Inferring the specific conductivity of lake water with scaled chrysophytes

Abstract

Siliceous scale‐bearing chrysophytes have been used successfully in reconstructing the historical pH of lake water. In addition to pH, the distributions of many taxa of scaled chrysophytes are also significantly correlated with the concentration of dissolved salt. A model (r2 of 0.87), based on scaled chrysophytes, was developed with weighted averaging regression to infer the specific conductivity of lake water. The model was applied downcore in a small soft‐water lake in Connecticut whose inferred pH had remained between 6.2 and 6.5 for the past 170 yr. Despite the relatively stable pH, the inferred specific conductivity had more than tripled since the turn of the century. The rise in the salt level of the lake water correlated with known changes in the watershed, including the building of lakeside cottages and establishment of a surface silica mine.