| 摘要: |
| 利用深海潜标所搭载的声学多普勒流速剖面仪(acoustic doppler current profiler,ADCP)得到的后向散射强度Sv,研究了黑潮-亲潮混合区浮游动物的垂向分布、其昼夜垂直迁移(diel vertical migration;DVM)的基本特征、多时间尺度变化及对反气旋式中尺度暖涡的响应。结果表明:该海区的浮游动物主要分布在200m以浅的上层海洋和300~800m之间的中层海洋。上层浮游动物受浮游植物影响,生物量春秋多、夏冬少;分布深度夏季最浅、秋冬逐渐加深。中层浮游动物受水温影响,生物量春夏多、秋冬少;分布深度春夏深、秋冬浅。400m层的浮游动物存在显著的DVM行为,表现为昼沉夜浮,年平均DVM幅度、时长和速度分别约为200m,2h和2.8cm/s,瞬时速度可高达9cm/s。DVM具有显著的多时间尺度变化特征。季节上,受浮游植物生物量和垂向分布的影响,DVM强度春季最强、秋冬次之、夏季最弱,DVM幅度(速度)夏季最大、春季次之、秋冬小。DVM起止时间由光照控制,与日落日出时刻的季节变化同步。季节内,DVM强度的变化与水温和流速相关。DVM强度随温度的升高(降低)而增强(减弱),并受到水平强流的削弱。通过个例研究,首次提出暖涡总体上抑制DVM,但涡旋不同位置对其影响不同:暖涡边缘的水平强流减弱DVM强度,而暖涡中心的高温减小DVM幅度。研究结果填补了黑潮-亲潮混合区浮游动物DVM研究的空缺,为该海区生态模型的优化和渔业资源的评估与预测奠定了基础。 |
| 关键词: 声学多普勒流速剖面仪回声 黑潮-亲潮混合区 浮游动物昼夜垂直迁移 多时间尺度变化 中尺度涡 |
| DOI：10.11693/hyhz20211000250 |
| 分类号: |
| 基金项目:中央高校基本科研业务费专项,202172001号;“鳌山人才”优秀青年学者计划项目,2017ASTCP-ES05号;山东省“泰山学者”青年专家项目,tsqn201812022号。 |
附件 |
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| DIEL VERTIAL MIGRATION OF ZOOPLANKTON IN THE KUROSHIO-OYASHIO MIXED ZONE BASED ON ADCP ECHO |
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LI Qi1, CHEN Zhao-Hui1,2
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1.Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Ocean University of China, Qingdao 266100, China;2.Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China
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| Abstract: |
| The backscattering strength Sv is calculated with echo intensity measured by acoustic doppler current profilers (ADCPs) that are mounted on a subsurface mooring in the Kuroshio-Oyashio mixed zone. Based on Sv derived from ADCP, we studied the vertical distribution of zooplankton, the basic feature of its diel vertical migration (DVM), and the multi-time scale variations and response to anticyclonic warm-core mesoscale eddy of DVM. Results show that the zooplankton are mainly distributed in the upper layer above 200 m and the intermediate layer between 300 and 800 m. Zooplankton in the upper layer is controlled by phytoplankton, with high biomass in spring and autumn while low in summer and winter, and the depth of distribution is the shallowest in summer and gradually deepening from autumn to winter. Differently, zooplankton in the intermediate layer is closely related to water temperature, with its biomass and depth of distribution both elevated in spring and summer and decreased in autumn and winter. It was found that zooplankton show significant DVM behavior in the depth of 400 m, which is characterized by daytime sinking and nighttime floating, with the average mean DVM amplitude, duration and velocity of about 200 m, 2 h and 2.8 cm/s, respectively, and a instantaneous velocity as high as 9.0 cm/s. The DVM shows apparent multi-time scale variations. Affected by the biomass and vertical distribution of phytoplankton, the DVM intensity is the strongest in spring, second strorg in autumn and winter, and weak in summer, and the DVM amplitude is the largest in summer, second large in spring, and small in autumn and winter. The starting and ending time of DVM is controlled by the sunlight, and synchronously follows the change of sunset and sunrise, respectively. The intra-seasonal variation of DVM strength is correlated to the changes of water temperature and current. The DVM strength enhances (reduces) as the water temperature increases (decreases) and weakens as the horizontal current gets strong. Based on case analysis, it is first proposed that the warm eddies generally suppress DVM, with different influence on DVM in different parts of eddy: the strong horizontal current at the eddy periphery damp the DVM intensity, and the high temperature at the eddy center reduce DVM amplitude. The results in this paper fill in the gap of zooplankton DVM research in the Kuroshio-Oyashio mixed zone, and lays a foundation for the optimization of ecological model and the evaluation and prediction of fishery resources in this area. |
| Key words: ADCP echo Kuroshio-Oyashio mixed zone diel vertical migration of zooplankton multi-time scale variations mesoscale eddy |
