Sedimentary chrysophycean cyst assemblages as paleoindicators in acid sensitive lakes

Abstract

Relationships between surface sediment cyst assemblages and lakewater characteristics were studies in 50 lakes located in central Ontario. The main purposes of the study were to identify the environmental factors most strongly controlling the distribution of chrysophycean cysts and to develop indices and equations to infer lake water pH from cyst assemblages. Principal components analysis indicates that alkalinity and associated TDS as well as elements related to trophic status are the factors most strongly correlated with the distribution of chrysophycean cysts. There are significant differences in the relative importance of these factors among the lakes. The transfer functions developed provide good prediction of pH values. This report also provides a descriptive analysis of the ‘fossil’ chrysophycean cyst flora of Ontario lakes. The descriptions include representative SEM micrographs and detailed characterization of each morphotype in consideration of the morphological variation observed among specimens of the same morphotype. Special attention has been paid to the anatomy of the collar complex and to the nature of the cyst surface ornamentation. One hundred and thirty seven morphotypes are described.