南极磷虾（）存在昼夜垂直移动现象，且具有集群特征。本研究从虾群形态特征及生物学角度对南奥克尼群岛海域南极磷虾昼夜垂直移动习性及虾群特征进行研究。结果表明，水平带状虾群在各时段呈主导性分布，但在各时段比例差异显著，曙光到黄昏时段，水平带状虾群比例存在先降后升的变化过程，在白天时段降到最低值，为65%；黄昏到曙光时段，水平带状虾群比例高且稳定。球状虾群保持着较为稳定的时间间隔，分散状虾群表现出在日升到白天时间段的连续性特征。南极磷虾虾群中心深度在不同时段具有较大差异，曙光和暮光时段是平均虾群中心深度的分界点；南极磷虾不同虾群形态中心深度也具有差异性，球状虾群平均虾群中心深度最大，分散虾群次之，水平带状虾群最小。不同时间段内虾群水温呈波动变化状态，变化范围为–1.6~1.3℃，最小值出现在暮光时段，最大值出现在夜间时段；虾群水温和虾群中心深度呈显著的负相关关系。南极磷虾体长在不同时段存在明显差异（<0.001），各时段优势体长组差异明显，白天到下午时段优势体长组要明显高于其他时段优势体长组。

Antarctic krill () is one of the largest single species of biological resource on the planet. It lives mostly in the waters south of 50° S in the Southern Ocean, and is distributed around the Antarctic. Studying the behavior patterns of Antarctic krill clusters is of great significance for understanding their distribution characteristics, the formation mechanism of Antarctic krill fishing grounds, and resource utilization. As Antarctic krill occupies a key position in Antarctica and the Southern Ocean ecosystem, the regionality of its living conditions, special rhythms, and vulnerability, have made it difficult to study the rules governing its aggregation. Antarctic krill uses the phenomenon of diel vertical migration and aggregation. In this study, diel aggregation and Antarctic krill biology were studied in the waters of the South Orkney Islands. The results show that the horizontal band which refers to the pattern of aggregation has a dominant distribution in each time period, but that the proportion of horizontal band in each time period is significantly different. From dawn to dusk, the proportion of the horizontal band decreased first, and then increased, reaching the lowest value in the daytime period (65%). From dusk to morning twilight, the proportion of the horizontal band was high and stable. Spherical distribution maintains a relatively stable time interval, and scattered distribution is a continuous feature from sunrise to the daytime. The central depth of the Antarctic krill aggregation varies greatly during different time periods; morning twilight and evening twilight are the dividing points of the average aggregation center depth. The central depth of Antarctic krill is also different in terms of aggregation. The average central depth of the spherical distribution is the largest, followed by scattered distribution. Alternately, the average central depth of the horizontal band is the least. The temperature of aggregation fluctuates in different time periods, ranging from -1.6℃ to 1.3℃. The minimum value appears during the evening twilight period, and the maximum value appears at night. The temperature of aggregation and the central depth of the Antarctic krill show a significant negative correlation. The body length of Antarctic krill is significantly different in different time periods (<0.001), and the dominant body length in different time periods is significantly different, with the dominant body length between daytime and afternoon being significantly higher than in other time periods.

S931

国家重点研发计划项目（2018YFC1406803）.