Primary plant succession was examined on the foreland of the retreating Twin Glacier at Alexandra Fjord, Ellesmere Island. The position of the glacial front was monitored directly from 1980 to 1995 (except 1986-1991), and airphotos show the position of the glacier in 1959. Hence, there was an excellent opportunity to study primary succession where there was adequate chronological control. Presently, a well preserved pre-Little Ice Age plant community and organically rich (paleo) soil are being released from the Twin Glacier, in addition to glacio-fluvial sediments, rendering this foreland study unique. A terrain age scheme was developed using direct retreat measurements, airphotos and Salix aging. The relationship between the clump diameters of Luzula confusa and terrain age was determined to provide an alternative to lichenometry. Vegetation cover was assessed in 1994 and 1995 using a stratified random design. TWINSPAN and canonical correspondence analysis (detrended and non-detrended) were used together to examine vegetation patterns in relation to environmental variables. Soil seed bank and seed rain patterns were examined in relation to the above-ground vegetation. The seed bank was sampled in 1994, including samples from paleo-soil and glacio-fluvial sediment. To assess the fall-winter seed rain, seeds were collected between mid-August 1994 and early June 1995, using seed traps (artificial turf). Winter seed rain was sampled by collecting snow-core samples in early June 1995. Terrain age accounted for most of the variation in species composition over the study area. By directional-replacement, the succession followed four main stages of dominance in 44+ years: mosses —> graminoid-forb —> deciduous shrub-moss —> evergreen dwarf-shrubmoss. There was little difference in the successional sequences exhibited by the vegetation growing on the paleo-soil compared to that growing on the glacio-fluvial sediment. The relationship between the Luzula confusa clump diameters and terrain age was logarithmic. Luzula confusa dominated the above-ground vegetation, as well as, the germinable seed bank and seed rain. The average germinable seed bank, fall-winter seed rain and winter seed rain densities were 367 ± 32, 384 ± 47 and 180 ± 53 seeds/m2, respectively. The seed bank was significantly positively correlated with the above-ground vegetation cover for all species combined, Luzula confusa (monocotyledons), dicotyledons and Papaver radicatum. There was a significant positive correlation between the fall-winter seed rain and the above-ground vegetation cover for Luzula confusa. No difference was detected in seed bank density between the paleo-soil and the glacio-fluvial sediment. However, the total vegetation cover was significantly higher on the paleo-soil. The relationship determined between Luzula confusa clump diameters and terrain age appears to be a valuable alternative to lichenometry on the Twin Glacier foreland. Although the results showed that directional-replacement is possible in high arctic environments, this mode of succession is likely atypical of such environments; the Twin Glacier foreland is located in one of the very few polar oases in the Queen Elizabeth Islands. The positive correlation of the above-ground vegetation with the seed bank and fall-winter seed rain suggests that colonization is largely constrained by seed availability. The winter seed rain appears to be relatively important on the Twin Glacier foreland. The higher vegetation cover on the paleosoil versus the glacio-fluvial sediment suggests, at least for some species, that the former provides conditions more favourable for establishment and growth than the latter. / Arts, Faculty of / Geography, Department of / Graduate

Macrofossils from a Mesozoic fossil flora from Ellesmere Island, North West Territories are described and their affinities discussed, Several rarely occurring genera and species ore discussed in detail. The deposit in which they occur is dated using the known ranges of identified macro fossils and miospores, rand the results compared with those of other workers. The described flora is compared with floras of similar age in other parts of the world. / Thesis / Master of Science (MS)

No description available.

A novel approach for screening metagenomic libraries by merging both metagenomic and microarray platforms was developed and optimized. This high-throughput screening strategy termed "metagenomic microarrays" involved the construction of two Arctic soil large-insert libraries and the high density arraying of the clone plasmid DNA (~50 kb) onto glass slides. A standard alkaline lysis technique used for the purification of plasmid DNA was adapted and optimized to function efficiently in a 96-well format, providing an economically viable means of producing sufficient high-quality plasmid DNA for direct printing onto microarrays. The amounts of printed material and probe, required for maximal clone detection, were optimized. To examine catabolic clone detection libraries were first screened by PCR for catabolic genes of interest. Two PCR-positive clones were printed onto microarrays, and detection of these specific clones in the printed libraries was achieved using labeled probes produced from PCR fragments of known sequence. Also, hybridizations were performed using labeled PCR fragments derived from the amplification of a catabolic gene from the total community DNA. The ability of selected probes to specifically target clones of interest was demonstrated. This merger of metagenomics and microarray technologies has shown great promise as a tool for screening the natural microbial community for catabolic potential and could also be used to profile microbial diversity in different environments.

A first approximation of ground ice volume for the area surrounding Eureka, Nunavut, indicates that it comprises 30.8% of the upper 5.9 m of permafrost. Volume depends on the type of ice examined, ranging from 1.8 to 69.0% in different regions of the study area. Excess ice makes up 17.7% of the total volume of frozen materials in the study area. Melt of ground ice in the past has produced thermokarst features which include ground subsidence of up to 3.2 m, formation of tundra ponds, degradation of ice wedges, thaw slumps greater than 50 m across, gullying, and numerous active layer detachment slides. With a doubling of atmospheric carbon dioxide, the rise in mean annual temperatures for the area is projected to be 4.9 to 6.6°C, which would lengthen the thaw season and increase thaw depths by up to 70 cm. The expected geomorphic changes to the landscape are discussed.

