香溪河小水电的梯级开发对浮游藻类的影响

以香溪河干流上5个连续的小水电站为对象，于2005年10月20—22日分别对其浮游藻类和主要理化指标进行研究.结果表明：硅藻占绝对优势(95.54%)，其中，线性曲壳藻(Achnanthes linearis)、披针曲壳藻椭圆变种(A. lanceolata var. elliptica)、扁圆卵形藻(Cocconeis placentula)为绝对优势种，其平均相对丰富度分别为23.96%、18.62%和12.48%；所有样点的平均藻类密度为6.29×10⁵ ind·L^-1，最高为1.81×10⁶ ind·L^-1，最低为2.35×10⁵ ind·L^-1.方差分析表明，流速变化是小水电站开发影响河流中浮游藻类的主要原因.电站取水坝的建立，使其下游生境(生境3)与其它4个生境显著不同，导致多个参数出现骤变，包括Margalef多样性指数、物种丰富度、属的丰富度、硅藻组成、硅藻百分含量等均受到显著影响.

Influence of cascaded exploitation of small hydropower on phytoplankton in Xiangxi River.

With the five small hydropowers (SHPs) from up- to downstream of Xiangxi River as test objects, this paper studied the influence of SHPs cascaded exploitation on the phytoplankton in the river. The results showed that phytoplankton assemblages were dominated by diatoms, occupying 95.54% of the total number of species. Achnanthes linearis, A. lanceolata var. elliptica and Cocconeis placentula were the most abundant species, with the relative abundance being 23.96%, 18.62% and 12.48%, respectively. The average algal density at 25 sampling sites was 6.29 x 10(5) ind x L(-1), with the maximum of 1.81 x 10(6) ind x L(-1) and the minimum of 2.35 x 10(5) ind x L(-1). Two-way ANOVA indicated that water flow velocity was the main factor affecting the phytoplankton. The establishment of the cascaded SHPs on the river made the habitat of lower reach has a significant difference with the others, resulting in a dramatic change of many parameters including Margalef diversity index, species richness, generic richness, taxonomic composition, and the percentage of diatoms.