Chlorophyll b was shown to be comparatively less affected by
detergent stress, and a significant decrease was observed at concentrations of 0.5% or above. However,
there was no prominent decrease in per cell (Euglena) concentration of any pigment. It can be concluded
that photosynthesis and light-harvesting pigments in E. gracilis were sensitive to detergent stress and can
be used as sensitive parameters in toxicity assessment of detergents in aquatic environments.