Forecasting cyanobacteria dominance in Canadian temperate lakes.

Predictive models based on broad scale, spatial surveys typically identify nutrients and climate as the most important predictors of cyanobacteria abundance; however these models generally have low predictive power because at smaller geographic scales numerous other factors may be equally or more important. At the lake level, for example, the ability to forecast cyanobacteria dominance is of tremendous value to lake managers as they can use such models to communicate exposure risks associated with recreational and drinking water use, and possible exposure to algal toxins, in advance of bloom occurrence. We used detailed algal, limnological and meteorological data from two temperate lakes in south-central Ontario, Canada to determine the factors that are closely linked to cyanobacteria dominance, and to develop easy to use models to forecast cyanobacteria biovolume.

UVR sensitivity of Chaoborus larvae.

In small temperate lakes, predation by fish generally regulates the species structure and abundance of larval Chaoborus. Yet, Chaoborus abundance may also vary appreciably among lakes with no fish. Many fishless lakes in Sudbury, Ontario, have transparent waters.