中文摘要：

灵水湖内沉水植物自2010年逐渐消亡,至2013年已基本消失,为探究岩溶水生态系统退化的原因,于2016年4、7、10月对灵水和罗波潭两个水环境相似的岩溶泉进行浮游植物调查和水环境监测。结果显示：灵水优势种共3门16种,罗波潭优势种共3门13种,两者的浮游植物相似性为60%。3次调查种类数基本不变,丰度均表现为4月〉7月〉10月。生物多样性指数和叶绿素水质评价均显示罗波潭优于灵水,说明沉水植物消亡会引发水环境退化。浮游植物与环境因子的RDA和相关性分析显示,总氮（TN）是浮游植物群落的决定性因子,而浮游植物对氮营养盐更强的摄食能力可能是灵水沉水植物消亡的原因之一。岩溶水环境的HCO3^-和Ca^2＋浓度可以指示浮游植物的生长状态。

英文摘要：

The submerged plants in the Lingshui lake has gradually reduced since 2010,and largely disappeared in 2013.In order to explore the causes of degradation of karst water ecosystem at this place,phytoplankton investigation and monitorin to the water environment have been conducted at the Lingshui and Luobotan karst springs in April,July and October of 2016,respectively.The results show dominant phytoplankton of 16 species belonging to 3 phyla at Lingshui and 13 phytoplankton species belonging to 3 phyla at Luobotan.The phytoplankton similarity reached 60% for both places.The basic types of phytoplankton species did not change during the three survey times,and the abundance was characterized by an order of April,July,and October from high to low.Water quality evaluation based on biodiversity indexes and chlorophyll shows that Luobotan was better than Lingshui,indicating that the water environment might degenerate after submerged plants died.RDA and correlation analysis between phytoplankton and environment shows that total nitrogen（TN）was the decisive factor for phytoplankton community.That phytoplankton has stronger absorptive capacity to nitrogen nutrient might be one of the reasons that submerged plants died in the Lingshui lake.The concentrations of HCO_3~- and Ca~（2＋） in the karst water environment can indicate the growth state of phytoplankton.