Experimental Marine Ecology Laboratory, National University of Singapore, Singapore.
Department of Biosciences, Swansea University, Swansea, UK.
Biol Lett. 2019 Oct 31;15(10):20190409. doi: 10.1098/rsbl.2019.0409. Epub 2019 Oct 2.
Non-consumptive fear effects are an important determinant of foraging decisions by consumers across a range of ecosystems. However, how fear effects associated with the presence of predators interact with those associated with habitat structure remain unclear. Here, we used predator fish models () and experimental patches of the macroalga of varying densities to investigate how predator- and habitat-associated fear effects influence herbivory on coral reefs. We found the removal of macroalgal biomass (i.e. herbivory) was shaped by the interaction between predator- and habitat-associated fear effects. Rates of macroalgal removal declined with increasing macroalgal density, likely due to increased visual occlusion by denser macroalgae patches and reduced ability of herbivorous fishes to detect the predators. The presence of the predator model reduced herbivory within low macroalgal density plots, but not within medium- and high-density macroalgal plots. Our results suggest that fear effects due to predator presence were greatest at low macroalgal density, yet these effects were lost at higher densities possibly due to greater predation risk associated with habitat structure and/or the inability of herbivorous fishes to detect the predator model.
非消耗性恐惧效应是消费者在一系列生态系统中进行觅食决策的一个重要决定因素。然而，与捕食者存在相关的恐惧效应与与栖息地结构相关的恐惧效应如何相互作用尚不清楚。在这里，我们使用了捕食性鱼类模型和不同密度的大型藻类实验斑块来研究与捕食者和栖息地相关的恐惧效应对珊瑚礁上的食草作用的影响。我们发现，大型藻类生物量的去除（即食草作用）受到与捕食者和栖息地相关的恐惧效应相互作用的影响。大型藻类去除率随着大型藻类密度的增加而下降，这可能是由于较密的大型藻类斑块增加了视觉遮挡，以及食草鱼类发现捕食者的能力降低。捕食者模型的存在减少了低密度大型藻类斑块内的食草作用，但在中密度和高密度大型藻类斑块内则没有。我们的结果表明，由于捕食者的存在而产生的恐惧效应在低密度大型藻类中最大，但在更高密度时这些效应消失，可能是由于与栖息地结构相关的更大的捕食风险和/或食草鱼类无法检测到捕食者模型。
