大水面控养条件下水葫芦与浮游藻类间的相互作用

Interaction between Eichhornia crassipe and Phytoplankton under Large Water Surface Controlled Growth of Eichhornia crassipe

在滇池外海北岸重污染水域的0.25 km2封闭性蓝藻治理试验示范区内控养水葫芦(Eichhornia crassipe),通过鉴定与计数水体浮游藻类及监测水葫芦生理指标的变化,研究大水面控养条件下水葫芦与浮游藻类间的相互作用。6月底按9.30kg·m^(-2)投放水葫芦种苗,12月底进行采收,水葫芦控养面积为2.51 hm2。结果显示,该水域共鉴定出浮游藻类隶属7门46种(属),控养水葫芦未显著影响浮游藻类群落结构;水葫芦控养区浮游藻类生物量高于对照区,控养区浮游藻类最大生物量为1.76×109 cells·L-1,是对照区的2.2倍;蓝藻门生物量占浮游藻类总生物量的88.0%以上,且以微囊藻为优势种群,控养区微囊藻生物量高达1.75×109 cells·L-1,是对照区的2.4倍;水葫芦根系对浮游藻类具有明显吸附作用,吸附的微囊藻最大生物量为1.67×109 cells·m^(-2)。吸附于水葫芦根系的高浓度浮游藻类未影响植株株高、根长、生物量的变化,对根系活力与叶片生理变化影响也较小,平均根系表面积和活跃面积分别为0.62和0.28 m2·g-1,平均叶片可溶性糖和可溶蛋白质分别为2.81和0.15 mg·g-1。综上分析,控养水葫芦改变浮游藻类空间分布特征,将其有效吸附滞留于控养区,防止其随风布满湖面;水葫芦根系吸附的高浓度浮游藻类未影响水葫芦正常生长。

In order to discuss the interaction between phytoplankton andEichhornia crassipeunder large water surface controlled condition, phytoplankton were indentified and counted, and the physiological changes ofE. crassipe were investigated in cyanoabacterial governance zone, an enclosed area （0.25 km2）, nearby north shore of Wai hai, Dianchi Lake. 9.30 kg·m-2 E. crassipe seedlings were planted with covering area of 2.51 hm2 at the end of June and harvested at the end of December. Results showed that 46 species of phytoplankton belonging to 7 genera were identified in the water area; the confined growth ofE. crassipehad no significant effects on the structure of the phytoplankton. The biomass of phytoplankton was higher in the region withE. crassipe than the area withoutE. crassipe, and the maximum biomass of phytoplankton in the region withE. crassipe was 1.76×10^9 cells·L-1, which was 2.2 times higher than the area withoutE. crassipe.Cyanobacteral biomass was more than 88.0% of the total phytoplankton biomass, andMicrocystiswas shown as the dominant species in the water area. The maximum biomass ofMicrocystis in the region withE. crassipe was 1.75×10^9 cells·L-1, which was 2.4 times higher than the area withoutE. crassipe. Considerable Microcystis were absorbed byE.crassipe root-mats, which the maximum biomass ofMicrocystis was 1.67×10^9 cells·L-1. Phytoplankton absorbed on theE.crassipe root-mats had no effects on changes of stem height, root length andE. crassipe biomass, and on the root activity and leaf physiological change were not affected by phytoplankton. The average root surface area and root active surface area were 0.62 and 0.28 mg2·g-1, respectively. The average leaf soluble sugar and soluble protein content were 2.81 and 0.15 mg·g-1, respectively. Results indicated thatE. crassipe could change spatial distribution of phytoplankton, strand them in special water area and prevent them from covering lake with the wind. Meanwhile,E. crassipecould grow normally under high concentration of phytoplankton condition.