基于稳定性同位素技术分析池塘养殖中华绒螯蟹成蟹各种食物的贡献率

Analysis of the contribution of various food items to adult Chinese mitten crabs in pond culture using stable isotope techniques

为确定池塘养殖中华绒螯蟹成蟹的食物来源及贡献比例,采用稳定性同位素技术,分析了池塘养殖的中华绒螯蟹成蟹肌肉、硬颗粒饲料、软颗粒饲料和池塘常见天然饵料中的碳、氮稳定性同位素特征。结果显示,中华绒螯蟹肌肉中的碳稳定性同位素(δ^(13)C)为(-19.86±0.03)‰,氮稳定性同位素(δ^(15)N)为(7.47±0.03)‰。配合饲料和池塘中天然饵料的δ^(13)C值分布范围为-27.04‰~-22.87‰,δ^(15)N值分布范围为1.46‰~7.20‰。通过食源贡献率分析,在养殖池塘中,中华绒螯蟹的第一食物来源为配合饲料,其中硬颗粒饲料占18.68%,软颗粒饲料占16.81%,其余饵料的贡献率由大到小依次为底栖生物、浮游动物、浮萍、本底中华绒螯蟹、沉积物、伊乐藻和浮游植物,贡献率分别为16.37%、12.72%、8.29%、7.91%、7.90%、5.79%和5.53%。综上,在养殖池塘中,硬颗粒饲料和软颗粒饲料为中华绒螯蟹成蟹的主要食物,两者约占总食物贡献的35.49%,底栖生物、浮游动物和水生植物等天然饵料的食物贡献率合计约为56.60%。

To determine the food sources and contribution proportion of adult Chinese mitten crab(Eriocheir sinensis)cultured in pond,stable isotope technique was used to analyze the^(δ)13C and^(δ)15N stable isotope characteristics of E.sinensis muscle,hard pellets,soft pellets and common natural food in earthen ponds.The values of^(δ)13C and^(δ)15N in the muscle of E.sinensis was(-19.86±0.03)‰and(7.47±0.03)‰respectively.The^(δ)13C values distribution of formula diets and natural food in the ponds ranged from-27.04‰to-22.87‰,and^(δ)15N values ranged from 1.46‰to 7.20‰.Through the analysis of food source contribution rate,the first food source of adult E.sinensis in the earthen pond was hard pellets which accounted for 18.68%of contribution,and the second food source was soft pellet which accounted for 16.81%of contribution.The contribution of other diets from large to small were benthos,zooplankton,Lemna minor L.,background crab,sediment organic matter,Elodea nuttallii and phytoplankton,they accounted for 16.37%,12.72%,8.29%,7.91%,7.90%,5.79%and 5.53%,respectively.In summary,pellets and soft diet were the main diets for adult E.sinensis reared in the earthen pond,accounting for about 35.49%contribution to the total diet,and the contribution rate of natural food such as benthos,zooplankton and aquatic plants was about 56.60%.