基于碳、氮稳定同位素技术分析黄鳝对稻田饵料资源的利用特征

Analysis of utilization characteristics of Monopterus albus to feed resources in rice field based on stable carbon and nitrogen isotopes

为探讨黄鳝对稻田资源的利用特征,连续监测水稻生长期内(6—10月)黄鳝潜在饵料资源的碳、氮稳定同位素值变化,利用IsoSource软件计算不同食物对消费者的贡献率,并根据营养级公式计算消费者的相对位置,应用“简化食物网”原则,构建稻鳝共作水体食物网,分析其结构特征。结果表明:6—10月,稻鳝共作水体的δ13 C值为-31.364‰—13.205‰,δ15 N值为-1.444‰—10.082‰。黄鳝的主要能量来源是沉积物、腐殖质、水生昆虫、寡毛类、浮萍和泥鳅;穗花狐尾藻、水花生和双穗雀稗固定的碳未流向黄鳝。水生昆虫、寡毛类贡献最大,贡献率平均值为68%,其次是泥鳅,为19.5%,螺蛳和浮萍贡献率为4.1%和3.3%,沉积物和腐殖质的贡献率较少,分别为1.9%和1.1%。黄鳝的营养级为(3.17±0.36),泥鳅的营养级为(3.22±0.21),食蚊鱼的营养级为(2.36±0.15),克氏原螯虾的营养级为(2.10±0.13),水生昆虫、寡毛类的营养级为(1.92±0.36),螺蛳的营养级为(2.00±0.08)。研究表明,泥鳅和螺蛳是仅次于水生昆虫、寡毛类被黄鳝摄食的种类,同时螺蛳也是泥鳅、食蚊鱼、克氏原螯虾等次级消费者的摄食来源之一,建议在稻鳝共作模式中投放一定比例的螺蛳。此外,建议在放养黄鳝苗种的同时,投放一定比例的适口泥鳅以促进黄鳝摄食生长。

In order to explore the utilization characteristics of Monopterus albus to rice field resources,the carbon and nitrogen stable isotope values of potential feed resources of Monopterus albus during the rice growing period(June-October)were monitored continuously.The contribution rates of different foods to consumers were calculated by IsoSource software,and the relative positions of consumers were obtained according to the formula of nutrition grade.The principle of“simplifying food web”was applied to construct the common feed resources of rice-eel co-culture system.The results showed that between June and October,theδ13 C andδ15 N values of rice eel co-culture water bodies were-31.364‰-13.205‰and-1.444‰-10.082‰.The main energy sources of Monopterus albus were sediments,humus,aquatic insects,oligochaetes,duckweed and loach.Fixed carbon of Myriophyllum spicatum,Alternanthera philoxeroides and Paspalum paspaloides did not flow to Monopterus albus.The contribution of aquatic insects and oligochaetes was the largest,with an average contribution rate of 68%,loach was the second,with a contribution rate of 19.5%,the contribution rate of snail and duckweed were 4.1%and 3.3%,respectively,while thd contribution rate of sediment and humus were 1.9%and 1.1%,respectively.The trophic levels of Monopterus albus,loach,mosquito fish,Procambarus clarkii,aquatic insects and Oligochaeta were(3.17±0.36),(3.22±0.21),(2.36±0.15),(2.10±0.13),(1.92±0.36)and(2.00±0.08),respectively.The results showed that loach and snail were the second only to aquatic insects and oligochaetes,which were eaten by Monopterus albus.At the same time,snails were also one of the feeding sources of loach,mosquitofish,crayfish and other secondary consumers.Therefore,it was suggested that a certain proportion of snails should be stocked in the rice-eel co-culture system.In addition,a certain proportion of loach should be stocked in order to promote Monopterus albus feeding while the eel fries were released.