Coupled Response of Bacterial Production to a Wind-Induced Fall Phytoplankton Bloom and Sediment Resuspension in the Chukchi Sea Shelf, Western Arctic Ocean
Coupled Response of Bacterial Production to a Wind-Induced Fall Phytoplankton Bloom and Sediment Resuspension in the Chukchi Sea Shelf, Western Arctic Ocean
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西北冰洋楚科奇海陆架细菌产生对风引起的秋季浮游植物大量繁殖和沉积物再悬浮的耦合响应
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发表时间：
2016
影响因子：
3.7
通讯作者：
T. Nagata
中科院分区：
文献类型：
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作者：
Mario Uchimiya;C. Motegi;S. Nishino;Y. Kawaguchi;J. Inoue;H. Ogawa;T. Nagata
异养细菌丰度和生产，溶解游离氨基酸（DFAA）和溶解结合氨基酸（DCAA）的浓度，以及其他微生物参数进行了测定，在一个固定站（最大水深，56米）部署在楚科奇海大陆架，在北冰洋西部，在2013年9月的16天期间收集的海水样品。在调查期间，采样站经历了强风和随后的浮游植物水华，这被认为是由增强的垂直混合和向上的营养通量引发的。在这项研究中，我们调查是否细菌和溶解的氨基酸参数改变，在这些物理和地球化学事件。上层细菌的丰度和产量随着叶绿素a浓度的增加而增加，尽管海水温度从3.2°C降低到1.5°C。水华期间高核酸含量细菌的比例显著高于水华前期。在水华前期和水华期，0-20 m深度的细菌生产力与初级生产力的比值变化不大，总体平均值为0.14 ± 0.03（±标准差，n = 8）。DFAA和DCAA浓度在整个调查期间在有限的范围内变化，表明不稳定的溶解氨基酸的供应和消耗是平衡的。这些结果表明，有一个紧密耦合的，大流量的有机碳从初级生产者异养细菌在秋季水华。我们的数据还显示，在强风事件，这是与沉积物再悬浮由于附近的海底湍流的底部nepheloid（低透光率）层的细菌产量和丰度高。预计随着无冰期的延长，秋风事件对楚科奇海大陆架细菌过程和有机物动态的影响将变得更加突出，这可能对北冰洋更广泛区域的生物地球化学循环和生态系统动态产生深远影响。
Heterotrophic bacterial abundance and production, dissolved free amino acid (DFAA) and dissolved combined amino acid (DCAA) concentrations, and other microbial parameters were determined for seawater samples collected at a fixed station (maximum water depth, 56 m) deployed on the Chukchi Sea Shelf, in the western Arctic Ocean, during a 16-day period in September 2013. During the investigation period, the sampling station experienced strong winds and a subsequent phytoplankton bloom, which was thought to be triggered by enhanced vertical mixing and upward nutrient fluxes. In this study, we investigated whether bacterial and dissolved amino acid parameters changed in response to these physical and biogeochemical events. Bacterial abundance and production in the upper layer increased with increasing chlorophyll a concentration, despite a concomitant decrease in seawater temperature from 3.2°C to 1.5°C. The percentage of bacteria with high nucleic acid content during the bloom was significantly higher than that during the prebloom period. The ratio of the depth-integrated (0–20 m) bacterial production to primary production differed little between the prebloom and bloom period, with an overall average value of 0.14 ± 0.03 (± standard deviation, n = 8). DFAA and DCAA concentrations varied over a limited range throughout the investigation, indicating that the supply and consumption of labile dissolved amino acids were balanced. These results indicate that there was a tightly coupled, large flow of organic carbon from primary producers to heterotrophic bacteria during the fall bloom. Our data also revealed that bacterial production and abundance were high in the bottom nepheloid (low transmittance) layer during strong wind events, which was associated with sediment resuspension due to turbulence near the seafloor. The impacts of fall wind events, which are predicted to become more prominent with the extension of the ice-free period, on bacterial processes and the dynamics of organic matter in the Chukchi Sea Shelf could have far-reaching influences on biogeochemical cycles and ecosystem dynamics in broader regions of the Arctic Ocean.