Picoplankton and nanophytoplankton cytometry data collected during the ABRACOS 2 survey performed along the northeast Brazilian continental shelf, slope and open ocean

During Abraços 2 (9-04 to 06-05 2017), picoplankton and nanophytoplankton samples were fixed with formaldehyde (2% final concentration), stored in liquid nitrogen (-196°C) until laboratory before counting using a Facs Aria Flow cytometer (Becton Dickinson, San Jose, CA, USA) equipped with a HeNe air-cooled laser (633 nm, 20 mW). Cells excited at 633 nm were detected and enumerated according to their forward-angle light scatter (FALS) and right-angle light scatter (RALS) properties and their orange fluorescence (576/26 nm) and red fluorescence (660/20 nm and 675/20 nm) from phycoerythrin, phycocyanin and chlorophyll pigments, respectively. Fluorescent beads (1-2 µm size for picophytoplankton and 3, 6 et 10 μm size for nanophytoplancton) were systematically added to each sample. True count beads (Becton Dickinson, San Jose, CA, USA) were added to determine the sample volume analyzed. List-mode files were analyzed using BD FACSDiva software. This method discriminates various autotrophic groups such as picoeukaryotes, picocyanobacteria (Prochlorococcus and Synechococcus) and nanophytoplankton (more larger organisms until 10µm) coupling the detection of cells size, their chlorophyll pigments and phycoerythrin, phycocyanin content (Bec et al., 2005). Abundances of organisms were expressed in number of individuals / L. Abundance and size of pico- and nanoplankton were obtained using a FACSCalibur flow cytometer (Becton Dickinson) equipped with a HeNe air-cooled laser (633 nm, 20 mW), following the protocol of Marie et al. (1997). Samples were analyzed with a mixture of fluorescent beds (‘Fluorebrite’ YG, Polysciences) of various nominal sizes. Autotrophic cells excited at 633 nm were detected and enumerated according to their forward-angle light scatter (FALS) and right-angle light scatter (RALS) properties, and their orange (576/26 nm) and red (660/20 nm and 675/20 nm) from phycoerythrin, phycocyanin and chlorophyll pigments, respectively. Fluorescent beads (1-2 µm for picophytoplankton and 3, 6 and 10 μm for nanophytoplankton) were added to each sample. True count beads (Becton Dickinson) were added to determine the volume analyzed. This method discriminates various autotrophic and mixotrophic groups such as PEUK, picocyanobacteria (Prochlorococcus and Synechococcus) and PNF. For HB, cells DNA was stained with SYBRGreen I and counted under the emission of green fluorescence. After the quantification of biovolumes, the biomass of pico- and nanoplankton was obtained from conversion factors reported in the literature as follows: Prochlorococcus (29 fgC cell-1), Synechococcus (100 fgC cell -1), PEUK (1500 fgC cell-1) (Zubkov et al. 2000), PNF (3140 fgC cell-1) (Pelegrí et al. 1999) and HB (12 fgC cell-1) (Fukuda et al., 1998). Biomass is given in µgCL

在Abraços 2航次期间（2017年4月9日至5月6日），研究人员以终浓度2%的甲醛固定超微浮游生物（picoplankton）和微型浮游植物（nanophytoplankton）样本，并将其保存在液氮（-196℃）中，直至实验室阶段采用配备氦氖风冷激光器（633 nm、20 mW）的FACSAria流式细胞仪（FACSAria Flow cytometer，碧迪医疗器械，Becton Dickinson, 美国加利福尼亚州圣何塞市）进行计数。以633 nm波长激发的细胞，根据其前向角光散射（FALS）、侧向角光散射（RALS）特性，以及分别来自藻红蛋白、藻蓝蛋白和叶绿素的橙色荧光（576/26 nm）与红色荧光（660/20 nm、675/20 nm）进行检测与计数。研究人员向每一份样本中均加入荧光微球（超微型浮游植物用1~2 µm粒径，微型浮游植物用3、6、10 µm粒径），并加入绝对计数微球（True count beads，碧迪医疗器械，美国加利福尼亚州圣何塞市）以确定样本分析体积。采用BD FACSDiva软件分析列表模式文件。该方法可区分多种自养类群，包括真核超微浮游生物（picoeukaryotes）、蓝细菌超微浮游生物（原绿球藻Prochlorococcus、聚球藻Synechococcus）以及微型浮游植物（粒径最大至10 µm的更大尺寸生物体），结合细胞大小、叶绿素及藻红蛋白、藻蓝蛋白含量进行判别（Bec等，2005）。生物体丰度以个体数/升为单位表示。

研究人员还采用配备氦氖风冷激光器（633 nm、20 mW）的FACSCalibur流式细胞仪（FACSCalibur Flow cytometer，碧迪医疗器械），参照Marie等（1997）的实验方案，获取超微和微型浮游生物的丰度与粒径。向每一份样本中加入不同标称粒径的荧光微球混合液（‘Fluorebrite’ YG，Polysciences公司），以633 nm波长激发的自养细胞，根据其前向角光散射、侧向角光散射特性，以及分别来自藻红蛋白、藻蓝蛋白和叶绿素的橙色荧光（576/26 nm）与红色荧光（660/20 nm、675/20 nm）进行检测与计数。向每一份样本中加入1~2 µm粒径的荧光微球（超微型浮游植物用）与3、6、10 µm粒径的荧光微球（微型浮游植物用），并加入绝对计数微球以确定样本分析体积。该方法可区分多种自养与混养类群，包括真核超微浮游生物（PEUK）、蓝细菌超微浮游生物（原绿球藻、聚球藻）以及微型浮游植物群（PNF）。

对于异养细菌（HB），研究人员使用SYBR Green I染料对细胞DNA进行染色，并通过绿色荧光发射通道进行计数。在生物体积定量完成后，根据文献报道的转换系数计算超微和微型浮游生物的生物量：原绿球藻（29 fgC 细胞⁻¹）、聚球藻（100 fgC 细胞⁻¹）、真核超微浮游生物（1500 fgC 细胞⁻¹，Zubkov等，2000）、微型浮游植物群（3140 fgC 细胞⁻¹，Pelegrí等，1999）以及异养细菌（12 fgC 细胞⁻¹，Fukuda等，1998）。生物量以微克碳每升（µg C L⁻¹）为单位给出。