抚仙湖浮游甲壳动物群落结构与空间分布

Community structure and spatial distribution of crustacean zooplankton in Lake Fuxian,Yunnan,China

云南抚仙湖是我国典型的高原深水湖泊,为揭示湖中浮游甲壳动物对生态系统变化的响应,研究了其群落结构与空间分布特征.2005年6-7月在抚仙湖共采集浮游甲壳动物8种,平均密度为27.6ind./L,优势类群为桡足类.桡足类优势种为舌状叶镖水蚤(Phyllodiaptomus tunguidus Shen et Tai),枝角类优势种为角突网纹溞(Ceriodaphnia cornuta Sars)和象鼻溞(Bosmina sp.).浮游甲壳动物主要分布在0-30m水层,密度随水深增加而下降;0-10m水层,枝角类和无节幼体占优势,大于10m水层,桡足类占优势.浮游甲壳动物密度南区大于北区(P<0.01),而沿岸区与湖心区之间、沉水植物区与非沉水植物区之间无显著性差异(P>0.05).相关分析表明:浮游甲壳动物密度的垂直分布与藻类密度和水体理化因子相关关系显著,而水平分布与藻类密度和水体理化因子相关关系不显著.与20世纪80年代相比,抚仙湖浮游甲壳动物优势种发生了演替,西南荡镖水蚤(Neutrodiaptomus mariadviagae mariadviagae(Brohm))消失,被舌状叶镖水蚤代替,可能与太湖新银鱼(Neosalanx taihuensi Chen)引入有关;浮游甲壳动物密度表现出增加趋势,但仍处于较低水平,与水体营养水平的提高及太湖新银鱼的捕食压力有关.

Lake Fuxian is a representative deep plateau lake located in Yunnan Province, China. To describe crustacean zooplankton＇s responses to ecological changes, we carried out studies on its community structure and spatial distribution. Altogether 8 taxa of crustacean zooplankton were founded in Lake Fuxian from June to July in 2005, and the average community density 27.6ind./L dominated by Copepoda. Dominant species of Copepoda were Phyllodiaptomus tunguidus Shen et Tai, and dominant species of cladoceran were Ceriodaphnia cornuta Sars and Bosmina sp. Crustacean zooplankton was mainly distributed from surface to 30m vertically, and its density decreased with the depth increase. Cladocera and Nauplii had the dominance in 0-10m layer, but Copepoda had the dominance when depth down to 10m. Average density of crustacean zooplankton was significantly higher in south lake than north lake （P〈0.01）, while there were no significant differences in average density between near shore region and open water region,and between maerophyte distributed region and no macrophyte distributed region （P〉0.05）. Correlation analysis indicated that there was significant correlation between the vertical density of crustacean zooplankton and algae density or water physical-chemical factors, but there was no significant correlation between the horizontal density and algae density or water physical-chemical factors. Compared with the surveys in 1980s, Neutrodiaptomus mariadviagae mariadviagae （Brohm）, one of the dominant species of crustacean zooplankton, disappeared in the lake and was replaced by P. tunguidus, which was probably caused by introduction of Neosalanx taihuensi Chen. The density of crustacean zooplankton showed an increasing tendency, but that was still rather low, likely a result of increased nutrient levels and predation by N. taihuensi.