雅砻江（锦屏段）及其主要支流底栖藻类群落与环境因子的关系

分别于2004年5月和11月对雅砻江(锦屏段)及其主要支流22个采样点的底栖藻类进行研究.共采获底栖藻类150种,分属3门(硅藻、绿藻和蓝藻),37属.其中硅藻门占绝对优势(96.5%),线性曲壳藻(Achnanthes linearis)和Achnanthes deflexa为绝对优势种,其相对丰富度分别为35.3%和11.0%.细端菱形藻(Nitzschia dissipata)和小型异极藻(Gomphonema parvulum)是雅砻江(锦屏段)干流的优势种,而线性曲壳藻、扁圆卵形藻(Cocconeis placentula)和Achnanthes deflexa是其他支流的优势种.基于底栖藻类的物种组成和相对丰度,对两次的采样点进行去势对应分析(DCA),结果发现:两次采样雅砻江(锦屏段)干流样点与其他支流样点在DCA第一轴上得到了很好的分化,表明研究区域底栖藻类群落存在明显的空间差异,这主要是由干流的特殊生境所致.典范对应分析(CCA)结果显示不同季节影响底栖藻类群落结构的环境因子有所差异.总磷(TP)是5月份影响底栖藻类空间分布的最主要因素;11月份影响底栖藻类空间分布的最主要环境因子为氨氮(NH4-N)和海拔(Elevation).

Benthic algal communities in Jinping reach of Yalong River and its main tributaries in relation to environmental variables

An investigation was carried out on the benthic algal communities at 22 sites in the Jinping reach of Yalong River and its main tributaries in May and November 2004, aimed to study the relationships between benthic algal distribution and environmental variables. A total of 150 taxa (mostly to species level) in 37 genera were observed, which belonged to Bacillariophyta, Chlorophyta and Cyanophyta. Diatoms comprised 96.5% of the total taxa. Achnanthes linearis and Achnanthes deflexa were the most abundant species, and the relative abundances were 35.3% and 11.0% of the total abundance, respectively. In May and November, Nitzschia dissipata and Gomphonema parvulum were the dominant species in Jinping reach of Yalong River, while Achnanthes linearis, Cocconeis placentula and Achnanthes deflexa dominated in its tributaries. Based on the species composition and their relative abundance, detrended correspondence analysis (DCA) showed that sites belonging to Yalong River and its tributaries were well separated on DCA axis 1. This may be explained by the special habitats of Yalong River like high velocity, wide channel width. Canonical correspondence analysis (CCA) on the relationships between benthic algal community structure and environmental variables indicated that in May, TP was the main environmental variable affecting the benthic algal distribution, while in November, NH4-N and elevation were the main ones.