【作者】 杨虹；

【导师】 由文辉；

【作者基本信息】 华东师范大学 ， 生态学， 2010， 硕士

【摘要】 淀山湖是上海市饮用水源保护地之一,兼具重要的生态、渔业、航道等功能。近年来,淀山湖富营养化程度不断加剧,夏季蓝藻水华频发,水环境安全受到严重威胁。为了了解淀山湖浮游植物群落的时空分布特点及与环境因子间的相互关系,分析浮游植物对不同生态修复工程的响应,为淀山湖富营养化防治提供基础资料,于2008年10月到2009年9月期间,在淀山湖设置了17个采样点,每月一次共计进行11次采样调查(2009年2月因天气原因未能采样),对各样点浮游植物的种类组成、数量变化、优势种、多样性指数及叶绿素a含量等进行了研究。主要研究结果如下：1调查期间共鉴定浮游植物8门147属503种(含变种、变型)。其中,绿藻门种类数最多,为65属204种,其次为硅藻门、蓝藻门和裸藻门,分别为32属148种,18属67种和7属59种。优势种主要由蓝藻门的色球藻属、微囊藻属、颤藻属,隐藻门的蓝隐藻属、隐藻属,绿藻门的小球藻属、丝藻属及硅藻门的直链藻属、菱形藻属等组成,尖尾蓝隐藻和小球藻为全年主要优势种,微囊藻属在夏末时成为部分区域主要优势种。淀山湖浮游植物类群密度受蓝藻水华期间情况影响较大。水华前：绿藻门、隐藻门、蓝藻门、硅藻门所占比例依次居前四位,而水华后：蓝藻门密度占55.61%,取代绿藻门成为浮游植物最主要的构成门类,绿藻门、隐藻门、硅藻门次之。2浮游植物种类数季节上表现为秋季>冬季>夏季>春季,空间分布特征为湖北>湖西及西南>湖南及湖东区域。浮游植物平均密度为6.16×106cells·L-1,呈双峰型变化,夏季峰远高于春季峰,夏季>春季>冬季>秋季。密度空间分布受水华影响较大。水华前,湖东、湖北区域密度较高,而水华后,湖西南、湖西区域密度更高,结合聚类分析结果,淀山湖西部、西南部为水华易发区域。Shannon-Weaver指数秋季>冬季>春季>夏季；Margalef指数秋季>冬季>春季>夏季；Pielou指数秋季>冬季>春季=夏季。空间上,大朱砂前置库、千墩浦前置库各点三种指数均高于其他,指示前置库附近物种丰富度,稳定性、均匀度相对更高。不同水深浮游植物群落差异较小,指示湖水上下分层并不明显。3浮游植物叶绿素a平均含量为20.51 mg／m3,春季>夏季>冬季>秋季,总体呈双峰型变化,夏季峰与春季峰水平相近。空间上,水华发生前,东部及北部水域叶绿素a含量高于西南部、西部,水华发生后,转变为西南部、西部和中部高于东部、南部等。不同深度叶绿素a含量随时间变化趋势基本一致,但变化幅度有所差距,总体上无显著差异。4调查期间,淀山湖除2008年11月和2009年3月为中营养外,其他各月均为轻度富营养状态。空间上,湖北区域营养状态指数较高,而西南部、南部区域相对偏低,指示湖北部富营养化程度高于南部。结合浮游植物调查结果分析可知,淀山湖营养盐和有机物含量丰富的水域具有更高的生物多样性指数。5利用SPSS软件分析浮游植物与环境因子的相关性,结果表明：影响淀山湖浮游植物的环境因子主要有水温、透明度、pH值、悬浮物、溶解氧、氨氮以及总氮,而总磷、BOD5、CODMn、浮游动物种类数、浮游动物密度等因子对浮游植物的影响较小。6对工程内外浮游植物群落各指标进行差异显著性分析,结果表明：除15号工程点和其对照点种类数、Margalef指数差异显著；5号工程点和其对照点浮游植物密度差异显著；7号工程点和其对照点Shonnon-Weaver和Pielou指数差异显著外,其余各指数在工程点和对照点间无显著差异。工程点内外浮游植物密度和叶绿素a含量差异随时间变化情况相近。2009年8月前,工程点浮游植物平均密度和叶绿素a含量分别低于对照点22.62%和31.89%。但水华后,工程点浮游植物平均密度和叶绿素a含量分别较对照点高了3.94倍和2.78倍。说明水华的发生对工程实施效果影响较大,需在水华易发季节加强维护。更多还原

