黄海小黄鱼不同组织中δ15N的分布特征r及其生态学意义

摘要

The stable nitrogen isotope ratio (δ15N) has been widely used in the analysis of marine ecosystem food webs and nutrient dynamics. It provides a powerful tool for estimating the trophic positions of consumers in food webs. Stable isotope analysis of fishes is often performed using muscle samples to study trophic position relationships as well as food webs in marine ecosystems; however, it requires the sacrifice of fishes. While few studies have reported the composition of stable isotopes in the different tissues and organs, fewer domestic studies have reported the δ15N value in the viscera, otolith, gill, fin, and scale to evaluate diet information, trophic position relationships, and food web analyses of ecosystems, and notably, the composition and measurement of the stable isotopic. The δ15N values of the muscle, viscera, otolith, gill, fin, and scale were determined by isotope ratio mass spectrometry, and statistical analysis was performed. The δ15N distribution characteristics in different tissues of small yellow croaker (Larimichthys polyactis) were investigated. The results showed that the δ15N values between the viscera, gill, fin, scale, and muscle were not significantly different (P>0.05). The highest δ15N levels was observed in the muscle followed by the scale, fin, viscera, and gill; and the average value ranged from 10.29‰ to 10.72‰. However, the δ15N value in the otolith was much lower than that in other tissues and was significantly different among other tissues and organ samples (P<0.01), and the average was 7.08‰. These results indicated that the otolith was different from the other tissues. Pearson correlation analysis showed that the correlation of δ15N between different tissues and the muscle was strong, and the correlation coefficient was more than 0.72. It is feasible to use tissues other than the muscle to study marine ecosystem dynamics. Our findings advocate the analysis of δ15N in tissues and organ to establish trophic level, food web structure, and mean trophic level in aquatic ecosystems.%本研究利用同位素质谱仪测定了黄海小黄鱼(Larimichthys polyactis)的肌肉、内脏、鱼鳃、鳞片和背鳍等不同组织器官中的氮稳定同位素的比值(δ15N).结果显示,内脏、鱼鳃、背鳍、鳞片与肌肉间 δ15N的平均值范围为10.29‰～10.72‰,无显著差异(P>0.05);而耳石中的 δ15N值低于其他组织器官中的 δ15N值,其平均值为7.08‰,差异极显著(P<0.01),可见耳石与其他组织器官中 δ15N值的组成明显不同.Pearson相关分析表明,内脏、背鳍、鳞片、鱼鳃、耳石与肌肉中的 δ15N值呈极显著正相关,其Pearson相关系数均>0.72,表明其他组织器官中 δ15N值可替代肌肉研究鱼类营养等级和构建海洋食物网结构的方法具有可行性.