Diatom-inferred pH calibration of lakes near Wawa, Ontario

Abstract

In the absence of long-term pH records for lakes, sedimentary diatoms have often been used to detect the extent of recent lake acidification. Although various methods have been used to relate surface-sediment diatom remains to contemporary lake-water pH, their usefulness and selection criteria have not been clearly defined for Canadian lakes. Surface-sediment diatoms of 28 lakes (pH 4.0–8.13) located northeast of Lake Superior were identified and enumerated. Lake-water pH estimates were made using multiple regression analyses of selected diatom taxa and Hustedt's pH indicator groups, as well as by index α and index B. Multiple regression, using the abundance of pH indicator assemblages, appears to be the most suitable method for the studied lake region. Discrepancies associated with other methods are discussed in details.