Polar Bear

Recent studies have added substantially to our knowledge of spatial and temporal trends of persistent organic pollutants and heavy metals in the Canadian Arctic marine ecosystem. This paper reviews the current state of knowledge of contaminants in marine biota in the Canadian Arctic and where possible, discusses biological effects. The geographic coverage of information on contaminants such as persistent organochlorines (OCs) (PCBs, DDT- and chlordane-related compounds, hexachlorocyclohexanes, toxaphene) and heavy metals (mercury, selenium, cadmium, lead) in tissues of marine mammal and sea birds is relatively complete. All major beluga, ringed seal and polar bear stocks along with several major sea bird colonies have been sampled and analysed for OC and heavy metal contaminants. Studies on contaminants in walrus are limited to Foxe Basin and northern Québec stocks, while migratory harp seals have only been studied recently at one location. Contaminant measurements in bearded seal, harbour seal, bowhead whale and killer whale tissues from the Canadian Arctic are very limited or non-existent. Many of the temporal trend data for contaminants in Canadian Arctic biota are confounded by changes in analytical methodology, as well as by variability due to age/size, or to dietary and population shifts. Despite this, studies of OCs in ringed seal blubber at Holman Island and in sea birds at Prince Leopold Island in Lancaster Sound show declining concentrations of PCBs and DDT-related compounds from the 1970s to 1980s then a levelling off during the 1980s and early 1990s. For other OCs, such as chlordane, HCH and toxaphene, limited data for the 1980s to early 1990s suggests few significant declines in concentrations in marine mammals or sea birds. Temporal trend studies of heavy metals in ringed seals and beluga found higher mean concentrations of mercury in more recent (1993/1994) samples than in earlier collections (1981–1984 in eastern Arctic, 1972–1973 in western Arctic) for both species. Rates of accumulation of mercury are also higher in present day animals than 10–20 years ago. Cadmium concentrations in the same animals (eastern Arctic only) showed no change over a 10-year period. No temporal trend data are available for metals in sea birds or polar bears. There have been major advances in knowledge of specific biomarkers in Canadian Arctic biota over the past few years. The species with the most significant risk of exposure to PCBs and OC pesticides may be the polar bear which, based on comparison with EROD activity in other marine mammals (beluga, ringed seal), appears to have elevated CYP1A-mediated activity. The MFO enzyme data for polar bear, beluga and seals suggest that even the relatively low levels of contaminants present in Arctic animals may not be without biological effects, especially during years of poor feeding.

A brief chapter of Alexander Neckam’s De naturis rerum (II, 24) mentions the existence of a fish that lives in the Northern Seas, has only one eye, in the shape of a triangular shield, and is the prey of the white polar bear. This is the very first mention of either of these animals in an encyclopedic text. If  the mention of the second is unproblematic, the first is not. We review the different Arctic marine mammals that could possibly hide behind this mysterious description. We identify Neckam’s sources (the Liber monstrorum and the Aeneid) in this passage. We then discuss the monstrous quality of the Cyclops fish. Finally, we study the reception and influence of this chapter of the De naturis rerum. Since this passage was used neither by Thomas of Cantimpré nor by Batholomaeus Anglicus, the Cyclops fish disappeared from encyclopedic texts. That said, this chapter is the probable reason for the inclusion of the white bear in English bestiaries that, until then, were unaware of its existence.

The tissue-specific composition of sum classes of brominated and chlorinated contaminants and metabolic/degradation byproducts was determined in adult male and female polar bears from East Greenland. Significantly (p < 0.05) higher concentrations of Σ-PCBs, various ...

Immobilization features and physiologic effects of combinations of xylazine-zolaze- pam-tiletamine (XZT) and zolazepam-tiletamine (ZT or Telazolt) were compared in nine captive and 17 free-ranging polar bears (Ursus maritimus) between 1998 and 2001. Although induction time was similar between drugs, induction dosage and volume were less with XZT. Induction of immobilization with XZT was predictable and smooth, muscle relaxation was good,

Scientific research has demonstrated negative effects caused by climate change on three of 19 polar bear populations' worldwide (Stirling et al. 1999; Aars et al. 2006). As a result the status of polar bears has been uplisted by the IUCN/SSC to vulnerable (Schliebe et al. 2006). At the same time, Inuit hunters in many areas of the Canadian arctic have

1: Introduction.- 2: Ontology for Spatio-temporal Databases.- 3: Conceptual Models for Spatio-temporal Applications.- 4: Spatio-temporal Models and Languages: An Approach Based on Data Types.- 5: Spatio-temporal Models and Languages: An Approach Based on Constraints.- 6: Access Methods and Query Processing Techniques.- 7: Architectures and Implementations of Spatio-temporal Database Management Systems.- 8: Advanced Uses: Composing Interactive Spatio-temporal Documents.- 9: Spatio-temporal Databases in the Years Ahead.

In April 2005, the stream cipher Polar Bear was proposed as a response to the eSTREAM Call for Primitives. Since then, a few attacks, [7] and [5], have indicated certain weaknesses in the design. In this paper we propose a new version of Polar Bear, called Polar Bear 2.0. The main difference is a key-dependent premixing of the D 8 table in conjunction with the key schedule. The new version does not only appear to be more secure, the performance on all packet sizes is improved.

Anthropogenic contaminants have been a concern in the Canadian arctic for over 30 years due to relatively high concentrations of bioaccumulating and biomagnifying organochlorine contaminants (OCs) and toxic metals found in some arctic biota and humans. However, few studies have addressed the potential effects of these contaminants in Canadian arctic wildlife. Prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects related to contaminant exposure, and compares new tissue concentration data to threshold effects levels. Weak relationships between cadmium, mercury and selenium burdens and health biomarkers in common eider ducks (Somateria mollissima borealis) in Nunavut were found but it was concluded that metals were not influencing the health of these birds. Black guillemots (Cepphus grylle) examined near PCB-contaminated Saglek Bay, Labrador, had enlarged livers, e...