tested for antibiotic susceptibility using agar dilution. Of the 42 Enterobacteriaceae isolates found, 39 belonged to the genus Edwardsiella. All isolates were susceptible to the 17 antibiotics tested. This implies that antibiotic selection pressure is a prerequisite to a high prevalence of antibiotic resistance, and in the absence of contact with human activities, antibiotic resistance in Enterobacteriaceae remains undetectable.
|
|
| 11. |
- Brutemark, A, et al.
(författare)
-
An experimental investigation of phytoplankton nutrient limitation in two contrasting low arctic lakes
- 2006
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 1432-2056 .- 0722-4060. ; 29:6, s. 487-494
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated whether phytoplankton communities in two lakes in SW Greenland were phosphorus or nitrogen limited. The study lakes have contrasting water chemistry (mean conductivities differ ten fold) and are located near Kangerlussuaq, SW Greenland (similar to 67 degrees N, 51 degrees W). A microcosm nutrient enrichment experiment was performed in June 2003 to determine whether nitrate or phosphate addition stimulated phytoplankton growth. Samples were analysed for species composition, biomass, and alkaline phosphatase activity (APA). Initially, both lakes had extremely low total phosphorus but high total nitrogen concentrations and high APA, suggesting that the phytoplankton were phosphorus limited prior to the start of the experiment. The phytoplankton composition and biomass (mainly Ochromonas spp.) responded to phosphate but not to nitrate addition. In both lakes, chlorophyll a increased significantly when phosphate was added. Furthermore, APA was significantly lower in the two lakes when phosphate was added compared to the control and the nitrogen addition treatment. The dominance of mixotrophic pbytoplankton and high DOC values suggest that these lakes may be regulated by microbial loop processes.
|
|
| 12. |
- Colesie, Claudia
(författare)
-
Genus richness of microalgae and Cyanobacteria in biological soil crusts from Svalbard and Livingston Island: morphological versus molecular approaches
- 2018
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 41, s. 909-923
-
Tidskriftsartikel (refereegranskat)abstract
- Biological soil crusts (BSCs) are key components of polar ecosystems. These complex communities are important for terrestrial polar habitats as they include major primary producers that fix nitrogen, prevent soil erosion and can be regarded as indicators for climate change. To study the genus richness of microalgae and Cyanobacteria in BSCs, two different methodologies were employed and the outcomes were compared: morphological identification using light microscopy and the annotation of ribosomal sequences taken from metatranscriptomes. The analyzed samples were collected from Ny-Alesund, Svalbard, Norway, and the Juan Carlos I Antarctic Base, Livingston Island, Antarctica. This study focused on the following taxonomic groups: Klebsormidiophyceae, Chlorophyceae, Trebouxiophyceae, Xanthophyceae and Cyanobacteria. In total, combining both approaches, 143 and 103 genera were identified in the Arctic and Antarctic samples, respectively. Furthermore, both techniques concordantly determined 15 taxa in the Arctic and 7 taxa in the Antarctic BSC. In general, the molecular analysis indicated a higher microalgal and cyanobacterial genus richness (about 11 times higher) than the morphological approach. In terms of eukaryotic algae, the two sampling sites displayed comparable genus counts while the cyanobacterial genus richness was much higher in the BSC from Ny-Alesund. For the first time, the presence of the genera Chloroidium, Ankistrodesmus and Dunaliella in polar regions was determined by the metatranscriptomic analysis. Overall, these findings illustrate that only the combination of morphological and molecular techniques, in contrast to one single approach, reveals higher genus richness for complex communities such as polar BSCs.
|
|
| 13. |
- Convey, Peter, et al.
