Effects of elevated CO2(5000 ?滋l/L) on sensitivity comparison of six species of algae and interspecific competition of three species of algae were in vestigated. The results showed that, the cell densities of six species of algae grown in elevated CO2 significantly increased compared to those in ambient CO2(3 60 ?滋l/L), and with the time prolonged, the increasing extent increased. Theref ore, elevated CO2 can promote the growth of six species of algae. However, there were differences in sensitivity between six species of algae. Based on the effe cts of elevated CO2 on biomass, the sensitive order(from high to low) was Platym anas sp., Platymanas subcordiformis, Nitzschia closterium, Isochrysis galbana Pa rke 8701, Dunaliella salina, Chlorella sp., on the condition of solitary cultiva tion. Compared to ambient CO2, elevated CO2 promoted the growth of three species of algae, Platymanas subcordiformis, Nitzschia closterium and Isochrysis galban a Parke 8701 under the condition of mixed cultivation. The sensitivity of the th ree species to elevated CO2 in mixed cultivation changed a lot compared to the c ondition of solitary cultivation. When grown in elevated CO2 under the condition of mixed cultivation, the sensitive order from high to low were Nitzschia clost ertium, Platymonas subcordiformis and Isochrysis galbana Parke 8701. However, un der the condition of solitary cultivation, the sensitive order in elevated CO2 w as Isochrysis galbana Parke 8701, Nitzschia clostertium, Platymonas subcordiform is, from sensitive to less sensitive. On the day 21, the dominant algae, the sub -dominant algae and inferior algae grown in elevated CO2 did not change. However , the population increasing dynamic and composition proportion of three algal sp ecies have significantly changed.
