Combined use of radiocarbon and stable carbon isotopes for the source mixing model in a stream food web
Combined use of radiocarbon and stable carbon isotopes for the source mixing model in a stream food web
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DOI：
10.1002/lno.11541
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发表时间：
2020-07-06
影响因子：
4.5
通讯作者：
Power, Mary E.
中科院分区：
文献类型：
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作者：
Ishikawa, Naoto F.;Finlay, Jacques C.;Power, Mary E.
在过去的十年中，放射性碳天然丰度（Delta C-14）已成为淡水生态学中有用的膳食示踪剂，但其分离水生和陆生资源的适用性尚未进行定量研究。在这里，我们报告三角洲的C-14值流无脊椎动物在不同的功能喂养组收集从上南福克鳗鱼河流域，北方加州。我们发现，食藻昆虫幼虫显示出较低的Delta C-14值（-43.1 +/-千分之21.8，平均值+/-标准差，N = 6），反映了溶解的无机碳从古老的无机碳风化或古老的有机碳呼吸的信号。相比之下，碎叶昆虫幼虫的Delta C-14值（千分之21.7 +/- 31.9，N = 5）接近当代大气CO（2）的值，但在SF鳗鱼河藻类产量最高。食肉动物的Delta C-14值（-6.1 +/-35.7 ‰，N = 14）介于食草动物和切碎机之间。在贝叶斯混合模型中，Delta C-14提供了一个更符合生态实际的估计，即陆地与水生来源对无脊椎动物的贡献，具有较低的不确定性（即，可信区间更窄）比稳定碳同位素（δ C-13）。这些结果表明，δ C-14可以与δ C-13结合使用，以更精确地估计河流动物的有机质来源。
Radiocarbon natural abundance (Delta C-14) has emerged as a useful dietary tracer in freshwater ecology for the past decade, yet its applicability for separating aquatic and terrestrial resources has not been examined quantitatively. Here, we report Delta C-14 values of stream invertebrates in different functional feeding groups collected from the upper South Fork Eel River watershed, northern California. We found that algae-grazing insect larvae show low Delta C-14 values (-43.1 +/- 21.8 parts per thousand, mean +/- standard deviation,N = 6), reflecting the signal of dissolved inorganic carbon weathered from ancient inorganic carbon or respiration of old organic carbon. In contrast, the Delta C-14 values of leaf-shredding insect larvae (21.7 +/- 31.9 parts per thousand,N = 5) were close to those of contemporary atmospheric CO(2)except at the SF Eel River where algal production was highest. The Delta C-14 values of predators (-6.1 +/- 35.7 parts per thousand,N = 14) were intermediate between those of grazers and shredders. In a Bayesian mixing model, Delta C-14 provided a more ecologically realistic estimate for terrestrial vs. aquatic source contributions to invertebrates with lower uncertainty (i.e., narrower credible interval) than did the stable carbon isotopes (delta C-13). These results demonstrate that Delta C-14 can be used, in combination with delta C-13, to more precisely estimate organic matter sources to stream animals.