【作者】 刘其根；

【导师】 陈立侨；

【作者基本信息】 华东师范大学 ， 动物学， 2005， 博士

【摘要】 千岛湖,位于人口稠密经济发达的长江三角洲地区西南缘,是我国的一座特大型水库,在水力发电、水资源供应、旅游、防洪和水产养殖等多方面发挥着重要作用。千岛湖的生态环境,不但是区域社会和经济发展的支柱,同时也对保障钱塘江中下游的环境质量和水体功能具有举足轻重的意义。尽管其面积(583km~2)仅为太湖的约1/4,但其储蓄的水量(176×10~8m~3)却在太湖的3倍以上,因此在水体富营养化日益严重、许多城市纷纷面临水质型缺水的长江三角洲地区,千岛湖的水资源日显珍贵。此外,千岛湖生态系统还要为10,442 km~2流域的社会发展无可推卸地继续承担污染物净化等生态服务,维护和保障千岛湖生态系统的健康和稳定具有重要意义。 近几十年来,虽然和我国的大多数湖泊(水库)一样,随着社会的发展,输入千岛湖的营养物也在不断增加,从而构成了对水体生态系统持续不断的环境压力。但是,和许多其他湖泊不同的是,千岛湖的水环境保护一直受到了当地政府和人民的高度重视,不但点源污染得到了很好的控制,而且千岛湖周围培植的茂密森林,也极大地削减了输入千岛湖的各种面源污染,从而得以使千岛湖的水质长期以来一直保持在国家Ⅰ类地表水标准。 然而就是环境如此优异的千岛湖,还是在1998、1999年连续2年暴发了大面积的蓝藻水华,并使水质产生了严重异味,从而引起了社会各界对千岛湖水环境保护的广泛关注和重视。水华的暴发也使湖泊渔业发展和水环境保护的关系问题再次成为争议的焦点。湖泊的渔业发展因此面临了生死存亡的抉择。 为了探寻千岛湖生态健康迅速恶化的成因,解决湖泊渔业发展和环境保护的矛盾,本研究以千岛湖各种历史资料为依据,对千岛湖水华的形成原因进行了深入的探讨,提出了对千岛湖水华形成机制的全新认识;在此基础上本研究也提出了以水环境保护为目的而开展渔业利用的保水渔业基本构想,并在千岛湖开展了长达数年的原位实验研究。同时,针对千岛湖生态学研究历史资料相对缺乏的现状,又开展了对千岛湖的基础生态学研究,就千岛湖的各种理化环境因子和生物群落特征进行了深入的调查,特别是对千岛湖的各种生态因子的垂直变动规律进行了探究,从而弥补了千岛湖这些方面研究的历史空白。同时,这些研究结果,不但为了解实施保水渔业对千岛湖的影响提供了佐证,同时也为了解和预测千岛湖生态系统的发育和演化提供了历史资料,为千岛湖水环境和渔业的科学管理和更多还原

【Abstract】 Lake Qiandaohu, located at the southwest edge of the Chinese most populated and economically developed Region, the Yangtze Delta, is one of the largest reservoirs in China. It has been playing a significant role in electric power generating, water supply, tourism, flood prevention and fishery etc., since its foundation in 1959. The lake ecosystem, not only serves as the underpinning to the regional social and economical development, but is also of great significance to assure the better environment quality and the water function of the mid-lower reaches of the Qiantangjiang River. The volume of L. Qiandaohu (176×10~8 m~3) is over 3 times as large as that of Lake Taihu, the Chinese third largest lake in the same region, though its surface area (583 km~2) is only about 1/4 of Lake Taihu. Thus water resources in L. Qiandaohu are becoming even more important, due to the widely water shortage faced in the region caused by poor water quality resulted from the increasing aquatic eutrophication. In addition, the lake ecosystem would inevasibly continue the ecological service such as pollutants purification etc. to the whole 10,442 km~2 drainage basin. So it is important to maintain and safeguard the health and stability of the lake ecosystem.In the recent decades, L. Qiandaohu, like most other lakes (and/or reservoirs) in China, has been continually challenged by the increasing influx of allochthonous nutrients, as the social development such as the rapid growth of human population, urbanization, and the development of both agriculture and industry. However, the stress of L. Qiandaohu by the increasing nutrients loading has been greatly reduced by the continual efforts paid by the local government and people through the control of point source of pollution and the shrinkage of non-point source of pollution by establishing forests round the lakes, which is quite different from most other lakes. It is these efforts that make the lake water quality to be continually maintained at the national surface water Class I.Unfortunately, even in such well-protected Lake Qiandaohu, a large algal (cyanobacterial) bloom had still repeatedly occurred in 1998 and 1999 and produced severe off-flavors to the water, which stimulated a wide concern for the better protection of lake environment and an urgent call for the exploration to the possiblecause of algal bloom and the corresponding technology of bloom control and prevention. The repeated outbreak of algal bloom also made the relationship between lake fishery development and aquatic environment protection to be the focus of dispute. "To be, or not to be", it was then a question for the lake fishery.In order to explore the cause of the rapid ecological deterioration of the lake ecosystem, and to find out a solution to harmonize lake fishery and environment protection, this study, based on historical data, made a scrutiny to all the blooming-related ecological factors and finalized a hypothesis to interpret the ecological mechanism of algal bloom occurred in the lake. This new interpretation of algal bloom mechanism, led us to the formulation of the theory, which we called aquatic environment protection oriented (AEPO) fishery, to develop lake fishery for the purpose of environment protection, that is, to improve the balance between top down and bottom up effects for the algae by stocking filter feeding Chinese carps, the silver carp and bighead carp for algal bloom prevention. We tested this theory by using an in-situ experiment in the lake in years. Meanwhile, due to the shortage of historical ecological study in the lake, a further ecological study on the basic chemophysical environment, and plankton community was carried out, especially the vertical variations of the major parameters were investigated, which not only supplied a gap to the ecological study of the lake, but also served as an evident of the effects resulted from the trial experiment of AEPO fishery in the lake. Besides, it would no doubt serve for the future research as historical reference data to the better understanding o更多还原