SS3.09 Climate-Lake Interactions
Date: Wednesday, June 12, 2002
Time: 2:45:00 PM
Location: Colwood
 
RuhlandKM, Queen's University, Kingston, Canada, 3kmr5@biology.queensu.ca
Smol, J, P, Queen's University, Kingston, Canada, smolj@biology.queensu.ca
Priesnitz, A, , Queen's University, Kingston, Canada, run@yahoo.com
 
CENTURY SCALE ENVIRONMENTAL CHANGES IN A SUITE OF LAKES ACROSS CANADIAN ARCTIC TREELINE
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Changes in the diatom assemblage composition between present-day and pre-industrial times were analyzed in a 50-lake paleolimnological study in the Canadian Arctic treeline region. The most apparent change observed was a shift towards higher relative abundances of planktonic, Cyclotella taxa (especially C. stelligera) in modern sediments from a more benthic assemblage consisting of higher relative abundances of small, Fragilaria taxa in the bottom sediments. Increases in Cyclotella taxa were more common in deeper lakes (> 6 meters). Several downcore studies from lakes in this region record distinct changes in the upper sediments (ca. mid-1800s, estimated 210Pb dates). Diatom assemblages were relatively stable, with low diversity throughout the earlier sediments of these lakes shifting, to a more complex and diverse diatom assemblage marked by increases in planktonic diatoms (most notably Cyclotella stelligera). Limnological effects as a result of climatic warming, including a shorter duration of ice cover, longer growing season and longer, more stable thermal stratification are thought to be important factors that would provide more favorable conditions for planktonic diatom expansion in these studies.