拟老年低额溞和大型溞控制水华藻类的实验研究

本文以2种大型浮游动物和1种绿藻、2种铜绿微囊藻为研究对象，初步研究了浮游动物对藻类的摄食关系。实验结果表明当栅藻和无毒铜绿微囊藻CHAB109密度均为1.02×106cells/ml时，拟老年低额溞对二者的去除率分别为54.20%和6.45%，大型溞的则为49.77%和64.77%。同时，拟老年低额溞对栅藻和CHAB109混合藻液中的两种藻均有较好的去除效果，分别为60.65%和34.43%，高于对纯种藻的去除率。在遮光条件下浮游动物摄食量更大，对藻的去除效果更优。拟老年低额溞在锡箔遮光情况下，对初始藻细胞密度为3.023×105cells/ml的有毒微囊藻PCC7806去除率达到32.37%。7d日龄的浮游动物个体大，摄食量也大，有较好的去除效果，且随着添加浮游动物数量的增加，去除率也随着提高。高浓度的藻细胞对两种浮游动物存活率影响较低浓度大。浮游动物应用于藻类水华的控制，作用不容忽视，且若条件适宜，浮游动物也可较好的控制有毒蓝藻。当选用浮游动物控藻藻类水华时，需综合考量选用物种种类、大小、添加数量等因素。

Potential for Using Simocephalus vetuloides and Daphnia magna for Controlling Algal Blooms

Foraging of algae by zooplankton is the basic principle behind the use of biomanipulation to controll algal blooms. Daphnia is an important fauna in the freshwater food chain and much research has been carried out on its use for controlling phytoplankton. Microcystis aeruginosa produces toxic-algae blooms in warm eutrophic waters and, because blooms tend to be long lasting and hard to control, research has focused on prevention and control of aglae blooms. The representative algal species Microcystis aeruginosa (non-toxic CHAB109; toxic PCC7806) and Scenedesmus obliquus and the large zooplankton species Simocephalus vetuloides and Daphnia magna were chosen to study zooplankton grazing on algal growth and the factors that influence grazing in order to verify the feasibility and effectiveness of different zooplankton species in controlling of algae bloom. Foraging trials were run under different algal densities, light conditions and zooplankton densities. Zooplankton and phytoplankton in all trials were sampled and analyzed each day at the same time. Results indicate that the removal rates of Scenedesmus obliquus and CHAB109 in Scenedesmus obliquus group and CHAB109 group (both initial density of 1.02×106 cells/mL) were 54.20% and 6.45% by Simocephalus vetuloides, and 49.77% and 64.77% by Daphnia magna. The removal rates of Scenedesmus obliquus and CHAB109 in mixture group of Scenedesmus obliquus with CHAB109 were 60.65% and 34.43% by Simocephalus vetuloides, higher than those in single algae groups. The results also reveal that zooplankton consumed larger amount of algae and displayed more effective removal of algae in the dark.The removal rate of PCC7806 with an initial density of 3.023×105 cells/mL was 32.37% by Simocephalus vetuloides under aluminium foil shading. In the trials, mature Daphnia magna (7d) had higher removal rates than the larvae due to the larger size and greater need for food and the removal rate increased with zooplankton density. However, the growth of zooplankton was also affected by the density of alage, with lower survival rate of zooplankton at higher algae density. Thus, zooplankton species diversity, size and density must be considered when used for algae control.