Stable nitrogen isotopic composition of amino acids reveals food web structure in stream ecosystems
Stable nitrogen isotopic composition of amino acids reveals food web structure in stream ecosystems
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氨基酸的稳定氮同位素组成揭示了河流生态系统中的食物网结构
DOI：
10.1007/s00442-014-2936-4
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发表时间：
2014
期刊：
影响因子：
2.7
通讯作者：
Tayasu I
中科院分区：
文献类型：
--
作者：
Ishikawa NF;Kato Y;Togashi H;Yoshimura M;Yoshimizu C; Okuda N;Tayasu I
近年来，在几个简单的食物链系统中，单个氨基酸的稳定氮同位素组成(SIAA)被用来估计动物的营养位置(TPS)。然而，目前尚不清楚SIAA是否适用于更复杂的食物网络分析。在这项研究中，我们测量了溪流大型无脊椎动物、鱼类及其潜在食物来源(陆生C3植物的附生植物和叶落叶)的SIAA，这些食物来自两个河岸景观不同的河流的上下两个地点。谷氨酸和苯丙氨酸稳定的N同位素比值证实，初级生产者(围生植物和C3凋落物)的TP为1，初级消费者(如蚂蚁和陆蝇幼虫)的TP为2。在TP计算之前，我们建立了一个双源混合模型，以估计水生和陆源对二级和更高消费群体(如石蝇幼虫和鱼类)的相对贡献。估计的TPS为2.3-3.5，分别对应于它们的杂食性和肉食性食性。我们发现，与传统的Bulk方法相比，SIAA方法在食物网络分析中具有显著的优势，因为它基于氨基的代谢途径定义了食物网络结构，并且可以在不能使用Bulk方法的条件下估计食物网络结构。我们的结果提供了证据，表明SIAA方法适用于分析复杂的食物网，其中异质资源混合。
The stable N isotopic composition of individual amino acids (SIAA) has recently been used to estimate trophic positions (TPs) of animals in several simple food chain systems. However, it is unknown whether the SIAA is applicable to more complex food web analysis. In this study we measured the SIAA of stream macroinvertebrates, fishes, and their potential food sources (periphyton and leaf litter of terrestrial C3 plants) collected from upper and lower sites in two streams having contrasting riparian landscapes. The stable N isotope ratios of glutamic acid and phenylalanine confirmed that for primary producers (periphyton and C3 litter) the TP was 1, and for primary consumers (e.g., mayfly and caddisfly larvae) it was 2. We built a two-source mixing model to estimate the relative contributions of aquatic and terrestrial sources to secondary and higher consumers (e.g., stonefly larva and fishes) prior to the TP calculation. The estimated TPs (2.3–3.5) roughly corresponded to their omnivorous and carnivorous feeding habits, respectively. We found that the SIAA method offers substantial advantages over traditional bulk method for food web analysis because it defines the food web structure based on the metabolic pathway of amino groups, and can be used to estimate food web structure under conditions where the bulk method cannot be used. Our result provides evidence that the SIAA method is applicable to the analysis of complex food webs, where heterogeneous resources are mixed.