Recent work using compound-specific stable isotopes of amino acids (CSI-AA) in proteinaceous deep-sea corals opens a new realm of high–fidelity reconstruction for biogeochemical and ecological changes in the ocean. However, underlying these CSI-AA paleoceanographic applications are a series of fundamental assumptions, which hold first that baseline-proxy AA isotope values fixed at the base of food webs represent integrated δ¹³C and δ¹⁵N values of primary production, and second they are unaltered during subsequent export and incorporation from particles into corals. We explored long-term δ¹³C and δ¹⁵N CSI-AA data on a sediment trap time series together with contemporaneous, geographically close deep-sea bamboo corals (Isidella sp.) in the California margin, first time directly testing these assumptions. Our data show that isotope values of essential (δ¹³C_EAA) and source AAs (δ¹⁵N_Phe) in sinking particles quantitatively track bulk δ¹³C and δ¹⁵N values of export production. These CSI-AA baseline proxies varied independently of carbon flux, trophic position (TP_CSI-AA) and microbial alteration, suggesting that they were well preserved in the sinking particles consumed by corals. Paired comparisons between sinking particles and corals revealed minor elevations of δ¹³C_EAA (by ∼2‰) and δ¹⁵N_Phe (by ∼1‰) in available coral specimens. We hypothesize the difference in δ¹³C_EAA is due to the geographic offset in δ¹³C values of primary production expected between the (more offshore) sediment trap site and (more onshore) coral specimens, whereas the δ¹⁵N_Phe offset is likely related to expected minor trophic fractionation. Using empirical models derived from the sediment trap time series, we demonstrate for the first time that CSI-AA in proteinaceous deep-sea corals can reconstruct known bulk δ¹⁵N values of export production, source nitrogen δ¹⁵N values, and exported TP_CSI-AA values with very good fidelity. Together, these findings represent a major advance in our understanding of AA isotope behavior in modern and paleoarchives, and can be used to underpin the rapidly evolving use of CSI–AA–based tools in multiple paleoceanographic studies and archives.

最近在蛋白质深海珊瑚中使用特定于化合物的氨基酸稳定同位素（CSI-AA）的研究为海洋生物地球化学和生态变化的高保真重建开辟了新领域。然而，底层这些CSI-AA古海洋应用程序是一系列的基本假设，其保持第一即固定在食物网的基基线代理AA同位素值代表集成δ ¹³ C和δ ^15个初级生产的N个值，并且第二它们在随后的出口以及从颗粒到珊瑚的结合过程中，这些元素保持不变。我们探讨长期δ ¹³ C和δ ¹⁵与同期上沉积物捕集时间N系列CSI-AA数据一起，地理上接近的深海珊瑚竹（Isidella sp。）在加利福尼亚州的边缘，首次直接检验了这些假设。我们的数据显示所必需的那个同位素值（δ ¹³ C ^ _EAA）和源AAS（δ ¹⁵ Ñ_的Phe下沉颗粒定量地跟踪散装δ）¹³ C和δ ^15个出口生产的N个值。这些CSI-AA基线替代物的变化与碳通量，营养位置（TP _CSI-AA）和微生物改变无关，这表明它们被保存在珊瑚消耗的下沉颗粒中。下沉颗粒和珊瑚之间配对比较揭示δ的次要凸起¹³ Ç _EAA（由〜2‰）和Δ ¹⁵可用珊瑚标本中的N _Phe（约1‰）。我们推测在δ之差¹³ Ç _EAA是由于地理在δ偏移^13个初级生产预期的（更近海）沉积物捕集器站点和（更陆上）珊瑚样本之间的C值，而δ ¹⁵ Ñ_的Phe偏移很可能与预期的少量营养级分有关。使用从沉积物捕集器时间序列衍生的经验模型，我们证明对于第一次，CSI-AA在蛋白质深海珊瑚可以重建已知散装δ ^15个出口生产，源氮的N个值δ ^15个N个值，并导出TP _{CSI -AA}保真度很高的值。总之，这些发现代表了我们对现代和古档案中AA同位素行为的理解的重大进展，可用于支持在多个古海洋研究和档案中快速使用基于CSI–AA的工具。