Collaborative Research: The Effects of Flow on the Nature and Strength of Indirect Effects

营养级联的经典观点强调捕食者对猎物的消耗效应和突发性的间接捕食者对基础资源的影响(密度中介间接相互作用，DMIIs)。然而，越来越清楚的是，非消耗性捕食者对猎物特征的影响也可以导致对较低营养水平的强大间接影响(特征介导的间接相互作用，TMII)。这种特征介导的级联在水生系统中非常常见，之所以出现，是因为猎物表现出对抗捕食者的行为，以响应水传播的化学信号，信号增加了捕食风险。这些化学物质通过流水在捕食者和猎物之间传输，因此受到水动力(如湍流)的影响，可以改变捕食者-猎物物种对的化学信号结构和化学感受能力。因此，湍流对化学感受的影响可能强烈影响DMIIs和TMIIs的相对重要性，这取决于这些效应如何影响捕食者寻找猎物的能力和猎物避免被吃掉的能力。这项研究的主要目的是研究流动效应对捕食者和猎物的感觉能力如何影响间接影响的性质和强度。Smee博士和Trussell博士将通过实验室和野外实验来探索这一问题，该食物链是一个三营养、多岩石的潮间带食物链，其中包括捕食性青蟹(Carcinus Maenas)、中间消费者(肉食性蜗牛Nucella Lapillus)和这种蜗牛的主要食物来源之一(藤壶，Semibalanus balanoides)。以前的工作表明，DMIIs和TMIIs都可以在这个食物链内运作，而且来自其他系统的良好证据表明，水动力条件可以强烈影响螃蟹捕食者及其猎物的趋化能力。本项目的核心问题是：1.水动力如何影响纽卡拉对青蟹风险线索的反应？2.水动力如何影响青蟹的觅食行为和成功？3.水动力如何塑造野外营养瀑布的性质和强度？研究结果将在水动力机制对捕食者-猎物化学信号的影响和间接捕食者效应之间提供一种新的联系，间接捕食者效应通常在自然群落的结构中发挥关键作用。该研究项目将为三名研究生、一名博士后和几名本科生提供培训。在这个由德克萨斯A&M、科珀斯克里斯蒂(TAMUCC)和东北大学参与的合作项目中。学生将体验丰富的跨学科研究环境，融合了化学生态学、水动力学和群落生态学的专业知识。

Classical views of trophic cascades emphasize the consumptive effects of predators on their prey and emergent indirect predator effects on basal resources (density-mediated indirect interactions, DMIIs). However, it is increasingly clear that non-consumptive predator effects on prey traits can also lead to powerful indirect effects on lower trophic levels (trait-mediated indirect interactions, TMIIs). Such trait-mediated cascades are quite common in aquatic systems and emerge because prey exhibit anti-predator behaviors in response to waterborne chemical cues signaling increased predation risk. These chemicals are transported between predators and prey by flowing water and are thus subject to hydrodynamic forces (e.g. turbulence) that can alter chemical signal structure and the chemoreceptive abilities of a predator-prey species pair. Hence, the effects of turbulence on chemoreception may strongly influence the relative importance of DMIIs and TMIIs depending on how such effects influence the ability of predators to find prey and the ability of prey to avoid being consumed. The primary goal of this research is to examine how flow effects on the sensory capabilities of both predators and prey influence the nature and strength of indirect effects. Drs. Smee and Trussell will explore this issue with laboratory and field experiments on a tri-trophic, rocky inter-tidal food chain containing the predatory green crab (Carcinus maenas), an intermediate consumer (the carnivorous snail, Nucella lapillus), and one of this snail's principal food resources (the barnacle, Semibalanus balanoides). Previous work has shown that both DMIIs and TMIIs can operate within this food chain and there is good evidence from other systems that hydrodynamic regime can strongly influence the chemoreceptive abilities of crab predators and their prey. The following questions are central to the project:1. How do hydrodynamic forces influence the responses of Nucella to green crab risk cues?2. How do hydrodynamic forces influence green crab foraging behavior and success?3. How do hydrodynamic forces shape the nature and strength of trophic cascades in the field? The results of the research will provide a novel link between the effects of hydrodynamic regime on predator-prey chemical signaling and indirect predator effects that often play a pivotal role in the structuring of natural communities. The research project will provide training for three graduate students, one postdoctoral fellow, and several undergraduate students. in the collaborative project involving Texas A&M, Corpus Christi (TAMUCC) and Northeastern University. Students will experience a rich interdisciplinary research environment that blends expertise in chemical ecology, hydrodynamics, and community ecology.