Measuring the in situ carbon isotopic composition of distinct marine plankton populations sorted by flow cytometry
Measuring the in situ carbon isotopic composition of distinct marine plankton populations sorted by flow cytometry
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DOI：
10.1002/lom3.10073
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发表时间：
2016-02-01
影响因子：
2.7
通讯作者：
Sessions, Alex L.
中科院分区：
文献类型：
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作者：
Hansman, Roberta L.;Sessions, Alex L.
海洋颗粒物的碳同位素比率(增量C-13值)是阐明海洋环境中碳流动途径的一种潜在有用的示踪剂。在不同的营养和生长条件下，不同种类的浮游植物在实验室培养中对二氧化碳的分馏作用最高可达千分之24，这一信号应该通过微生物食物网传播。然而，由于分析的限制，这种对比很难在现场测量中得到证实。在这里，我们结合了荧光激活细胞分选(FACS)和专门的微燃烧界面和同位素比质谱仪(SWIM-IRMS)，提供了一些首次直接测量野生特定浮游植物种群的全细胞增量C-13值。在2010-2011年在斯克里普斯码头采集的三个样本中，聚球藻的C-13值平均为-25.7+/-2.0‰，原氯球菌平均为-23.0‰+/-1.3，硅藻平均为-20.8‰+/-1.7‰。与仲夏(2010年7月)相比，在水华期间(2011年3月)测量的硅藻与富含C-13三角洲的硅藻相似。被认为代表活的异养菌的分类颗粒平均为-25.4+/-2.5‰，而总可过滤颗粒平均为-19.6+/-1.0‰，表明与硅藻生物量非常相似。这些变化表明，不同颗粒种群之间在Delta C-13的原位差异可以被利用来跟踪碳流通过连续的营养水平，以及整个有机质的再矿化、下沉和保存。
The carbon isotope ratio (delta C-13 value) of marine particulates is a potentially useful tracer for elucidating pathways of carbon flow in the marine environment. Different species of phytoplankton vary in fractionation vs. CO2 by up to 24 parts per thousand in laboratory cultures under varying nutrient and growth conditions, a signal that should propagate through the microbial food web. However, such contrasts have been difficult to confirm in field measurements due to analytical limitations. Here, we combine fluorescence-activated cell sorting (FACS) with a specialized micro-combustion interface and isotope-ratio mass spectrometry (SWiM-IRMS) to provide some of the first direct measurements of whole-cell delta C-13 values for specific phytoplankton populations in the wild. For three samples collected off Scripps Pier in 2010-2011, Synechococcus averages delta C-13 values of -25.7 +/- 2.0 parts per thousand, Prochlorococcus averages -23.0 +/- 1.3, and diatoms average -20.8 +/- 1.7 parts per thousand. Diatoms were similar to 3 parts per thousand enriched in delta C-13 when measured during a bloom (March 2011) as compared with mid-summer (July 2010). Sorted particles thought to represent living heterotrophic bacteria averaged -25.4 +/- 2.5 parts per thousand, whereas total filterable particles averaged -19.6 +/- 1.0 parts per thousand, indicating a strong similarity to diatom biomass. These variations demonstrate that in situ differences in delta C-13 among different populations of particles can be exploited to follow carbon flow through successive trophic levels, and throughout organic matter remineralization, sinking, and preservation.