Microbe abundance and biomass in the euphotic zone of the Aegean Sea at Station MARCH-1997-GN36199704601MSB06 in spring 1997

10-30 ml subsamples were concentrated on 25 mm black polycarbonate filters (0.6 µm for NF, 0.2 µm for B), stained with DAPI for 10 min and filtered. NF were counted using UV and blue excitation and enumerated. Heterotrophic B were counted using UV excitation. NF were classified in size categories and biovolume was calculated. NF abundance data were converted into C biomass using 220 fgC µm**-3. Bact abund data were converted into C biomass using 20 fgC cell**-1. BP C was estimated by the 3H-leucine approach according to Kirchman et al. (1986) and Kirchman D.L., 1993. Leucine incorporation as a measure of biomass production by heterotrophic bacteria. In: Kemp P.F. et al. (eds), 1993. Handbook of methods in aquatic microbial ecology. Lewis Publishers, Ann Arbor, 509-512). At each depth duplicate samples and a control one were incubated with 1 nM L-[4,5 3H]-leucine (specific activity 128 Ci/mmol) and 18 nM non-radioactive leucine. Samples were incubated in the dark at in situ temperature.将10~30 mL的子样品浓缩至25 mm黑色聚碳酸酯滤膜上（纳米鞭毛虫（NF）采用孔径0.6 µm滤膜，异养细菌（B）采用孔径0.2 µm滤膜），经4',6-二脒基-2-苯基吲哚（DAPI）染色10分钟后进行过滤。通过紫外与蓝光激发对纳米鞭毛虫进行计数并统计其丰度；异养细菌则通过紫外激发完成计数。将纳米鞭毛虫按尺寸类别进行分类，并计算其生物体积。利用220 fgC·μm⁻³的转换系数，将纳米鞭毛虫的丰度数据转换为碳生物量；利用20 fgC·cell⁻¹的转换系数，将细菌丰度数据转换为碳生物量。细菌生产碳（BP C）采用³H-亮氨酸法进行估算，参照Kirchman等人（1986）及Kirchman D.L. 1993年的研究：《亮氨酸掺入法作为异养细菌生物量生产的测定指标》，收录于Kemp P.F.等主编的《水生微生物生态学实验方法手册》，刘易斯出版社，安阿伯，第509-512页。在每个深度层设置平行样品与1个对照样品，加入1 nM L-[4,5-³H]-亮氨酸（比活度128 Ci/mmol）与18 nM非放射性亮氨酸进行孵育。样品于暗处、原位温度下完成孵育。