基于Ecopath模型的西南黄海生态系统结构和能量流动分析

Analysis of structure and energy flow in southwestern Yellow Sea ecosystem based on Ecopath model

构建了包括20个功能组的西南黄海生态通道模型(Ecopath Model)。分析结果表明:各功能组营养级的范围在1. 000~4. 509之间,鸟类、鱼类、头足类等主要高营养级生物的营养级范围为3. 417~4. 509。该生态系统的能量流动主要发生在食物网的低营养级部分,在7个系统整合营养级间,能量传递效率沿食物链逐级降低,各营养级生物的消耗量和产出量也急剧减少。从第I营养级到高营养级间的逐级转换效率分别为11. 33%、13. 16%、15. 50%、14. 67%、13. 61%和15. 68%,系统平均转化效率为13. 22%;来源于碎屑的能量转化效率为13. 35%,来自初级生产者的转化效率为13. 14%。在总能流中,直接来自碎屑的占43%,来自初级生产者的占57%,说明系统的能流通道以牧食食物链为主导。混合营养评价显示,系统生产者碎屑与浮游植物对其他多数功能群有积极影响,蟹类、鲽形目、水母、大型底栖和浮游生物中同类竞争的消极影响尤为明显。西南黄海生态系统总初级生产力与总呼吸量比值为2. 541,Finn’s循环指数和Finn’s循环路径长度分别为3. 983、2. 444。通过模型输出的系统生态参数分析,当前西南黄海生态系统仍处于不成熟的、不稳定的阶段。

20 functional groups based on fish landing from southwestern Yellow Sea were chosen to form the basic components of the Southwestern Yellow Sea Ecosystem( SYSE) Ecopath model. Modelling results showed that the trophic level of all functional groups lies between 1. 000-4. 509 while the range of those functional groups,such as birds,carnivorous fishes and cephalopods having high trophic level lies between 3. 417-4. 509. System energy was mostly distributed in the lower part of trophic level in the food web. In 7 integrated trophic levels where the efficiency of energy transfer increased gradually from low to high levels along the food chain and the consumption and output of different trophic levels increased rapidly. The energy conversion efficient with average 13. 22% was11. 33%,13. 16%,15. 50%,14. 67%,13. 61% and 15. 68% from level I to level Ⅶ,respectively,of which the efficient for debris took up 13. 35% and for primary producer,13. 14%. Energy from primary producer took up57% and debris shared 43% in the SYSE indicating that the grazing food chain dominated the energy flow. Mixed trophic evaluation showed that phytoplankton and debris,as producers of the system,had a positive impact on most other functional groups. The competitions among the groups had clearly negative effects,particularly among the crab,flounder,jellyfish,macrobenthos and plankton. The ratio of total primary productivity to total respiration in the SYSE was 2. 541,and the Finn’s cycle index and the Finn’s cycle path length were 3. 983 and 2. 444,respectively. It concludes that the SYSE was still in an immature and unstable stage according to the ecosystem parameters of the model output.