BACKGROUND While nitrogen and carbon stable isotope values can reflect ecological segregation, prey choice and spatial distribution in seabirds, the interpretation of bulk stable isotope values is frequently hampered by a lack of isotopic baseline data. In this study, we used compound-specific isotope analyses of amino acids (CSIA-AA) to overcome this constraint and to study interspecific differences, seasonal and historical changes in trophic positions of five seabird species, three penguins and two petrels, from a sub-Antarctic seabird community. RESULTS CSIA-AA allowed comparing trophic positions of seabirds with temperate and polar distributions. Gentoo and Magellanic penguins had the highest trophic positions during the breeding season (3.7 and 3.9), but decreased these (2.9 and 3.3) during the feed-up for moult. Intra-specific differences were also detected in Thin-billed prions, where carbon isotope values clearly separated individuals with polar and temperate distributions, both in the breeding and interbreeding periods. Thin-billed prions that foraged in polar waters had lower trophic positions (3.2) than conspecifics foraging in temperate waters (3.8). We further investigated historical changes by comparing museum samples with samples collected recently. Our pilot study suggests that Rockhopper penguins, Magellanic penguins and Thin-billed prions with temperate non-breeding distributions had retained their trophic levels over a 90-100 year period, while Gentoo penguins and Thin-billed prions with polar non-breeding distributions had decreased trophic levels compared to historical samples. In contrast, Wilson's storm-petrels had slightly increased trophic levels compared to samples taken in 1924-1930. CONCLUSIONS We applied compound-specific stable isotope analyses across a range of contexts, from intra-specific comparisons between stages of the breeding cycle to inter-specific seabird community analysis that would not have been possible using bulk stable isotope analyses alone due to differences in isotopic baselines.

中文翻译：

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福克兰群岛海鸟中特定于化合物的稳定同位素分析揭示了营养位置的季节性变化。

背景技术尽管氮和碳的稳定同位素值可以反映海鸟的生态隔离，猎物的选择和空间分布，但是缺乏同位素基线数据常常阻碍了对总体稳定同位素值的解释。在这项研究中，我们使用氨基酸的特定化合物同位素分析（CSIA-AA）克服了这一限制，并研究了一个亚种中五个海鸟物种，三个企鹅和两个海燕的营养位置的种间差异，季节和历史变化。 -南极海鸟社区。结果CSIA-AA可以比较温带和极地分布的海鸟的营养位置。Gentoo和麦哲伦企鹅在繁殖季节的营养位最高（3.7和3.9），但在换羽期却降低了营养位（2.9和3.3）。在细嘴病毒中也检测到种内差异，在繁殖和杂交期间，碳同位素值清楚地分离了具有极性和温带分布的个体。在极地水域觅食的细嘴病毒的营养位置（3.2）比在温带水域觅食的同种s虫（3.8）低。我们通过将博物馆样本与最近收集的样本进行比较来进一步调查历史变化。我们的初步研究表明，具有温带非繁殖分布的Rockhopper企鹅，麦哲伦企鹅和细嘴病毒在90-100年的时间内保持了营养水平，而具有极地非繁殖分布的Gentoo企鹅和细嘴had病毒却减少了与历史样本相比的营养水平。相比之下，威尔逊 与1924年至1930年采集的样本相比，海燕的营养级略有增加。结论我们在各种背景下应用了化合物特异性稳定同位素分析，从繁殖周期各阶段的种内比较到种间海鸟群落分析，由于同位素差异，单独使用批量稳定同位素分析不可能实现基线。