【作者】 宋兵；

【导师】 陈立侨； 陈勇；

【作者基本信息】 华东师范大学 ， 动物学， 2004， 博士

【摘要】 太湖是中国第三大淡水湖，水域面积2338km~2，占太湖流域湖泊总面积的74％，具有蓄洪、供水、渔业、航运、旅游、科研等多方面的生态服务功能，为太湖流域的可持续发展提供了不可替代的自然支持系统。近40年来，太湖流域经济发展极为迅速，1999年以仅占全国的0.4％土地面积创造了占全国10.1％的GDP。在经济高速发展的同时，太湖所承受的捕捞强度和污染负荷日益增加。湖泊水质平均十年下降一个等级，水体富营养化严重，生物多样性显著下降，渔业捕捞面临严重的小型化和低值化问题。2000年，太湖被国家环保总局列为“三河”“三湖”水污染防治计划及其规划的重点对象之一。计划在1997～2010年间投资204.3亿元，解决太湖的富营养化问题。此外，每年为维持太湖渔业资源所投放的鱼苗高达410～924×10~4尾。然而，有关太湖污染治理和渔业管理的工作尚未在“生态系统的架构”下统一管理目标和行动。比如在强调污染源控制的同时，湖泊生态系统的恢复工作尚未充分展开。渔业生产仍然着眼于短期利益，捕捞结构不尽合理，捕捞强度控制不力，过度的捕捞和养殖仍然在加速破坏太湖生态系统的正常结构。 为探讨太湖生态健康恶化的成因，解决其环境污染和渔业资源衰退的问题，有关科研单位对太湖的环境、生态、渔业和生物资源等，进行了多次大规模的调查和长期的监测统计工作，开展了许多深入的研究，积累了相当全面、系统的基础资料。但是，以往的研究大多只针对生态系统中一种或几种环境、生物因子，未能充分整合有关太湖完备的基础数据和资料。采用基于食物网的计算机模型，从整个生态系统的角度来探讨渔业和环境影响的研究在国内也不多见。本论文综合运用生态学、水生生物学、生态经济学以及计算机科学的理论和方法，构建了反映太湖生态系统结构和发育过程的EwE模型，得出了量化和综合的结果，对太湖的渔业和环境决策也具有一定的指导意义。该论文首次从生态系统发育(ecosystem development)的角度，指出“幼态化”是太湖生态系统结构的现状特征，其发育的过程是由“成熟态”向“幼态”逆向演替；对太湖生态系统的发育进行了动态模拟，得出了与其发育进程相一致的结果，分析了渔业和富营养化 摘要 一一一一一一一一---一-一--一一一对生态系统发育影响的“下行”和“上行”机制;对太湖生态系统各功能组以及渔业之间的相互关系进行了量化分析，并对相关捕捞策略进行了动态模拟，指出适当降低捕捞强度，尤其是控制对顶级捕食者的捕捞，可显著改善太湖生态系统的结构，提高渔业收益;运用生态系统服务和自然资本评价的理论和方法;首次对太湖生态系统的服务价值进行了初步研究，指出其服务价值主要由间接使用价值构成，太湖生态系统的服务功能在30年间遭到了严重破坏。具体结果及结论如下。1.太湖生态系统结构的Ecopath模型分析 构建了一个具有22个功能组的Ecopath模型，并利用其基本分析和网络分析(network analysis)功能，对1 991~1 995年间太湖生态系统的结构和特征进行了量化和系统的研究。整个太湖生态系统主要由4个整合营养级构成。由于水体的富营养化，营养级I的营养流量(湿重)达9956.107灯bllZ行ear，然而其利用率极低，浮游植物和碎屑的生态营养效率(ee以rophic efficiency)仅为0.413和0.326。小型鱼虾类如刀鳞、新银鱼、野杂鱼和虾蟹类等在系统中占优势地位，其生产量和营养流量分别占所有鱼虾类的84.26%和86.18%。刀鳞、野杂鱼等低值鱼类与新银鱼之间的饵料重叠指数较高，分别为0.963，0.845，表明其间存在激烈的饵料竞争关系。红白鱼对大多数鱼虾类的混合营养负效应(negative而xedthophic effect)都较低，对新银鱼和虾蟹类反而表现出正值。渔业捕捞对大部分鱼虾类，尤其是对大中型鱼类的混合营养效应都表现出较高的负值，其影响程度大大超过了系统中的顶级捕食者。过高的净初级生产力(NPP)、净初级生产力/呼吸(NPP瓜)以及较低的联结指数(CI)、系统杂食指数(soI)和Finn、循环指数(FCI)等，则表明太湖是一个典型的尚处于“幼态”的生态系统。2.太湖生态系统发育的Ecopath比较研究 采用Eeopath，构建了太湖1 960(1 961~1 965)，1 980(1 981~1 985)和1990(1991一1995)年代的生态系统模型。比较了这3个模型在基本生态参数、系统总体特征、食物网关系以及营养流的分布和循环等方面的差异。模型参数估计表明，大中型鱼类尤其是肉食性鱼类的生物量在3个年代段均呈现下降趋势，而小型鱼虾类生物量则显著上升。各种鱼虾类的P忍系数以及捕捞死亡占鱼虾类生产量的比例在3个年代段均显著上升，表明捕捞压力的日益增强。初级生产力、总 摘要 一一一一一一-一一一-一----生物量以及总物流在3个年代段均显著上升。尤其是在1980年代至1990年代之间，上述指标分别增长了135.7%、40.9%和49.5%。因沉积而脱离系统的碎屑，1980年代比1960年代增长24%，1990年代比1980年代增长了4.42倍，表明虽然系统的总体规模?更多还原

