Plankton community respiration and bacterial metabolism in a North Atlantic Shelf Sea during spring bloom development (April 2015)
Plankton community respiration and bacterial metabolism in a North Atlantic Shelf Sea during spring bloom development (April 2015)
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DOI：
10.1016/j.pocean.2017.11.002
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发表时间：
2019-10-01
影响因子：
4.1
通讯作者：
Robinson, Carol
中科院分区：
文献类型：
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作者：
Garcia-Martin, E. Elena;Daniels, Chris J.;Robinson, Carol
春季浮游植物大量繁殖是陆架海中上层系统的重要事件，因为碳生产的增加导致更高营养水平的食物供应增加，并将碳输出到更深的沃茨和海底。人们通常认为，浮游植物丰度和产量的增加伴随着浮游生物呼吸的增加。然而，这一预期是从实地研究中得出的，时间采样分辨率较低（5-15天）。在这项研究中，我们测量了浮游生物丰度，总初级生产力，浮游生物群落呼吸，浮游生物大小级（>0.8 μ m和0.2-0.8 μ m）的呼吸和浮游生物群落（包括浮游植物，微型浮游动物和颗粒附着细菌）的0.8 μ m大小级的细菌产量的时间过程。在取样的第一天（4月4日）和叶绿素a峰值后的几天（4月20日和25日）之间，0.2-0.8 μ m粒级（主要是自由活细菌）的真光深度综合呼吸降低，然后保持相对稳定（16 +/- 3 - 11 +/- 1 mmol O-2 m（-2）d（-1））。最近本地合成的有机碳是足够多的，以满足细菌的碳需求在透光层在这一生产期。细菌生长效率（BGE，细菌产量与细菌碳需求的比率）的变化是由细菌生产率的变化驱动的，从4月4日的< 30 +/- 14%增加到4月25日的51 +/- 11%。因此，这项研究表明，在春季水华的发展过程中，初级生产力和群落呼吸的同时而不是阶段性的增加归因于细胞> 0.8 μ m，随后5天后细菌生产的高峰。此外，大小分级呼吸速率和高生长效率表明，自由生活的细菌是不是二氧化碳的主要生产者之前，期间和几天后，这个货架海春季浮游植物水华。
Spring phytoplankton blooms are important events in Shelf Sea pelagic systems as the increase in carbon production results in increased food availability for higher trophic levels and the export of carbon to deeper waters and the sea-floor. It is usually accepted that the increase in phytoplankton abundance and production is followed by an increase in plankton respiration. However, this expectation is derived from field studies with a low temporal sampling resolution (5-15 days). In this study we have measured the time course of plankton abundance, gross primary production, plankton community respiration, respiration of the plankton size classes (>0.8 mu m and 0.2-0.8 mu m) and bacterial production at 0.8 mu m size fraction of the plankton community (which would include phytoplankton, microzooplankton and particle attached bacteria). Euphotic depth-integrated respiration of the 0.2-0.8 mu m size fraction (predominantly free living bacteria) decreased and then remained relatively constant (16 +/- 3 - 11 +/- 1 mmol O-2 m(-2) d(-1)) between the first day of sampling (4th April) and the days following the peak in chlorophyll-a (20th and 25th April). Recent locally synthesized organic carbon was more than sufficient to fulfil the bacterial carbon requirement in the euphotic zone during this productive period. Changes in bacterial growth efficiencies (BGE, the ratio of bacterial production to bacterial carbon demand) were driven by changes in bacterial production rates increasing from < 30 +/- 14% on 4th April to 51 +/- 11% on 25th of April. This study therefore shows a concurrent rather than a phased increase in primary production and community respiration attributable to cells > 0.8 mu m during the development of the spring bloom, followed 5 days later by a peak in bacterial production. In addition, the size fractionated respiration rates and high growth efficiencies suggest that free living bacteria are not the major producers of CO2 before, during and a few days after this shelf sea spring phytoplankton bloom.