The ratios of stable isotopes of carbon and nitrogen provide important information on food sources of aquatic organisms and trophic structure of aquatic food webs. For many studies, trophic position and food source are linked to bioaccumulation and trophic transfer of contaminants from prey to predators. In these cases, it is useful to use measurements on whole organisms to make direct comparisons of contaminant bioaccumulation and food web attributes. There is a great deal of variation in methods used for stable isotope analysis, particularly in the selection of tissue type and sample preparation prior to stable isotope analysis. While there have been aquatic studies that examined methodological differences, few have focused on estuarine organisms. In this study, the effects of depuration and tissue dissection on the stable isotope enrichment of common estuarine invertebrates and fish were examined. Homogenized tissues of non-depurated whole organisms were compared to dissected muscle tissue or depurated whole organisms. A 24 h depuration did not change the mean δ15N and δ13C values for most species examined. Additionally, as expected, significant differences in carbon and nitrogen signatures were found when muscle tissues were compared to whole organisms. However, differences were small enough that food source as inferred by δ13C or trophic level as inferred from δ15N would not be inaccurately represented (differences of <1.9‰ for δ13C and <1.2‰ for δ15N). The results of this study suggest that for these common estuarine fish and macroinvertebrates, stable isotopes ratios of samples can be analyzed without depuration in the same way as samples for contaminant analysis, but differences in tissue types must be taken into account when combining data from different sources.

中文翻译：

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在污染物生物积累研究的背景下，样品制备对河口大型动物稳定同位素特征的影响

碳和氮的稳定同位素比为水生生物的食物来源和水生食物网的营养结构提供了重要信息。对于许多研究，营养位置和食物来源与污染物从猎物到捕食者的生物积累和营养转移有关。在这些情况下，使用对整个生物体的测量来直接比较污染物的生物积累和食物链属性是很有用的。用于稳定同位素分析的方法有很大差异，特别是在稳定同位素分析之前选择组织类型和样品制备方面。虽然有研究方法差异的水生研究，但很少有人关注河口生物。在这项研究中，检查了净化和组织解剖对常见河口无脊椎动物和鱼类的稳定同位素富集的影响。将未净化的完整生物体的均质组织与解剖的肌肉组织或净化的完整生物体进行比较。24 小时净化没有改变大多数检查物种的平均 δ15N 和 δ13C 值。此外，正如预期的那样，当将肌肉组织与整个生物体进行比较时，发现碳和氮特征存在显着差异。然而，差异足够小，以至于 δ13C 推断的食物来源或 δ15N 推断的营养水平不会被不准确地表示（δ13C 的差异 <1.9‰ 和 δ15N 的 <1.2‰ 差异）。这项研究的结果表明，对于这些常见的河口鱼类和大型无脊椎动物，