This study is ecological in objective; primarily it attempts to evaluate environmental factors limiting the distribution of a wide-ranging species of fish, Gasterosteus aculeatus, in one sector of its holarctic range. Two approaches to this investigation are made: comparative and deductive. The comparative method is possible because many studies have been made on temperate-zone populations of the species; modified behaviour observed in the present study are consequently viewed as probably adaptive to the different environmental conditions of the north. [...]

Climate change will affect Arctic plant communities directly, by altering growth and recruitment, and indirectly, by increasing the frequency of natural disturbance. Since the structure of northern vegetation influences global climate, understanding both temperature and disturbance effects on vegetation is critical. Here, I investigate the influence of temperature and disturbance on Low Arctic vegetation at several spatio-temporal scales in the Mackenzie Delta Region, N.W.T. To disentangle the relative impact of temperature and disturbance on forest-tundra and tundra ecosystems, I sampled microenvironmental variability, plant community composition, and green alder abundance, growth, and reproduction on disturbed (burns and thaw slumps) and undisturbed sites across a regional temperature gradient. Disturbed areas showed increases in alder productivity, catkin production, and seed viability, as well as differences in plant community composition and microenvironment. The magnitude of plot-level responses to disturbance compared to variation across the temperature gradient suggests that in the short-term, increasing the frequency of disturbance may exert a stronger influence on tundra ecosystems than changes in temperature. At the plot level, increases in alder seed viability and recruitment at warmer sites point to the fine-scale mechanisms by which shrub abundance will change. To examine the relative influence of temperature and biophysical variables on landscape-level patterns of shrub dominance, I mapped Low Arctic vegetation using aerial photos. At this broader scale, correlations between temperature and the areal extent of shrub tundra suggest that warming will increase the dominance of shrub tundra. To assess the magnitude of changes in temperature and thaw slump activity, I analyzed climate records and mapped retrogressive thaw slumps using aerial photographs. An increase in thaw slump activity in recent decades, coincident with higher temperatures, suggests that continued warming will change the area affected by thermokarst disturbances like slumps. Taken together, my research indicates that the effects climate change will be magnified by shifts in the frequency of disturbance, initiating changes to Arctic vegetation with significant implications for global climate. My work also shows that to fully understand the influence of patch-landscape feedbacks on Arctic vegetation dynamics, the effects of disturbance must be examined across longer temporal and broader spatial scales.

In this thesis, a semi-permeable lining system was proposed to upgrade arctic wastewater stabilization ponds, acting as a biofilter. Although commonplace at lower latitudes, the effects of cold temperatures and short-duration summers on biofilter performance are inadequately studied. The goal of this research was to study the hydraulic and treatment performance of geotextile substrate biofilters under arctic conditions. Filtration experiments were conducted in a laboratory environment. Municipal wastewater was passed through columns containing nonwoven geotextiles over 10 cm of gravel. Three experimental trails were conducted at either 10? or 2?, each lasting 12 weeks. Weekly samples taken before and after filtration were analyzed for various water quality parameters. Hydraulic conductivity was monitored using weekly constant head permeameter tests. Results showed that biomat accumulation is possible on geotextile material over 12 week period. Significant removal of TSS and BOD5 was observed, along with a 1-log reduction in hydraulic conductivity.

High Arctic meromictic lakes are frequently used to generate detailed records of past environmental variability within their sedimentary profiles. However, without detailed analyses of sedimentation influences over time, their paleoclimate records cannot be accurately interpreted. This thesis presents a comprehensive examination of the sedimentology and paleoenvironmental records of meromictic Lake A, Ellesmere Island (83°00’N, 75°30’W), including detailed analysis of the sedimentary history, development and evaluation of several paleoclimate records. The sedimentary record was primarily composed of clastic material but varying inputs of authigenic components from biological and chemical processes in the water column resulted in a complex history of lake sedimentation. Under chemically stratified conditions during the past millennium, annual laminae (varves) formed and were used to develop a sedimentary chronology. Sedimentary pellets were most likely formed by ice-rafting processes and were deposited during high melt years in this perennially ice-covered lake. The pellet frequency record indicated that the twentieth century contained the most frequent reduced ice cover summers during the past millennium, although the 1500s and 1600s were also inferred warm periods. Comparison with instrumental climate data indicated that varve thickness was primarily related to late summer and autumn snowfall in the previous year, which highlighted the importance of snow availability in spring rather than melt energy in sediment transfer to the lake in this non-glacial catchment. The varve thickness and grain size records suggested increased flow competency and autumn snowfall particularly during the late-1000s to early-1100s and first half of the 1900s. Paleoenvironmental records from Lake A corresponded well with many regional proxy records and provided a long-term framework within which to examine observed environmental change along the northern Ellesmere Island coast during the past century. Finally, these analyses would not have been possible without obtaining high quality sediment cores. This research also investigated the effectiveness of a gel seal method for preserving the fragile sediment-water interface during transport and its results could be useful for other sediment core studies. / Thesis (Ph.D, Geography) -- Queen's University, 2008-05-08 13:34:14.044

