Geology and structure of 1,000 square miles of granulite-upper amphibolite facies gneisses cut by syn- and late-kinematic intrusions are described. The circular post-kinematic Mutton Bay alkaline syenite (631 m.y.) is divided into three main intrusive groups on the basis of chemistry, mineralogy, and field relations. Differentiation includes gravity settling and flow differentiation, while intrusion involved early stoping and assimilation with late faulting. Depth of the present level below the roof of the intrusion is estimated at 6-8 miles and temperature of crystallization of felspars in the early magmas at greater than 1015°C at less than 500 bars water pressure. Orthoclase inverted to microcline in foliated rocks that intruded as crystal mushes. A giant gabbro dyke with syenite differentiate (470 m.y.) is intruded by diabase and trachyte dykes. Carbonate enrichment in the trachytes is accompanied by high potash felspar content. Sandstone dykes are the only Paleozoic sediments.

Large ice blocks containing enough sediment to be denser than sea water form in the Minas Basin of the Bay of Fundy. The timing of ice block formation and ice block composition were monitored to improve understanding of the potential threat to tidal power generators posed by collision with ice blocks. Large blocks are produced from ice cliffs that form when anchored ice obstructs tidal channels and decreases flow speed. Decreased flow causes the channel cross-sectional area to decrease. In 2012, the Kennetcook River cross- sectional area decreased by 21% due to the formation of ice cliffs. Large ice blocks separated from the walls during the two spring tides following a 20-day time lag of the minimum air temperature. Ten percent of sampled ice blocks were denser than freshwater. Four of twelve ice cores collected from the ice cliffs along the Kennetcook River contained enough sediment to become denser than seawater.

The goal of this study was to investigate the effects of intertidal mudflat biofilms on sediment erosion in the Minas Basin of the Bay of Fundy, Canada. From April through November 2012, sediment cores were collected biweekly and eroded using a Gust micro- cosm. Half of the cores were eroded without undergoing prior treatment, while the other half were treated with bleach prior to erosion to destroy biofilms. Size-specific sediment retention by biofilms was evaluated by comparing the disaggregated inorganic grain size (DIGS) distributions of sediment resuspended from untreated and treated cores, while seasonal variation in natural sediment erodibility was assessed by focusing on the mass eroded from untreated cores only. Results show that biofilms preferentially retained clays and very fine silts (< 10 μm), and that overall sediment erodibility decreased from spring to fall. Results also indicate that abundance of the infaunal amphipod Corophium volutator and rainfall increased sediment erodibility.

No description available.

The genetic structuring of populations can be influenced by present processes and past events. One of the largest historical events to affect the distribution and genetic characteristics of present-day North American biota is the Pleistocene glaciation. Thus, the study of post-glacial colonization patterns of species in northern landscapes can relay important ecological information, as species had to expand their range extensively following the retreat of the glaciers and are often at the terminal end of their expansion. These species consequently exhibit the genetic fingerprints of sequential founder events, in turn decreasing the genetic variation available for adaptation. Using amphibians to investigate post-glacial range expansion is advantageous, as they have limited dispersal abilities revealing fine-scale patterns and they are thought to be one of the first vertebrates to colonize post-glacial habitat. Therefore, to model the phylogeography of a primary colonizer and the population structure of anurans in northern landscapes, population genetics analyses of wood frogs (Lithobates sylvaticus) were performed in the James Bay area. Wood frogs were sampled from 17 localities around James Bay and genetic analyses were conducted with seven microsatellite loci and mitochondrial DNA sequences of the ND2/tRNATRP genes. Results show that the post-glacial recolonization of the James Bay area by wood frogs originated from the putative refugium in western Wisconsin, an area known as the Driftless Area. Two routes were taken by founders to colonize the James Bay area: one north-west of Lake Superior, colonizing western Ontario, and one through the Upper Peninsula of Michigan, colonizing southern and eastern Ontario and western Québec. Interestingly, the meeting of the two lineages south-west of James Bay led to the establishment of a zone of higher genetic variation than expected under the founder effect hypothesis. Additionally, population structure analyses revealed the segregation of three genetic populations east, north-west, and south-west of the bay, the latter showing the highest genetic variation and likely representing a zone of secondary contact. This study shows that past events such as post-glacial range expansions can explain present patterns of genetic variation and population structure, and that studies in northern landscapes may be very useful in understanding genetic patterns throughout the range of a species.

