基于稳定同位素的草鱼推水养殖系统食物网的研究

Study on food web of grass carp(Ctenopharyngodon idellus)push-water aquaculture ecosystem by stable isotope analysis

推水养殖系统是集循环养殖、高效集污、生物净化及自动控制等技术为一体的生产方式。但该系统营养物质归趋尚未明晰,造成饵料资源浪费和养殖调控失策。该研究以草鱼(Ctenopharyngodon idellus)推水养殖系统为实验组,以普通池塘养殖系统为对照组,利用稳定同位素[碳(δ13C)、氮(δ15N)]技术研究两种养殖系统生物食物组成和系统食物网结构。结果表明,草鱼推水养殖系统各生物组分δ13C介于(-25.76±0.23)‰^(-22.26±0.20)‰,普通池塘系统δ13C介于(-25.83±0.24)‰^(-22.38±0.15)‰;推水养殖系统各生物组分δ15N介于(6.73±0.08)‰^(12.34±0.11)‰,普通池塘系统δ15N介于(6.73±0.08)‰^(12.14±0.11)‰。稳定同位素混合模型分析结果显示,两组系统中草鱼饲料和底泥碎屑是消费者的主要食物来源。其中,草鱼的主要食物来源是草鱼饲料,鳙(Aristichthys nobilis)的主要食物来源是草鱼饲料、大型浮游动物,鲫(Carassius auratus)的主要食物来源是底泥碎屑,底泥碎屑的主要来源是草鱼饲料。推水养殖系统草鱼饲料对草鱼的食物组成贡献率高于普通池塘系统。因此,采用推水养殖模式,可促进养殖生物对饲料的摄食,提高饲料利用效率。

Push-water aquaculture ecosystem is a kind of production mode which integrates recycling aquaculture,high efficiency sewage collection,biological purification and automatic control technology.However,the fate of nutrients in this system is not clear,which results in the waste of food resources and the improper regulation of aquaculture.Therefore,in this study,Ctenopharyngodon idellus push-water aquaculture ecosystem was used as the treatment group,and common pond aquaculture system as the control group.Stable isotope(δ13C,δ15N)technology was used to investigate the bio food composition and system food web structure of the two aquaculture systems.The results show that the stable carbon isotopeδ13C were(−25.76±0.23)‰−(−22.26±0.20)‰and(−25.83±0.24)‰−(−22.38±0.15)‰in the treatment and control groups,respectively.The stable carbon isotopeδ15N were(6.73±0.08)‰−(12.34±0.11)‰and(6.73±0.08)‰to(12.14±0.11)‰in the treatment and control groups,respectively.The stable isotope mixing model reveals that the artificial feed of grass carp and the sediment detritus were the main food sources for consumers in these two groups.To be specific,the artificial feed of grass carp was the main food source for grass carp;the artificial feed of grass carp and the macrozooplankton were the main food source for bighead carp;and the sediment detritus was the main food source for crucian carp.The contribution rate of forage to the food composition of grass carp in push-water aquaculture ecosystem was higher than that in common pond system.Therefore,the adoption of the former can promote the feed intake of cultured organisms and improve the efficiency of feed utilization.