Abstract: After many years purification,the concentration of heavy metals in a Typha purification pond are decreased and water quality is improved. The species and biomass of algae,bacteria and aquatic animals are increased correspondingly. Only a species of algae,Nitzschia sp.,can survive in the area with higher concentration ofheavy metals(e.g. in a shallow influent area), and most algae are existed in the area with lower concentration of heavy metals and deeper water, among which. Nitzschia and Phormidium are the dominant groups and have greater resistance to Pb-Zn pollution. They can to selected out for purifying Pb-Zn sewage.

Key words: Caenorhabditis elegans, selfing, hybridization, heat stress.