Stable hydrogen and oxygen isotopes in aquatic food webs are tracers of diet and provenance
Stable hydrogen and oxygen isotopes in aquatic food webs are tracers of diet and provenance
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DOI：
10.1111/1365-2435.12054
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发表时间：
2013-04-01
影响因子：
5.2
通讯作者：
Hobson, Keith A.
中科院分区：
文献类型：
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作者：
Soto, David X.;Wassenaar, Leonard I.;Hobson, Keith A.
动物组织中稳定的氢和氧同位素(2H和18O)是陆地迁徙生态学和野生动物取证的可靠示踪剂。然而，由于环境水和食物的输入，这些同位素在水生生态系统中的行为及其作为食物和产地示踪剂的潜力是复杂的。我们进行了以水族馆为基础的受控实验，以量化水生物种内部和之间驱动氢和氧同位素流动的机制。在6个等温处理中，代表两个营养水平的两个水生物种(摇蚊和网纹摇蚊)的水和食物的同位素组成发生了变化。这两个物种都是从幼年成长到成年的，以确保组织与它们的饮食和环境条件(环境水、食物、溶解氧)保持同位素平衡。我们测量了2H或18O的水、溶解氧、饮食、组织蛋白和血脂。利用稳态多水池质量平衡模型，对水生生物组织形成过程中的氢、氧同位素流动进行了参数化。环境H2O对两个物种的组织蛋白H和O同位素的贡献很大(2H和>分别为3050%和80%；18O)。对~2H有明显的营养效应，对~(18)O(约千分之15)有水和蛋白质的同位素分辨作用。我们的同位素数据和模型揭示了2H和18O测量在水生食物网生态研究中的潜在应用和注意事项。组织2H值可能是水生食物网中的补充营养示踪剂，但只有在适当考虑主要控制机制的情况下(即蛋白质合成过程中与水的氢同位素交换和代谢水的影响)。另一方面，18O的测量反映了水的测量，因此可以用于预测水生生物起源的同位素分配，因为没有复杂的营养效应，但可能需要更多的18O现场数据和提高的分析精度，才能更好地确定生态应用的优势。
The stable hydrogen and oxygen isotope (2H and 18O) composition of animal tissues are well-established tracers for terrestrial migration ecology and wildlife forensics. However, the behaviour of these isotopes in aquatic ecosystems and their potential as tracers of diet and provenance are complicated because of inputs from ambient H2O and diet. We conducted controlled aquaria-based experiments to quantify the mechanisms that drive the H and O isotopic flow within and among aquatic species. The isotopic composition of water and diet of two aquatic species (Chironomus tentans and Poecilia reticulata), representing two trophic levels, was varied in six isothermal treatments. Both species were raised from juvenile to adult to ensure that tissues were in isotopic equilibrium with their dietary and environmental conditions (ambient water, food, dissolved oxygen). We measured water, dissolved O2, diet, tissue protein and lipids for 2H or 18O. The flows of H and O isotopes for tissue formation in aquatic organisms were parameterized using a steady-state multi-pool mass-balance model. The ambient H2O contribution to tissue protein H and O isotopes in both species was significant (3050% for 2H and >80% for 18O). An apparent trophic effect for 2H and isotopic discrimination between water and protein for 18O (c. 15 parts per thousand) were identified. Our isotopic data and model revealed potential applications and cautions in using 2H and 18O measurements for ecological studies in aquatic food webs. Tissue 2H values may be a complementary trophic tracer in aquatic food webs, but only when the main controlling mechanisms are properly accounted for (i.e., H isotopic exchange with water during protein synthesis and influence of metabolic water). Measurements of 18O, on the other hand, reflect that of water and so can be used for predicting isotopic assignment to origin of aquatic organisms as there is no complicating trophic effect, but more 18O field data and improved analytical precision may be required to better establish the strengths to ecological applications.