(författare)
-
The importance of understanding annual and shorter term temperature patterns and variation in the surface levels of polar soils for terrestrial biota
- 2018
-
Ingår i: Polar Biology. - : Springer Publishing Company. - 0722-4060 .- 1432-2056. ; 41:8, s. 1587-1605
-
Tidskriftsartikel (refereegranskat)abstract
- Ground temperatures in the top few centimetres of the soil profile are key in many biological processes yet remain very poorly documented, especially in the polar regions or over longer timescales. They can vary greatly seasonally and at various spatial scales across the often highly complex and heterogeneous polar landscapes. It is challenging and often impossible to extrapolate soil profile temperatures from meteorological air temperature records. Furthermore, despite the justifiably considerable profile given to contemporary large-scale climate change trends, with the exception of some sites on Greenland, few biological microclimate datasets exist that are of sufficient duration to allow robust linkage and comparison with these large-scale trends. However, it is also clear that the responses of the soil-associated biota of the polar regions to projected climate change cannot be adequately understood without improved knowledge of how landscape heterogeneity affects ground and sub-surface biological microclimates, and of descriptions of these microclimates and their patterns and trends at biologically relevant physical and temporal scales. To stimulate research and discussion in this field, we provide an overview of multi-annual temperature records from 20 High Arctic (Svalbard) and maritime Antarctic (Antarctic Peninsula and Scotia Arc) sites. We highlight important features in the datasets that are likely to have influence on biology in polar terrestrial ecosystems, including (a) summer ground and sub-surface temperatures vary much more than air temperatures; (b) winter ground temperatures are generally uncoupled from air temperatures; (c) the ground thawing period may be considerably shorter than that of positive air temperatures; (d) ground and air freeze–thaw patterns differ seasonally between Arctic and Antarctic; (e) rates of ground temperature change are generally low; (f) accumulated thermal sum in the ground usually greatly exceeds air cumulative degree days. The primary purpose of this article is to highlight the utility and biological relevance of such data, and to this end the full datasets are provided here to enable further analyses by the research community, and incorporation in future wider comparative studies.
|
|
| 14. |
- Coulson, Stephen
(författare)
-
Distribution and population characteristics of the soil mites Diapterobates notatus and Svalbardia paludicola (Acari: Oribatida: Ceratozetidae) in High Arctic Svalbard (Norway)
- 2017
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 40, s. 1545-1555
-
Tidskriftsartikel (refereegranskat)abstract
- The Oribatida of High Arctic Svalbard are faunistically relatively well known, but the distribution, density, stage structure and other population parameters of most species are unknown. Here we focus on two ceratozetid species, Diapterobates notatus (Thorell, 1871) and Svalbardia paludicola Thor, 1930, and investigate the summer density, stage and sex structure, proportion of gravid females and the body size of these species in 33 locations and 11 vegetation classes of Svalbard. Diapterobates notatus occurred in all vegetation classes and at 29 locations, whereas S. paludicola occurred in only two vegetation classes and at three locations. The common occurrence of D. notatus in Svalbard may be due to: (1) cosmopolitan nature of this species which inhabits all vegetation classes but with a preference for open Dryas/Carex rupestris communities, (2) high biological potential (females were more abundant than males and carried 6-7 large eggs) resulting in a high proportion of juveniles, and (3) juvenile morphology which possesses long setae that may enhance passive dispersal by the wind. Adult body size was found to be greatest in the floristically diverse Arctic meadows. Svalbardia paludicola was particularly abundant in the Arctic meadow at Reinsdyrflya where juveniles were more plentiful than the adults. The nymphs of this species have shorter gastronotal setae than those of D. notatus which may limit their passive transport by the wind. Scutozetes clavatosensillus Ermilov, Martens & Tolstikov, 2013 was found in Mosselbukta (north Spitsbergen); this is the first observation of this species in Svalbard.
|
|
| 15. |
- Coulson, Stephen
(författare)
-
No indication of arthropod-vectored viruses in mosquitoes (Diptera: Culicidae) collected on Greenland and Svalbard
- 2018
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 41, s. 1581-1586
-
Tidskriftsartikel (refereegranskat)abstract
- Viruses transmitted to vertebrates via arthropod vectors (so-called arboviruses) include many important pathogens such as dengue virus, Zika virus, and Sindbis virus. Mosquitoes represent the major vectors of many of these arboviruses and occur in all climatic zones, including the Arctic. The focal species, Aedes nigripes (Diptera: Culicidae), is the most widely distributed mosquito species in the Arctic. We screened over 11,000 specimens collected between 2012 and 2016 on Greenland (Kangerlussuaq) and Svalbard (Petuniabukta) for the presence of arboviruses which have previously been reported in latitudes up to 70A degrees N. Assays for arbovirus detection using RT-PCR with primers specific for the genera Alphavirus (family Togaviridae), Orthobunyavirus, Phlebovirus (Bunyaviridae), Flavivirus (Flaviviridae), and Orbivirus (Reoviridae) were negative for all specimens. Similar results were recently obtained in a screening focused on tick-borne pathogens on Svalbard. The findings suggest that the circulation of arboviruses at studied localities is currently negligible or nonexistent, possibly due to dispersal, climate, or biotic restrictions. However, global climate change could enhance vector abundance and activity, introduction of invasive host species, and increase in tourism which then could lead to emerging arbovirus outbreaks in the future, with considerable impact on local ecosystems.
|
|
| 16. |
- Coulson, Stephen
(författare)
-
The Araneae of Svalbard: the relationships between specific environmental factors and spider assemblages in the High Arctic
- 2018
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 41, s. 839-853
-
Tidskriftsartikel (refereegranskat)abstract
- As top predators in the Arctic invertebrate fauna, spiders in Svalbard are key components of the terrestrial ecosystem. However, most descriptions consist of observations of species occurrence and few repeated sampling campaigns investigating these heterogeneous assemblages, or the relationship between microhabitats and seasonality, exist. Spider assemblages were evaluated along four altitudinal transects (c. 10-300 m above mean sea level) on the west coast of Spitsbergen, Svalbard, throughout the summer of 2012. The slopes were selected to include most of the vegetation types typical for this region of Svalbard. Eleven of the known 15 native spider species were collected (10 Linyphiidae and 1 Gnaphosidae). We used Generalised Linear Models (GLM) for each spider species to identify the factors best explaining spider species abundance and distribution. The distribution of the majority of spider species was best described by vegetation or topography and none was accurately predicted by temperature. Only two species (Erigone arctica palaearctica and Hilaira glacialis) were common at all four sites and these two constituted 54% (1650 and 639 individuals, respectively) of the total spider individuals trapped. That assemblages of linyphiid spiders can differ greatly over small local and temporal scales further demonstrates the complexity of the Arctic terrestrial invertebrate community.
|
|
| 17. |
- Coulson, Stephen
(författare)
-
The terrestrial invertebrate fauna of EdgeOya, Svalbard: Arctic landscape community composition reflects biogeography patterns
- 2019
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 42, s. 837-850
-
Tidskriftsartikel (refereegranskat)abstract
- Colonisation and immigration history is often neglected as a factor when investigating community or species distribution patterns. However, for dynamic systems that are still reacting to large-scale environmental change, such as the retreat of the ice since the last glacial maximum, colonisation history may explain a large amount of the variation between geographically distinct communities. The High Arctic archipelago of Svalbard presents an opportunity to test whether it is possible to observe the effects of large-scale biogeographical patterns on species distribution at landscape scales. Svalbard has one of the best described inventories of the invertebrate fauna in the Arctic. Nonetheless, the majority of the species records originate from the more accessible west coast and the invertebrate fauna of the whole eastern region, including EdgeOya, is virtually unknown. EdgeOya is located at the eastern fringe of the archipelago on the boundary between Palaearctic and Nearctic faunas. It was expected that post-colonisation dispersal within EdgeOya would conceal routes to the archipelago. Samples were obtained from six locations along the coast of EdgeOya between 2009 and 2010. 140 invertebrate species were identified belonging to 69 different genera of which 16 are new records for Svalbard. Most new species present an eastern Palaearctic distribution. Habitat variables (percentage cover of moss, lichen, vascular plant, or bare soil) fail to explain 35.5% of the differences among sites. However, cluster analysis reveals a clear east-west distribution pattern across the island suggesting that pan-Arctic dispersal routes can be identified even at relatively short geographical scales.
|
|
| 18. |
- Dalerum, Fredrik, et al.
(författare)
-
Spatial variation in Arctic hare (Lepus arcticus) populations around the Hall Basin
- 2017
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 40:10, s. 2113-2118
-
Tidskriftsartikel (refereegranskat)abstract
- Arctic environments have relatively simple ecosystems. Yet, we still lack knowledge of the spatio-temporal dynamics of many Arctic organisms and how they are affected by local and regional processes. The Arctic hare (Lepus arcticus) is a large lagomorph endemic to high Arctic environments in Canada and Greenland. Current knowledge about this herbivore is scarce and the temporal and spatial dynamics of their populations are poorly understood. Here, we present observations on Arctic hares in two sites on north Greenland (Hall and Washington lands) and one adjacent site on Ellesmere Island (Judge Daly Promontory). We recorded a large range of group sizes from 1 to 135 individuals, as well as a substantial variation in hare densities among the three sites (Hall land: 0 animals/100 km(2), Washington land 14.5-186.7 animals/100 km(2), Judge Daly Promontory 0.18-2.95 animals/100 km(2)). However, pellet counts suggested that both Hall land and Judge Daly Promontory hosted larger populations at other times. We suggest that our results could have been caused by three spatially differentiated populations with asynchronous population fluctuations. With food limitation being a likely driver behind the observed variation, we argue that food limitation likely interacts with predation and competition in shaping the spatial dynamics of Arctic hares in this region.
|
|
| 19. |
- Einarsdottir, Ingibjörg, 1951, et al.
(författare)
-
Temperature influence on Arctic charr (Salvelinus alpinus L.) antibody response to a cellular antigen.
- 2000
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 23:4, s. 231-235
-
Tidskriftsartikel (refereegranskat)abstract
- In order to elucidate the immune responses of Arctic charr in relation to temperature, groups were acclimated to a moderate (9 degrees C) and a cold temperature regime (4 degrees C), as well as subjected to a temperature decrease (from 9 to 4 degrees C) immediately prior to an immunization with sheep red blood cells. The charr kept at 9 degrees C responded with increased primary and secondary antibody titres, as seen by direct haemagglutination, while fish at 4 degrees C, as well as the fish subjected to a temperature reduction, displayed lower and lowest antibody titres, respectively, and only after a second immunization, It is concluded that Arctic charr can respond to a cellular antigen with a humoral immune response typical for other teleosts, but that the immune response is delayed and diminished at low temperatures. This temperature-induced immune suppression is intensified if the fish have not been acclimated to cold water prior to immunization.
|
|
| 20. |
- Ekelund, Nils, 1956-
(författare)
-
Studies on the effects of UV-B radiation on phytoplankton of Sub-Antarctic lakes and ponds
- 1992
-
Ingår i: Polar Biology. - 0722-4060 .- 1432-2056. ; 12, s. 533-537
-
Tidskriftsartikel (refereegranskat)abstract
- Experiments were performed to determine the effects of UV-B (ultraviolet, 280–320 nm) radiation on motility and growth of phytoplankton from lakes and ponds in South Georgia. After 4 h of solar radiation and 4h artificial radiation (UV-BBE 11.6 kJ m-2 day-1, UV-B lamps) the swimming velocity of Cryptomonas sp. decreased. The growth rate of Botryococcus, Lyngbya sp. and Stauraslrum sp. did not show any significant variations between the different light conditions. The UV-B component was reduced by filtering solar radiation through glass bottles und cellulose acetate. Cloudy days had only 30% of the radiation of clear days in both the PAR (photosynthetic active radiation) and UV-B regions. The ponds contained large amounts of humic substances, which are responsible for the absorbance in the UV region.
|
|
| 21. |
- Elmhagen, Bodil, et al.
(författare)
-
From breeding pairs to fox towns : the social organisation of arctic fox populations with stable and fluctuating availability of food
- 2014
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 37:1, s. 111-122
-
Tidskriftsartikel (refereegranskat)abstract
- Food availability can impact group formation in Carnivora. Specifically, it has been suggested that temporal variation in food availability may allow a breeding pair to tolerate additional adults in their territory at times when food abundance is high. We investigate group occurrence and intraspecific tolerance during breeding in a socially flexible canid, the arctic fox (Vulpes lagopus). We compare Iceland and Sweden where resource conditions differ considerably. A breeding pair was the most common social unit in both populations, but as predicted, groups were more frequent where food abundance varied substantially between years (Sweden: 6 %) than where food availability was stable (Iceland: ≤2 %). Within Sweden, supplemental feeding increased group occurrence from 6 to 21 %, but there was no effect of natural variation in lemming (Lemmus lemmus) availability since group formation was rare also at lemming highs. Thus, additional factors appeared to influence the trade-off between intraspecific territoriality and tolerance. We report two cases where related females showed enduring social relationships with good-neighbour strategies. Related females also engaged in alloparental behaviour in a ‘fox town’ with 31 foxes (4 adults, 3 litters). In contrast, when unrelated foxes bred close to each other, they moved or split their litters during summer, presumably because of territorial conflict. We suggest that fluctuating food availability is linked to group formation in this Arctic carnivore, but also when food availability increases, additional factors such as relatedness, alloparental benefits, competition and predator defence appear necessary to explain group formation.
|
|
| 22. |
- Gehrmann, Friederike, et al.
