Abundance of mesozooplankton from the S-IT3 cruise in the Sicily Channel in March 2008

The "SESAME_IT3_ZooAbundance_0-50-100m_SZN" dataset contains data of mesozooplankton species composition and abundance (ind. m-3) from samples collected in the Sicily Channel in the early spring of 2008 (17,18 March) during the SESAME-WP2 cruise IT3. Samples were collected by vertical tows with a closing WP2 net (56 cm diameter, 200 µm mesh size) in the following depth layers: 100-200 m, 50-100 m, 0-50 m. Sampling was always performed in light hours with the exception of station S-IT3-03 where zooplankton were collected in dark hours. A flowmeter was applied to the mouth of the net, however, due to its malfunctioning, the volume of filtered seawater was calculated by multiplying the the area by the height of the sampled layer from winch readings. After collection, each sample was split in two halves (1/2) after careful mixing with graduated beakers. Half sample was immediately fixed and preserved in a formaldehyde-seawater solution (4% final concentration) for species composition and abundance. The other half sample was kept fresh for biomass measurements (data already submitted to SESAME database in different files).Here, only the zooplankton abundance of samples in the upper layers 0-50 m and 50-100 m are presented. The abundance data of the samples in the layer 50-100 m will be submitted later in a separate file. The volume of filtered seawater was estimated by multiplying the the area by the height of the sampled layer from winch readings. Identification and counts of specimens were performed on aliquots (1/20-1/5) of the fixed sample or on the total sample (half of the original sample) by using a graduate large-bore pipette. Copepods were identified to the species level and separated into females, males and juveniles (copepodites). All other taxa were identified at the species level when possible, or at higher taxonomic levels. Taxonomic identification was done according to the most relevant and updated taxonomic literature. Total mesozooplankton abundance was computed as sum of all specific abundances determined as explained above."SESAME_IT3_ZooAbundance_0-50-100m_SZN"数据集包含2008年早春（3月17日、18日）于西西里海峡SESAME-WP2航次IT3中采集的中型浮游动物（mesozooplankton）物种组成与丰度（单位：个/立方米）数据。样品采用闭合式WP2网（closing WP2 net，直径56 cm，网目尺寸200 μm）进行垂直拖网采集，采样水层依次为100~200 m、50~100 m及0~50 m。除S-IT3-03站在夜间采集浮游动物样品外，其余所有站位采样均于白昼进行。研究人员曾在网口安装流量计（flowmeter），但因流量计故障，过滤海水体积通过绞车读数获取的采样层高度乘以网口面积计算得到。样品采集后，经分度烧杯充分混匀，均分为两份（各占原样品的1/2）：其中一份立即使用终浓度为4%的甲醛海水溶液（formaldehyde-seawater solution）固定保存，用于物种组成与丰度分析；另一份新鲜保存，用于生物量测定（相关数据已通过其他文件提交至SESAME数据库）。本数据集仅展示0~50 m与50~100 m上层水层样品的浮游动物丰度，50~100 m水层样品的丰度数据将后续以单独文件提交。 过滤海水体积仍通过采样层高度乘以网口面积，结合绞车读数估算得到。样品的物种鉴定与计数工作通过大口径刻度移液管（graduate large-bore pipette）完成：取固定样品的1/20~1/5等分试样，或直接取全部半份原样品进行操作。桡足类（Copepods）鉴定至物种水平，并区分为雌性、雄性及幼体（桡足幼体，copepodites）；其余类群尽可能鉴定至物种水平，无法鉴定至种的则鉴定至更高分类阶元。分类鉴定依据当前最权威且最新的分类学文献完成。总中型浮游动物丰度为上述所有物种丰度的总和。