氮磷比率对两种蓝藻和两种绿藻生长的影响

Effect of nitrogen and phosphorus ratios on the growth of cyanobacteria and chlorophyta

基于千岛湖2009-2010年春夏硅藻不占优势,蓝藻和绿藻发生相互演替的现象,选取千岛湖两种优势蓝藻和两种优势绿藻进行室内生态实验来比较氮磷比对于蓝藻和绿藻生长的影响,得到的主要结果如下:室内条件下,以BG-11培养基为基础设置了5组氮磷比(原子比:N/P=76.77、N/P=307.06、N/P=153.53、N/P=15.35、N/P=3.84)的培养液,研究氮磷比变化对两种蓝藻(水华微囊藻Microcystis flos-aquae和蓝纤维藻Dactylococcopsis sp.)和两种绿藻(小球藻Chlorella sp.和四尾栅藻Scenedesmus quadricauda)的影响,利用logistic生长方程描述四种藻生长曲线且拟合度均较高,水华微囊藻和四尾栅藻随着氮磷比的降低,最大生物量K值和内禀增长率r值均升高,蓝纤维藻则在接近于Redfield比值的培养基中r值最高,小球藻在接近于或低于Redfield比值的培养基中出现暴发性增殖。水华微囊藻在高氮磷比组(N/P=307.06和N/P=153.53)实验结束时藻体累积的总氮含量显著低于其他组(P<0.05),四尾栅藻低氮磷比组(N/P=3.84)单细胞氮含量也显著低于其他各组(P<0.05),四种藻类藻体中总磷的变化则是随着氮磷比的降低而显著升高(P<0.05)。

Planktonic algae have the considerable periodicity in species composition and abundance, and this seasonal succession pattern is the important characteristic of algae fluctuations. The mechanisms by which environmental factors affect algae succession are complex. Besides, algae succession varies in lakes or reservoirs of different limnological features and trophic state. Although hypotheses of algae succession have been stated in some researches, there is uncertainity for specific lake and specific species. Based on planktonic algae succession in Qiandao Lake during 2009 - 2010, the effect of nitrogen and phosphorus ratitos on the growth of cyanobacteria and chlorophyta under the laboratory conditions is studied in order to further verify the impact of nutrients on the succession pattern. The main results and conclusions are as follows ： Under the laboratory conditions, we set five N/P ratio treating groups （ N/P = 307.06, N/P = 153.53, N/P -76.77, N/P = 15.35 and N/P = 3.84） based on the BG-11 cultures to explore the effects of different N/P ratio on blue-green algae （Microcystis flos-aquae, Dactylococcopsis sp. ） and chlorophyta （Chlorella sp., Scenedesmus quadricauda） growth. The results indicated that the logistic model can well describe the growth of four kinds of algae. Microcystisflos-aquae grew better with the decrease of N/P ratio （ the maximum biomass K and the specific growth rate r increased significantly）. Scenedesmus quadricauda had the higher value of K and r with the increase of N/P ratio. Dactylococcopsis sp. favored the relative high N/P ratio cultures and the highest value of r at N/P - 15.35 group which was close to Redfield ratio. ChloreUa sp. presented algal bloom in N/P - 15.35 and N/P = 3.84 groups. At the end of the experiment, the accumulated TN concentration of Microcystis flos-aquae was the significantly lower in N/P = 307.06 and N/P = 153.53 groups than that in others （P 〈 O. 05 ） , Scenedesmus quadricauda had the lower TN concentration per cell in N/P = 3.8d group than that in others （P 〈 0.05）. TP concentration per cell in four kinds of algal body significantly increased with the decrease of N/P ratio （P 〈 0.05）.