Using Paleolimnology to Reconstruct Past Environments of Lakes Affected by Direct Anthropogenic Activities
Diatoms , Environmental Change , Paleolimnology
Although the magnitude of recent anthropogenic environmental change is unprecedented, humans have been leaving measurable footprints on the landscape prior to the era of industrialization. This thesis examines the long-term impacts of human activities on aquatic ecosystem by using limnological and paleolimnological approaches to examine: 1) the long-term impacts of a small oil and gas operation located in the Cameron Hills, Northwest Territories, on local aquatic ecology; and 2) the impacts of a Dorset Palaeoeskimo settlement on a nearby lake at Port au Choix, Newfoundland. In the Cameron Hills, water samples and dated sediment cores were analyzed in order to assess modern-day as well as long-term impacts of oil and gas activities on aquatic ecosystems. Both modern water chemistry and paleolimnological records provided evidence of catchment disturbance and localized acidification in lakes more closely associated with the oil and gas operations. Nonetheless, changes recorded in the sediment record suggested that recent climate warming is the dominant driver of changes in these lakes. At Port au Choix, paleolimnology was used to examine changes in aquatic ecology related to Dorset Palaeosekimo sealskin processing activities and to assess changes in the environment that might have led to the abandonment of the site at ~1180 cal BP. Concurrent elevated periods in sedimentary δ15N and chlorophyll-a concentrations provided evidence of Dorset activities. In addition, changes in diatom assemblages were suggestive of ecological shifts related to nutrient additions, likely as a result of past seal processing activities. Analysis of nearby reference ponds provided no indication of changes in climate that might have resulted in site abandonment. Collectively, these studies demonstrate how paleolimnology can be used to increase our understanding of the impact of human activities on aquatic ecosystems in a variety of settings.