Polar Research (E-Journal)
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Review of Biocultural diversity and indigenous ways of knowing: human ecology in the Arctic, by Karim-Aly S. Kassam
No full textThe perspective put forth in Human ecology in the Arctic by K.-A. Kassam, although not one that is fundamentally foreign to Northern social scientists, is intended to challenge what I suspect the author considers more orthodox and less socially aware approaches to research. Focusing as it does on how Indigenous Northerners learn the environment (and how to learn what they learn), this book has its closest intellectual articulation in Ingold’s approach to human–environment relations
Cloning and heterologous expression of two cold-active lipases from the Antarctic bacterium Psychrobacter sp. G
No full textAntarctic bacteria producing extracellular lipolytic enzymes with activity at low temperature were isolated, and the most promising strain, named G, was identified as a Psychrobacter species based on 16S rDNA sequence alignment. The genomic DNA of this bacterium was used to construct its plasmid genomic library into pUC118 plasmid vectors, and to screen the cold-active lipolytic enzyme genes. Two genes encoding for cold-active lipolytic enzymes, Lip-1452 (with an open reading frame of 1452 bp in length) and Lip-948 (with an open reading frame of 948 bp in length), were screened. The primary structure of the two lipases deduced from the nucleotide sequence showed a consensus pentapeptide containing the active serine (Lip-1452, GDSAG, and Lip-948, GNSMG) and a conserved His-Gly dipeptide in the N-terminal part of the enzyme. Protein sequence alignment and conserved regions analysis indicated that the two lipases probably belonged to family IV and family V of the bacterial lipolytic enzymes, respectively. The upstream and downstream sequences of the two lipolytic lipases were also obtained. The two lipase genes were cloned into the expression vector pCold III and integrated into Escherichia coli BL21 (DE3). The functional expression of both lipase genes by E. coli BL21 (DE3) cells was observed as the formation of clear haloes around colonies on a 1% (vol/vol) tributyrin plate upon induction with isopropyl-b-Dthiogalactopyranoside at 5°C. A lipase activity assay showed that the specific activity of the pCold III+Lip-948 expression system was up to 3.7 U ml-1, whereas that of pCold III+Lip-1452 was very low
At the uttermost ends of the Earth: The physiology of polar fishes, edited by Anthony P. Farrell & John F. Steffensen
No full textEcologists and physiologists have always been interested in organisms living in extreme environments because of the light they shed on fundamental problems, and the general public has long been fascinated by animals living in climates so inhospitable that unprotected humans would rapidly perish. The pioneering physiologists of the early 20th century had quickly recognized that teleost fi shes with their dilute blood would have real problems in the cold waters of the polar regions, and when Johan Ruud collected the fi rst scientifi c specimens of an icefi sh he was able to confi rm that there really did exist a group of polar fi shes with no blood pigment. The scene was thereby set for an exploration of the physiology of polar fi shes, and this remains a vibrant fi eld of research to this day
Review of Marine mammals of Svalbard, by K. M. Kovacs, I. Gjertz & C. Lydersen
No full textEvery year, tourists converge on Svalbard hoping to catch sight of the big marine mammals. But most tourists are not zoologists. For a temporary visitor, it is no easy task to recognize marine mammals. Of course polar bears and walruses are easy to distinguish—and they also top the visitor’s wish list—but tourists also want to see seals and especially whales. These animals seldom “pose” the way polar bears and walruses sometimes do. They may give you no more than a brief glimpse and then leave you wondering: What was that? How big is a seal? What does it eat
Trichinella sp. in polar bears from Svalbard, in relation to hide length and age
No full textDiaphragm and masseter muscles from 376 polar bears ((irsur maririmus), 252 ringed seals (Phocn hispida), 84 bearded seals (Erignarhus barbarus), and 77 arctic foxes (Alopex lagopus) from Svalbard were examined for Trichinelln. Infection rates in polar bears varied between 23 and 58%, and between 3 and 67% in arctic fox. None of the seals were infected. Trichrnella in polar bears is probably transferred through cannibalism and scavenging upon polar bear carcasses. Infection rate in arctic fox was high when they preyed upon polar bear carcasses before polar bear hunting was prohibited in 1973. A low infection rate seems more natural when such prey is not available. No difference could be found in infection rate between male and female polar bears. There is only a slight increase in infectlon rate with age, as calculatcd from hide lengths, and many adult animals remain uninfectcd. Geographlcal isolation of polar bear populations may explain differences in Trichinella infection rates between beara from arctic Amcrica and arctic Europe. Possible explanations are that discrete polar bear populations have different food habita. or that they are exposed to different Trichinella strains
