Changes in diatom assemblages since pre-industrial times in 40 reference lakes from the Experimental Lakes Area (northwestern Ontario,Canada) |
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Authors: | Mihaela D Enache Andrew M Paterson Brian F Cumming |
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Institution: | (1) Department of Biology, Paleoecological Environmental Assessment and Research Laboratory (PEARL), Queen’s University, Kingston, ON, K7L 3N6, Canada;(2) Ontario Ministry of the Environment, Dorset Environmental Science Centre, 1026 Bellwood Acres Road, P.O. Box 39, Dorset, ON, P0A 1EO, Canada;(3) Present address: The Academy of Natural Sciences, Patrick Center for Environmental Research, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103, USA |
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Abstract: | Diatom assemblages in recent versus pre-industrial sediments were examined in 40 relatively undisturbed lakes from the Experimental
Lakes Area (ELA). The ELA region of northwestern Ontario receives low amounts of acidic deposition and the lakes have been
minimally disturbed by watershed development or other human activities. Consequently, this region represents an important
location to detect possible changes in lakes due to climate change. In over half of the lakes, planktonic taxa (especially
Discostella stelligera) increased between 10 and 40% since pre-industrial times. Changes in diatom assemblages are consistent with taxa that would
benefit from enhanced stratification and a longer ice-free season. We hypothesized that there should be a relationship between
stratification and measured chemical and physical characteristics of the study lakes. Multiple correlation analysis was undertaken
to see the relationship between planktonic taxa and D. stelligera since pre-industrial times and the physical and chemical characteristics of the study lakes. Lake depth was consistently
identified as an important variable. The timing of the increase in planktonic taxa within cores from these lakes will be needed
to rule out other possible regional changes that may also be occurring in the ELA region. |
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