Limnological Institute, University of Konstanz, 78457 Konstanz, Germany.
J Fish Biol. 2009 Jan;74(1):150-66. doi: 10.1111/j.1095-8649.2008.02120.x.
The diel vertical distribution of young-of-the-year (YOY) burbot Lota lota in the pelagic zone of Lake Constance was compared to light intensity at the surface and to the light intensity at their mean depth. Lota lota larvae inhabited the pelagic zone of Lake Constance from the beginning of May until the end of August. From early June, after the stratification of the water column, fish performed diel vertical migrations (DVM) between the hypolimnion and epilimnion. The amplitude of DVM increased constantly during the summer and reached 70 m by the end of August. Lota lota started their ascent to the surface after sunset and descended into the hypolimnion after sunrise. As the YOY fish grew from May to August, they experienced decreasing diel maximum light intensities: in May and early June L. lota spent the day at light intensities >40 W m(-2), but they never experienced light intensities >0.1 W m(-2) after the end of June. From this time, L. lota experienced the brightest light intensities during dusk and dawn, suggesting feeding opportunities at crepuscular hours. The present study implies, that YOY L. lota in the pelagic zone of Lake Constance increased their DVM amplitude during the summer to counteract a perceived predation risk related to body size and pigmentation.
对博登湖幼龄白北鲑（Lota lota）在浮游区的昼夜垂直分布与水面光照强度和其平均深度光照强度进行了比较。Lota lota 幼鱼于 5 月初至 8 月底栖息在博登湖的浮游区。从 6 月初开始，在水柱分层之后，鱼类在深湖层和表水层之间进行昼夜垂直洄游（DVM）。夏季期间，DVM 的幅度不断增加，到 8 月底达到 70 米。幼鲑在日落后开始上升到水面，日出后下降到深湖层。随着幼鱼从 5 月到 8 月的生长，它们经历的昼夜最大光照强度逐渐降低：在 5 月和 6 月初，L. lota 处于光照强度>40 W m(-2)的环境中，但 6 月底后，它们从未经历过光照强度>0.1 W m(-2)的环境。从那时起，L. lota 在黄昏和黎明时分经历最亮的光照强度，表明在黄昏时分存在觅食机会。本研究表明，博登湖浮游区的幼龄白北鲑在夏季增加了昼夜垂直洄游的幅度，以抵消与体型和色素沉着有关的感知捕食风险。
