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.

Student Independent Projects Environmental Studies 2011: The Humber River Basin Human Values Project: Designing a Sampling Strategy for a Pilot Survey in the Corner Brook Area

Sustainability can be indicated by a number of factors. Populations need to be aged evenly, ensuring a healthy equilibrium. Job opportunities must be numerous and of wide varieties to balance incomes from different employment sectors. Regions must also sustain vital natural resources in the area which are directly related to a place being self-sustaining. These indicators prove to be true, especially in Newfoundland, where people have struggled to remain in the small traditional communities that they consider being there 'home.' The population of Corner Brook and the surrounding areas can be stratified according to the values people hold to their special place. Even though people in western Newfoundland hold strong ties to their home, some parts of the region even though people in western Newfoundland hold strong ties to their home, some parts of the region struggle with employment, low incomes, out-migration, and dependency on declining natural resources. The aim of this paper is to present the process of designing a sample strategy for a human values pilot survey conducted in the city of Corner Brook. It will present a theoretical background over the period 2002-2006 to be used for sampling strategy.

Toxic Legacies, Slow Violence, and Environmental Injustice at Giant Mine, Northwest Territories

For fifty years (1949–99) the now-abandoned Giant Mine in Yellowknife emitted arsenic air and water pollution into the surrounding environment. Arsenic pollution from Giant Mine had particularly acute health impacts on the nearby Yellowknives Dene First Nation (YKDFN), who were reliant on local lakes, rivers, and streams for their drinking water, in addition to frequent use of local berries, garden produce, and medicine plants. Currently, the Canadian government is undertaking a remediation project at Giant Mine to clean up contaminated soils and tailings on the surface and contain 237,000 tonnes of arsenic dust that are stored underground at the Giant Mine. Using documentary sources and statements of Yellowknives Dene members before various public hearings on the arsenic issue, this paper examines the history of arsenic pollution at Giant Mine as a form of “slow violence,” a concept that reconfigures the arsenic issue not simply as a technical problem, but as a historical agent of colonial dispossession that alienated an Indigenous group from their traditional territory. The long-term storage of arsenic at the former mine site means the effects of this slow violence are not merely historical, but extend to the potentially far distant future.