Relationship between phytoplankton and environmental factors in Dajinzhong reservoir of Guangzhou

Carrying out 5 sampling tests for Dajinzhong reservoir after one year operation and maintenance,the temporal and spatial variation of phytoplankton in the reservoir was studied after remediation,the relationship between the variations of phytoplankton and environment factors was also analyzed by using the correlation coefficient method.The results illustrated that when the water temperature fell the biomass of warm-preferred cyanophytes reduced drastically and showed significant positive correlation with temperature(r=0.986,p0.05),while the other kinds of algae increased and were no longer restrained by cyanophytes,especially the diatom and chlorella,which took place of cyanophytes becoming the dominant species.The increase in concentration of organics promoted phytoplankton growth.The diatom and chlorella had significant positive correlation with COD and BOD5,and the correlation coefficient was between 0.6 and 0.9.The cyanophytes had negative correlation with COD and BOD5 because of the early blue-algal bloom.As the concentration of TN and TP were too high in the reservoir,which were no longer the limiting factors for phytoplankton growth,the phytoplankton biomass had insignificant negative correlation with TN and TP,and the correlation coefficient was-0.532 and-0.557 respectively.Along with the decrease of phytoplankton biomass,the oxygen consumption reduced and the concentration of DO increased.