尼洋河不同河段浮游植物群落多样性差异研究

VARIATIONS OF PHYTOPLANKTON BIODIVERSITY IN DIFFERENT STREAMS OF NIYANG RIVER

2009年8月对尼洋河流域浮游植物群落的种类组成、分布和数量特征进行了调查:共发现浮游植物共26属74种(变种),以硅藻为主,大多数种类的相对丰富度较低,优势种不明显,平均相对丰富度大于5%的种类分别是极细微曲壳藻(9.0%)、弧型蛾眉藻线形变种(5.4%)、中型脆杆藻(5.3%)和尖针杆藻(5%);其出现频次分别是19、20、17和20次。种类分布均匀,平均细胞密度为2.25×104 ind./L,远低于一般河流和湖泊。分析显示绝大多数样点浮游植物的多样性和均匀度指数都很高,其均值分别为3.64和0.95。以上结果表明该流域浮游植物群落结构比较复杂、处于较完整的稳定状态,体现了尼洋河流域贫营养河流水体的特征。TWINSPAN和DCA分析表明海拔高度和环境的稳定程度可能是影响该流域浮游植物群落多样性的主要因子。

Taxonomic composition, distribution and cell densities of phytoplankton community of Niyang River were investigated in August 2009. The phytoplankton was mainly composed of diatom, 204 taxa belong to 24 genus （including variations） were observed. Relative abundances of most taxa were low, dominant species were not outstanding, the taxa of mean relative abundance more than 5% were Achnanthes minutissima （9.0%） ,Ceratoneis arcus var. linearis （5.4%） ,Fragilaria interrnedia （5.3%） and Synedra acus （5.0 %） ; their appearance frequencies were 19,20,17 and 20, respectively. Distribution of taxa is even, the mean density of phytoplankton was 2.25 X 104 ind./L during the studying period,this value was far below the general rivers and lakes. Shannon-Weaver index of diversity and the evenness index of phytoplankton were very high in most sampling sites, their mean values was 3.64 and 0.95, respectively. These structure characteristics indicated that phytoplankton of this valley was a complex, stable community, and trophic state of Niyang River was oligotraphentic. The detrended correspondence analysis （DCA） was consistent with that of two-way indictor species analysis （TWINSPAN） ,the result of DCA showed that altitude and environmental stabilization were the major factor that affected diversity of phytoplankton community in Niyang River.