Geology and structure of 1,000 square miles of granulite-upper amphibolite facies gneisses cut by syn- and late-kinematic intrusions are described. The circular post-kinematic Mutton Bay alkaline syenite (631 m.y.) is divided into three main intrusive groups on the basis of chemistry, mineralogy, and field relations. Differentiation includes gravity settling and flow differentiation, while intrusion involved early stoping and assimilation with late faulting. Depth of the present level below the roof of the intrusion is estimated at 6-8 miles and temperature of crystallization of felspars in the early magmas at greater than 1015°C at less than 500 bars water pressure. Orthoclase inverted to microcline in foliated rocks that intruded as crystal mushes. A giant gabbro dyke with syenite differentiate (470 m.y.) is intruded by diabase and trachyte dykes. Carbonate enrichment in the trachytes is accompanied by high potash felspar content. Sandstone dykes are the only Paleozoic sediments.

Geology and structure of 1,000 square miles of granulite-upper amphibolite facies gneisses cut by syn- and late-kinematic intrusions are described. The circular post-kinematic Mutton Bay alkaline syenite (631 m.y.) is divided into three main intrusive groups on the basis of chemistry, mineralogy, and field relations. Differentiation includes gravity settling and flow differentiation, while intrusion involved early stoping and assimilation with late faulting. Depth of the present level below the roof of the intrusion is estimated at 6-8 miles and temperature of crystallization of felspars in the early magmas at greater than 1015°C at less than 500 bars water pressure. Orthoclase inverted to microcline in foliated rocks that intruded as crystal mushes. A giant gabbro dyke with syenite differentiate (470 m.y.) is intruded by diabase and trachyte dykes. Carbonate enrichment in the trachytes is accompanied by high potash felspar content. Sandstone dykes are the only Paleozoic sediments.

No description available.

A simple linear reduced-gravity ocean model is developed to simulate the North Water polynya located in northern Baffin Bay. The model is an extension of Pease (1987) latent-heat model for a coastal polynya. Both northerly surface wind forcing and coastal upwelling processes are taken into account in modelling the steady state and time-dependent water velocities, upper layer depth, and polynya width measured southward from its northern boundary. Also, both uniform and variable wind forcing are considered. In most of this thesis a semi-infinite domain model is used in which upwelling occurs along the eastern boundary (the Greenland coast). It is found that the steady state polynya width is a strong function of the air temperature, but a weak function of the wind speed. The model results show that in the upwelling region near the Greenland coast, the polynya width is larger than further offshore (distance $>$ 2 Rossby radii), where it is a constant (the limiting Pease width). For a variable wind forcing, the southern ice edge of the North Water has a form that is similar to that of the wind forcing. In a channel, upwelling occurs in the eastern part and downwelling in the western part. Thus the polynya is much wider near Greenland and narrower near the Canadian Islands.

Current trends toward warmer air temperatures and longer ice free seasons in Hudson Bay are expected to cause changes in Arctic marine ecosystem dynamics. Ringed seals (Phoca hispida) will likely experience changes in levels of predation, competition, and prey availability. The purpose of this thesis was to investigate seasonal, inter-annual, and spatial variation in Hudson Bay ringed seal feeding ecology. Fatty acid composition, δ15N, and δ13C varied significantly by season, suggesting seasonal changes in foraging habitat and diet. Spatial differences in ringed seal stable isotope ratios occurred between western and eastern Hudson Bay, and there was a strong relationship between spring air temperature and δ15N. Peak δ15N occurred within a range in spring air temperatures between approximately -5°C and -2°C. I propose that the high δ15N observed in ringed seals within this temperature range is indicative of relatively greater importance of capelin (Mallotus villosus) in the ringed seal diet.