人工饵料对主养黄颡鱼和主养草鱼池塘沉降颗粒有机质贡献的同位素示踪

研究假定池塘中沉降颗粒有机质主要来自残饵、粪便和悬浮颗粒物三种的混合， 利用碳氮稳定性同位素示踪技术对主养草鱼（Ctenopharyngodon idellus）和主养黄颡鱼（Pelteobaggrus fulvidraco）池塘沉降颗粒中人为有机质（残饵）来源进行定量研究， 同时分析了不同主养模式池塘沉降颗粒中碳氮营养物质的变化特征。结果表明: 两种主养模式池塘沉降颗粒中总氮（Total nitrogen， TN）、总碳（Total carbon， TC）、总有机碳（Total organic carbon， TOC）以及总有机氮（Total organic nitrogen， TON）都呈现出从养殖初期到末期逐渐降低的趋势； 并且主养黄颡鱼池塘颗粒沉降物中TN、TC、TON和TOC含量均显著高于主养草鱼池塘。主养黄颡鱼池塘沉降颗粒有机质碳氮稳定性同位素（13C和15N）平均值分别为-25.3和6.2； 主养草鱼池塘沉降颗粒有机质13C和15N的平均值分别为-25.4和5.9。利用同位素混合模型计算出两种主养模式池塘沉降颗粒中人为有机质（残饵）贡献率分别为15.6%-35.4%（主养黄颡鱼池塘）和30.1%-70.1%（主养草鱼池塘）， 统计分析结果表明， 两种主养模式池塘从养殖初期到末期沉降颗粒中饵料贡献率均显著降低（主养黄颡鱼池塘: r=-0.537，P0.05； 主养草鱼池塘: r= -0.800， P0.01）。  

CARBON AND NITROGEN STABLE ISOTOPES AS TRACERS TO SOURCE ARTIFICIAL ORGANIC MATTER OF SEDIMENTARY PARTICLE IN GRASS CARP AND YELLOW CATFISH POLYCULTURED PONDS

Carbon and nitrogen stable isotopes were as tracers to source artificial organic matter in which Ctenopha-ryngodon idellus or Pelteobaggrus fulvidraco were mainly cultured, and meanwhile the characteristic of carbon and nitrogen nutrient in the deposited particulate matter in different culture modes were also analyzed. Results showed that Total nitrogen (TN), Total carbon (TC), Total organic carbon (TOC) and Total organic nitrogen (TON) concentrations of the deposited particulate matter declined from April to October. Nitrogen and carbon concentration in sedimentary par-ticles of Pelteobaggrus fulvidraco ponds were significantly higher than that of Ctenopharyngodon idellus ponds. The average content of 15N and 13C of organic matter in the deposited particulate matter were 6.2 and -25.3 in Pel-teobaggrus fulvidraco-cultured ponds, 5.9 and -25.4 in Ctenopharyngodon idellus-cultured ponds, respectively. The contribution rate of residual feeds to the organic matter in the deposited particulate matter ranged from 15.6% to 35.4% in Pelteobaggrus fulvidraco-cultured ponds and from 30.1% to 70.1% in Ctenopharyngodon idellus-cultured ponds. Meanwhile, the contribution of residual feeds to organic matter in two polycultured models significantly de-creased during this cultural period (Pelteobaggrus fulvidraco-cultured ponds, r= -0.537, P0.05; Ctenopharyngodon idellus-cultured ponds, r= -0.800, P0.01).