ABSTRACT: Trophic cascades are a powerful result of predator-prey relationships in an ecosystem. In aquatic environments, the signals associated with predators and predation are used by prey as a cue to avoid encountering predators when foraging for food. These behavioral cues can be powerful enough to control prey populations and indirectly protect primary producers. Here, we evaluated the effects of cues associated with predation on the purple urchin Heliocidaris crassispina and examined effects of hunger state and season, using time-lapse photography. A series of laboratory and in situ manipulative experiments were conducted to determine patterns of foraging behavior and behavioral modifications. We showed that starved urchins were less sensitive to predation cues compared to normally fed urchins. Field experiments indicated that 70% of fed urchins fled when exposed to a predation cue (presence of a dead urchin) whereas starved urchins remained regardless of the cue, supporting results from the laboratory using dead urchin and algal cues. Sea urchin activity and feeding rates were lower in winter-spring than in summer-autumn. Results suggest that hunger state has a large influence over the behavioral response of sea urchins, while also being affected by season due to metabolic control. In general, starvation appears to override predator avoidance behaviors, which exposes prey species to higher risks of predation.

中文翻译：

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死亡物种，饥饿状态和季节对紫色海胆Heliocidaris crassispina觅食行为的影响

摘要：营养级联是生态系统中食肉动物与猎物之间关系的有力结果。在水生环境中，与捕食者和掠食有关的信号被猎物用作提示，以避免在觅食时遇到掠食者。这些行为线索可能足以控制猎物种群并间接保护初级生产者。在这里，我们使用延时摄影技术评估了与捕食相关的线索对紫色海胆Heliocidaris crassispina的影响，并研究了饥饿状态和季节的影响。一系列实验室和原位进行操纵实验以确定觅食行为和行为改变的模式。我们显示，饥饿的海胆与正常进食的海胆相比对捕食线索的敏感性较低。野外实验表明，有70％的进食的野孩子在暴露于捕食线索（有死顽童）时逃跑，而饥饿的顽童不顾任何线索而残留，这支持了实验室使用死顽童和藻类线索的结果。冬春季海胆活动和摄食率低于夏季秋季。结果表明，饥饿状态对海胆的行为反应有很大的影响，同时由于代谢控制也受季节的影响。一般而言，饥饿似乎超越了捕食者的回避行为，这使猎物物种面临更高的捕食风险。