Brodin Tomas, Johansson Frank
Animal Ecology, Department of Ecology and Environmental Science, Umeå University, 90187, Umeå.
Oecologia. 2002 Jul;132(2):316-322. doi: 10.1007/s00442-002-0938-0. Epub 2002 Jul 1.
We investigated how the lethal and non-lethal presence and absence of a fish predator, perch (Perca fluviatils), influenced behaviour, numbers emerging, size at emergence, and development rate of the damselfly Lestes sponsa. The experiment was carried out in outdoor artificial ponds and spanned from the egg stage to emergence of the damselflies. During the experiment food resources for the damselflies were continuously monitored. Damselflies exposed to a lethal predator showed a significantly lower activity level than those in the absence of predators or subjected to a non-lethal predator. Half-way through the larval stage the reduction in activity level was correlated with the presence of lethal predators, and at the end of the larval stage with higher zooplankton densities. Though larvae decreased activity level, size at emergence was larger and development time faster for individuals in the lethal predator treatment. Since fewer larvae emerged from that treatment we interpret the larger size at emergence to be an effect of a combination of thinning and higher zooplankton densities.
我们研究了食鱼性鲈鱼（河鲈）的致死性和非致死性的有无如何影响豆娘（Lestes sponsa）的行为、羽化数量、羽化时的大小以及发育速率。实验在室外人工池塘中进行，涵盖了豆娘从卵期到羽化的整个过程。在实验期间，持续监测豆娘的食物资源。暴露于致死性捕食者的豆娘活动水平显著低于无捕食者或处于非致死性捕食者环境中的豆娘。在幼虫阶段中期，活动水平的降低与致死性捕食者的存在相关，而在幼虫阶段末期，则与较高的浮游动物密度相关。尽管幼虫的活动水平降低了，但在致死性捕食者处理组中，个体羽化时的体型更大，发育时间更快。由于该处理组中羽化的幼虫较少，我们将羽化时体型较大解释为是稀疏效应和较高浮游动物密度共同作用的结果。
