Nymphon is the largest genus of Pycnogonida reaching its greatest diversity in the Polar regions. A revision of the genus within the Eastern Arctic has proved necessary due to the numerous nomenclatural complexities which have accumulated in the literature since its last major revision by Sars in 1891. This has been achieved using multivariate analyses involving the measurement of over 1500 specimens. Fifteen species are now recognized from the area and each has been redrawn and redescribed. It has not proved necessary to propose any new species. Two distinct sub-groups are found within the genus in this area, differing in leg morphology and reproductive strategy. The first group, exemplified by Nymphon stromi, has a leg morphology suited to walking or striding. A large number of lightly yolked eggs are typically produced and the larvae spend only a short period of their development on the male ovigers before they disperse. The other group, exemplified by Nymphon hirtipes, has a leg morphology more suited to clinging. Fewer eggs are produced but these are richer in yolk and the male overwinters with the larvae which are lost only when metamorphosis is nearly complete. These interspecific differences have been discussed and it is thought that they may enable direct competition to be avoided by the exploitation of different facets of the same environment. In addition, differences in the musculature have been discussed for species within Nymphon and for the Pycnogonida generally. The male ovigers of all species examined show various adaptations which increase the surface area compared with that of the female. These modifications have been discussed and are shown to afford a greater area for attachrnent of the maturing egg masses. A histological examination of the internal structure of the femoral cement glands of Nymphon hirtipes has revealed that the adult males have a broad band of glandular tissue lying under the epidermis whereas specimens in the final larval stage have little or none. The life-cycle of Nymphon hirtipes is postulated, showing the species to take between two and a half and three years to attain maturity. It breeds only once, during its final summer. This is compared with existing knowledge of the life cycles of shallow and tropical water species.

A detailed examination of low visibility (LV) occurrences and the weather types that cause low visibility, with a focus on fog, was performed for five weather stations in the western Canadian Arctic, in the vicinity of the Amundsen Gulf area of the eastern Beaufort Sea. A series of climatologies were developed that established patterns of LV occurrence as a proportion of all observations and as a function of LV events caused by fog. Frequency climatologies for other weather types were also performed; in particular, for snow, blowing snow, rain, and drizzle. Annual climatologies were used to identify trends in several weather parameters over the 1980-2015 period of study. Monthlies were used to identify typical patterns of occurrence over the course of a year, and hourlies over the course of a day. A dataset of multi-hour fog events was also created; some of these were related to synoptic patterns. Analysis was also broken down by season. Results indicate several things. Monthly climatologies showed considerable diversity across the study area. Three distinct groupings were noted: Tuktoyaktuk and Ulukhaktok with a maximum frequency of LV conditions in February, Aklavik and Inuvik with a maxiumum frequency in October, and Sachs Harbour in August. The February maximum in Tuktoyaktuk and Ulukhaktok was related to cold air temperatures combined with small amounts of moisture from sea ice leads. The Alkavik and Inuvik October maximum was related to moisture advected over land from remaining open water, as well as diurnal snow melt adding moisture to the boundary layer that condenses as the evening cools off. The August maximum in Sachs Harbour is a reflection of proximity to open water and cold air temperatures. Hourly climatologies in the spring/fall season showed most stations have maximum occurrence of LV events caused by fog in the early morning. This is a radiative effect; cooling overnight causes radiation fog that peaks in occurrence just as morning begins. This peak is pushed into the midday in the winter, and is much weaker in the summer, both reflections of the changing pattern of daylight hours. / Graduate

The formation and dissolution of the North Water Polynya (an area of open water surrounded by a sea-ice covered ocean) was examined to determine the spatial and temporal variability of the Smith Sound ice arch (a feature that prevents ice from covering the polynya). A passive microwave, sea ice concentration dataset was used to create an index classification algorithm that categorized the formation and dissolution of the North Water Polynya from 1979 to 2012. Multiple years were classified as atypical, with the polynya forming earlier, the ice arch not forming at Smith Sound, or the ice arch not forming at all. Secondly, we compare and contrast atmospheric factors that influenced the formation of the ice arch during a typical (2010-2011) and an atypical (2009-2010) formation year. A significant southerly wind event in 2009-2010 could have displaced the ice pack and prevented the consolidation of the ice arch. The importance of the changing ice pack in Nares Strait to the formation of the polynya is also discussed. / May 2016

