亚热带河流型水库浮游植物群落研究———以分水江水库为例

为了了解亚热带河流型水库蓄水后的水体富营养化状况与浮游植物群落结构特征，于2006年1月至2007年12月，对其进行了20次采样调查。结果表明，分水江水库总氮浓度较高平均值大于2mg/L，氮污染严重，磷污染较轻，水质总体评价较差。分水江水库浮游植物密度范围在0.07×105 ~16831×105ind./L，群落组成以硅藻、隐藻和绿藻为主，在丰度上水库浮游植物主要以富营养指示种为主。浮游植物组成随季节变化而有不同，春季以直链藻（Melosira）、实球藻（Pandorina）、盘星藻（Pediastrum）为优势类群，夏季以微囊藻（Microcystis）、鱼腥藻（Anabaena）、脆杆藻(Fragilaria)为优势类群，秋冬季以小环藻（Cyclotella）、针杆藻（Synedra）、蓝隐藻（Chroomonas）为主。分水江水库浮游植物密度、叶绿素a与降雨量均呈显著正相关，浮游植物的生长受水文特征变化的影响较大，这也间接说明分水江水库受面源污染比较严重。浮游植物与理化因子也有较强的相关性，特别是水温、pH、溶解氧、高锰酸盐指数和总磷均与浮游植物呈显著正相关，但是总氮浓度较高且与浮游植物不相关，说明氮元素不是水库藻类生长的限制因子。

Phytoplankton Community of Subtropical Riverine Reservoir——A Case Study of Fenshuijiang Reservoir

This study examined eutrophication status and phytoplankton characteristics in a subtropic riverine reservoir(Fenshuijiang Reservoir) during Jan.2006 and Dec.2007,with a total of 20 samples surveyed.The result indicated that the concentration of total nitrogen(TN) was comparatively high,and water quality was of Grade V,with average value for TN concentration over 2 mg/L and with nitrogen pollution severe,whereas with less grave phosphorous contamination.The phytoplankton density ranging from 0.7×104 to 168310×104 ind./L,the phytoplankton community in Fenshuijiang Reservoir comprised Bacillariophyta,Chlorophyta and Cryptophyta,dominant in eutrophication phytoplankton.the composition of phytoplankton varied with the change of seasons,dominant species being Melosira,Pandorina and Pediastrum in spring,Microcystis,Anabaena and Fragilaria in summer,Cyclotella,Synedra and Chroomonas in autumn and winter.A significant positive correlation could be observed,(between phytoplankton density and precipitation,chlorophyll a and precipitation respectively) and growth of phytoplankton in Fenshuijiang Reservoir was conditioned by hydrometeorology status,which indirectly demonstrated that Fenshuijiang Reservoir was severely affected by non-point source pollution.Besides,significant positive correlations also existed between phytoplankton density,chlorophyll a and water physiochemical factors,specifically in terms of water temperature,pH,DO(dissolved oxygen),permanganate index,and TP(total phosphorus).High TN concentration but poor relationship with phytoplankton density implied that nitrogen was not a limiting factor in Fenshuijiang Reservoir.