新疆博斯腾湖浮游甲壳动物群落结构

Crustacean zooplankton community structure in Lake Bosten,Xinjiang

2010年6-11月和2011年1月,对博斯腾湖的浮游甲壳动物群落进行了调查,并分析了环境因子对其群落结构的影响.结果表明,不管是在种类数量,还是在密度和生物量上,浮游甲壳动物都主要由枝角类组成,且优势物种存在明显的季节变化.在夏季,浮游甲壳动物主要由大型的僧帽溞和短尾秀体溞组成;在秋冬季,随着大型种类现存量的减少,小型的长额象鼻溞优势逐渐增加,表明不同大小的枝角类间存在着明显的竞争作用.回归分析显示,浮游甲壳动物生物量和平均体长均与水温存在显著的线性关系.相关分析显示,长额象鼻溞和僧帽溞生物量与透明度显著正相关,同时与Chl.a显著负相关,表明藻类的大量繁殖对浮游甲壳动物优势种群有抑制作用.多元统计分析发现,环境因子总共解释了浮游甲壳动物群落结构总变异的56.8%,水温是影响浮游甲壳动物群落演替的最重要因子,其次是水深.剑水蚤、僧帽溞和短尾秀体溞易于在高温季节繁茂.长额象鼻溞喜好在浅水而僧帽溞、短尾秀体溞喜好在深水区域形成密度高峰,这种分布格局上的差异可能与鱼类的捕食有关.

Crustacean zooplankton community in Lake Bosten was monitored and the impacts of environmental factors on curstacean zooplankton community structure were assessed during Jun.-Nov.2010 and Jan.2011.Results showed that crustacean zooplankton was mainly dominated by Cladocera,not only in species number,but also in density and biomass,with dominant species succeeding seasonally.In summer,crustaceans were dominated by large-sized Daphnia cucullata and Diaphanosoma brachyurum.With the decrease of large-sized zooplankton in fall and winter,the percentage of small-sized Bosmina coregoni increased,suggesting that competition works between zooplankton of different body size.Regression analyses indicated that crustacean biomass and mean body length were positively correlated with water temperature.Correlation analyses revealed that the biomass of B.longirostris and D.cucullata was positively correlated with transparency,but negatively with Chl.a,indicating these two dominant species being inhibited by the overgrowth of phytoplankton.Multivariate statistical analyses showed that 56.8% of the total variance in crustacean community structure was explained by environmental factors,with water temperature being the most important factor and water depth the second.High water temperature favoured the development of cyclopoids,D.cucullata and D.brachyurum.Meanwhile,B.coregoni preferred to flourish in shallow stations while D.cucullata and D.brachyurum in deep stations.The difference in distribution pattern of dominant species might be due to the fish predation.