An evaluation of home range models for marine fish tracking and fine scale habitat use and movement patterns of age 1 Greenland cod (Gadus macrocephalus ogac)

My thesis examines fine-scale habitat use and movement patterns of age 1 Greenland cod (Gadus macrocephalus ogac) tracked using acoustic telemetry. Recent advances in tracking technologies such as GPS and acoustic telemetry have led to increasingly large and detailed datasets that present new opportunities for researchers to address fine-scale ecological questions regarding animal movement and spatial distribution. There is a growing demand for home range models that will not only work with massive quantities of autocorrelated data, but that can also exploit the added detail inherent in these high-resolution datasets. Most published home range studies use radio-telemetry or satellite data from terrestrial mammals or avian species, and most studies that evaluate the relative performance of home range models use simulated data. In Chapter 2, I used actual field-collected data from age-1 Greenland cod tracked with acoustic telemetry to evaluate the accuracy and precision of six home range models: minimum convex polygons, kernel densities with plug-in bandwidth selection and the reference bandwidth, adaptive local convex hulls, Brownian bridges, and dynamic Brownian bridges. I then applied the most appropriate model to two years (2010-2012) of tracking data collected from 82 tagged Greenland cod tracked in Newman Sound, Newfoundland, Canada, to determine diel and seasonal differences in habitat use and movement patterns (Chapter 3). Little is known of juvenile cod ecology, so resolving these relationships will provide valuable insight into activity patterns, habitat use, and predator-prey dynamics, while filling a knowledge gap regarding the use of space by age 1 Greenland cod in a coastal nursery habitat. By doing so, my thesis demonstrates an appropriate technique for modelling the spatial use of fish from acoustic telemetry data that can be applied to high-resolution, high-frequency tracking datasets collected from mobile organisms in any environment.

Environmental controls on bioturbation processes in marine benthic habits

Through bioturbation, the macrofauna mediate chemical, physical and biological processes in marine benthic ecosystems. Because of the importance of bioturbation as ecosystem mediator, various studies have been conducted on bioturbation intensity and depth, and the relation of bioturbation processes to environmental condition and ecosystem state. This thesis builds on those previous studies, using a standard field and analytical protocol and by expanding the geographical scale to three climatic regions along Canada’s East Coast and Arctic margins, the Arctic Archipelago, the coastal Subarctic (Labrador Fjords), and the temperate continental climate zone (Gulf of Maine and adjacent Scotian shelf/slope). This Ph.D. study provides a comprehensive assessment of environmental influences on bioturbation along gradients in latitude and ocean depth. Bioturbation intensity, mixing depth, and bioturbation structures were studied in relation to the quantity and quality of potential food sources (organic matter) and substrate characteristics to gain an understanding of the environmental controls on bioturbation in these regions. The three main research chapters of this thesis are divided based on the contrasting climatic and geographical regions studied. The analytical approach included seabed sampling with a boxcorer, describing the sedimentary fabric and bioturbation structures by X-radiography, estimating bioturbation intensity and depth applying a biodiffusion model to particle tracer profiles of ²¹⁰Pbₓs, ²²⁸Thₓs, ²³⁴Thₓs, and chlorophyll-a, and analyzing benthic organic matter and substrate characteristics. Strong regional and cross-climatic relations of bioturbation processes with combinations of environmental factors were observed. In particular, bioturbation depth and the vertical extent of bioturbation structures responded to the environmental patterns observed and, therefore, represented potentially applicable predictors of environmental conditions and ecosystem state. The results of this Ph.D. study may be further extended to other geographical regions with similar environmental characteristics to predict the effects of benthic habitat alterations through environmental stresses on a global scale. Integrated with biological data produced by fellow CHONe scientists the presented data may provide valuable information about functional roles of macrofaunal species and community traits in marine benthic ecosystems along Canada’s extensive East Coast and Arctic margins.

Environmental and biological drivers of feeding and spatial dynamics in the green sea urchin, Strongylocentrotus droebachiensis

In eastern Canada, the destruction of foundational kelp beds by dense aggregations (fronts) of the omnivorous green sea urchin, Strongylocentrotus droebachiensis, is a key determinant of the structure and dynamics of shallow reef communities. Current knowledge about factors affecting the ability of S. droebachiensis to exert top-down community control is based largely on observational studies of patterns in natural habitats, yielding fragmentary, and sometimes contradictory, results. The present research incorporated laboratory microcosm experiments and surveys of urchins in natural habitats to test the effects of abiotic (wave action, water temperature) and biotic (body size, population density) factors on: (1) individual and aggregative feeding on the winged kelp, Alaria esculenta; and (2) displacement, microhabitat use, distribution, and aggregation in food-depleted habitats. Wave action, water temperature, and body size strongly affected the ability of urchins to consume kelp: individual feeding increased with increasing body size and temperature, while aggregative feeding decreased with increasing wave action. Yet, feeding in large urchins dropped by two orders of magnitude between 12 and 18°C. Increasing wave action triggered shifts in urchin displacement, microhabitat use, distribution, and aggregation: urchins reduced displacement and abandoned flat surfaces in favour of crevices. They increasingly formed two-dimensional aggregations at densities ≥110 individuals m⁻². Collectively, results provide a foundational understanding of some of the drivers of feeding and spatial dynamics of S. droebachiensis and potential impacts on the formation of grazing fronts.

Five times daily: the dynamics of prayer worship among Muslim immigrants in St. John's, NL

This thesis explores the ritual of prayer among Muslim immigrants in the city of St. John's, NL. Immigration across national, cultural, religious, and ethnic borders is a moment in an individual's life marked by significant change. My premise is that in such contexts the relatively conservative nature of religious ritual can supply much-needed continuity, comfort, and consolation for individuals living through the immigrant experience. As well, ritual forms are often put under stress when transferred to a considerably different place and cultural context, where “facts on the ground” may be obstacles to traditional and familiar ritual forms. Changes to the understanding or practice of ritual are common in new cultural and geographic situations, and ritual itself often becomes not merely a means of social identification and cohesion, but a practical tool in processing change - in the context of immigration, in learning to live in a new community. St. John's is a lively and historic city and while Muslim immigrants may be a small group within it they nevertheless contribute to the city's energy and atmosphere. This thesis endeavours to better understand the life stories of ten of these newcomers to St. John's, focusing on their religious backgrounds and lives. In particular, this thesis seeks to better understand the place of prayer in the immigrant experience.