亚热带水库浮游植物群落季节变化及其影响因素分析——以汤溪水库为例

通过调查汤溪水库2003年水文、水质和浮游植物数据，分析了浮游植物群落季节变化的影响因素。结果表明，汤溪水库浮游植物丰度与群落结构具有明显季节变化。丰水期浮游植物丰度明显高于枯水期，并以7月份最高（〉10^4 cells ml^-1）。全年中，蓝藻（Cyanophyta）与硅藻（Bacillariophyta）比例变化较大，二者呈相反的变化趋势。1月份硅藻占较高比例（63.1％），蓝藻较低（〈20％）；3、5、7月份蓝藻比例较高（分别为45．6％、55．9％、87．7％），而硅藻较低（30．1％、25．9％、1．1％）；11月份硅藻与绿藻比例相当（各占40％），蓝藻低于20％；12月份硅藻与蓝藻比例分别为25．6％与38．2％。3月份和丰水期浮游植物优势种主要为铜绿微囊藻（Microcystis aeruginosa）、假鱼腥藻（Pseudoanabaena）和线形粘杆藻（Gloeothece linearis）等蓝藻种类，枯水期的1月、11月和12月主要以曲壳藻类（Achnanthes）、模糊直链藻（Melosira ambigua）、颗粒直链藻（Melosira granulata）和梅尼小环藻（Cyclotella meneghiniana）等硅藻种类为优势种。枯水期营养盐可能对浮游植物生长彤成限制，但相关性分析表明，营养盐并不是汤溪水库浮游植物群落季节变化的主要影响凶素。汤溪水库全年水体较稳定，在全年范刚内水动力学对浮游植物群落季节变化没有明显影响，但丰水期5月份至7月份优势种的变化可能主要受水动力学的影响。水温与蓝藻丰度呈显著正相关，与硅藻呈显著负相关，表明水温可能是引起汤溪水库浮游植物群落季节变化的主要因素。

Seasonal Change in Phytoplankton Communities in Tangxi Reservoir and the Effecting Factors

Hydrological conditions, water quality and the distribution of phytoplankton assemblage were surveyed in Tangxi Reservoir, Yaoping County (Guangdong Province), in 2003, to analyze the effecting factors on seasonal changes in phytoplankton growth. Results demonstrated that phytoplankton abundance in flood season, with the highest in July (>104 cells ml-1), was significantly higher than that in dry season. In January, Bacillariophyta was the dominant alga (63.1%), while Cyanophyta was less than 20%. In March, May and July, Cyanophyta was the dominant one, with high proportions of 45.6%, 55.9% and 87.7%, respectively, whereas the proportions forBacillariophyta decreased to 30.1%, 25.9%, and 1.1%, respectively. In November, proportions for Bacillariophyta and Chlorophyta were equivalent, 40% each, and the Cyanophyta composed below 20%. In December,Bacillariophyta made up 25.6% and Cyanophyta 38.2%. In March, May and July, dominant species of Cyanophytawere Microcystis aeruginosa, Pseudoanabaena, and Gloeothece linearis. In dry January, November and December, species of Bacillariophyta were dominated by Achnanthes sp., Melosira ambigua, Melosira granulata and Cyclotella meneghiniana. No close correlation was found between nutrient concentrations in reservoir and seasonal change of phytoplankton community throughout the year. In flood season (from May to July), obvious variation of dominant species seemed influenced mainly by temporal change of hydrodynamics. Water temperature was positively related to the abundance of Cyanophyta, but negatively to that of Bacillariophyta. It is indicated that water temperature seemed tobe the main factor affecting seasonal change of phytoplankton community in Tangxi reservoir.