LATE LITTLE ICE AGE AND 20TH CENTURY DROUGHT HISTORY INFERRED FROM OSTRACODE DATA, KENOSEE LAKE, SASKATCHEWAN, CANADA

Ostracode assemblages from lake sediment cores are used to establish latest Holocene hydrologic variations at Kenosee Lake, a relatively large, hyposaline lake located in southeastern Saskatchewan, Canada. ²¹⁰Pb dating of extracted core material constrains the chronology of the core. Modern analog analyses of fossil ostracode assemblages indicate that recent water quality deterioration is due to the recurrence of common regional environmental conditions and signals a return to lower regional mean annual precipitation. Collected ostracode data indicate that as the Little Ice Age closed, 1890 - 1900, this region received higher precipitation than that experienced during the early 20^th century. Further, sediments dated between the years 1970 - 1978 record the freshest water conditions indicated during the most recent 150-year period. The ostracode assemblages, collected from a Kenosee Lake short core, contain the same faunal elements as those found in a Holocene record of this lake (Vance et al., 1997) and include Candona rawsoni, Candona ohioensis, Candona candida, and Limnocythere ceriotuberosa. The abundance of C. ohioensis and C. candida, found in samples dated 1950 to 1978, indicates freshening of the lake attributable to periods of high annual precipitation. Samples dominated by C. rawsoni and L. ceriotuberosa are the most common fossil ostracode assemblage prior to 1950, and indicate periods of higher salinity, fluctuating lake levels, and lower annual precipitation. Previous studies of Kenosee Lake dynamics have established long-term susceptibility of the northern Great Plains region water resources to periodic climate change. In- depth study of collected short core data allows clearer definition of decadal scale short-term climate controlled water quality fluctuations from the Little Ice Age to present.