Matassa Catherine M, Trussell Geoffrey C
Marine Science Center, Northeastern University, East Point, Nahant, MA 01908, USA
Marine Science Center, Northeastern University, East Point, Nahant, MA 01908, USA.
Proc Biol Sci. 2014 Dec 7;281(1796):20141952. doi: 10.1098/rspb.2014.1952.
The ecological impacts of predation risk are influenced by how prey allocate foraging effort across periods of safety and danger. Foraging decisions depend on current danger, but also on the larger temporal, spatial or energetic context in which prey manage their risks of predation and starvation. Using a rocky intertidal food chain, we examined the responses of starved and fed prey (Nucella lapillus dogwhelks) to different temporal patterns of risk from predatory crabs (Carcinus maenas). Prey foraging activity declined during periods of danger, but as dangerous periods became longer, prey state altered the magnitude of risk effects on prey foraging and growth, with likely consequences for community structure (trait-mediated indirect effects on basal resources, Mytilus edulis mussels), prey fitness and trophic energy transfer. Because risk is inherently variable over time and space, our results suggest that non-consumptive predator effects may be most pronounced in productive systems where prey can build energy reserves during periods of safety and then burn these reserves as 'trophic heat' during extended periods of danger. Understanding the interaction between behavioural (energy gain) and physiological (energy use) responses to risk may illuminate the context dependency of trait-mediated trophic cascades and help explain variation in food chain length.
捕食风险的生态影响受到猎物在安全和危险时期如何分配觅食努力的影响。觅食决策不仅取决于当前的危险，还取决于猎物管理其被捕食和饥饿风险的更大的时间、空间或能量背景。利用一个岩石潮间带食物链，我们研究了饥饿和饱腹的猎物（滨螺）对来自捕食性螃蟹（平背蜞）不同时间模式风险的反应。在危险时期，猎物的觅食活动会下降，但随着危险时期变长，猎物的状态改变了风险对猎物觅食和生长影响的程度，这可能会对群落结构（对基础资源紫贻贝的性状介导间接影响）、猎物适合度和营养能量传递产生影响。由于风险在时间和空间上本质上是可变的，我们的结果表明，非消费性捕食者效应可能在生产力较高的系统中最为明显，在这些系统中，猎物可以在安全时期积累能量储备，然后在长时间的危险时期将这些储备作为“营养热量”消耗掉。理解行为（能量获取）和生理（能量利用）对风险反应之间的相互作用，可能会阐明性状介导的营养级联的背景依赖性，并有助于解释食物链长度的变化。
