Abundance of bacteria and virus during the METEOR cruise M87/1

In temperate, subpolar and polar marine systems, the classical perception that bacteria are carbon limited by end of winter and respond in activity and abundance to the production of new carbon during the diatom spring bloom and post bloom. Contrary to this view, we here document an strong increase in bacterial abundance and activity (latter measured by increasing high nuclei acid (HNA) to low nuclei acid (LNA) bacteria ratio) during the winter-spring transition, where phytoplankton smaller than 10 µm dominate. Further DNA-virus were enumerated and revealed the virus to bacteria ratio (VBR) to be decreasing during winter-spring transition, indicating that the virus did not increase in number accordingly to bacteria. During repeated visits to stations in the deep Icelandic and the Norwegian Basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the abundance of bacteria and the succession of HNA:LNA bacteria and VBR. Water samples were collected from CTD rosette .10 L Niskin bottles and fixed in glutaraldehyde (final conc. 5%), flash frozen in liquid Nitrogen and stored at -80°C until analysis.

温带、亚极区与极地海洋系统中，传统认知认为细菌于冬末受碳源限制，并在硅藻春季水华及水华后期响应新碳生成，进而改变其活性与丰度。本研究对此观点提出挑战，我们记录到冬春过渡期细菌丰度与活性显著提升（其中活性通过高核酸（High Nucleic Acid, HNA）与低核酸（Low Nucleic Acid, LNA）细菌的比值升高进行量化），该时期粒径小于10微米的浮游植物占据优势。此外，本研究对DNA病毒进行了计数，结果显示冬春过渡期病毒-细菌比值（Virus to Bacteria Ratio, VBR）呈下降趋势，表明病毒丰度并未随细菌同步增长。2012年3月26日至4月29日期间，我们对冰岛海盆、挪威海盆的深水站位以及设得兰陆架的浅水站位开展了多次巡航采样，调查了细菌丰度、HNA:LNA细菌比值的演替规律以及VBR的变化特征。水样通过温盐深采水器架（CTD rosette）搭载的10升尼斯金采水瓶（Niskin bottles）采集，使用终浓度为5%的戊二醛（glutaraldehyde）固定后，经液氮快速冷冻，并保存于-80℃直至后续分析。