Opposing diel migration of fish and zooplankton in the littoral zone of a large lake
Opposing diel migration of fish and zooplankton in the littoral zone of a large lake
复制标题
大湖沿岸鱼类和浮游动物的昼夜洄游
作者：
A. Lorke;A. Weber;H. Hofmann;F. Peeters
对声学多普勒电流剖面仪的反向散射数据进行分析，以同时估计博登湖沿岸地区人工鱼礁附近水蚤的相对浓度和幼鲈的相对丰度。这些长期（3 个月）和高分辨率（1 小时）观测表明鱼类和浮游动物存在相反的昼夜迁移模式。数据显示，洄游模式将幼鱼以垂直洄游的浮游动物为食的时间限制在日出和日落前后的几个小时内。与反向散射信号同时记录的温度表明鱼类的昼夜活动模式和垂直分布不受高频内波运动产生的强烈温度波动的影响。然而，风暴引起的表面混合层加深后，内波活动突然下降，似乎是昼间活动变化的触发因素，从而导致捕食者与猎物相互作用的强度发生变化。
Backscatter data from an acoustic Doppler current profiler are analyzed to provide simultaneous estimates of relative concentration of Daphnia and relative abundance of young-of-the-year perch in the vicinity of an artificial reef in the littoral zone of Lake Constance. These long-term (3 months) and high-resolution (1 h) observations demonstrate the existence of opposing diel migration patterns in fish and zooplankton. According to the data, the migration pattern constrains feeding of young-of-the-year fish on vertically migrating zooplankton to a few hours around sunrise and sunset. Temperature recorded simultaneously with the backscatter signal indicates that the diurnal activity pattern and the vertical distribution of the fish are not affected by strong temperature fluctuations generated by high-frequency internal wave motions. The abrupt decline of internal wave activity following a storm-induced deepening of the surface mixed layer, however, seems to be a trigger for changes in the diurnal activity and hence the intensity of predator–prey interactions.