拉萨河中上游夏秋季纤毛虫群落时空变动及其与环境的关系

为揭示中国西藏高原河流浮游纤毛虫群落结构特征及与水环境的关系,于2015—2016年的8月和11月,利用25号浮游生物网,分别在拉萨河中上游共8个代表性采样点,共采集64个水样。物种鉴定采用活体观察和固定染色相结合的方法。共鉴定出纤毛虫91种,夏季49种,各样点物种数由小到大依次为:S2S4S8S5S1S3=S7S6。秋季64种,各样点物种数由小到大依次为:S4S3=S1=S2=S5S8S6=S7。夏季各样点丰度为1.2×10~4—5.6×10~5个/L,秋季各样点丰度在1.2×10~4—2.6×10~5个/L之间。夏、秋季的优势种均为12种且优势种组成与分布不同,表现该流域纤毛虫存在明显的时空差异;群落结构分析显示:纤毛虫群落结构简单,物种组成多样性低而分布均匀;纤毛虫营养功能结构分析表明,夏季B、S类群的物种丰富度低于秋季;相关分析表明,总磷和总氮是影响夏季纤毛虫物种多样性的主要环境因子,并且浊度、NH_4-N和NO_3-N是影响秋季纤毛虫的主要环境因子。

Spatial and temporal variation in ciliate communities and relationships with environmental conditions in the middle and upper reaches of the Lhasa River

In order to explore the community structure of planktonic ciliates in the Tibetan plateau river of China and their relationship with the environmental factors, investigation was carried out from August 2015 to November 2016 in the upper and middle reaches of the Lhasa River. A total of 64 samples were collected from eight representative areas using 25# standard plankton net. Species identification using live observation and fixed-staining method. As a result, 91 species of ciliates were identified in this study:49 species in summer, the order of species number in eight areas is as follows:S2 < S4 < S8 < S5 < S1 < S3=S7 < S6; 64 species in autumn, the order is:S4 < S3=S1=S2=S5 < S8 < S6=S7. The abundance of ciliates of each area was ranged from 1.2×10⁴ ind/L to 5.6×10⁵ ind/L in summer, and from 1.2×10⁴ ind/L to 2.6×10⁵ ind/L in autumn. There were 12 dominant species in summer and autumn, respectively, but the composition and distribution were different, which revealed the spatial and temporal variation in ciliates in this basin. The community structure analysis indicated that the ciliate community has a simple structure, low diversity, and uniform distribution. The structural analysis of the nutritional function of ciliates showed that the abundance of B and S groups in summer was lower than that in autumn. Correlation analysis suggested that total phosphorus and total nitrogen were main environmental factors which influenced the diversity of summer ciliates; additionally, turbidity, NH₄-N, and NO₃-N were the main environmental factors influencing autumn ciliates.