LE3 .A278 2018

2018

Spooner, Ian
Mallory, Mark

Acadia University

Master of Science

Masters

Biology

Biology

In Atlantic Canada, historical logging practices and watershed development for hydroelectric power generation has significantly altered flow dynamics, stream and sediment biogeochemistry, and seasonal discharge in forested upland rivers. In this study, the paleolimnological method was used to determine the immediate and legacy impacts of these practices on sedimentation rate, particle size, organic fraction, and bulk geochemistry, on a fluvial lake along the West Branch of the Avon River, Nova Scotia. Sediment cores were obtained in May of 2015 and either extruded and sliced on-site or frozen and split to reveal comparative stratigraphy. Extruded sediment was analyzed by XRF, particle size analysis, and loss on ignition. Chronological constraints (210Pb and 14C) and stable isotope (13C and 15N) data were obtained by outside laboratories. Quantitative data were analyzed in conjunction with historical records and local ecological accounts to create a chronology of disturbance in the area. This research determined that:[1] fluvial lake sediments can provide an effective archive of watershed disturbance when coupled with historical records; [2] historical logging produced significant short-term unconformities in the sediment record, increased allochthonous contaminant load, and altered redox chemistry; [3] damming decreased the clastic fraction and particle size of sediment, reduced system energy and dissolved oxygen, altered redox conditions, and initiated biological regime shifts; [4] concentrations of all metals, except lead, decreased post-damming, despite increased adsorbsion and complexation characteristics of the system, indicating a significant loss of geogenic input due to watershed reduction; and [5] the sedimentary strontium record seems to reflect logging and damming disruptions in anadromous fish visitation.

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https://scholar.acadiau.ca/islandora/object/theses:3229