RAPID: Ecological responses to large-scale climate disturbance: Could the interaction of overfishing and disturbance initiate phase-shifts in tropical seagrass ecosystems?

智力优势：大型海洋捕食者分别通过与捕食相关的清除和与恐吓相关（即非消耗性）的行为改变，对其群落的其他成员产生直接和间接的影响。因此，大型捕食者可以对生态系统的其他方面产生级联效应。了解顶端捕食者对生态系统结构和功能影响的细微差别是一个具有浓厚生态学兴趣的话题，对保护和管理具有重要意义。pi已经在澳大利亚西部鲨鱼湾的原始海草生态系统中工作了15年。他们的研究表明，虎鲨导致儒艮对海草的摄食减少，这使得一种生长缓慢但非常美味的海草（南极两栖海草）得以持续存在，甚至占据主导地位。生长缓慢的海草最近经历了大范围的死亡，两个重要的问题是：(1)对生态系统的直接影响是什么；(2)鲨鱼的存在或消失如何影响该物种的重建，以及对该系统的长期影响？南极冰原的自然枯死提供了一个独特的机会来研究这些多样性、结构和持久性问题，并检查自然干扰对原始生态系统的影响，这些问题已经被研究了很多年。需要快速奖励，以便在骚乱发生后不久利用这种情况。更广泛的影响：该项目将对气候变化和过度捕捞对生态系统动态的影响提供重要的见解，项目倡议组织将把结果整合到他们正在进行的外联项目中，包括一个网站（www.sberp.org）、公开讲座和面向小学、初中和高中学生的视频项目。数据将提供给西澳大利亚环境和保护部，以协助他们管理鲨鱼湾，以及美国的数据存储库。该项目将为一名博士生、一名博士后和多名本科生助理提供研究支持。

Intellectual Merit: Large-bodied marine predators have both direct and indirect effects on other members of their communities through predation-related removals and intimidation-related (that is, non-consumptive) changes in behavior of other organisms, respectively. Thus, large-bodied predators can produce cascading effects on other aspects of the ecosystem. Understanding the nuances of top predator effects on ecosysytem structure and function is a topic of keen ecological interest with strong implications for conservation and management. The PIs have been working for 15 years in the pristine seagrass ecosystem of Shark Bay, western Australia. Their work has shown that tiger sharks induce a reduction in seagrass grazing by dugongs which allows a slow-growing but highly palatable seagrass (Amphibolis antarctica) to persist and even dominate. The slow-growing seagrass has recently experienced a widespread die-off, and two important questions are: (1) what are the immediate effects on the ecosystem; and (2) how does the presence or absence of sharks affect re-establishment of this species, with long-term consequences for the system? The natural die-back of A. Antarctica provides a unique opportunity to study these questions of diversity, structure, and persistence, and to examine the effects of a natural disturbance in a pristine ecosystem that has been studied for many years. A RAPID award is needed to take advantage of this situation shortly after disturbance.Broader Impacts: The project will provide important insights into the impacts of climate change and overfishing on ecosystem dynamics, and the PIs will integrate results into their on-going outreach programs, including a website (www.sberp.org), public lectures, and video-based projects for elementary, middle, and high school students. Data will be provided to the Department of Environment and Conservation of Western Australia to assist in their management of Shark Bay, as well as US data depositories. The project will provide support for research by a PhD student, a postdoc, and multiple undergraduate assistants.