【Abstract】 Taihu lake is the third largest freshwater lake in China with an area of 2338 km2, which is 74% of the total area of all lakes in Taihu basin. Its aquatic system provides lots of ecosystem services such as flood controlling, water supplying, fishery, shipping, touring and culture, and affords a undisplaced natural supporting system for the sustainable social and economic development of Taihu basin. In the recent 40 years, Taihu lake sustained more and more stress from fisheries and pollution. The water quality reduced one class every 10 years and the water body sustained serious eutrophication. The biodiversity declined remarkably and the composition of fishery products was composed of small species with lower value. In 2000, Taihu lake was listed in "water pollution prevention and control on the three rivers and three lakes" by the state environmental protection administration of China. The government planed to solve its eutrophication problem with a investment of 20.43 billion yuan RMB in 1997-2010. And 4.1-9.24 million fry was put into Taihu lake every year to maintain the fishery resources. But the efforts of pollution controlling and fishery management have not been integrated in the "frame of ecosystem". As the pollution sources were controlled, the rebuild of the aquatic ecosystem was not processed on schedule. The composition of catches was not reasonable and the fishing intensity was not controlled effectively yet. The excessive fishery and aquaculture kept on destroying the structure of Taihu lake ecosystem.For revealing the facts affects the health of Taihu ecosystem and figuring out the problems of environmental pollution and fishery degradation, some academic groups have carried out several large-scale investigations and long-term monitoring on the environment, ecology, fishery and biological resources of Taihu lake. Lots of the researches have studied the relationship between pollution, fishery and ecology, andprovided comprehensive and systematic information about Taihu ecosystem. But the former studies just focused on one or several environmental and biological facts of the system. Most of the basal data was not utilized and integrated in them. The study based on food-web models, which was constructed in the "frame of ecosystem", was still few in the study of lake ecosystem in China. The paper constructed static and dynamic models using Ecopath with Ecosim, which was a ecosystem modeling software based on food-web. The structures, functions and services value of Taihu lake ecosystem in different decades were studied by 3 static mass-balanced models as viewed form maturity and ecosystem development. The developments of the ecosystem in the stress of fishery and pollution were simulated by several dynamic food-web models. The mechanisms of eutrophication and fishery degradation were revealed, and the effects of future alternative management strategies on ecosystem and fishery profits were evaluated. The results and conclusions are described in detail as follows. 1. The modeling analysis of the structure of Taihu lake ecosystemUsing the basic and network analysis function of Ecopath, a mass-balanced model with 22 groups was constructed to proceed a quantitative and synthetic analysis for the structure of Taihu lake ecosystem. The Taihu lake ecosystem was composed of 4 aggregated trophic levels. Because of the eutrophication, the throughput of trophic level I was as high as 9956.11t/km2/y. But the ecotrophic efficiency (EE) of phytoplankton and detritus were only 0.413 and 0.362. It meaned that the utilizing efficiency of trophic level I was very low. Small pelagic species such as tapertail anchovy (TapA), silver fish (SilF), macrocrustacean (MacC) and other pelagic fishes (OthF) dominate the ecosystem. The prey overlap index of TapA, OthF, SilF and MarC were higher than 0.8, which meant that there was intensive food competition between the small pelagic species. The negative mixed thophic effects (MTE) of large culters (LarC) on most of its preys were much lower than the trawl fishery. On the oth更多还原