Surface-sediment chrysophytes from 35 Quebec lakes and their usefulness in reconstructing lake-water pH

Abstract

Chrysophyte scales from surface sediment samples of 35 Quebec lakes were analyzed to examine their relationship with lake-water pH. The percent composition of common chrysophyte taxa were plotted against the measured lake-water pH. The distribution of many taxa was found to be closely associated with pH. The pH indicator status and abundance-weighted mean pH values of the majority of taxa of the studied region agreed with the published work. Chrysophyte counts were quantified to establish a predictive pH model using multiple regressions of pH indicator chrysophyte assemblages with lake-water pH. A strong relationship (r2 = 0.72) was observed between measured and inferred pH values. The pH predictive ability of chrysophytes was further corroborated by reconstructing the recent pH history of Lake Bonneville. Over the last 30 years, the inferred pH of this lake has declined ≈ 1 pH unit. The present study accentuates that stratigraphic analysis of chrysophytes will provide useful measurements of the extent of lake-water acidity in Quebec.