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滇池微囊藻越冬及复苏的生态生理学研究
Alternative TitleEco-physiological Study on Overwintering and Recruitment of Microcystis in Lake Dianchi
万能
Subtype博士
Thesis Advisor宋立荣
2008-06-16
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Keyword模拟装置 越冬 复苏 抗氧化酶 光合系统 重培养 时空差异 种群演替
Abstract自上世纪80年代以来,滇池水体富营养化程度迅速加深,蓝藻水华频发,且暴发强度大,时间跨度长,在世界范围内也属罕见,其水华优势种主要为铜绿微囊藻(Microcystis aeruginosa)。但通过近几年来的调查发现,在初春季节滇池地区存在明显的水华束丝藻(Aphanizomenon flos-aquae)向铜绿微囊藻转换的种群演替现象。本研究中,我们自行改进设计了一套底泥环境模拟装置并应用于滇池底泥环境模拟实验及滇池福保湾原位围隔实验,研究了微囊藻细胞(以铜绿微囊藻为主)在底泥环境中的细胞形态学、光合系统、抗氧化系统及重培养特征及变化,并发现了原位实验与模拟实验对M. aeruginosa的不同影响,这一结果可应用于对M. aeruginosa越冬及复苏期种群竞争优势的评价;同时,通过对不同越冬时段微囊藻的培养及不同底质对微囊藻复苏能力影响的实验证明了滇池M. aeruginosa复苏率存在明显的时空差异性;进一步的研究发现,M. aeruginosa与A. flos-aqaue在滇池早春水华蓝藻复苏期的种群演替现象应该与M. aeruginosa复苏时空差异性有密切相关。主要研究结果如下: 1.自行改进设计了一套底泥环境模拟的装置,用于研究M. aeruginosa在底泥环境中的生态生理学响应,并在实际应用中表现出良好的操作性和广泛的适用性,可为今后研究底泥中藻类生理生态学提供新思路及新方法; 2.模拟实验结果表明,M. aeruginosa在刚进入底泥环境时表现出了主动防御不利环境胁迫的应激生理学特征,抗氧化系统及光合系统在受到损伤后,能迅速启动修复机制;但随着环境胁迫的继续,细胞膜应受到损伤,膜通透性增大,抗氧化系统活性降低,但PS II在修复后没有出现继续受损的现象,Fv/Fm维持稳定;细胞形态学有显著变化,群体解聚,小群体(10个细胞左右)及单细胞大量存在,且后期样品观察不到胶被和伪空胞的存在,重培养后,细胞在经历较长延滞期(9天)后能恢复生长;以上结果表明M. aeruginosa在底泥环境中,初期表现出了较强的抗逆性,但后期随着膜的受损,仅光合系统能维持稳定正常状态,但在正常条件下进行重培养时能恢复生长; 3. 原位实验研究结果表明,M. aeruginosa在不同深度底泥中形态学变化没有显著差异,仅固化区底泥中细胞群体稍大于对照区,实验末期仍有大量群体细胞存在,底泥中的厌氧环境及底栖动物牧食压力的减小应该是群体细胞得以长期维持的重要因素;M. aeruginosa在底泥环境中抗氧化系统活性的变化过程,暗示在受到胁迫时M. aeruginosa细胞抗氧化活性存在垂直差异,且中、下层细胞在后期仍具有较高的抗逆性;藻毒素含量随时间变化总体水平下降,对照区底泥对藻毒素的生物降解作用强于固化区,藻毒素含量激增的时间,与抗氧化系统活性的升高时间相吻合; 4.M. aeruginosa不同越冬时段收集的样品重培养实验结果表明,越冬初期样品能保持较高的生理活性,而末期的藻细胞在实验中基本没有观察到对数生长期,且最终达到的生物量极低,初春的M. aeruginosa细胞经过在底泥表面的恢复生长,细胞形态和颜色已逐步显示出复苏迹象;表明M. aeruginosa复苏能力存在时间差异性; 5.M. aeruginosa的复苏表现出对不同底质的不同适应性,其复苏率及藻类复苏后达到的最大生物量均存在差异,结果表明福保湾入湖河流河口区藻类复苏能力远低于吹填区和对照区,暗示了重污染底泥不适合M. aeruginosa的复苏,福保湾藻类水华的种源贡献主要应该是外源性输入,即湖流场和风向所导致的藻类水平迁移贡献远远大于底泥复苏至水体的垂直迁移; 6.水华蓝藻复苏期全湖调查结果表明,春季滇池藻类主要分属于5门21属,其浮游植物多样性指数较以前有下降趋势;蓝藻生物量在复苏期存在明显的空间差异;单位生物量内多糖含量的变化结果也显示出时空差异性,南部位点单位多糖含量高于北部;藻类光合活性垂直差异不显著,但随时间变化,中、南部表层水样中样品Fv/Fm逐渐上升,暗示这些点位藻类样品光合活性逐步恢复,很可能与藻细胞的复苏有关;由以上结果推测,南部藻细胞的复苏迟于北部,调查期间大部分细胞还存在于水柱底层,随着时间变化,逐渐上升至上层水体; 7.水华蓝藻复苏期,Microcystis sp.和Aphanizomenon sp.的演替明显存在,且与藻类复苏,特别是微囊藻复苏应有密切相关,也存在时空差异性,南部位点相对于北部有滞后效应,应可根据北部藻类种群的变动趋势推测南部藻类的种群变动情况。
Other AbstractEutrophication in Lake Dianchi was accelerated since 1980’s. From then on, cyanobacterial blooms occurred more frequently and heavily. Lake Dianchi was thus regarded as one of most polluted large shallow lakes all over the world. Microcystis aeruginosa is the most popular species dominating this lake. In the past years, some investigation showed that there was an obvious succession (Aphanizomenon flos-aquae to M. aeruginosa) in early spring. In present study, a sediment environments simulation device was designed and modified to trace the cell morphology, photosystem, antioxidant enzyme activities and reculture characters and variations of Microcystis aeruginosa in enclosures and Lake Dianchi. We found some differences between the field studies and simulated studies, and the results could be used to assess the advantages in species competition of M. aeruginosa