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武汉东湖浮游植物生态学研究
Alternative TitleEcological Studies on Phytoplankton of the Shallow, Eutrophic Lake Donghu
唐汇娟
Subtype博士
Thesis Advisor谢平
2002
Degree Grantor中国科学院水生生物研究所
Place of Conferral中国科学院水生生物研究所
Degree Discipline水生生物学
Keyword浮游植物 滤食性鱼类 营养 蓝藻水华 东湖 底泥
Abstract该文研究了武汉东湖浮游植物的季节演替与历史变化,并通过围隔实验分别研究了滤食性鱼类和营养盐对浮游植物的影响.东湖Ⅰ、Ⅱ站浮游植物生物量的最高值出现在冬季和春季,而Ⅲ站生物量的最高值则出现在夏季.由于受到滤食性鱼类摄食、较高的营养水平以及较低的透明度的影响,东湖的浮游植物主要由双鞭藻(隐藻、真蓝裸甲藻)、中心硅藻纲的小环藻和直链藻以及小型的绿球藻和蓝藻所组成.该实验了表明滤食性鱼类对浮游植物的影响主要取决于浮游植物的大小和大型浮游甲壳动物.该实验还表明,一定密度的滤食性鲢鱼对小型浮游植物也具有相当的抑制作用.围隔中氮磷比的改变并没有对围隔中浮游植物的组成产生很大影响,所有围隔均爆发微囊藻水华,浮游植物的生物量以添加氮的围隔最高,而以添加磷的围隔最低.东湖的浮游植物组成和生物量在蓝藻水华消失后相当稳定.20世纪80年代初期的东湖和现在的东湖分别处于超富营养化的两种状态,即以蓝藻占优势的状态和以鞭毛藻和C-选择者占优势的全营养(Holotrophic)状态.在东湖,滤食性鱼类的摄食是导致这两种状态相互转换的关键因子.
Other AbstractSpecies composition and seasonal dynamics of phytoplankton in the shallow, eutrophic Lake Donghu were studied during a two years period (Sep. 1999 - Aug. 2001), and the historical changes of phytoplankton over the past 20 years were also reviewed with emphasis on the mechanisms underlying these changes. The impacts of both filter-feeding fishes and nutrient levels on phytoplankton were studied through enclosure experiments. The phytoplankton biomass in the lake during the period of Sep. 1999- Aug. 2001 was much lower when compared with many other eutrophic lakes with similar or even lower nutrient concentrations. It was probably due to both high grazing pressures by filter-feeding fishes and light limitation. Phytoplankton in Lake Donghu is mainly composed of flagellated Cryptomonas and Gymnodinium eucyaneum, centric Cylotella spp and Melosira ambigua, small sized cyanobacteria and Chlorococcales, most of which were typical species in condition of high grazing and high nutrient level. In the 1999 enclosure experiment when phytoplankton were dominated by nanophytoplankton, an outburst of Daphnia occurred in fishless enclosures where phytoplankton biomass was the lowest and water transparency significantly increased. While in the 1992 enclosure experiment when the phytoplankton were dominated by Microcystis bloom, the addition of filter-feeding fishes resulted in great declines in phytoplankton biomass, in contrast to the grass carp addition and the control. It suggested that the impact of filter-feeding fishes on phytoplankton might also be dependent on the composition of phytoplankton. Nutrient addition experiment was carried out to test the role of N/P ratios on phytoplankton in Lake Donghu. It was found that neither nitrogen nor phosphorus addition had significant effect on the composition and biomass of phytoplankton and dense Microcystis bloom occurred in all the enclosures. It was concluded that suitable biological (absence of filter feeding silver carp and bighead carp) and physical environment (high transparency and high pH) combined with saturated nutrient concentration contribute to the nuisance Microcystis bloom in the enclosures. The effect of sediments and water with different nutrient contents on phytoplankton was tested. Both nutrient and phytoplankton biomass were significantly higher in enclosures with nutrient-saturated sediment than that with nutrient-poor sediments. Consistently dense Microcystis blooms only occurred in enclosures with nutrient-saturated sediment. However, water with different nutrient contents had no significant impact on phytoplankton biomass (n=64, p=0.11) especially when the sediment was rich in nutrient. In Lake Donghu, the biomass of phytoplankton remained at relatively low levels with little change in species composition since the disappearance of cyanobacterial blooms in mid-1980s. Before the mid-1980s, Lake Donghu was classified as hypereutrophic, dominated by heavy cyanobacterial bloom. Afterwards, the lake shifted to a so-called holotrophic state, characterized by abundant flagellates and C-strategy species by the definition of Reynolds. The shift between the two statuses was most likely induced by the change in stocking rate of filter-feeding fishes.
Pages150
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12640
Collection学位论文
Recommended Citation
GB/T 7714
唐汇娟. 武汉东湖浮游植物生态学研究[D]. 中国科学院水生生物研究所. 中国科学院水生生物研究所,2002.
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