The Arctic is undergoing a rapid environmental shift with increasing temperatures and precipitations expected to continue over the next century. Yet, little is known about how microbial communities and their underlying metabolic processes will respond to ongoing climatic changes. To address this question, we focused on Lake Hazen, NU, Canada. As the largest High Arctic lake by volume, it is a unique site to investigate microbial responses to environmental changes. Over the past decade, glacial coverage of the lake has declined. Increasing glacial runoff and sedimentation rates in the lake has resulted in differential influx of nutrients through spatial gradients. I used these spatial gradients to study how environmental changes might affect microbial community structure and functional capacity in Arctic lakes. I performed a metagenomic analysis of microbial communities from hydrological regimes representing high, low, and negligible influence of glacial runoff and compared the observed structure and function to the natural geochemical gradients. Genes and reconstructed genomes found in different abundances across these sites suggest that high-runoff regimes alter geochemical gradients, homogenise the microbial structure, and reduce genetic diversity. This work shows how a genome-centric metagenomics approach can be used to predict future microbial responses to a changing climate.

This thesis investigates the causes and patterns of glacier and ice shelf changes across Northern Ellesmere Island, including rapid recent changes to marine-terminating glaciers and the mass balance of the Milne Ice Shelf along Ellesmere Island’s northern coastline. The first part describes the change in the areal extent of 1773 glacier basins across northern Ellesmere Island between ~1999 and ~2015 that were measured from optical satellite imagery. The results show that the regional ice coverage decreased by 1705.3 km2 over the ~16-year period, a loss of ~5.9%. This indicates a marked acceleration compared to the 3.4% loss recorded by Sharp et al. (2014) between ~1960 and ~2000. Ice shelves had the greatest losses relative to their size, of ~42.4%. Glaciers feeding into ice shelves reduced in area by 4.7%, while tidewater glaciers reduced in area by 3.3%. Marine-terminating glaciers with floating ice tongues reduced in area by 4.9% and 19 of 27 ice tongues disintegrated, causing these glaciers to retreat to their grounding lines. Land-terminating glaciers lost 4.9% of their 1999 area, including the complete loss of three small ice caps (<1.5 km2). These changes indicate the high sensitivity of the ice cover of northern Ellesmere Island to recent climate warming, and that continued losses are likely to occur in the future. In particular, the ice masses most susceptible to further losses are marine-terminating glaciers with floating termini and small land-terminating ice caps at low elevations. To further investigate the forcings leading to the recent losses of floating ice tongues, the second part focuses on marine-terminating glacier changes in the Yelverton Bay region of northern Ellesmere Island since 1959. From 1959-2017, the total ice tongue area decreased by 49.07 km2, with the majority of this loss occurring from 2005-2009 (34.68 km2). The loss of ice tongues since 2005 occurred when open water replaced multi-year landfast sea ice and first-year sea ice in the regions adjacent to the ice tongues. These changes were accompanied by an increase in mean annual mid-depth (i.e., 100 and 200 m) ocean temperatures from -0.29°C from 1999-2005 to 0.67°C from 2006-2012. Despite the recent return of ocean temperatures to below pre-2006 levels, atmospheric summer temperatures have continued to rise (+0.15°C decade-1 between 1948 and 2016), with open water continuing to occur. This suggests that loss of buttressing from sea ice appears to be the primary control on ice tongue losses, with air and ocean warming important in weakening the sea ice and ice tongues, together with offshore wind events in some years. Based on current climate it is unlikely that ice tongues will reform in the future. To examine the stability of the remaining ice shelves, the Milne Ice Shelf was selected as a case study to analyse the processes and patterns of surface mass balance. In 2008 a mass balance network of eight stakes was established across the Milne Ice Shelf and over the past 10 years has revealed a mean annual surface mass balance of -0.33 ±0.04 m water equivalent yr-1. Comparison of this surface mass balance rate with past ice thickness change measurements made by Mortimer et al. (2012) indicate that recent thinning may be limited to the surface, and accelerating over time. Individual stake and snow measurements reveal a surface mass balance gradient, whereby ablation decreases with proximity to the seaward edge of the ice shelf. The ablation gradient is driven by the microclimatology recorded at three automatic weather stations installed along the ice shelf, which show that air temperature and solar radiation decreases towards the coastline, while snow accumulation increases. Climate analysis suggests that the entire Milne Ice Shelf is in a state of negative mass balance in years with >200 melting degree days (MDD), while the one net positive balance year (in 2013) occurred when MDD totals were 105 yr-1. Although the Milne Ice Shelf is the most stable remaining ice shelf along the northern coast of Ellesmere Island, the relationship between climate and mass balance, along with a recent increase in calving along its landward margins, indicate that it is out of equilibrium with current climate. Overall, the ice coverage across northern Ellesmere Island is shrinking. The land-terminating ice that formed under cooler climatic conditions of the past, particularly low-lying small ice caps, are out of equilibrium with current climatological conditions. In addition, recent changes in the ice tongues and ice shelves demonstrate that the northern coastline of Ellesmere Island is approaching a future where the permanent floating ice cover can no longer be sustained.