during its overwintering and recruitment. The novel device showed a good maneuverability in simulation study as well as in field study. And we could expect an excellent performance in future studies. M. aeruginosa showed acute responses when met sediment environments in the study, the antioxidant system and photosystem could be partly repaired. But as stress went on, cell membranes suffered more than beginning, and the antioxidant enzyme activities decreased finally. Fv/Fm remained a relative stable value after the recover of PS II until the end of the study. Cell morphology was greatly changed during the study, the samples were observed as small colonies and single cells in the end, sheath and gas vacuoles were hardly observed. The re-culture data showed the samples could grow well after the stress in sediments except for a pretty longer lag phase (9 days). In situ research data indicated that the cell morphology had no significant differences among the samples set in different layers of sediments, and there were a great deal of colonies at the end of study. Colony size of Microcystis in fixation sediments was larger than control. We supposed that the lack of benthos and the anaerobic environment could be primary reasons for this. Vertical diversity in antioxidant activities was obviously observed, and which were coincident with microcystins concentration variations. Simultaneously, we confirmed that the recruitment of Microcystis did have spatio-temporal diversity via experiments on re-culture. The samples collected at the beginning stage of overwintering showed nothing different with the fresh sample except for the 10-day-lag phase, while the samples taken from the late stage of the overwintering showed no log phase. Recruitment rate of M. aeruginosa in different sediments were quite different. Our data indicated that the sediments taken from the estuary of Fubao Bay were organic polluted heavily, and M. aeruginosa recruitment rate in these kind of sediments was quite lower than others. We hypothesized that the horizontal movements of M. aeruginosa populations which induced by wind-driven current contribute much more than original recruitment to the blooms, and the formation of blooms could be some kind of external loading. Furthermore, we investigated the succession of in early spring, which was considered to be the most crucial period of M. aeruginosa. All the results from the investigation revealed that M. aeruginosa cells in south bay could recruit later than central and north bay. The biomass of M. aeruginosa moved from overlying water to surface water as the investigation time past, and this biomass shift coupled well with the A. flos-aquae and M. aeruginosa succession. The results implied that the succession could be partly induced by the spatio-temporal patterns of recruitment of M. aeruginosa in Lake Dianchi.
Pages119
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12434
Collection学位论文
Recommended Citation
GB/T 7714
万能. 滇池微囊藻越冬及复苏的生态生理学研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2008.
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