【作者】 王娣娟；

【导师】 杨劭；

【作者基本信息】 华中师范大学 ， 环境科学， 2012， 硕士

【摘要】 在世界范围内,富营养化已经成为影响湖泊水质的主要问题。欧美等国研究证明经典生物操纵是湖泊富营养化和水华治理的有效方法,并且已有很多成功的案例,但是在我国成功的案例却较少。同时,在我国很多湖泊中都养殖有经济型的鱼类,而鱼类是经典生物操纵实施过程中的制约因素。本实验针对我国浅水湖泊中常见的鱼类,分析在水体富营养化的条件下不同鱼类对经典生物操纵的影响,为通过生物操纵的手段治理富营养化的湖泊具有重要的指导意义。本研究在东湖共建立21个围隔,从2011年8月到10月进行围隔实验,为期3个月。在实验系统中通过人工添加大型枝角类大型溞(100ind./L)和几种我国长江中下游鱼类(四种鱼投放量均为50g/m3)至围隔中开展实验。结果显示养殖鲢鱼的围隔与对照相比大型溞密度下降最低；鳙鱼、鲤鱼和鲫鱼的围隔均使大型溞的存活均率大大降低。与此同时,养殖鲢鱼使围格内蓝藻和绿藻的密度较对照组有降低,养殖鲤鱼和鲫鱼使围格内蓝藻密度明显增加。在不同的鱼类以及浮游动植物密度变化的影响下使得各个围隔内的水体物理化学指标均产生了不同的变化。养殖鲢鱼的围隔内水体透明度较养殖其他鱼的围格较高。养殖鲤鱼和鲫鱼的围隔均使水体的TP、TN上升,叶绿素a含量也增加。可见,适当密度的养殖鲢鱼对经典生物操纵有一定的促进作用,而养殖鲤鱼和鲫鱼则不利于经典生物操纵的进行。以围隔实验研究了在低氮和高氮两种不同营养盐水平下鲢鱼对经典生物操纵的影响。结果显示在低氮水平下(TP=50μg/L,TN≤1.5mg/L),添加鲢鱼和Daphnia的围隔对比高氮水平(TP=50μg/L,TN<3mg/L)中透明度较高,总磷、高锰酸钾指数和叶绿素含量均较低,并且蓝藻和绿藻的密度也明显较低。这揭示了在较低的总氮水平下密度合适的鲢鱼对经典生物操纵更能起到积极的促进作用。通过在室内进行的不同鱼类在不同温度下对大型溞的摄食的实验显示了在三种温度水平下,对大型溞摄食最多的为鲤鱼,其次是鳙鱼,最少的为鲢鱼。在30℃时,各种鱼类对大型溞的摄食量均是最高的,其次是25℃。综上所述,在我国养殖有适当密度的适当鱼类的湖泊中开展经典生物操纵来治理湖泊的富营养化是具有极强的可行性的。更多还原

【Abstract】 Eutrophication has become the main problems affecting the lake water quality all around the world. Studies in Europe and the United States have shown that traditional biomanipulation is an effective method dealing with eutrophic lakes and water governance, and many successful traditional biomanipulation exercises have been conducted internationally, but in China the case is less successful. Because a lot of lakes in China are breeding economical fish which is a restricting factor of the implementation of traditional biomanipulation.This paper studied common fish’s effect on traditional biomanipulation in the shallow lakes with eutrophication in China, which has an important significance for dealing with eutrophic lakes by means of traditional bio-manipulation.The experiments were conducted in21experimental enclosures in East Lake. The experiment time was three months from August2011to October. The experiment chose one enclosure only with large Cladocera Daphnia (100ind./L) as control group, the other enclosures were not only with large Cladocera Daphnia but also with fish from the middle and lower reach of the Yangtze River (each amount is50g/m3). The density of Daphnia magna in enclosures with silver carp decreased to the minimum; in bighead carp, common carp and crucian carp enclosures, Daphnia magna survival are greatly reduced compared with the control. Meanwhile, the density of cyanobacteria and green algae in silver carp enclosure is lower than the control group, the density of cyanobacteria in carp and crucian carp enclosures increased significantly. Physical and chemical indicators of water bodies within each enclosure changed differently under the influence of different fish and plankton density. Silver carp enclosure has higher water transparency than others. In the common carp and crucian carp enclosures, the content of water’s TP, TN and chlorophyll a also rise. Accordingly, the appropriate density of silver carp have a certain role in promoting traditional biomanipulation while breeding common carp and crucian carp is not conducive to traditional biomanipulation.This experiment has studied the effect of silver carp in the low and high nitrogen levels on the classical biological manipulation.The results showed that the different total nitrogen nutritional level has different effects on traditional biomanipulation. Low nitrogen levels (TP=50μg/L, TN≤1.5mg/L) contrast of high nitrogen levels (TP=50μg/L, TN≤3mg/L) in the higher degree of transparency, total phosphorus, potassium permanganate index and chlorophyll content were lower, and the density of cyanobacteria and green algae also significantly lower. This reveals the density of silver carp in the lower level of total nitrogen play a positive role in promoting traditional biomanipulation.The indoor experiment of different fish feeding on Daphnia magna at different temperatures shows the most average daily feeding of Daphnia magna is by crucian carp, followed by bighead carp, at least by silver carp at three different temperatures. At30℃, the volume of a variety of fish feeding on Daphnia magna is the highest, followed by25℃.In summary, it is useful to carry out classical biological manipulation for controlling lake eutrophication in appropriate fish lakes of the appropriate density.更多还原