The microalga Euglena was selected as a bioindicator
for determining genotoxicity potencies of organic
pollutants in Meiliang Bay of Taihu Lake, Jiangsu, China
among seasons in 2008. Several methods, including the
comet assay to determine breaks in DNA and quantification
of antioxidant enzymes were applied to characterize
genotoxic effects of organic extracts of water from Taihu
Lake on the flagellated, microalga Euglena gracilis. Contents
of photosynthetic pigments, including Chl a, Chl
b and carotenoid pigments were inversely proportion to
concentrations of organic extracts to which E. gracilis was
exposed. Organic extracts of Taihu Lake water also
affected activities of superoxide dismutase (SOD) and
peroxidase (POD) of E. gracilis. There were no statistically
significant differences in SOD activities among seasons
except in June but significant differences in POD activities
were observed among all seasons. The metrics of DNA
fragmentation in the alkaline unwinding assay