COLLABORATIVE RESEARCH: Factors Affecting the Nature and Strength of Indirect Effects: A Modeling and Empirical Approach

营养级联体现了间接效应对生态群落动态和结构的重要性。营养级联的经典观点强调捕食者通过消耗猎物对基础资源的积极间接影响。然而，越来越多的证据表明，我们必须改进我们对不同营养水平如何动态联系的看法，因为营养级联也可能由捕食者引起的猎物行为（如觅食活动）的变化引起。尽管有丰富的理论，但我们对影响个体觅食决定的因素的经验理解有限，而这些因素反过来又决定了自然群落中间接影响的性质和强度。Drs。Trussell和Luttbeg将使用模型比较和零假设方法来探索密度（DMIIs）和性状介导的间接相互作用（TMIIs）对岩石潮间带海岸营养级联的相对重要性。利用三营养食物链作为模型系统，他们将操纵预测的影响猎物行为的因素，从而影响营养级联中tmii的相对强度。研究人员将通过解决以下问题来实现这些目标：资源水平、猎物状态和捕食风险如何影响猎物觅食和生长功能？2. 资源水平、猎物状态和捕食强度如何塑造猎物死亡率函数？3. 什么样的模型能最好地描述这些因素对猎物觅食行为的短期影响和突发间接效应的强度？4. 短期数据支持的模型能准确预测长期猎物的行为和突发间接效应的强度吗？通过探索对个体行为的关注是否能提高我们预测自然系统中间接影响的性质和强度的能力，这项研究将对生态学做出重大的智力贡献。通过用经验数据评估替代模型，我们的研究是新颖的，并将在生态学理论与其经验基础之间建立更强的联系。此外，由于物种相互作用是生态学中主要问题的核心，例如利用营养级联理论来管理自然系统，因此了解环境如何改变行为是至关重要的。更广泛的影响是相当大的。这项研究将允许所有教育水平的学生追求他们对生态学的兴趣。研究生和本科生的培训将在研究的各个阶段进行。作为东北的一部分？此外，每年还将向海洋科学中心下属的海岸海洋科学学院（COSA）的高中生提供暑期研究实习机会。外展人员。这些学生大多来自波士顿地区公立高中的弱势群体。除了为这些学生提供大量的实地经验外，他们还将教他们如何(1)进行基本的统计分析，(2)撰写科学论文，以及(3)开发并向海洋科学中心社区口头介绍他们的实习经历。

The trophic cascade exemplifies the importance of indirect effects to the dynamics and structure of ecological communities. Classical views of trophic cascades emphasize the positive indirect effect that predators have on basal resources through their consumption of prey. Yet growing evidence indicates that we must refine our view of how different trophic levels are dynamically linked because trophic cascades can also be caused by predator-induced changes in prey behavior such as foraging activity. Despite abundant theory we have a limited empirical understanding of the factors that shape individual foraging decisions that, in turn, dictate the nature and strength of indirect effects in natural communities. Drs. Trussell and Luttbeg will use a model comparison and null hypothesis approach to explore the relative importance of density (DMIIs) and trait-mediated indirect interactions (TMIIs) to trophic cascades on rocky intertidal shores. Using a tri-trophic food chain as a model system, they will manipulate factors predicted to influence prey behavior and thus the relative strength of TMIIs in trophic cascades. The researchers will achieve these objectives by addressing the following questions: 1. How do resource levels, prey state, and predation risk shape prey foraging and growth functions? 2. How do resource levels, prey state, and predation intensity shape prey mortality functions? 3. What model best describes the short-term influence of these factors on prey foraging behavior and the strength of emergent indirect effects? 4. Do models supported by short-term data accurately predict longer-term prey behavior and the strength of emergent indirect effects? The research will make significant intellectual contributions to ecology by exploring whether attention to individual behavior improves our ability to predict the nature and strength of indirect effects in natural systems. By evaluating alternative models with empirical data, our research is novel and will build a stronger connection between ecological theory and its empirical base. Moreover, because species interactions are central to major issues in ecology, such as the use of trophic cascade theory to manage natural systems, it is critical that we understand how behavior is modified by environmental context. Broader impacts are considerable. The research will allow students at all educational levels to pursue their interests in ecology. Graduate and undergraduate training will occur during all phases of the research. As part of Northeastern?s Young Scholars Program they also will offer a summer research internship each year to a high school student from the Coastal Ocean Science Academy (COSA) that is taught by the Marine Science Center?s Outreach staff. These students are largely members of under-represented groups from Boston area public high schools. In addition to providing these students with plenty of field experience, they also will teach them how to (1) conduct basic statistical analyses, (2) write a scientific paper, and (3) develop and deliver an oral presentation on their internship experience to the Marine Science Center community.