Coccolithophore species fluxes in the Australian sector of the southern Antarctic Zone

Coccolithophore fluxes were investigated over a one-year period (2001-02) at the southern Antarctic Zone in the Australian Sector of the Southern Ocean at the site of the SouthernOcean Iron Release Experiment (SOIREE) near 61°S, 140°E. Two vertically moored sediment traps were deployed at 2000 and 3700 m below sea-level during a period of 10 months. In these data sets we present the results on the temporal and vertical variability of total coccolith flux, species composition and seasonal changes in coccolith weights of E. huxleyi populations estimated using circularly polarised micrographs analysed with C-Calcita software. A description of the field experiment, diatom and biogeochemical fluxes can be found in Rigual-Hernández et al. (2015), while a detailed description of sample processing and counting of coccolithophores can be found in Rigual-Hernández et al. (2018). Moreover, an explanation of the estimation of Emiliania huxleyi coccoliths using C-Calcita software can be also found in Rigual-Hernandez et al. (2018). Coccolithophore assemblages captured by the traps were nearly monospecific for Emiliania huxleyi morphotype B/C. Coccolith fluxes showed strong seasonal cycle at both sediment trap depths. The maximum coccolith export occurred during summer and was divided into two peaks in early January (2.2 x 109 coccoliths m-2 d-1 at 2000 m) and in mid-February (9.8 x 108 coccoliths m-2 d-1). Coccolith flux was very low in winter (down to ~7 x 107 coccoliths m-2 d-1). Coccolith fluxes in the deeper trap (3700 m) followed a similar pattern to that in the 2000 m trap with a delay of about one sampling interval. Coccoliths intercepted by the traps exhibited a weight and length reduction during summer. The annual coccolith weight at both sediment traps was 2.11 plus or minus 0.96 and 2.13 plus or minus 0.91 pg at 2000 m and 3700 m, respectively. Our coccolith mass estimation was consistent with previous reports for morphotype B/C in other regions of the Southern Ocean. Data available: two excel files containing sampling dates and depths, raw counts, relative abundance and fluxes (coccoliths m-2 d-1) of the coccolithophore species, and morphometric measurements of Emiliania huxleyi coccoliths made with C-Calcita software. Each file contains four spreadsheets: raw coccolith counts, relative abundance of coccolithophore species and coccolith flux of each coccolithophore species identified and E. huxleyi morphometrics. Detailed information of the column headings is provided below.Cup – Cup (=sample) numberDepth – vertical location of the sediment trap in meters below the surface Mid-point date - Mid date of the sampling intervalLength (days) – number of days the cup was open

本研究针对颗石藻（Coccolithophore）通量开展了为期一年（2001-2002年）的调查，站位位于南大洋澳大利亚管辖海域的南极带南部，即南大洋铁释放实验（SouthernOcean Iron Release Experiment, SOIREE）的布设点，地理坐标约为南纬61°、东经140°。研究期间部署了两套垂直锚定沉积物捕集器，分别布设于海平面下2000米与3700米水深处，布放时长为10个月。

本数据集呈现了总颗石藻通量、物种组成的时间与垂向变化特征，以及利用圆偏振显微图像结合C-Calcita软件分析得到的艾氏颗石藻（Emiliania huxleyi）种群颗石重量的季节变化规律。野外实验、硅藻及生物地球化学通量的相关描述详见Rigual-Hernández等人（2015）的研究；样品处理与颗石藻计数的详细方法可参考Rigual-Hernández等人（2018）的工作，而利用C-Calcita软件估算艾氏颗石藻颗石重量的原理同样见于该2018年的文献。

捕集器捕获的颗石藻群落几乎为单一物种，即艾氏颗石藻B/C型形态。两个水深的沉积物捕集器均观测到颗石藻通量呈现显著的季节周期变化：颗石藻输出通量的峰值出现在夏季，分为两个高峰——1月初（2000米水深处为2.2×10⁹ 颗石藻·米⁻²·天⁻¹）与2月中旬（9.8×10⁸ 颗石藻·米⁻²·天⁻¹）；冬季颗石藻通量极低，最低可至约7×10⁷ 颗石藻·米⁻²·天⁻¹。

3700米水深的深层捕集器的颗石藻通量变化模式与2000米水深捕集器相似，但滞后约一个采样周期。捕集器捕获的颗石藻在夏季出现重量与长度的减小现象。两个沉积物捕集器的年平均颗石重量分别为2.11±0.96皮克（2000米水深）与2.13±0.91皮克（3700米水深）。本研究的颗石藻质量估算结果与南大洋其他海域针对B/C型形态的已有报道一致。

可用数据集包含两个Excel文件：其一包含采样日期、采样深度、颗石藻物种的原始计数、相对丰度与通量（单位：颗石藻·米⁻²·天⁻¹）；其二包含利用C-Calcita软件测得的艾氏颗石藻颗石形态测量数据。每个文件包含四个工作表，分别为：颗石藻原始计数表、颗石藻物种相对丰度表、已鉴定颗石藻物种的颗石通量表，以及艾氏颗石藻形态测量数据表。

各列表头的详细说明如下：
Cup：采样杯（即样品）编号
Depth：沉积物捕集器的垂向布设深度（单位：米，以海面为基准）
Mid-point date：采样间隔的中间日期
Length (days)：采样杯开启时长（单位：天）