The purpose of the thesis is to examine future international relations in the Arctic as a theoretical exercise based on realism and liberalism. As the ice cap shrinks, and the region's environment changes, developing costs will decrease allowing for resource-extraction while new transit routes emerge. The opportunities to develop resources and ship via the Arctic are economic and strategically valuable, altering the geopolitics of the region. This thesis seeks to explore how resource development and new transit routes will affect regional politics through the lens of two theories. The two theoretical approaches will examine states and actors' interests and possible actions. Concluding, that realism will best describe the Arctic as states strive to be the regional hegemon by controlling transit routes and resources or defending the regional status quo, creating tension and a security competition between the U.S., China, and Russia. States will jockey for position within institutions before the ice cap disappears and transit routes emerge. These states seek to grow regional governance in their favor, providing support for a liberal framework, and possibly creating a structure strong enough to reduce tension before states strive to be the Arctic hegemon.

Lilliputian Arctic Deviation is a work for small orchestra inspired by average snow and ice extent in the Northern Hemisphere over four decades. Something so large as forty years of snow and ice coverage can be interpreted as what Timothy Morton calls a hyperobject, an entity so vast in space and time that we as human beings cannot experience it within our limited senses and lifespans. For example, we can’t experience 150 years of global warming directly, but we can conceptualize it as an idea, or observe it as a graph. Like a graph, Lilliputian Arctic Deviation is an attempt to experience a hyperobject, while also allowing the composer free rein to creatively interpret and comment on the hyperobject. The Rutgers University Global Snow Lab records weekly and monthly snow extent averages for the Northern Hemisphere from 1967 until the present day. Lilliputian Arctic Deviation focuses on the summer yearly averages. Certain characteristics of the data, when graphed, show patterns that have both scientific and, after translation through algorithmic processes, musical significance. These characteristics are: 1. A significant decline in average snow extent from 1967 to the present; and 2. A transition from drastic yearly differences in the late 1960s through early 1990s to more consistent and predictable values in the late 1990s to 2015. Lilliputian Arctic Deviation proceeds in chronological order, starting with 1967 and ending with 2015. The density of the musical texture reflects the shape of the graph. Higher yearly averages involve more instruments sounding simultaneously, and lower yearly averages involve fewer instruments. Similar yearly average data values are reflected through shared musical materials; the range under which data points are located have similar characteristics. I group the data into eight regions: 3–3.9, 4–4.9,…10–10.9. Data points falling within a similar region share motivic, melodic, harmonic, and timbral materials. Other musical aspects of the piece reflect summer’s place within the larger hyperobject that includes all four seasons. The general characteristics of fall, winter, and spring are implied through listening to the summer, Lilliputian Arctic Deviation. Generally, Lilliputian Arctic Deviation features sharp articulated sounds of short duration, while sustained pitches are dynamically soft and fade in and out of the overall texture. Certain timbres are tight and subdued, such as a prevalence of muted brass, pizzicato and col legno battuto in the strings, and the use of wooden percussion. Set class (014) is used exclusively throughout the piece and is reflective of the small amount of snow and ice in the Northern Hemisphere respective to the amount found in the winter. Finally, since this process of the Earth has been and will continue to happen long before and after the years featured in this piece, this musical composition serves as an interpretation of a small fraction of the overall process, a hyperobject well beyond our ability to experience in our lifetimes.

