Mesozooplankton average mass during Mikhail Lomonosov cruise ML25, Part I

Mesozooplankton was sampled by open-closing JUDAY net with a 36 cm ring diameter and mesh size of 125 µm. The open-closing mechanism used was the Nansen mechanical lock system allowing nets to be vertically towed through standard depths (0-10, 10-25, 25-50, 50-100, 100-200, 200-300, 300-500 m) and closed at the upper depth level. Depth of tow was evaluated by wire paid out and the angle of wire inclination. The 10-20 ml samples were preserved in 3-4% buffered formaldehyde and processed on return to the laboratory. All of copepods were identified to genus level, other taxanomic groups - to type, class, order and family levels.本数据集采用网口直径36 cm、网目尺寸125 µm的开闭式JUDAY网（JUDAY net）采集中型浮游动物（Mesozooplankton）。该网搭载南森机械锁定系统（Nansen mechanical lock system）作为开闭机构，可实现网具在0-10 m、10-25 m、25-50 m、50-100 m、100-200 m、200-300 m、300-500 m的标准水层中垂直拖曳，并在各水层的上层位置完成闭合。拖曳水深通过放出的钢缆长度与钢缆倾角进行评估。采集得到的10~20 mL样品采用3%~4%的缓冲甲醛（buffered formaldehyde）固定，于返航后带回实验室开展后续处理。所有桡足类（copepods）均鉴定至属级分类单元，其余分类类群则分别鉴定至型、纲、目及科级分类水平。