Microbe abundance and biomass in waters of the Cretan Sea at Station SEPTEMBER-1995-D4@en

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.取10~30 mL子样本，经过滤浓缩于25 mm黑色聚碳酸酯滤膜（纳米鞭毛虫[NF]使用孔径0.6 μm滤膜，细菌[B]使用孔径0.2 μm滤膜），随后以DAPI（4',6-二脒基-2-苯基吲哚）染色10 min后完成过滤。采用紫外与蓝光激发对纳米鞭毛虫（NF）进行计数统计，异养细菌（B）则通过紫外激发完成计数。对纳米鞭毛虫按尺寸类别进行划分，并计算其生物体积；纳米鞭毛虫的丰度数据以220 fgC μm⁻³的转换系数换算为碳生物量，细菌丰度数据则以20 fgC cell⁻¹的转换系数换算为碳生物量。细菌生产力碳量（BP C）采用³H-亮氨酸法进行估算，参照Kirchman等人（1986）及Kirchman D.L. 1993年的研究成果：《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. 等人主编的《水生微生物生态学方法手册》，Lewis出版社，安阿伯，第509~512页。每个深度设置重复样本与1个对照样本，加入1 nM的L-[4,5-³H]-亮氨酸（比活度128 Ci/mmol）及18 nM的非放射性亮氨酸，样本于黑暗环境中以原位温度进行孵育。