No description available.

No description available.

Alkane monooxygenases (encoded by the alkB gene) are a group of microbial enzymes that catalyze the first reaction of alkane degradation. Studies to determine the diversity and prevalence of alkB genotypes in the environment have focused on culturable organisms. The goal of this research was to use culture-independent methods (DGGE, clone library) to identify and characterize alkB genes, and to determine their prevalence in Arctic contaminated soils. General alkB PCR degenerate primers (alkB-Mc) were designed using the conserved nucleotide sequences of the Histidine I Box and Histidine III Box. General alkB-Mc and alkM (Acinetobacter spp. alkane monooxygenase genes) primers were used to screen the soils for the presence of alkane monooxygenase genotypes. A predominance of the Rhodococcus spp. alkB genotypes and the absence of alkM genotypes in these soils was found. alkB PCR fragments amplified from the soils were analyzed by DGGE (Denaturing Gradient Gel Electrophoresis). BlastN and blastX results of the DGGE bands sequences showed that they were similar to Rhodococcus spp. alkB genotypes (~80-90% DNA identity and ~80-90% amino acid homology). An alkB clone library was built using the general alkB-Mc primer set, screened by RFLP (Restriction Fragment Length Polymorphism) and characterized by sequencing of alkB clones. BlastN and blastX results of the alkB clone sequences showed the presence of divergent alkB genotypes (≤ 70% DNA identity and ≤ 67% of amino acid homology to data base sequences). The alignment of the clone-derived amino acid sequences to confirm functional alkane monooxygenase sequences revealed the presence of Histidine Box II and the HYG motif in all of the deduced amino acid clone sequences. These results indicate that the alkB sequences from the clone library represent novel alkB sequences. Both alkB DGGE and clone library techniques were independently able to identify alkB genotypes from High G+C microorganisms as predominant in the 1A03 soil sample. Nevertheless, only the clone library approach identified putative novel alkB sequences. Mineralization of hexadecane and naphthalene was clearly observed at subzero temperatures (-5ºC) in Arctic contaminated soils, proving that the indigenous microbial communities could mineralize these representative hydrocarbons at subzero temperatures in an environment that is predominantly frozen for most of the year.

No description available.

A succession of late Early through Medial Permian conodont faunas is documented for the first time from the calcareous, fine grained, quartzose sandstones of the Assistance and Trold Fiord Formations on northern Elles-mere Island, Northwest Territories. Of the taxa identified and described, one species and three subspecies are proposed as new. The taxa include, in chronological order: Neogondolella idahoensis subsp. indet., Neostrep-tognathodus prayi, Neogondolella idahoensis n.subsp. A, Anchignathodus minutus, Neogondolella serrata(?), N. n.sp. B, N. postserrata(?), N. bitteri n.subsp. C, and N. rosenkrantzi n.subsp. D. Numerous ramiform elements are also associated with Neogondolella idahoensis n.subsp. A. These elements may comprise part of a multielement Neogondolella apparatus or they may represent separate form species. In observation of their questionable status, a somewhat unsatisfactory dual taxonomy is proposed for these elements, and includes the following taxa: N. idahoensis n.subsp. A - Xanio-gnathus tortilis, N. idahoensis n.subsp. A - Ellisonia excavata, N. idahoensis n.subsp. A - Ellisonia tribulosa, and N. idahoensis n.subsp. A - Pri-oniodella decrescens. Statistical work on the abundant platform elements of N. idahoensis n.subsp. A provides evidence for minor 'evolutionary trends of increasing size and increasing number of denticles upsection. Comparison of these con-odonts with N. serrata.and N. postserrata from the Great Basin of SW USA suggests that the phylogenetic development of Permian Neogondolella followed an,, evolutionary path.more appropriate to punctuated equilibria than to phyletic gradualism. The conodont taxa indicate that the Assistance Formation is Upper Leonardian to Uppermost Roadian in age whereas the Trold Fiord Formation includes most of the Wordian.stage. These two formations have been separated into five subdivisions on the basis of both lithology. and the presence or absence of various biota 1 A sixth, subdivision is described for the Sabine Bay Formation which underlies the Assistance and where conodonts are apparently absent. Lithologic and biotic evidence (including trace fossils and mega- and microbiota) point to shallow, offshore marine conditions well within the photic zone and characterized by low energy and slow depositional rates, for most of the conodont bearing strata. A much thicker correlative section to the south represents, in large part, a delta front sequence. The Sabine Bay Formation, on the other hand, is composed of shoreface sandstones, possibly in a barrier island setting. The results of this research indicate that conodonts may be very promising for correlation of Permian strata in the Canadian Arctic Archipelago and for worldwide comparison. More work within the Sverdrup Basin, including both marginal and basinal sections , is necessary to provide a good biozonation of these marine Permian strata. The use of the abundant brachiopods in combination with the conodonts is probably the best way to resolve this zonation. The taxonomic.descriptions and subdivisions proposed herein should provide a foundation for future work. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate