Relationship between Chrysophyte Assemblages and Environmental Variables in Seventy-Two Sudbury Lakes as Examined by Canonical Correspondence Analysis (CCA)

Abstract

Relationship between surface sediment chrysophyte scales and limnological variables in 72 Sudbury lakes was examined using canonical correspondence analysis (CCA). CCA is a recently developed multivariate direct gradient analysis that has many advantages over indirect gradient analyses. Lakewater pH was identified as the most important variable influencing the distribution of scaled chrysophytes in Sudbury lakes. Almost all common chrysophyte taxa can be assigned a pH indicator value. In addition to pH, many chrysophyte taxa are sensitive to metal concentrations. A calibration model was developed to predict chrysophyte inferred pH using CCA. The model proved to be far superior to traditionally used models derived from multiple regression of pH indicator chyrsophyte assemblages. Applicability of the predictive pH equation was examined by reconstructing the recent pH history of Lohi Lake. The study provides compelling evidence that canonical correspondence analysis offers great promise in surface sediment calibration and pH reconstruction studies.