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

在陆地群落中，食草动物促进植物真菌病的研究已经进行了一个多世纪。尽管这种相互作用在陆地系统中普遍存在，但直到研究者最近在盐沼的工作中，人们才认为它与海洋植物群落的结构有关。通过控制食草动物和真菌的存在，他证明了蜗牛放牧和随后的真菌感染在活草中导致植物生长急剧减少，并且在高食草动物密度下，破坏树冠。如果食草动物对海洋植物真菌疾病的传播不局限于沼泽（正如对4种海洋植物生态系统的全球调查的初步数据所表明的那样），那么从植物身上咬下一小口的小型食草动物可能对全球的海洋植物施加同样强大但未被发现的控制。此外，由于物理压力通常会降低植物的免疫反应，与海洋全球变化相关的多重压力源的加剧可能会加剧和破坏这些未经研究的食草动物-疾病-植物相互作用。为了测试这种潜在的关键生态相互作用的全球普遍性，该项目将通过跨2大洲的4个生态系统的多地点调查和操作来回答以下问题：1)食草动物促进海洋植物真菌疾病是一种常见但被忽视的相互作用吗？2)食草动物真菌感染对海洋植物生长的最终影响是什么？3)多种应激源如何影响海洋植物中食草动物对真菌病害的诱导强度？这项工作代表了我们对海洋生态系统中植物-食草动物相互作用的理解向前迈出了变革性的一步，因为它填补了我们对海洋植物生态系统自上而下控制的理解中100年来的知识空白：小型食草动物通常会促进海洋植物的真菌疾病吗？这种相互作用会抑制植物生长吗？关于食草动物调控海洋植物这一神秘而强大的机制的证据，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，并导致海洋食物网生态学中疾病动态的广泛整合。海洋植物生态系统健康对人类的影响是深远的，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，并制定有效的保护策略。为了帮助将植物病害动态整合到海洋生态学和保护中，研究者将：(1)编写一本关于海洋生态系统食物网和疾病的编辑卷；(2)与大自然保护协会密切合作，将研究结果纳入他们的全球海洋学习交流中。此外，综合教育计划将提高学生：(1)对海洋生态系统中疾病和食物网动态的理解；(2)对海洋科学事业的考虑。这一目标将通过课堂发展和早期学生接触实地学习和独立研究来实现。在过去的三年里，研究者在佛罗里达大学成功组织了一个本科海洋实地课程。他将通过整合基于食物网疾病-植物相互作用的新讲座和实验室来加强课程。他将把这项综合教育工作扩展到高中学生，让那些在实践、实地科学和潜在职业机会方面表现优异（童子军）和有风险（成绩低、出勤率低）的学生参与其中：1)为期两周的实地课程，提供综合网络支持；2)指导海洋植物疾病的夏季研究；3)在佛罗里达大学2008年发起的海洋研讨会上发表研究成果。本项目由生物海洋学计划、海洋科学教育计划和国际科学与工程办公室美洲计划提供资金。

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.