CGRG Bibliography of Canadian Geomorphology
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Author : Hall, R.I.; Leavitt, P.R.; Dixit, A.S.; Quinlan, R.; and Smol, J.P.
Date : 1999
Title : Limnological succession in reservoirs: a paleolimnological comparison of two methods of reservoir formation.
Publication : Canadian Journal of Fisheries and Aquatic Sciences
Issue : 59(6):
Page(s) : 1109-1121
Abstract
Analysis of diatoms, algal pigments, and chironomids in sediment cores from two otherwise similar prairie reservoirs demonstrated that differences in reservoir formation (river valley impoundment versus lake inundation) and hydrological regime (variable versus stable water level) resulted in distinct patterns of aquatic community change. Lake Diefenbaker, a 500-km2 reservoir created by damming the South Saskatchewan River in 1968, experiences water level fluctuations of 6 mˇyear-1. In contrast, impoundment of Buffalo Pound Lake in 1952 flooded a natural lake, raised mean water levels ca.2.0 m, and reduced water level fluctuations from ca.3 to <1 mˇyear-1. Comparison of fossil records showed that reservoir formation did not inevitably lead to eutrophication. Lake Diefenbaker exhibited typical reservoir ontogeny with three trophic periods, including an initial ca.4-year period of eutrophy, a decade of mesotrophy, and a gradual shift to modern productive conditions. Planktonic taxa dominated diatom communities at all times, whereas benthic chironomid and algal remains were rare. In contrast, pigment analyses suggested that phytoplankton standing crops declined after impoundment in Buffalo Pound Lake but that chironomid and macrophyte populations expanded. Such site specificity in trophic development appears to result from differences in the extent of inundation (500 versus ca.5 km2) and the magnitude of subsequent water level fluctuations (6.3 versus <1 m).
Bibliography of Canadian Geomorphology