Midwater zooplankton and suspended particle dynamics in the North Pacific Subtropical Gyre: A stable isotope perspective
Midwater zooplankton and suspended particle dynamics in the North Pacific Subtropical Gyre: A stable isotope perspective
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DOI：
10.4319/lo.2013.58.6.1931
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发表时间：
2013-11-01
影响因子：
4.5
通讯作者：
Drazen, Jeffrey C.
中科院分区：
文献类型：
--
作者：
Hannides, Cecelia C. S.;Popp, Brian N.;Drazen, Jeffrey C.
我们使用氨基酸（AA）化合物特定的同位素分析（Δ N-15（AA）和Δ C-13（AA）值）的中层浮游动物和悬浮颗粒，以研究其在中层区的动态。悬浮颗粒N-15（AA）值随深度增加高达千分之14，而颗粒营养状态（营养位置，TP）保持不变，为1.6 +/- 0.07。将瑞利蒸馏模型应用于这些结果得到了观察到的5.7 +/- 0.4份/千的动力学同位素分馏，类似于先前测量的蛋白质水解。基于AA的降解指数值也随着颗粒上的深度而降低，而异养再合成（Sigma V）的测量值保持恒定在1.2 +/-0.3。驱动N-15富集悬浮颗粒的主要机制似乎是同位素分馏与异养降解，而不是营养状态或N源随深度的变化。在浮游动物的“源”AA苯丙氨酸（苯丙氨酸）成为N-15丰富的千分之3.5的深度，而浮游动物TP增加了0.65之间的海洋表面和中层。这两个变化的三角洲N-15值的食物资源的基础上的浮游动物食物网和浮游动物TP的变化驱动器观察到的浮游动物N-15富集与深度。中层浮游动物三角洲N-15（Phe）值比悬浮颗粒低5-8千分之一，表明该有机物池不是一个重要的浮游动物食物资源。相反，62-88%的氮维持中层水浮游动物是表面衍生的，通过消耗下沉颗粒，食肉垂直移民，或直接在表面沃茨在夜间进食。
We used amino acid (AA) compound-specific isotope analysis (delta N-15(AA) and delta C-13(AA) values) of midwater zooplankton and suspended particles to examine their dynamics in the mesopelagic zone. Suspended particle delta N-15(AA) values increased by up to 14 parts per thousand with depth, whereas particle trophic status (measured as trophic position, TP) remained constant at 1.6 +/- 0.07. Applying a Rayleigh distillation model to these results gave an observed kinetic isotope fractionation of 5.7 +/- 0.4 parts per thousand, similar to that previously measured for protein hydrolysis. AA-based degradation index values also decreased with depth on the particles, whereas a measure of heterotrophic resynthesis (Sigma V) remained constant at 1.2 +/- 0.3. The main mechanism driving N-15 enrichment of suspended particles appears to be isotope fractionation associated with heterotrophic degradation, rather than a change in trophic status or N source with depth. In zooplankton the "source" AA phenylalanine (Phe) became N-15 enriched by up to 3.5 parts per thousand with depth, whereas zooplankton TP increased by up to 0.65 between the surface ocean and midwaters. Both changes in the delta N-15 values of food resources at the base of the zooplankton food web and changes in zooplankton TP drive observed zooplankton N-15 enrichment with depth. Midwater zooplankton delta N-15(Phe) values were lower by 5-8 parts per thousand compared with suspended particles, indicating this organic matter pool is not a significant zooplankton food resource at depth. Instead, 62-88% of the N sustaining midwater zooplankton is surface derived, obtained through consumption of sinking particles, carnivory of vertical migrants, or direct feeding in surface waters at night.