Hydrogen-Peroxide As A Potential Algicide For Oscillatoria-Rubescens Dc

The algicidal properties of hydrogen peroxide (H 2 O 2 ) for Oscillatoria rubescens were evaluated at different concentrations between 0 and 7 ppm. The toxicity threshold, under laboratory conditions, was about 1.75 ppm depending on culture density. Higher concentrations of H 2 O 2 destroyed more than 90% of biliproteins and carotenoids and nearly 50% of chlorophyll, whereas they had no noticeable effect on Pandorina morum , a chlorophyte tested for comparison. This differential sensitivity is discussed on the basis of chemical and physical pigment fragility. Mixed continuous culture experiments suggest a possible shift from blue-greens to volvocales following the use of H 2 O 2 as an algicide.