Stable isotopes from multiple tissues reveal diet switching in sharks
Stable isotopes from multiple tissues reveal diet switching in sharks
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DOI：
10.3354/meps302199
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发表时间：
2005-01-01
影响因子：
2.5
通讯作者：
Fisk, AT
中科院分区：
文献类型：
--
作者：
MacNeill, MA;Skomal, GB;Fisk, AT
海洋系统中的食物网络关系传统上是通过胃内容物分析来定义的，但最近出现了生物化学技术来验证和拓宽临时饮食模式。稳定同位素分析已成为评估水生系统中这些关系的实用工具；然而，常规的肌肉组织采样只能捕获每种动物可获得的营养信息的一部分。我们比较了来自西北大西洋的蓝鲨Prionace gluca、尖吻短鳍金枪鱼和普通短鳍金枪鱼的肝脏、肌肉和软骨的Delta N-15和Delta C-13值，以展示多组织采样如何捕捉到仅通过肌肉组织看不到的摄食关系。具体地说，我们在春季的短鳍金枪鱼中展示了头足类到蓝鱼的食性转换的证据，发现蓝鲨和普通脱粒鱼的食性在全年都是一致的。我们的结论是，在多个组织中观察到的稳定同位素值之间的一致性表明，该鱼处于稳定状态，与其饲料的同位素比例有关，因此，应将多个组织用于大型中上层鱼类的营养评估。需要进一步的实验来量化稳定同位素在不同组织和物种中的周转，以提高稳定同位素分析的准确性。
Food web relationships in marine systems have traditionally been defined through stomach content analysis, but biochemical techniques have recently emerged to validate and broaden temporal diet patterns. Stable isotope analysis has become a practical tool for evaluating these relationships in aquatic systems; however, routine sampling of muscle tissue captures only part of the trophic information available from each animal. We compared delta N-15 and delta C-13 values among liver, muscle and cartilage in the blue shark Prionace glauca, shortfin mako Isurus oxyrinchus, and common thresher Alopias vulpinus from the northwest Atlantic to show how multiple-tissue sampling captured feeding relationships which would have been invisible to muscle tissue alone. Specifically, we demonstrated evidence of a cephalopod to bluefish Pomatomus saltatrix diet switch in the shortfin mako in spring, and found that the blue shark and common thresher have consistent diets throughout the year. We concluded that consistency observed among stable isotope values in multiple tissues implied that the fish were in steady-state with the isotope ratios of their diet and that multiple tissues should be used in trophic assessments of large pelagic fishes. Further experiments to quantify the turnover of stable isotopes in different tissues and species are needed to improve the accuracy of stable-isotope analyses.