The investigation of a species’ repertoire and the contexts in which different calls are used is central to understanding vocal communication among animals. Beluga whale, Delphinapterus leucas, calls were classified and described in association with behaviours, from recordings collected in the Churchill River, Manitoba, during the summers of 2006-2008. Calls were subjectively classified based on sound and visual analysis into whistles (64.2% of total calls; 22 call types), pulsed or noisy calls (25.9%; 15 call types), and combined calls (9.9%; seven types). A hierarchical cluster analysis, using six call measurements as variables, separated whistles into 12 groups and results were compared to subjective classification. Beluga calls associated with social interactions, travelling, feeding, and interactions with the boat were described. Call type percentages, relative proportions of different whistle contours (shapes), average frequency, and call duration varied with behaviour. Generally, higher percentages of whistles, more broadband pulsed and noisy calls, and shorter calls (<0.49s) were produced during behaviours associated with higher levels of activity and/or apparent arousal. Information on call types, call characteristics, and behavioural context of calls can be used for automated detection and classification methods and in future studies on call meaning and function.

The investigation of a species’ repertoire and the contexts in which different calls are used is central to understanding vocal communication among animals. Beluga whale, Delphinapterus leucas, calls were classified and described in association with behaviours, from recordings collected in the Churchill River, Manitoba, during the summers of 2006-2008. Calls were subjectively classified based on sound and visual analysis into whistles (64.2% of total calls; 22 call types), pulsed or noisy calls (25.9%; 15 call types), and combined calls (9.9%; seven types). A hierarchical cluster analysis, using six call measurements as variables, separated whistles into 12 groups and results were compared to subjective classification. Beluga calls associated with social interactions, travelling, feeding, and interactions with the boat were described. Call type percentages, relative proportions of different whistle contours (shapes), average frequency, and call duration varied with behaviour. Generally, higher percentages of whistles, more broadband pulsed and noisy calls, and shorter calls (<0.49s) were produced during behaviours associated with higher levels of activity and/or apparent arousal. Information on call types, call characteristics, and behavioural context of calls can be used for automated detection and classification methods and in future studies on call meaning and function.

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.

Rapidly changing climates in northern Canada make the western Hudson Bay region an area of high importance for paleoenvironmental studies. Long-term changes in assemblages of diatoms (microscopic algae) were analyzed from lake sediment cores from Baker Lake, Nunavut, and Lake AT01, northern Ontario, to track responses to past environmental changes. Diatom assemblages dating to 6700 years ago in AT01 were initially characterized by cold- tolerant Fragilarioid assemblages, but shifted to an assemblage dominated by large benthic species and Cymbella diluviana consistent with the timing of the Holocene Thermal Maximum after 6300 years BP. A possible drainage event in Lake AT01 may have added significant hydrologic control on the diatom assemblages. The post-industrial period is marked by the largest compositional shifts in both records. Assemblages during the 20th century are indicative of reduced ice cover and enhanced thermal stratification linked to a climate regime shift noted in Hudson Bay since the mid-1990’s.

Rapidly changing climates in northern Canada make the western Hudson Bay region an area of high importance for paleoenvironmental studies. Long-term changes in assemblages of diatoms (microscopic algae) were analyzed from lake sediment cores from Baker Lake, Nunavut, and Lake AT01, northern Ontario, to track responses to past environmental changes. Diatom assemblages dating to 6700 years ago in AT01 were initially characterized by cold- tolerant Fragilarioid assemblages, but shifted to an assemblage dominated by large benthic species and Cymbella diluviana consistent with the timing of the Holocene Thermal Maximum after 6300 years BP. A possible drainage event in Lake AT01 may have added significant hydrologic control on the diatom assemblages. The post-industrial period is marked by the largest compositional shifts in both records. Assemblages during the 20th century are indicative of reduced ice cover and enhanced thermal stratification linked to a climate regime shift noted in Hudson Bay since the mid-1990’s.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 829-838).

No description available.

<p> This study focuses on the relations hip between ice cover and wind frequency, wind speed and air temperature. Results showed that there are four distinct MELT periods along the west coast of Hudson Bay. With a standardized MELT period, stations are generally higher correlated with their southern neighbours. Onshore wind frequencies increased signficantly from the NOMELT to the MELT period, and were associated with air temperatures 3 to 4 degrees Celsius colder than those of offshore winds. </p> <p> Mean air temperature was most highly correlated with percent ice cover. Ice cover was most strongly correlated with mean air temperature at Chesterfield Inlet and least so at Churchill. Thus, freeze-up and melt at Chesterfield Inlet are most strongly influenced by air temperature whereas at Churchill, other factors, presumably wind direction and currents, strongly influence the ice cover. Ice cover was most strongly influenced by air temperature during the NOMELT period. This shows that cold temperatures hasten freezeback more than warm temperatures hasten MELT. </p> / Thesis / Bachelor of Arts (BA)

This thesis examines the development and validation of Canadian Land Surface Scheme (CLASS) for various wetland landscapes individually, along with an evaluation of modelled results over a heterogeneous surface with airborne observations. A further statistical analysis of the effects of land surface classification procedures over the study area and their influence on modelled results is performed. CLASS is tested over individual wetland types: bog, fen and marsh in a stand-alone (non-GCM coupled) mode. Atmospheric conditions are provided for the eight site locations from tower measured data, while each surface is parameterized within the model from site specific measurements. Resulting model turbulent and radiative flux output is then statistically evaluated against observed tower data. Findings show that while CLASS models vascular dominated wetland areas (fen and marsh) quite well, non-vascular wetlands (bogs) are poorly represented, even with improved soil descriptions. At times when the water table is close to the surface, evaporation is greatly overestimated, whereas lowered water tables generate a vastly underestimated latent heat flux. Because CLASS does not include a moisture transfer scheme applicable for non-vascular vegetation, the description of this vegetation type as either a vascular plant or bare soil appears inappropriate. / CLASS was then tuned for a specific bog location found in the Hudson Bay Lowland (HBL) during the Northern Wetlands Study (NOWES). With bog surfaces better described within the model, testing of CLASS over a highly heterogeneous 169 km2 HBL region is then undertaken. The model is first modified for lake and pond surfaces and then separate runs for bog, fen, lake and tree/shrub categories is undertaken. Using a GIS, the test region under which airborne flux measurements are available is divided into 104 grid cells and proportions of each surface type are calculated within each cell. Findings indicate that although the modelled grid average radiation and flux values are reasonably well reproduced (4% error for net radiation, 10% for latent heat flux and 30% for sensible heat flux), spatial agreement between modelled and observed grid cells is disappointing. (Abstract shortened by UMI.)

No description available.