Figure 1From: Stability of toxin gene proportion in red-pigmented populations of the cyanobacterium Planktothrix during 29 years of re-oligotrophication of Lake ZürichHistory of phytoplankton and total phosphorus concentrations between 1980 and 2008. (A) Annual mean ± SE biovolume of total phytoplankton, Planktothrix and concentration of total phosphorus in Lake Zürich from 1980 to 2008. Biovolume in mm3 L-1, determined by microscopic counting, total phosphorus in μg L-1. (B) Annual mean ± SE percentage of Planktothrix and chlorophyta out of total phytoplankton.Back to article page