Nutrients enrichment and algal response based on <i>in situ</i> experiments of NEB in summer:a comparative study of Lakes Dianshan, Xiaoxingkai and Erhai

Abstract

淀山湖、小兴凯湖和洱海分别处在不同的营养阶段,夏季都存在蓝藻水华现象,有效控制蓝藻水华应控氮还是控磷一直存在争议.本研究采用营养物加富生物测试的试验方法,研究和比较三个湖泊限制性营养元素(N和P)夏季对浮游藻类生长的刺激作用,并采用多因素方差分析和两两比较方法(LSD)检验试验结果的显著性.结果表明:淀山湖(TN/TP=10左右)、洱海(TN/TP=29左右)、小兴凯湖(TN/TP=9左右)在夏季分别表现出显著的氮响应、氮磷双重响应、氮响应;较低氮磷比的营养程度较高的湖泊(淀山湖和小兴凯湖)夏季应控制氮含量,若添加氮更容易引发蓝藻(微囊藻)水华,而高氮磷比的初期富营养化湖泊(洱海)夏季应同时控制氮磷含量,同时添加氮磷的交互作用容易引发蓝藻(微囊藻)水华.;Lakes Dianshan, Xiaoxingkai and Erhai represent different trophic status respectively, and each of them is suffering severe cyanobacteria blooms in summer. Nutrient enrichment bioassays were conducted in the fields to compare the effects of nutrients (N and P) on cyanobacteria growth in the three lakes in summer. Significant differences between/among the treatments of the experiments were tested by Univariate and LSD. The results showed that Lakes Dianshan, Erhai and Xiaoxingkai have significant responses to N, N and P, N in summer, and add N to the Lake Dianshan and Lake Xiaoxingkai with low N:P ratio which may cause cyanobacteria(Microcystis) blooms easily, while N and P interaction may induce cyanobacteria bloom in lake(Lake Erhai) with high N:P ratio.