基于Ecopath模型分析分水江水库生态系统结构和功能

Structure and function of Fenshuijiang Reservoir ecosystem based on the analysis with Ecopath model

根据2008—2009年浙江分水江水库渔业资源和生态环境调查数据,采用Ecopathwith Ecosim软件构建了分水江水库的物质平衡Ecopath模型.模型构成包括鲢、鳙、鳊、花鱼骨、翘嘴鲌、鲴类、其他鱼类、寡毛类、水生昆虫、浮游动物、浮游植物、有机碎屑等14个功能组,较好地模拟了分水江的水库生态系统.结果表明:分水江水库生态系统包含5个营养级,且营养物质流动主要发生在前3个营养级.牧食食物链和碎屑食物链是系统中的主要能流,但是食物网结构较简单,容易受到外界干扰的影响.转移效率在低营养级较低,表明系统的能量利用较低,过多的营养物质储存在系统中可能导致富营养化的发生.较低的联结指数、系统杂食性系数、Finn氏循环指数以及Finn氏平均路径长度值都表明该生态系统处于不稳定状态,而生产量/总呼吸和生产量/生物量的值较高,说明此生态系统的初级生产力远高于其呼吸量,系统处于生态发育前期.分水江水库由于发育历史较短,仍处于由不成熟向成熟发育的过程中.

Based on the 2008-2009 survey data of fishery resources and eco-environment of Fenshuijiang Reservoir,a mass balance model for the Reservoir ecosystem was constructed by Ecopath with Ecosim software.The model was composed of 14 functional groups,including silver carp,bighead carp,Hemibarbus maculates,Cutler alburnus,Microlepis and other fishes,Oligochaeta,aquatic insect,zooplankton,phytoplankton,and organic detritus,etc.,being able to better simulate Fenshuijiang Reservoir ecosystem.In this ecosystem,there were five trophic levels（TLs）,and the nutrient flow mainly occurred in the first three TLs.Grazing and detritus food chains were the main energy flows in the ecosystem,but the food web was simpler and susceptible to be disturbed by outer environment.The transfer efficiency at lower TLs was relatively low,indicating that the ecosystem had a lower capability in energy utilization,and the excessive stock of nutrients in the ecosystem could lead to eutrophication.The lower connectance index,system omnivory index,Finn＇s cycled index,and Finn＇s mean path length demonstrated that the ecosystem was unstable,while the high ecosystem property indices such as Pp/R and Pp/B showed that the ecosystem was immature and highly productive.It was suggested that Fenshuijiang Reservoir was still a developing new reservoir ecosystem,with a very short history and comparatively high primary productivity.