【Abstract】 Lake Dianshan is one of the drinking water conservation areas in Shanghai with other important functions in ecology, fishery, water transportation, etc. Recently, the aggravation of eutrophication and high frequency of algae bloom severely threaten the aquatic ecosystem security. In order to evaluate the spatial and temporal variation of phytoplankton community structure in Lake Dianshan and their relationship with environmental factors and also to analysis the impact of ecological restoration project on phytoplankton, an investigation was carried out from October 2008 to September 2009. In this period,17 sampling sites were selected and the samples were run once a month (the investigation was interrupted by heavy rain and wind in February 2009).The species composition, density variation, dominated species, bio-diversity indexes and chlorophyll-a content were studied and the main results are as follow:1 A total of 8 phylum,147genera,503 species of phytoplankton were identified(with varietas and metatype). The phytoplankton community was mainly composed of Chlorophyta(65 genera 204 species), Bacillariophyta (32 genera 148 species),Cyanophyta(18 genera 67 species) and Euglenophyta(7 genera 59 species). The dominated species were mainly Chroococcus, Microcystis, Oscillatoria in Cyanophyta, Chroomonas, Cryptomonas in Cryptophyta, Chlorella, Ulothrix in Chlorophyta and Melosira, Nitzschia in Bacillariophyta. In quantity, Chroomonas acuta, Chlorella vulgaris were the dominated species all year round and Microcystis was in the summer for some areas.The group density of phytoplankton in Lake Dianshan was affected deeply by the algal bloom. Before the algal bloom, Chlorophyta, Cryptophyta, Bacillariophyta, Cyanophyta were dominant. However, after the algal bloom, Cyanophyta replaced the Chlorophyta to be the main group with a proportion of 55.61% followed by Chlorophyta, Cryptophyta and Bacillariophyta.2 The seasonal order of phytoplankton species number from high to low was autumn,winter, summer, spring, while the spatial order is north,west and southwest,south and southeast. The phytoplankton density was on average 6.16×10cells·L-1 with double peaks in a year. Moreover, the summer peak was much higher than that in spring. Generally, the phytoplankton density ranged from high to low in the following season order:summer, spring, winter, autumn. In Lake Dianshan, the spatial variation was affected deeply by the algal bloom too. Before the algal bloom, the density in east and north areas were higher than the others, but after the bloom, the density in southwest and west area were higher. With regards to the results of cluster analysis, the west and southwest areas in Lake Dianshan are vulnerable spots for algal bloom.The seasonal order of Shannon-Weaver index from high to low was autumn, winter, spring, summer and the Margalef index was the same. Meanwhile, the Pielou index was in the order of autumn, winter, and spring equal to summer. In space, the bio-diversity indeces of front damming at Da Zhusha and Qian Dunpu were higher than that in the other areas.This observation showed that the abundance, stability and uniformity of phytoplankton species were better than the other areas. The otherness of phytoplankton at different depth was low which showed that the stratification effect of water in Lake Dianshan was not obvious.3 The chlorophyll-a content of phytoplankton was on average 20.51 mg/m3, and ranged from high to low in the following season order:spring, summer, autumn, winer. There were double peaks in a year, and the peak in summer was almost the same as that in the spring. Before the algal bloom, the chlorophyll-a content in east and north areas were higher than that in the southwest and west. However after the algal bloom, the northwest, west and middle areas had higher chlorophyll-a content. The trend of temporal variation on chlorophyll-a content was almost the same at different depth, but the range was different. Generally, there was no significant difference between the phytoplankton communities at different depth.4 During the investigation, most of the time, Lake Dianshan was at light eutrophication level, except for the November 2008 and March2009 which were at the middle level, in most months of the year. Spatially, the comprehensive nutrition index in the north part was higher than the others while the southwest and north areas were lower, which showed that the nutrition state in the north was more serious. Combined with the phytoplankton bio-diversity indices at different sites, the areas with higher nutrients and organism had higher bio-diversity indices in Lake Dianshan.5 The SPSS software was used to analysis the correlation between phytoplankton and environmental factors, and the results were as follows:the main factors that impact the distribution and variation of phytoplankton in Lake Dianshan were water temperature, transparency, pH, suspended substance, dissolved oxygen, ammonia nitrogen and total nitrogen. However, the total phosphorus, BOD5, CODMn, species number and density of zooplankton had smaller impact on phytoplankton.6 The results of significance difference analyses on phytoplankton community between interior and exterior sites of the project were as follows:no other significant difference of phytoplankton parameters was showed between the interior and exterior except for the species number and Margalef index at site 15, phytoplankton density at site 5 and Shonnon-Weaver and Pielou indices at site 7. The temporal variation trend of phytoplankton density was the same as that of chlorophyll-a content interior and exterior the restoration projects. Before August 2009, the phytoplankton density and chlorophyll-a content in the project were lower than the outside by about 22.62% and 31.89% respectively. On the contrary, after the algal bloom, the two parameters above for within the project were 3.94 and 2.78 times higher than that of the outside, respectively. The above phenomenon showed that the ecological restoration projects were easily affected by algal bloom, and stricter precautionary measure should be taken during the algal bloom.更多还原