metazoan zooplankton carbon biomass

This data was collected as a part of a mesocosm study to investigate the ecosystem impacts of ocean alkalinity enhancement, within the EU H2020 OceanNETs project. Nine mesocosms were deployed in Taliarte Harbour (Gran Canaria, Spain) and were regularly sampled using integrated water samplers between 10th September-25th October 2021. A gradient design was used in this experiment with a total of nine different alkalinity concentrations. Seawater alkalinity ranged between ambient (0 µeq kg-1 added alkalinity, OAE0) and 2400 µeq kg-1 additional alkalinity (OAE2400). The alkalinity levels increased in equal intervals of 300 µeq kg-1 across nine mesocosms (OAE0, OAE300, OAE600, OAE900, OAE1200, OAE1500, OAE1800, OAE2100, OAE2400). This data set contains metazoan zooplankton biomass (µgC per L) from these nine mesocosms. Biomass was calculated based on zooplankton abundances transformed using carbon mass conversion factors. Metazoan zooplankton were sampled with apstein net (ø17cm, mesh size 55µm, 64.06285L) hauls taken every two days (except for days 5 and 9). Zooplankton were size fractioned and assessed in the correspondent size class (small: 55-200µm; medium: 200-500µm; large: 500µm-3mm). Within each size class, all organisms were counted and identified to the lowest possible taxonomic level, and developmental stages were differentiated where possible. Zooplankton abundances (individuals per L) converted to carbon biomass (µgC per L) using biomass conversion factors. Conversion factors are obtained from different sources (Sanchez et al. (in prep)). Briefly: i) metazoan zooplankton functional groups were sampled and measured for carbon biomass using an elemental analyser at specific points throughout the experiment, ii) individual zooplankton were photographed, measured, and their biovolumes and carbon masses derived using standard conversions cited in the literature, iii) zooplankton conversion factors from KOSMOS Gran Canaria 2019 (https://doi.pangaea.de/10.1594/PANGAEA.971765). The experiment, which lasted 33 days, was divided into four response phases (see Sánchez et al. (in prep)): i) pretreatment (days 1 to 4, treatment was implemented on day 4), ii) immediate (days 5-10), iii) shorter term (days 11-22), iv) longer term (days 23 to 33).

本数据是欧盟H2020 OceanNETs项目下，为研究海洋碱度增强（Ocean Alkalinity Enhancement，OAE）的生态系统影响而开展的中型围隔（mesocosm）研究的一部分。九个中型围隔部署于西班牙大加那利岛的塔利尔特港（Taliarte Harbour, Gran Canaria, Spain），并在2021年9月10日至10月25日期间使用综合水样采集器定期采样。实验采用梯度设计，共设置九个不同碱度浓度：海水碱度范围从环境本底（添加碱度0 µeq kg⁻¹，OAE0）到额外添加2400 µeq kg⁻¹碱度（OAE2400），九个围隔的碱度水平以300 µeq kg⁻¹的等间隔递增（OAE0、OAE300、OAE600、OAE900、OAE1200、OAE1500、OAE1800、OAE2100、OAE2400）。

本数据集包含上述九个中型围隔中的后生浮游动物生物量（单位：µgC/L）。生物量计算基于浮游动物丰度，并通过碳质量转换因子转换得到。后生浮游动物采用Apstein网（直径17cm，网目大小55µm，采样体积64.06285L）每两天拖网采集一次（第5天和第9天除外）。浮游动物按大小分级，归入相应尺寸类别：小型（55-200µm）、中型（200-500µm）、大型（500µm-3mm）。在每个尺寸类别中，对所有生物进行计数，并尽可能鉴定至最低分类阶元；若条件允许，还会区分其发育阶段。浮游动物丰度（单位：个/L）通过生物量转换因子换算为碳生物量（单位：µgC/L）。转换因子来源于多个渠道（Sanchez et al.，待发表）：具体包括：i）实验期间特定时间点对后生浮游动物功能群采样，利用元素分析仪测定其碳生物量；ii）对单个浮游动物进行拍照与测量，通过文献中引用的标准转换方法推导其生物体积及碳质量；iii）2019年大加那利岛KOSMOS项目的浮游动物转换因子（https://doi.pangaea.de/10.1594/PANGAEA.971765）。

本实验持续33天，分为四个响应阶段（参见Sánchez et al.，待发表）：i）预处理阶段（第1-4天，处理措施于第4天实施）；ii）即时响应阶段（第5-10天）；iii）短期响应阶段（第11-22天）；iv）长期响应阶段（第23-33天）。