PREDATOR-INDUCED DIEL VERTICAL MIGRATION IN A PLANKTONIC COPEPOD
PREDATOR-INDUCED DIEL VERTICAL MIGRATION IN A PLANKTONIC COPEPOD
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DOI：
10.1093/plankt/11.5.1047
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发表时间：
1989-09-01
影响因子：
2.1
通讯作者：
FROST, BW
中科院分区：
文献类型：
--
作者：
BOLLENS, SM;FROST, BW
捕食者逃避是最常见的假设的原因，昼夜垂直迁移的各种湖泊和海洋中的水生生物，但直接的证据仍然难以捉摸。我们测试了捕食假说，通过暴露封闭的海洋桡足类Acartia hudsonica的群体，他们的自然捕食者，食鱼Gasterosteus aculeatus的笼或自由放养的个人。一个多星期后，成年桡足类改变其垂直分布和迁移行为取决于捕食的存在或不存在。只有自由放养的鱼类诱导桡足类种群的垂直迁移。笼养鱼没有影响，表明垂直迁移不是一个简单的化学介导的反应桡足类的捕食者。相反，桡足类似乎通过其他方式，也许是视觉或机械刺激，对捕食者的存在作出反应，并表现出向下的逃避反应，因为遇到视觉定向的鱼主要发生在白天，有效地限制了桡足类的出现在上层水柱的夜间时间。另外，由于鱼类对桡足类造成了严重的死亡率，有可能是选择性捕食改变了具有固定的、遗传决定的迁移行为的个体的比例。我们建议实验来区分这些替代品。
Predator evasion is the most commonly hypothesized reason for diel vertical migrations undertaken by a wide variety of planktonic organisms in lakes and seas, yet direct evidence remains elusive. We tested the predation hypothesis by exposing enclosed populations of a marine copepod Acartia hudsonica to caged or free-ranging individuals of their natural predator, the planktivorous fish Gasterosteus aculeatus. After little more than a week, adult copepods changed their vertical distribution and migration behavior depending on the presence or absence of predation. Only free-ranging fish induced vertical migration in the copepod population. Caged fish had no effect, indicating that vertical migration was not a simple chemically mediated response of copepods to the predator. Rather, copepods seemed to react to the presence of predators by other means, perhaps visual or mechanical stimuli, and to exhibit a downward escape response which, because encounters with visually orienting fish occur chiefly in the daytime, effectively limited the copepods'' occurrence in the upper water column to the night-time hours. Alternatively, because fish imposed heavy mortality on copepods, it is possible that selective predation altered the proportions of individuals with fixed, genetically determined migration behaviors. We suggest experiments to distinguish these alternatives.