受多种因素影响，滇池外海北部水域为蓝藻富集区。调查研究了蓝藻生物量季节性变动规律，对区域原水（不过滤）和净水（过滤了藻类）中N和P含量的变化也进行了监测。目的是研究蓝藻季节性消长对水体N和P含量的影响。结合生态化学计量学理论和方法，分析两者之间的关系。研究表明， 4—11月，为蓝藻水华爆发的时段，其中以5—9月最为严重。通过分析，水体N和P随蓝藻生物量呈现相应变动规律，水体叶绿素和TN，TP之间都呈现正相关关系，相关系数分别为0.955 和0.952 。利用生态化学计量学分析，蓝藻和水体中N∶P比值没有固定性，表明蓝藻没有表现出强烈的化学计量特征，而蓝藻的季节性变动也没有导致本区域水体具化学计量特性。通过分析滇池水体N∶P比值与蓝藻生物量变化之间相关关系,相关系数为-0.308，表明富营养化水体中N∶P比率对蓝藻生物量直接影响不大。因此,只有通过降低水体中N和P的浓度，才能控制蓝藻的爆发。

For several reasons, the north area of the Dianchi Lake is prolific of blue-green alga. In this paper, the dynamic biomass of alga was investigated. Both of the concentrations of N and P in original water and in filtered water were also be monitored. The aim of the study is to figure out the alga's influence on the concentrations of N and P in the water, and to analyze the relationship between them by using the method of ecological stoichiometry. It is disclosed that from April to November is the main stage of alga blooming. Especially, alga blooms seriously and is uncontrolled from May to September. By data analysis, we find that the concentrations of N and P vary conforming to the dynamic of the biomass of alga, and there is positive correlation-ship between them. The correlation coefficient between the concentrations of N in water and alga's biomass is 0.955, between the concentrations of P in water and alga's biomass is 0.952. By taken the method of stoichiometry analysis, we find both the N∶P ratios of alga and water are not constant, and both of them have no significant ecological stoichiometry of the N∶P ratio. We also made correlation-ship analysis between the N∶P ratio of water and biomass of alga. The correlation-ship between them is 0.308, which illustrats that the biomass of alga is not related to the N∶P ratio of water. Thus we can declare that there is only one most efficient way to control blue-green alga booming, to reduce the concentration of N and P in water of eutrophic lakes.