Arctic Ocean contributes to the global oceanic uptake of CO2 by about 5% to 14% in taking up from 66 to 199 TgC yr-1. However, the role of the marine cryosphere was ignored because it is considered as an impermeable barrier, impeding the gas exchanges between the ocean and the atmosphere [Bates and Mathis, 2009]. However, a growing body of evidence suggests that gases exchange could occur between sea ice and the atmosphere. In this context, two Arctic surveys were carried out in the framework of the International Polar Year (IPY). From there, we present a snapshot of the partial pressure of CO2 (pCO2) dynamics firstly during the initial sea ice growth and secondly from early spring to the beginning of the summer. We confirmed previous laboratory measurement findings that growing young sea ice acts as a source of CO2 to the atmosphere by measuring CO2 efflux from the ice (4 to 10 mmol m-2 d-1). We also confirmed the precipitation of calcium carbonate as ikaite in the frost flowers and throughout the ice and its negligible role on the effluxes of CO2. In early spring, supersaturations in CO2 (up to 1834 µatm) were observed in sea ice as consequence of concentration of solutes in brines, CaCO3 precipitation and microbial respiration. As the summer draw near, brine shifts to a marked undersaturation (down to almost 0 µatm) because of the brine dilution by ice meltwater, dissolution of CaCO3 and photosynthesis during the sympagic algal bloom. Out of the winter, soon as the ice becomes permeable, CO2 fluxes were observed: (i) from the ice to the atmosphere, as the brine were supersaturated, (ii) from the atmosphere to the ice, as brine shift to an undersaturation. Temperature appears to be the main driver of the pCO2 dynamics within sea ice. It mainly controls the saturation state of the brine (where others processes may be added, e.g., CaCO3 precipitation, primary production) and thus, the concentration gradient of CO2 between sea ice and the atmosphere. It also controls the brine volume and so the brine connectivity, allowing the gas exchanges between sea ice and the atmosphere. We also present a new analytical method to measure the pCO2 of the bulk sea ice. This method, based on equilibration between an ice sample and a standard gas, was successfully applied on both artificial and natural sea ice. However, this method is only applicable for permeable sea ice (i.e., brine volume > 5% [Golden et al., 1998; 2007]) to allow the equilibration between the ice and the standard gas.

The purpose with this report was to compare three commonly occurring methods for measuring plant available nitrogen in soils. The methods extraction, incubation and Plant root simulator (PRS) probe - an ion exchange membrane (Western Ag Innovations, Inc., Saskatoon, Canada) method were used and comparison between these methods were conducted. A full factorial experiment were set up in northern Finland with the treatments excluding herbivores, warming and fertilization to see how the inorganic nitrogen content in the soil was effected by the treatments. Soil cores were taken and from them a subsample was incubated for 18 days and thereafter analyzed for inorganic N in laboratory. PRS- probes were in the ground for 1 month. It was a strong positive correlation between extracted and incubated samples but no correlation between the PRS- probes and extraction or incubation samples. The PRS- probes showed several significant changes in inorganic N content after the treatments where fertilization increased the tot-N and NO3 levels and warming reduced the inorganic tot-N, NH4 and NO3. These findings were not confirmed by the results of the extraction. The incubation showed negative net mineralization rates for tot- N and NH4. PRS- probes showed a slightly dominance of NO3 over NH4 while extraction showed a many times higher amount of NH4 compared to NO3. Extraction shows a strong correlation with incubation even though extraction measure an instantaneous value and incubation measure the production of inorganic nitrogen over time.

The Arctic is subject to growing economic and political interest. Meanwhile, its water and climate systems are in rapid transformation. Relevant and accessible information about water and climate is therefore vital to detect, understand and adapt to the changes. This thesis investigates hydrological monitoring systems, climate model data, and our understanding of hydro-climatic change, for adaptation to water system changes in the Arctic. Results indicate a lack of harmonized water chemistry data, which may impede efforts to understand transport and origin of key waterborne constituents. Further development of monitoring cannot rely only on a reconciliation of observations and projections on where climate change will be the most severe, as they diverge in this regard. Climate model simulations of drainage basin temperature and precipitation have improved between two recent model generations, but large inaccuracies remain for precipitation projections. Late 20th-century discharge changes in major Arctic rivers generally show excess of water relative to precipitation changes. This indicates a possible contribution of stored water from permafrost or groundwater to sea level rise. The river contribution to the increasing Arctic Ocean freshwater inflow matches that of glaciers, which underlines the importance of considering all sources when assessing change. To provide adequate information for research and policy, Arctic hydrological and hydrochemical monitoring needs to be extended, better integrated and made more accessible. This especially applies to hydrochemistry monitoring, where a more complete set of monitored basins is motivated, including a general extension for the large unmonitored areas close to the Arctic Ocean. Improvements in climate model parameterizations are needed, in particular for precipitation projections. Finally, further water-focused data and modeling efforts are required to resolve the source of excess discharge in Arctic rivers. / <p>At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 4: Manuscript</p>