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SEASONAL CHARACTERIZATION OF DIATOMS IN THE LORD LINDSAY RIVER, BOOTHIA PENINSULA, NUNAVUT

STEWART, KAILEY A  Queen's University.
Lamoureux, Scott F  Queen's University.

The purpose of this study was to characterize the diatom assemblage of a large middle arctic river in order to examine the potential for enhancing interpretations of the lake sedimentary record. The ability to isolate species that show a strong affinity for the lotic environment presents an opportunity to interpret stratigraphic changes in these species in terms of past hydrological change. Significantly higher relative abundances of Achnanthes minutissima Kützing, Fragilaria capucina Lange-Bertalot, Diatoma tenuis Agardh, and Cymbella arctica (Lagerstedt) Schmidt, C. minuta Hilse, C. silesiaca Bleisch and C. fogedii Hĺkansson in the lotic environment throughout the 2001 growing season compared to the sedimentary record suggest that these species characterize the Lord Lindsay River diatom assemblage. Comparison of seasonal abundances of these taxa to hydrological parameters including river discharge, electrical conductivity, and water temperature reveal key information about the character of this community. The fact that the lotic assemblage changes very little throughout the sampling period, despite major changes in hydrological conditions, suggests a high degree of resiliency and inherent structure in the community. However, a decrease in diatom productivity in response to rapid and dramatic changes in hydrological conditions following a major rain event suggests that a threshold tolerance may exist, with potentially important implications for interpreting changes in the paleoenvironmental record. Stratigraphic changes of the lotic assemblage in the sedimentary record track changes in mean varve thickness and suggest that these species may be used to infer past hydrological and ecological conditions in the Lord Lindsay River.


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