Collaborative Research: Mechanisms of resistance and resilience to system-wide loss of a keystone predator in an iconic intertidal community

危害捕食者健康的疾病可能会导致生态系统结构发生重大、突然、有时意想不到的变化。该项目将结合实地调查、操纵实验和数学模型，以了解和预测史无前例的海星衰减病(SSWD)爆发对生态系统层面的影响，这种疾病在美国西海岸肆虐，摧毁了关键捕食者--黄鱼的种群。具体地说，该项目将确定(1)促进或损害潮间带生态系统对海星消耗疾病的适应能力的生态和环境因素；(2)记录整个美国西海岸从这一重大干扰中恢复的速度和程度；以及(3)确定可作为保护这些标志性生态系统的重要保护目标的海星消耗疾病恢复能力的热点。这项研究将通过在疾病生态学、海洋生物学、数学建模和生物统计学方面对本科生和研究生进行交叉培训来满足重要的社会需求。来自代表性不足群体的学生将广泛从西海岸各州招收。每年夏天，四名本科生将接受岩石潮间带野外研究技术培训。将开发以SSWD为重点的模块，并在每个机构的生态学课程中使用，以强调定量和跨学科培训对于解决生物学中的重要问题的重要性。研究生将与俄勒冈州移民领导学院(OMLI)合作，为移民工人及其子女创建关于SSWD的研讨会。PIS将继续与媒体和公众团体互动，并将通过自然保护协会和海岸观察为有兴趣让学生参与海星监测的高中教师举办讲习班，扩大外联活动，以确保这一项目的成果传播到传统学术界之外。最后，作为该项目的一部分，将创建一系列基于模型的互动网络模块，向更广泛的公众说明海星衰减病对生态系统的影响。对这一模型系统的研究将有助于更好地理解其他生态系统如何抵抗或易受人类活动(如捕鱼、狩猎和栖息地破坏)的影响，这些活动对顶级捕食者的影响是不对称的。威胁捕食者健康的疾病可以减少它们自上而下的影响，从而导致生态系统结构的显著变化。2013-15年，海星衰减病(SSWD)在北美西海岸摧毁了最初的Keystone捕食者--赭鱼的种群，这是有记录以来最广泛的海洋疾病事件之一。该项目将利用这次史无前例的爆发，通过记录和解释SSWD生态系统恢复的时间速度、地理范围和时空共生，来测试和扩展Keystone捕食理论。这一疾病事件还提供了一个机会，以前所未有的规模测试一个经过充分研究的生态系统的抵抗力和弹性。在14个地点中的每个地点，研究人员将量化该系统对海星丧失的潜在抵抗力的过程(猎物招募和定居、贻贝生长、捕食强度、固着生物之间的促进相互作用，以及替代捕食者的影响)。在后一项实验中，私人投资者将进行笼养排斥实验，以测试较大的(例如鸟类)和较小的(例如海螺)替代捕食者对已开垦土地的猎物重新繁殖的影响。研究人员还将进行一系列新的实验，以操纵影响藤壶和草皮形成藻类促进贻贝生长的因素。所有这些经验性研究都将用于将建模工作参数化，以探索这些过程对这一系统和其他生态系统的更长期和更大规模的影响。具体地说，PIs将使一个新的空间-显式元群落模型与经验数据相适应，以确定种内和种间阻力与弹性机制在历史沿海尺度SSWD干扰后恢复潮间带生态系统中的相对重要性。

Diseases that compromise the health of predators can lead to large, abrupt and sometimes unexpected changes in the structure of ecosystems. This project will combine field surveys, manipulative experiments and mathematical models to both understand and predict the ecosystem-level effects of the unprecedented sea star wasting disease (SSWD) outbreak that devastated populations of Pisaster ochraceus, a critical predator, across the West Coast of the United States. Specifically, the project will determine (1) the ecological and environmental factors that promote vs. compromise the resilience of intertidal ecosystems to sea star wasting disease, (2) document the pace and extent of recovery from this major disturbance across the West Coast of the United States, and (3) identify hotspots of resilience to sea star wasting disease that may serve as important conservation targets to preserve these iconic ecosystems. The research will address important societal needs by cross-training undergraduate and graduate students in disease ecology, marine biology, mathematical modeling and biostatistics. Students from underrepresented groups will be recruited broadly from West Coast states. Each summer, four undergraduate students will be trained in rocky intertidal field research techniques. SSWD-focused modules will be developed and used in ecology courses at each institution to emphasize the importance of quantitative and interdisciplinary training for addressing important questions in biology. Graduate students will work with the Oregon Migrant Leadership Institute (OMLI) for migrant workers and their children to create workshops for students about SSWD. The PIs will continue interacting with the media and public groups, and will expand outreach activities through The Nature Conservancy and CoastWatch-sponsored workshops for high school teachers interested in involving students in sea star monitoring to ensure that the results of this project are disseminated beyond traditional academic circles. Finally, a series of model-based interactive web modules will be created as part of this project to illustrate the ecosystem-level effects of sea star wasting disease to the broader public. The studies on this model system will lead to a better understanding of how other ecosystems may resist or be vulnerable to human activities (e.g., fishing, hunting and habitat destruction) that asymmetrically influence top predators.Diseases that threaten the health of predators can reduce their top-down influence and thus lead to significant changes in ecosystem structure. In 2013-15, sea star wasting disease (SSWD) devastated populations of Pisaster ochraceus, the original keystone predator, along the west coast of North America in one of the most extensive marine disease events ever recorded. This project will leverage this unprecedented outbreak to test and extend keystone predation theory by documenting and explaining the temporal pace, geographical extent, and spatiotemporal co-occurrence of ecosystem recovery from SSWD. The disease event also provides an opportunity to test the resistance and resilience of a well-studied ecosystem at an unprecedented scale. At each of 14 sites, the investigators will quantify processes that underlie potential resistance of the system to loss of sea stars (prey recruitment and colonization, mussel growth, predation intensity, facilitative interactions among sessile organisms, and the effect of alternative predators). In the latter experiments, the PIs will conduct caging exclusion experiments to test the effects of both larger (e.g., birds) and smaller (e.g., whelks) alternative predators on prey recolonization of cleared plots. The investigators will also conduct a novel set of experiments to manipulate factors affecting facilitation of mussels by barnacles and turf-forming algae. All these empirical studies will be used to parameterize modeling efforts that will explore the longer-term and larger-scale implications of these processes, both for this system and for other ecosystems. Specifically, the PIs will fit a novel spatially-explicit metacommunity model to the empirical data in order to determine the relative importance of intraspecific and interspecific resistance vs. resilience mechanisms for the recovery of intertidal ecosystems following a historical, coastal-scale SSWD disturbance.