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dc.contributor.authorRajaratnam, Thiyakeen
dc.date2009-09-10 15:18:07.01
dc.date.accessioned2009-09-10T21:41:54Z
dc.date.available2009-09-10T21:41:54Z
dc.date.issued2009-09-10T21:41:54Z
dc.identifier.urihttp://hdl.handle.net/1974/5146
dc.descriptionThesis (Master, Biology) -- Queen's University, 2009-09-10 15:18:07.01en
dc.description.abstractThe current study developed a paleolimnological approach to assess changes in diatom assemblages (class Bacillariophyceae) from present-day lake sediments in comparison to those deposited before significant human impact (ca. pre-1850) from 51 Halifax (Nova Scotia, Canada) region lakes in conjunction with a regional diatom-based transfer functions for pH and total phosphorus. All 51 lakes showed changes in diatom assemblages between the present-day and pre-industrial assemblages that was greater than would be expected (i.e. similarity between ‘top’ and ‘bottom’ samples was much less than the similarities within triplicate ‘top’ and ‘bottom’ samples). To help identify the most important environmental stressors impacting diatom assemblages in these lakes, diatom-based reconstructions of inferred changes in pH (DI-pH) and total phosphorus (DI-TP) that were greater than the Root Mean Squared Error (RMSE) of the respective inference models were reconstructed for each of the 51 lakes. For example, a decrease in DI-pH greater than the RMSE of the pH model would be a strong indication of recent acidification, whereas an increase in DI-TP greater than the RMSE of the model indicates nutrient enrichment. Based on this approach, 4% of the lakes are showing acidification-related trends occurring in lakes with low pre-industrial pH values and relatively undisturbed watersheds. Almost 14% of the study lakes have been impacted by nutrients and characterized by watershed development and high concentrations of TP. Approximately 4% of lakes showed oligotrophication and acidification. Diatom assemblages from almost 20% of the study lakes that were relatively unimpacted by the afore-listed environmental stressors show trends consistent with climate warming. These lakes show an increase in DI-pH greater than the RMSE of the inference model, and floristic changes typically showed a decrease in the relative abundance of Aulacoseira distans paralleled with increase in Cyclotella stelligera and other planktonic diatoms in the modern sediments. In addition, Diatoma tenue and Diploneis parma, diatoms tolerant of high conductivity, increased in 45% of the study lakes suggesting road salt as an additional stressor. This thesis provides a rapid paleolimnological-based technique to assess regional water-quality changes, and further demonstrates the complexity of ecological changes within freshwater resources.en
dc.format.extent1528462 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectDiatomsen
dc.subjectAcidificationen
dc.subjectNutrient Enrichmenten
dc.subjectClimate Changeen
dc.subjectUrban Developmenten
dc.subjectHalifaxen
dc.subjectNova Scotiaen
dc.subjectPaleolimnologyen
dc.subjectMultiple-Stressorsen
dc.titleAssessment of Long-Term Changes in Water Quality from Halifax Region Lakes (Nova Scotia, Canada) Using Paleolimnological Techniquesen
dc.typethesisen
dc.description.degreeM.Sc.en
dc.contributor.supervisorSmol, John P.en
dc.contributor.supervisorCumming, Brian F.en
dc.contributor.departmentBiologyen
dc.degree.grantorQueen's University at Kingstonen


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