The most typical phytoplankton taxa in four types of boreal lakes

The monitoring of phytoplankton quantities and species composition in Finnish lakes started in the early 1960s. In addition, a substantial number of physical and chemical variables have been measured and recorded from the monitored lakes. The purpose of the present evaluation is to differentiate the phytoplankton taxa of the lakes being classified as acidic, oligotrophic, dystrophic and eutrophic. At present, these four lake types are differentiated on the bases of concentration of total phosphorus (µg l-1), water colour (mg l-1 Pt), and Secchi-disc transparency. A total of 38 lakes with 163 samples from the years 1984 to 1994 were selected for this study.