CAREER: Small Grazers, Multiple Stressors and the Proliferation of Fungal Disease in Marine Plant Ecosystems

在陆地群落中，植物中真菌疾病的放牧促进作用已经被研究了一个多世纪。尽管这种相互作用在陆地系统中很普遍，但直到这位研究人员最近在盐沼进行的工作才被认为与海洋植物群落的结构有关。通过操控食草者和真菌的存在，他证明了蜗牛吃草和随后在活草上感染真菌导致植物生长急剧减少，在高食草者密度下，树冠遭到破坏。如果食草动物在海洋植物中促进真菌疾病的传播并不局限于沼泽(正如世界范围内对4种海洋植物生态系统的初步调查数据所表明的那样)，那么从植物身上小咬一口的小型食草动物可能对全球海洋植物施加同样强大的、但未被发现的控制。此外，由于物理胁迫通常会降低植物的免疫反应，与海洋全球变化相关的多种应激源的加剧可能会加剧和破坏这些未被研究的食草动物-疾病-植物相互作用。为了测试这种潜在的Keystone生态相互作用的全球普遍性，该项目将结合横跨两大洲的4个生态系统的多点调查和操作来回答以下问题：1)海洋植物中食草动物促进真菌疾病是一种常见但被忽视的相互作用？2)食草动物促进真菌感染对海洋植物生长产生什么影响？3)多重应激源如何影响海洋植物食草动物促进真菌疾病的强度？这项工作代表着我们对海洋生态系统中植物-食草动物相互作用的理解迈出了革命性的一步，填补了我们理解海洋植物生态系统自上而下控制的100年知识空白：小型食草动物通常会促进海洋植物中的真菌疾病吗？这种相互作用是否会抑制植物的生长？这种神秘而强大的海洋植物食草动物调控机制的证据将迫使海洋生态学家重新评估我们对自上而下控制的理解，并导致海洋食物网络生态系统中疾病动力学的广泛整合。海洋植物生态系统健康的后果对人类来说意义深远，因为这些群落提供了许多基本服务。这项研究的结果将使管理者能够更好地预测疾病和全球变化对海洋植物系统的影响，并制定有效的保护战略。为了帮助将植物疾病动态纳入海洋生态和保护，调查员将：(1)编写一本关于海洋生态系统中的食物网和疾病的编辑卷，(2)与自然保护协会密切合作，将研究结果纳入其全球海洋学习交流。此外，综合教育计划将增加学生：(1)了解海洋生态系统中的疾病和食物网动态，以及(2)考虑海洋科学职业。这一目标将通过班级发展和学生早期接触实地学习和独立研究来实现。在过去的三年里，这位调查员在密歇根大学成功地组织了一门本科海洋野外课程。他将通过纳入基于食物网、疾病-植物相互作用的新讲座和实验室来加强其课程。他将通过吸引优秀的(童子军)和处于危险中(低分，出勤率)的学生，通过以下方式将这种综合教育努力扩展到高中学生：1)为期两周的综合网络支持的野外课程，2)关于海洋植物疾病的指导夏季研究，3)在2008年于加州大学发起的海洋研讨会上展示结果。该项目的资金由生物海洋学项目、海洋科学教育项目和国际科学与工程美洲项目办公室提供。

In terrestrial communities, grazer-facilitation of fungal disease in plants has been studied for over a century. Despite the prevalence of this interaction in terrestrial systems, it was not considered relevant to the structure of marine plant communities until the investigator's recent work in salt marshes. By manipulating both grazer and fungal presence, he demonstrated that snail grazing and subsequent fungal infection in live grass led to drastic reductions in plant growth and, at high grazer densities, destruction of canopy. If grazer promotion of fungal disease in marine plants is not limited to marshes (as suggested by preliminary data from a world-wide survey of 4 marine plant ecosystems) then small grazers that take small bites out of plants could be exerting similarly strong, but undetected control over marine plants globally. In addition, since physical stress commonly reduces plant immune responses, intensifying multiple stressors associated with marine global change could intensify and destabilize these unstudied grazer-disease-plant interactions. To test the global generality of this potentially keystone ecological interaction, this project will answer the following questions with a combination of multi-site surveys and manipulations across 4 ecosystems spanning 2 continents: 1) Is grazer facilitation of fungal disease in marine plants a common but overlooked interaction? 2) What is the resultant impact of grazer-facilitated fungal infection on marine plant growth? 3) How do multiple stressors impact the strength of grazer facilitation of fungal disease in marine plants? The work represents a transformative step forward in our understanding of plant-grazer interactions in marine ecosystems as it fills a 100-year intellectual gap in our understanding of top-down control in marine plant ecosystems: Do small grazers commonly facilitate fungal disease in marine plants and does this interaction suppress plant growth?Evidence for this cryptic, yet powerful mechanism of grazer regulation of marine plants will compel marine ecologists to reevaluate our understanding of top-down control and lead to widespread integration of disease dynamics in marine food web ecology.The consequences of marine plant ecosystem health are far-reaching for humans, since these communities provide many essential services. Results from this study will allow managers to better predict effects of disease and global change on marine plant systems and formulate effective strategies for conservation. To help integrate plant disease dynamics into marine ecology and conservation, the investigator will: (1) produce an edited volume on Food Webs and Disease in Marine Ecosystems and (2) work closely with The Nature Conservancy to incorporate findings into their global marine learning exchanges. In addition, an integrated educational plan will increase student: (1) understanding of disease and food web dynamics in marine ecosystems and (2) consideration of marine science careers. This goal will be accomplished through class development and early student exposure to field-based learning and independent research. Over the past 3 years, the investigator has organized a successful undergraduate marine field course at UF. He will enhance its curriculum by incorporating new lectures and laboratories based on food web disease-plant interactions. He will expand this integrated educational effort to high school students by engaging students that are excelling (boy scouts) and at-risk (low grades, attendance) in hands-on, field science and potential career opportunities through: 1) a two-week field class with integrated web support, 2) mentored summer research on marine plant disease and 3) presentation of results at the Marine Symposium initiated at UF in 2008.Funding for this project was provided by the Biological Oceanography Program, Ocean Science Education Program, and Office of International Science and Engineering Americas Program.