滇池浮游植物群落结构的时空变化及与环境因子的关系

在滇池外海选取8个样点,调查分析主要的环境因子和浮游植物群落的季节和年际变化,并识别其相关关系。在滇池共检测出浮游植物6门49属84种,其中绿藻门的种类数最多,占59.2%,其次是蓝藻门,占16.67%,硅藻门占5.95%;全年蓝藻门占优势,春季隐球藻(Aphanocapsasp.)占优势,其他季节微囊藻(Microcystis sp.)占绝对优势。研究结果表明:1)藻密度和生物量的季节变化不一致,与藻类组成的季节演替以及不同藻类的生物量大小存在较大差异有关;2) Shannon-Wiener物种多样性指数(H)较小,季节变化不显著;3)藻密度和生物量与TP正相关,与NO3-和N:P负相关;而H与TP负相关,与NO3-和N:P正相关;4)营养盐是影响浮游植物群落分布的关键因子,滇池最重要的优势种微囊藻的密度和生物量与pH、NH4+和TP浓度正相关,与NO3-、N:P、TN、DOC和TOC的浓度负相关。推测除环境因子外,绿藻、硅藻等优势度较小的藻类受其他生物因素的影响较大(如种间竞争和捕食等),掩盖了环境因子对藻类的真实影响。

Seasonal and Spatial Variations of Phytoplankton Communities and Correlations with Environmental Factors in Lake Dianchi

The spatial and seasonal variations of environmental factors and phytoplankton community in Lake Dianchi was investigated. The statistical analysis found that a total of 84 phytoplankton taxon, belonging to 49 genera 6 phyla were identified, of which Chlorophyte were the most abundant, accounting for 59.2%, followed by Cyanophyta, accounting for 16.67% and diatom accounting for 5.95%. The trend of seasonal variation of algae density and biomass was not the same, which was caused by the biomass differences of various species. The Shannon Wiener index (H) was very small throughout the year, and seasonal variation was not significant. Algae density and biomass were positively correlated with total phosphorus (TP), and negatively correlated with nitrate (NO₃^-) and nitrogen phosphorus ratio (N:P). H was positively correlated with NO₃^- and N:P, while negatively correlated with TP. Nutrients had great influences on the density and biomass distributions of various taxa of phytoplankton community. The density and biomass of the most dominant species Microcystis sp. had the same relationships with the environmental factors, which were positively correlated with pH, TP and ammonia (NH₄⁺), and negatively correlated with NO₃^-, N:P, total nitrogen (TN), dissolved organic carbon (DOC) and total organic carbon (TOC). Some biological factors may cause stronger effects on density and biomass distribution of chlorella and diatom, such as interspecific competition and predation, covering the influences of environmental factors.