The ratio of diatom frustules to chrysophycean statospores: A useful paleolimnological index

Stratigraphic analyses of the postglacial sediments of Little Round Lake and the recent sediments of two additional southern Ontario lakes were used to compare the relative abundance of fossil diatom frustules to chrysophycean statospores. Relatively few statospores were recorded during eutrophic phases in the lakes' histories such as during periods of anthropogenic activity in the lakes' catch me nt, when diatom frustules were abundant. The increased relative abundance of statospores during the early postglacial in Little Round Lake was attributed to both oligotrophy and a short growing season, conditions that currently exist in many high arctic lakes. From these data it is seen that the ratio of fossil diatom frustules to chrysophycean statospores may provide a useful paleolimnological index of trophic status in temperate lakes. The advantages of this index include its simplicity, the fact that frustules and statospores can be enumerated from the same microscope slides, and that the ratio is independent of sedimentation rates.