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Distinguishing zooplankton fecal pellets as a component of the biological pump using compound-specific isotope analysis of amino acids
Limnology and Oceanography ( IF 3.8 ) Pub Date : 2021-05-19 , DOI: 10.1002/lno.11793
Shannon C. Doherty 1 , Amy E. Maas 2 , Deborah K. Steinberg 3 , Brian N. Popp 4 , Hilary G. Close 1
Affiliation  

Zooplankton contribute a major component of the vertical flux of particulate organic matter to the ocean interior by packaging consumed food and waste into large, dense fecal pellets that sink quickly. Existing methods for quantifying the contribution of fecal pellets to particulate organic matter use either visual identification or lipid biomarkers, but these methods may exclude fecal material that is not morphologically distinct, or may include zooplankton carcasses in addition to fecal pellets. Based on results from seven pairs of wild-caught zooplankton and their fecal pellets, we assess the ability of compound-specific isotope analysis of amino acids (CSIA-AA) to chemically distinguish fecal pellets as an end-member material within particulate organic matter. Nitrogen CSIA-AA is an improvement on previous uses of bulk stable isotope ratios, which cannot distinguish between differences in baseline isotope ratios and fractionation due to metabolic processing. We suggest that the relative trophic position of zooplankton and their fecal pellets, as calculated using CSIA-AA, can provide a metric for estimating the dietary absorption efficiency of zooplankton. Using this metric, the zooplankton examined here had widely ranging dietary absorption efficiencies, where lower dietary absorption may equate to higher proportions of fecal packaging of undigested material. The nitrogen isotope ratios of threonine and alanine statistically distinguished the zooplankton fecal pellets from literature-derived examples of phytoplankton, zooplankton biomass, and microbially degraded organic matter. We suggest that δ15N values of threonine and alanine could be used in mixing models to quantify the contribution of fecal pellets to particulate organic matter.

中文翻译:

使用氨基酸的化合物特异性同位素分析区分浮游动物粪便颗粒作为生物泵的组成部分

浮游动物通过将消耗的食物和废物包装成可快速下沉的大而致密的粪便颗粒,为海洋内部颗粒状有机物质的垂直通量做出了重要贡献。量化粪便颗粒对颗粒有机物的贡献的现有方法使用视觉识别或脂质生物标志物,但这些方法可能排除形态上不明显的粪便材料,或者可能包括除粪便颗粒之外的浮游动物尸体。基于七对野生浮游动物及其粪便颗粒的结果,我们评估了氨基酸化合物特异性同位素分析 (CSIA-AA) 在化学上区分粪便颗粒作为颗粒有机物质中的末端材料的能力。氮 CSIA-AA 是对先前使用的大量稳定同位素比率的改进,无法区分基线同位素比率的差异和由于代谢过程导致的分馏。我们建议使用 CSIA-AA 计算的浮游动物及其粪便颗粒的相对营养位置可以提供用于估计浮游动物膳食吸收效率的指标。使用这个指标,这里检查的浮游动物具有广泛的膳食吸收效率,其中较低的膳食吸收可能等同于较高比例的未消化材料的粪便包装。苏氨酸和丙氨酸的氮同位素比率在统计上将浮游动物粪便颗粒与浮游植物、浮游动物生物量和微生物降解的有机物的文献来源实例区分开来。我们建议δ 我们建议使用 CSIA-AA 计算的浮游动物及其粪便颗粒的相对营养位置可以提供用于估计浮游动物膳食吸收效率的指标。使用这个指标,这里检查的浮游动物具有广泛的膳食吸收效率,其中较低的膳食吸收可能等同于较高比例的未消化材料的粪便包装。苏氨酸和丙氨酸的氮同位素比率在统计上将浮游动物粪便颗粒与浮游植物、浮游动物生物量和微生物降解的有机物的文献来源实例区分开来。我们建议δ 我们建议使用 CSIA-AA 计算的浮游动物及其粪便颗粒的相对营养位置可以提供用于估计浮游动物膳食吸收效率的指标。使用这个指标,这里检查的浮游动物具有广泛的膳食吸收效率,其中较低的膳食吸收可能等同于较高比例的未消化材料的粪便包装。苏氨酸和丙氨酸的氮同位素比率在统计上将浮游动物粪便颗粒与浮游植物、浮游动物生物量和微生物降解的有机物的文献来源实例区分开来。我们建议δ 这里检查的浮游动物具有广泛的膳食吸收效率,其中较低的膳食吸收可能等同于较高比例的未消化材料的粪便包装。苏氨酸和丙氨酸的氮同位素比率在统计上将浮游动物粪便颗粒与浮游植物、浮游动物生物量和微生物降解的有机物的文献来源实例区分开来。我们建议δ 这里检查的浮游动物具有广泛的膳食吸收效率,其中较低的膳食吸收可能等同于较高比例的未消化材料的粪便包装。苏氨酸和丙氨酸的氮同位素比率在统计上将浮游动物粪便颗粒与浮游植物、浮游动物生物量和微生物降解的有机物的文献来源实例区分开来。我们建议δ苏氨酸和丙氨酸的15 N 值可用于混合模型,以量化粪便颗粒对颗粒有机物的贡献。
更新日期:2021-07-18
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