In June 2005, fieldwork was conducted during the spring snowmelt period at Cape Bounty, Melville Island, Nunavut to examine the relationships between snow accumulation, runoff, and nutrient fluxes in two High Arctic watersheds. The snowcover was quantified by means of eleven depth and three density measurements at 42 survey transects (100 m) distributed throughout the West and East watersheds. River discharge was monitored at the watershed outlets, where water samples were collected four times daily during the first ten days of melt and twice daily once flow receded. Water samples were also collected from headwater and tributary sites in the two watersheds, and samples were analyzed for DOC, DON and DIN (NH4+ and NO3-). An objective terrain classification weighted equally on slope, aspect and land surface curvature was applied to the two watersheds using an ISODATA unsupervised classification scheme to determine watershed SWE. The terrain model confirmed that topography likely explains greater SWE in the West watershed, and provides a method for reproducible estimates of watershed SWE in future years. However, improved methods for estimating SWE in channels and deep snowbanks are required to ensure accurate assessments of watershed SWE. The seasonal trends in DOC, DON, and DIN concentrations and specific fluxes are reported for both watersheds. The export of DON and DIN was strongly correlated with DOC in the West watershed, indicating that the flushing of terrestrial nutrients from surficial soils by snowmelt runoff governs nutrient export. Despite less watershed SWE (51%), the East watershed exported greater specific fluxes of DOC (33%) and DON (43%) during the melt season. This suggests that the East watershed had greater connectivity with OM sources early in the melt season. Furthermore, low DOC:DON ratios (< 15) in the East River indicate that a larger portion of DOM was likely derived from algal or microbial sources in the East watershed relative to the West watershed. The export of DIN was similar in the two watersheds, and results suggest that DIN export was likely controlled by watershed vegetation coverage and runoff volumes during snowmelt. / Thesis (Master, Geography) -- Queen's University, 2008-07-08 00:31:46.107

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This thesis investigates the relationships between mercury (Hg) and stable isotope of carbon (δ13C) in marine pelagic zooplankton (Calanus spp., Themisto spp. and Euchaeta spp.) with water mass characteristics in the North Water Polynya (NOW) and in the Mackenzie shelf – Amundsen Gulf area. Two ship based sampling field expeditions were carried out in late summer of 2005 and 2006 in both regions on board the CCGS Amundsen. In the North Water (NOW) polynya, higher levels of water Hg, depleted δ18O, lower salinity and lower nitrate levels were measured at sampling locations near the Prince of Wales glacier (POW) on the eastern coast of Ellesmere Island in the Smith Sound area. These results suggest that the glacier may be a source of Hg to this region which, in turn, is responsible for the correspondingly high concentrations of THg and MMHg measured in Calanus spp. and Euchaeta spp. at the same locations. The Mackenzie shelf – Amundsen Gulf region was characterized by fresher surface water properties (low salinity and depleted δ18O) in the western part and was strongly linked to the influence of the Mackenzie River. Higher THg concentrations in zooplankton were associated with larger fractions of both meteoric water and sea-ice melt. These findings suggest that in the western Arctic, inorganic Hg uptake in zooplankton via-absorption near surface water was highly driven by freshwater inputs into the system. Based on the analysis of three main genus Calanus spp. (mostly adult females Calanus hyperboreus), Euchaeta spp. and Themisto spp. (mostly adult Themisto libellula), THg and MMHg concentrations were the highest in the carnivorous copepod Euchaeta spp. in the North Water polynya followed by the omnivorous hyperiid amphipod Themisto spp. The herbivorous copepod Calanus spp. had both the lowest THg and MMHg concentrations in the Eastern and the Western Arctic. In addition, the Western Arctic is the area in which each zooplankton genus had the most depleted carbon and the most enriched nitrogen. The highest concentrations of THg in Calanus spp., Euchaeta spp. and Themisto spp. were measured in the Western Arctic as well as the highest MMHg in Calanus spp. and Themisto spp. The highest %MMHg was calculated in the Archipelago for Themisto spp., in the Eastern Arctic for Euchaeta spp. and in the Western Arctic for Calanus spp. The relationships observed between THg, MMHg, %MMHg and δ13C in all three major zooplankton taxa and water mass properties were in agreement with what have been previously described in the literature. Our findings suggested that both Hg and δ13C can be used as tracers to help understand zooplankton vertical distribution, feeding ecology and ultimately to predict climate changes impact at lower trophic level in the pelagic food web. The implications for marine mammals foraging in these regions are also discussed.