(författare)
-
Sub-Arctic alpine Vaccinium vitis-idaea exhibits resistance to strong variation in snowmelt timing and frost exposure, suggesting high resilience under climatic change
- 2020
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 43:10, s. 1453-1467
-
Tidskriftsartikel (refereegranskat)abstract
- In tundra ecosystems, snow cover protects plants from low temperatures in winter and buffers temperature fluctuations in spring. Climate change may lead to reduced snowfall and earlier snowmelt, potentially exposing plants to more frequent and more severe frosts in the future. Frost can cause cell damage and, in combination with high solar irradiance, reduce the photochemical yield of photosystem II (ΦPSII). Little is known about the natural variation in frost exposure within individual habitats of tundra plant populations and the populations' resilience to this climatic variation. Here, we assessed how natural differences in snowmelt timing affect microclimatic variability of frost exposure in habitats of the evergreen Vaccinium vitis-idaea in sub-Arctic alpine Finland and whether this variability affects the extent of cell damage and reduction in ΦPSII. Plants in early melting plots were exposed to more frequent and more severe frost events, and exhibited a more pronounced decrease in ΦPSII, during winter and spring compared to plants in late-melting plots. Snowmelt timing did not have a clear effect on the degree of cell damage as assessed by relative electrolyte leakage. Our results show that sub-Arctic alpine V. vitis-idaea is currently exposed to strong climatic variation on a small spatial scale, similar to that projected to be caused by climate change, without significant resultant damage. We conclude that V. vitis-idaea is effective in mitigating the effects of large variations in frost exposure caused by differences in snowmelt timing. This suggests that V. vitis-idaea will be resilient to the ongoing climate change.
|
|
| 23. |
|
|
| 24. |
- Godoy, Erika, et al.
(författare)
-
Mating patterns in an inbred Arctic carnivore
- 2018
-
Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 41:5, s. 945-951
-
Tidskriftsartikel (refereegranskat)abstract
- Mating patterns are highly context-dependent and the outcome of selection pressures formed by ecological factors, inbreeding levels and access to available partners. In small and inbred populations, matings are limited by high kin encounter rates and access to mates. In this paper, we use background pedigree data to investigate mating patterns and inbreeding avoidance in an isolated and critically endangered Arctic fox (Vulpes lagopus) population. Empirical data showed avoidance of matings within natal family. Based on 35 documented matings, we only recorded two full-sibling matings and these occurred between individuals from different natal families. Matings between second-order relatives, however, occurred to the same extent as between unrelated individuals. To test how this influenced the population development of inbreeding (f), we simulated scenarios of random mating, exclusion of natal family and exclusion of individuals in already existing pair bonds. The observed development of inbreeding did not correspond the expected scenario of random mating (linear regression, r2 = 0.354, P = 0.20), but showed a comparable outcome as the simulated development of discriminating natal family (linear regression, r2 = 0.980, P < 0.001). We conclude that behavioural, pre-copulatory inbreeding avoidance strategies occur in this population and that exclusion of mating with natal family causes a slower increase in inbreeding levels compared to random mating. This study demonstrates how long-term monitoring, pedigree construction and simulations can generate information valuable for an in-depth understanding of both conservation genetics and behavioural ecology in threatened populations.
|
|
| 25. |
- Gonzalez-Acuna, Daniel A., et al.
(författare)
-
Parasites of chinstrap penguins (Pygoscelis antarctica) from three localities in the Antarctic Peninsula and a review of their parasitic fauna
- 2021
-
Ingår i: Polar Biology. - : Springer. - 0722-4060 .- 1432-2056. ; 44, s. 2099-2105
-
Tidskriftsartikel (refereegranskat)abstract
- Studies of parasitism in chinstrap penguins (Pygoscelis antarctica) are infrequent and mainly refer to the identification and description of its parasites, with little ecological data. In an attempt to address that lack of knowledge, we collected endo- and ecto-parasites from 326 live and four dead of chinstrap penguins, in three different localities of Antarctica not studied before. Three species of endoparasites and two of ectoparasites were found parasitizing birds: two tapeworms, Tetrabothrius pauliani (Cestoda: Tetrabothriidae) and Parorchites zederi (Cestoda: Dilepididae); one roundworm, Stegophorus macronectes (Nematoda: Acuariidae), and one feather louse: Austrogoniodes gressitti (Insecta: Phthiraptera: Philopteridae). Ticks (Ixodes uriae-Acari: Ixodidae) were collected from the ground near the penguin nesting colonies at two localities, Shirreff Cape and Narebsky Point. New ecological data are given for the two species of ectoparasites. No parasites were found in the blood collected from 300 live penguins.
|
|
