Polluted water bodies have usually high abundance of plants like Nostoc and Oscillatoria. Give reasons

Some -cyanobacteria or blue-green algae like Nostoc and Oscillatoria can tolerate adverse conditions including pollutants very well, as compared to other aquatic plants. This is due to the presence of mucilage covering, resistant proteins and the absence of sap vacuoles. They release large quantity of spores, which are always remain present in air.