Patterns of variation of serum oxidative stress markers in two seabird species
No full textVariation in oxidative stress markers in natural populations may provide a useful background for understanding variation in life history strategies. In this study, we seek to evaluate patterns of variation in levels of reactive oxygen metabolites (markers of oxidative damage), serum antioxidant capacity, and serum concentration of thiols (antioxidants endogenously synthesized) in nestling and breeding blue petrels (Halobaena caerulea) and in breeding Antarctic prions (Pachyptila desolata). Male and female prions and nestling petrels did not differ in any of the oxidative stress markers. The serum antioxidant capacity positively correlated with the sample time in nestling blue petrels. Breeding petrels with higher body condition index had higher serum antioxidant capacity and circulating thiols. Finally, both seabird species showed lower levels of reactive oxygen metabolites and higher levels of serum antioxidant capacity than previously studied bird species
A review of snow manipulation experiments in Arctic and alpine tundra ecosystems
No full textSnow cover is one of the most important factors controlling microclimate and plant growing conditions for Arctic and alpine ecosystems. Climate change is altering snowfall regimes, which in turn influences snow cover and ultimately tundra plant communities. The interest in winter climate change and the number of experiments exploring the responses of alpine and Arctic ecosystems to changes in snow cover have been growing in recent years, but their outcomes are difficult to summarize because of the large variability in manipulation approaches, extents and measured response variables. In this review, we (1) compile the ecological publications on snow manipulation experiments, (2) classify the studies according to the climate scenarios they simulate and response variables they measure, (3) discuss the methods applied to manipulate snow cover, and (4) analyse and generalize the response in phenology, productivity and community composition by means of a meta-analysis. This meta-analysis shows that flowering phenology responded strongly to changes in the timing of snowmelt. The least responsive group of species were graminoids; however, they did show a decrease in productivity and abundance with experimentally increased snow covers. The species group with the greatest phenological response to snowmelt changes were the dwarf shrubs. Their abundance also increased in most long-term snow fence experiments, whereas species richness generally declined. We conclude that snow manipulation experiments can improve our understanding of recently observed ecosystem changes, and are an important component of climate change research
Review of Earth under fire: how global warming is changing the world, by Gary Braasch
No full textEarth under fire claims to be a photographic journal of the author’s voyage to document past and current climate change. This would be no bad thing from a photographer capable of both beautiful and informative photography. In fact, though, only the preface contains many photographs; the rest of the book gradually becomes a literature review, with the last two of five chapters concerning the future, and parts of the book have been written by others. This makes it more of an intermediate scientific review than was probably intended
An extreme precipitation event in Dronning Maud Land, Antarctica: a case study with the Antarctic Mesoscale Prediction System
No full textAn extreme precipitation event that influenced almost the whole polar plateau of Dronning Maud Land, Antarctica, is investigated using Antarctic Mesoscale Prediction System archive data. For the first time a high-resolution atmospheric model especially adapted for polar regions was used for such a study in Dronning Maud Land. The outstanding event of 21–25 February 2003 was connected to a strong north-westerly flow, caused by a blocking high above eastern Dronning Maud Land, that persisted for several days and brought unusually large levels of moisture to the Antarctic Plateau. This weather situation is most effective in bringing precipitation to high-altitude interior Antarctic ice-core drilling sites, where precipitation in the form of diamond dust usually dominates. However, a few such precipitation events per year can account for a large percentage of the annual accumulation, which can cause a strong bias in ice-core data. Additionally, increased temperatures and wind speeds during these events need to be taken into account for the correct climatic interpretation of ice cores. A better understanding of the frequency of occurrence of intermittent precipitation in the interior of Antarctica in past and future climates is necessary for both palaeoclimatological studies and estimates of future sea-level change