Environmental forcing and predator consumption outweigh the nonconsumptive effects of multiple predators on oyster reefs
Environmental forcing and predator consumption outweigh the nonconsumptive effects of multiple predators on oyster reefs
复制标题
环境强迫和捕食者的消耗超过了多种捕食者对牡蛎礁的非消耗性影响
DOI：
10.1002/ecy.3041
复制
发表时间：
2020
期刊：
影响因子：
4.8
通讯作者：
White, J. Wilson
中科院分区：
文献类型：
--
作者：
Kimbro, David L.;Tillotson, Hanna G.;White, J. Wilson
预测捕食者如何构建生态系统的能力取决于捕食者对猎物适应度的消耗效应和非消耗效应。猎物种群也可能受到多种捕食者之间的相互作用的影响，在整个生命阶段的猎物和环境因素，如干扰。然而，这些多个驱动程序的猎物动态的交集还有待经验评估。我们解决了这一知识差距使用东部牡蛎（Crassostrea virginica），一种已知遭受NCE的物种，作为焦点猎物。超过4个月，我们操纵正交的生命阶段（无，少年，成年人，或两者兼而有之），牡蛎经历了模拟捕食（CE）和暴露于嗅觉线索的少年牡蛎捕食者（螃蟹），成年捕食者（海螺），顺序螃蟹，然后海螺，或没有。我们复制了这个实验在三个站点沿着在佛罗里达（美国）河口的环境梯度。对于幼牡蛎和成年牡蛎，生存率仅由CE降低，生长变化最好由水流中的站点间变化解释，捕食者线索的负面影响要小得多。暴露于海螺线索的成年人表现出减少的增长（NCE），但这种影响被一个积极的CE增长超过：存活的牡蛎在较低的密度下生长得更快。最后，海螺线索减少幼虫定居（另一个NCE），但这是淹没在幼虫供应的网站之间的变化。这项研究强调了如何强大的环境梯度和捕食者CE可能超过NCE的影响，即使在猎物已知的捕食者的线索作出反应。这些研究结果作为一个警示故事的重要性，评估NCE过程的时间尺度和跨环境梯度相关的猎物人口。
The ability to predict how predators structure ecosystems has been shown to depend on identifying both consumptive effects (CEs) and nonconsumptive effects (NCEs) of predators on prey fitness. Prey populations may also be affected by interactions between multiple predators across life stages of the prey and by environmental factors such as disturbance. However, the intersection of these multiple drivers of prey dynamics has yet to be empirically evaluated. We addressed this knowledge gap using eastern oysters (Crassostrea virginica), a species known to suffer NCEs, as the focal prey. Over 4 months, we manipulated orthogonally the life stage (none, juvenile, adult, or both) at which oysters experienced simulated predation (CE) and exposure to olfactory cues of a juvenile oyster predator (crab), adult predator (conch), sequentially the crab and then the conch, or none. We replicated this experiment at three sites along an environmental gradient in a Florida (USA) estuary. For both juvenile and adult oysters, survival was reduced solely by CEs, and variation in growth was best explained by among‐site variation in water flow, with a much smaller and negative effect of predator cue. Adults exposed to conch cue exhibited reduced growth (an NCE), but this effect was outweighed by a positive CE on growth: Surviving oysters grew faster at lower densities. Finally, conch cue reduced larval settlement (another NCE), but this was swamped by among‐site variation in larval supply. This research highlights how strong environmental gradients and predator CEs may outweigh the influence of NCEs, even in prey known to respond to predator cues. These findings serve as a cautionary tale for the importance of evaluating NCE processes over temporal scales and across environmental gradients relevant to prey demography.