湖南镇水库浮游生物及其影响因子的典范对应分析

Structure and dynamics of plankton community and their impact factors based on CCA analysis in Hunanzhen Reservoir

2006年至2007年间调查了蓝藻(Cyanophyta)暴发水体——湖南镇水库的浮游生物群落结构及其变化,研究了其与环境参数之间的关系。调查期间,共鉴定出浮游植物96种(属),浮游动物73种(属)。单位水体浮游植物平均细胞数量变化于0.49×106～16.71×106L-1之间,浮游动物则变化于8～3548L-1之间。春、夏季螺旋鱼腥藻(Anabaena sporoides)水华持续数月,水体表层细胞密度高达2.28×108L-1,进入秋季后其优势逐渐被颤藻属(Oscillatoria)蓝藻取代。典范对应分析显示,浮游植物的季节演替规律与螺旋鱼腥藻数量、总溶解固形物(TDS)和透明度(SD)存在较高的相关性,浮游动物演替主要与溶解在水中的微囊藻(Microcystis)毒素(EMC)、营养盐和螺旋鱼腥藻数量相关。由于高水平营养盐的存在,上行效应无法有效限制蓝藻的发生,水华蓝藻以其数量优势改变了水体理化条件,成为影响浮游植物群落的潜在因素,而营养盐可能通过主导可食藻类的生长,间接影响浮游动物的动态。将水华蓝藻数量及藻毒素浓度作为环境因子进行多元分析,分别提高了对浮游植物、动物群落的解释15.6%和25.8%,说明水华蓝藻和藻毒素的存在对浮游生物群落的组成和结构具有较大的影响。

In the present study, the blue-green algae bloom water-Hunanzhen Reservoir, the third largest reservoir in Zhejiang Province, was monitored between 2006 and 2007. Plankton abundance was measured and correlated to environmental parameters. 96 taxa of phytoplankton and 73 taxa of zooplankton were identified. Phytoplankton had an abundance ranging from 0.49 ×10^6～16.71×10^6L-1, and the abundance of zooplankton varied from 8 to 3 548 ind./L. The cyanobacterial bloom ofAnabaena sporoides lasted several months with the highest density of the surface water being 2.28 × 10^8L^-1, and then Oscillatoria were dominant during autumn months. Ordination by CCA showed that the seasonal phytoplanktonic succession was mainly correlated with density of A. sporoides, total dissolved solids and transparency, and the seasonal zooplanktonic succession was mainly correlated with extracellular microcystin, nutrients and the density ofA. sporoides. Due to the occurrence of high level nutrients, the development of blue-green algal may not be regulated by ＂bottom up＂ forces effectively. The bloom-forming cyanobacteria became the potential factor that influenced the community of phytoplankton by its competitive advantage. Nutrients do not influence the zooplankton community directly, but control the edible phytoplankton growth, which in turn influence the dynamics of zooplankton. By considering not only the environmental parameters but also the occurrence of cyanobacterial blooms and algal toxin as explanatory variables in a canonical correspondence analysis, the variance explained for the phytoplanktonic and zooplanktonic assemblage during the study period was increased 15.6% and 25.8% respectively, indicating a correlation that blue-green algae and the bloom-forming cyanobacteria may affect the structure and composition of plankton community. [Journal of Fishery Sciences of China, 2008, 15 （6） ： 950-960]