Aquatic Sciences Meeting, Albuquerque 2001

PC18 Biogeochemical Cycles

Date: Thursday, February 15, 2001

Location: Southwest Hall

Kasian, S, E, Freshwater Institute, Winnipeg, Canada, kasians@dfo-mpo.gc.ca

Stainton, M, P, Freshwater Institute, Winnipeg, Canada, staintonm@dfo-mpo.gc.ca

Hesslein, R, H, Freshwater Institute, Winnipeg, Canada, hessleinr@dfo-mpo.gc.ca

THREE DECADES OF VARIATION IN CHEMISTRY OF 17 PRISTINE BOREAL SHIELD LAKES: IMPLICATIONS FOR DETECTING CLIMATE CHANGE

The long-term ecological research program at the Experimental Lakes Area provides a unique opportunity to investigate natural spatial and temporal variability over decadal time scales in pristine lakes of the Canadian Boreal Shield. Chemistry analyses were available for 17 unmanipulated lakes, streams, and precipitation. Lakes and streams were sampled at least monthly for periods of 7 to 30 years. Lakes vary in surface area (4-56 ha), in depth (4-33 m), and in ratio of surface to drainage areas (3-626). All share common geography, geology and climate. Total variances of epilimnetic concentrations of 21 chemical constituents (nutrients, anions, cations, chlorophyll, DOC, pH) are examined and partitioned into 4 major components. Relative magnitudes of lake-to-lake, year-to-year, lake-year interaction, and seasonal variances are related to lake area and depth, watershed area and flushing rate. Finally, we test our ability to predict lake masses of selected constituents using only precipitation and stream loadings and physiogeographic features of the lakes. Results have implications for designing monitoring programs, assessing experimental manipulations and detecting trends due to climate change.

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Aquatic Sciences Meeting, Albuquerque 2001

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