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 Southern
Ocean 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) number
Depth – vertical location of the sediment trap in meters below the surface
Mid-point date - Mid date of the sampling interval
Length (days) – number of days the cup was open

本研究于2001-2002年的一年周期内，在南大洋澳大利亚海域南极带南部的南大洋铁释放实验（Southern Ocean Iron Release Experiment, SOIREE）站位（约61°S、140°E）开展了颗石藻通量调查。研究于该站位部署了两套垂直锚定沉积物捕集器，布设水深分别为海平面下2000米与3700米，布放时长共计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直变化特征，以及利用圆偏振显微图像结合C-Calcita软件分析估算的赫氏颗石藻（Emiliania huxleyi）种群颗石重量的季节变化。野外实验、硅藻及生物地球化学通量的详细描述可参见Rigual-Hernández等人（2015）的研究；样品处理与颗石藻计数方法的细节则见于Rigual-Hernández等人（2018）的工作。此外，关于利用C-Calcita软件估算赫氏颗石藻颗石的相关说明，同样可参考Rigual-Hernández等人（2018）的成果。

捕集器捕获的颗石藻群落几乎为单优群落，优势类群为赫氏颗石藻（Emiliania huxleyi）B/C型形态。两个水深的颗石藻通量均呈现显著的季节周期：夏季为颗石藻输出峰值期，存在两个峰值，分别出现在1月初（2000米水深处为2.2×10⁹ 颗石·米⁻²·天⁻¹）与2月中旬（9.8×10⁸ 颗石·米⁻²·天⁻¹）。冬季颗石藻通量极低，最低仅约7×10⁷ 颗石·米⁻²·天⁻¹。3700米水深的深层捕集器所测得的颗石藻通量变化模式与2000米水深捕集器基本一致，但滞后约一个采样周期。夏季捕获的颗石藻颗石表现出重量与长度的降低趋势。两个捕集器的年平均颗石重量分别为2.11±0.96 pg（2000米水深）与2.13±0.91 pg（3700米水深）。本研究的颗石质量估算结果与南大洋其他区域针对B/C型形态赫氏颗石藻的既往报道一致。

本数据集包含两份Excel文件，记录了采样日期与水深、原始计数数据、颗石藻物种的相对丰度与通量（单位：颗石·米⁻²·天⁻¹），以及利用C-Calcita软件测得的赫氏颗石藻颗石形态测量数据。每份文件包含四个工作表：原始颗石计数表、颗石藻物种相对丰度表、已鉴定颗石藻物种的颗石通量表，以及赫氏颗石藻形态参数表。

列标题的详细说明如下：
Cup – 样杯（采样单元）编号
Depth – 沉积物捕集器的垂直布设水深（单位：米，以海面为基准）
Mid-point date – 采样间隔的中间日期
Length (days) – 样杯的投放时长（单位：天）