Relating low δ15N values of zooplankton to N2-fixation in the tropical North Atlantic:: insights provided by stable isotope ratios of amino acids
Relating low δ15N values of zooplankton to N2-fixation in the tropical North Atlantic:: insights provided by stable isotope ratios of amino acids
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DOI：
10.1016/s0967-0637(03)00073-6
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发表时间：
2003-07-01
影响因子：
2.4
通讯作者：
Montoya, JP
中科院分区：
文献类型：
--
作者：
McClelland, JW;Holl, CM;Montoya, JP
最近对全球氮收支的评估包括大大增加了对海洋沃茨中N-2固定的估计。在热带和亚热带海洋的浮游生物食物网中，低的稳定氮同位素比值被用作N-2固定重要性的一个指标。然而，当它们所包含的源和过程信息不能被清楚地分离时，散装稳定氮同位素比值的解释可能会混淆。在本文中，我们使用稳定的N同位素比的氨基酸，以帮助分离源和营养的影响与整个热带北大西洋浮游动物的散装稳定的N同位素比的变化。沿沿着从佛得角群岛到巴巴多斯的一个断面的氨基酸的稳定的N同位素比值的模式确定的N源支持浮游动物生产的变化，几乎没有变化的营养位置的浮游动物大小类从东部到西部的热带北大西洋。此外，浮游动物中的氨基酸的稳定N同位素比值与束毛藻的比较表明，固氮生物的低稳定N同位素比值的横断面的西端的来源。氨基酸的稳定氮同位素比值提供的证据支持解释的大规模模式散装稳定氮同位素比值，N-2固定确实作出了重大贡献的全球N预算。(C)2003爱思唯尔科技有限公司版权所有。
Recent evaluations of the global nitrogen budget include greatly increased estimates of N-2-fixation in oceanic waters. Low stable N isotope ratios in planktonic food webs of tropical and subtropical oceans have been used as one indication of the importance of N-2-fixation. Interpretation of bulk stable N isotope ratios can, however, be confounded when the source and process information that they contain cannot be separated clearly. In this paper, we use stable N isotope ratios of amino acids to help separate source and trophic effects associated with changes in bulk stable N isotope ratios of zooplankton across the tropical North Atlantic. Patterns in stable N isotope ratios of amino acids along a transect from the Cape Verde Islands to Barbados identify a change in N source supporting zooplankton production, and virtually no change in the trophic position of zooplankton size classes from the eastern to the western side of the tropical North Atlantic. Furthermore, comparison of stable N isotope ratios of amino acids in zooplankton with those in Trichodesmium suggests that diazotrophs are the source of the low stable N isotope ratios at the western end of the transect. The evidence provided by stable N isotope ratios of amino acids supports the interpretation of large-scale patterns in bulk stable N isotope ratios that N-2-fixation indeed makes a major contribution to the global N budget. (C) 2003 Elsevier Science Ltd. All rights reserved.