Behaviorally mediated indirect species interactions in a subtropical seagrass community

亚热带海草群落中行为介导的间接物种相互作用

• 批准号: 0526065
• 负责人: Michael Heithaus
• 金额: --
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0526065&HistoricalAwards=false
• 关键词: Behaviorally; mediated; indirect; species; interactions

A functional knowledge of habitat use by large marine vertebrates may be critical forunderstanding the structure and dynamics of many marine communities. For example, grazing vertebrates can substantially alter species composition and biomass of seagrasses, which may in turn affect many other marine species. Large-bodied predators also may be important in structuring marine communities, through direct and indirect routes. Sub-lethal predator effects, such as induced selection of low-risk habitats for foraging, or reduced foraging rates when risk is high, may have important implications for prey populations, rivaling or even exceeding those of lethal effects. Importantly, these sub-lethal effects of predators can transcend the prey species whose behavior they affect, thereby creating behaviorally-mediated indirect species interactions (BMII). While BMII have been studied in mesocosm experiments, there exists a critical need to gather field data in complex communities to fully understand the nature and importance of these phenomena, particularly in marine communities. This project will investigate a potential BMII that may influence the structure of a subtropical seagrass community. Do tiger sharks (Galeocerdo cuvier) have non-lethal indirect effects on seagrass communities mediated by predation-risk sensitive foraging by dugongs (Dugong dugon), the community's largest grazer? Preliminary evidence shows that dugongs respond behaviorally to shark predation risk, and studies in other locations have shown that dugongs can impact seagrass communities. This study will be undertaken in Shark Bay, Western Australia, which contains one of the world's largest and most secure dugong populations, and where dugongs routinely forage in seagrass communities with temperate species. Tiger sharks are extremely abundant in the bay and show considerable spatial and temporal variation in abundance. Patterns of variation in predation risk and surveys of seagrass biomass and quality will be used to address how energy (or nutrient) availability and predation risk influence habitat and microhabitat use of dugongs, as well as their foraging time budgets and energy and nutrient intake rates. Indirect effects of tiger sharks on seagrass communities, mediated by dugong foraging, will be determined using exclosures and controls that separate the impacts of dugong and sea turtle grazing as well as the effects of experimental manipulations.Broader Impacts: This study will enhance an understanding of BMII in general and their role in determining community structure as well as offer insights into the importance of shark predation risk and dugong grazing in marine communities. This project will be the first to explicitly address the role of a large shark in structuring a marine community. This project will fund a PhD student and a postdoctoral investigator. Many undergraduates will also be involved, in the field and the laboratory, from Florida International University, a minority-serving institution. Undergraduates will also be recruited from small liberal arts colleges in Ohio and Michigan. Finally, results will be disseminated to the public through a website, television documentaries, and public talks.

大型海洋脊椎动物对栖息地利用的功能性知识对于理解许多海洋群落的结构和动态可能是至关重要的。例如，食草脊椎动物可以大大改变海草的物种组成和生物量，这反过来又可能影响到许多其他海洋物种。大型食肉动物也可能通过直接和间接的途径在构建海洋群落方面发挥重要作用。亚致死的捕食者效应，如诱导选择低风险栖息地觅食，或降低觅食率时，风险高，可能有重要的影响猎物种群，媲美甚至超过那些致命的影响。 重要的是，捕食者的这些亚致死效应可以超越它们影响其行为的猎物物种，从而产生行为介导的间接物种相互作用（BMII）。虽然BMII已在围隔实验中进行了研究，但迫切需要在复杂的群落中收集实地数据，以充分了解这些现象的性质和重要性，特别是在海洋群落中。 该项目将调查一种可能影响亚热带海草群落结构的潜在BMII。 虎鲨（Galeocerdo cuvier）是否对海草群落有非致命的间接影响，介导的是儒艮（Dugong dugon）对捕食风险敏感的觅食，儒艮是海草群落中最大的食草动物？ 初步证据表明，儒艮对鲨鱼捕食风险的行为反应，在其他地方的研究表明，儒艮可以影响海草群落。 这项研究将在西澳大利亚的鲨鱼湾进行，那里有世界上最大和最安全的儒艮种群之一，儒艮经常在温带物种的海草群落中觅食。虎鲨在海湾中极为丰富，并在空间和时间上表现出相当大的变化。 捕食风险的变化模式和海草生物量和质量的调查将被用来解决如何能源（或养分）的可用性和捕食风险影响生境和微生境使用儒艮，以及他们的觅食时间预算和能量和养分摄入率。 虎鲨对海草群落的间接影响是由儒艮觅食介导的，将通过隔离区和控制区来确定，隔离区和控制区将儒艮和海龟觅食的影响以及实验操作的影响分开。这项研究将提高对BMII的一般理解及其在决定群落结构方面的作用，并深入了解鲨鱼捕食风险和儒艮的重要性。在海洋群落中放牧。该项目将是第一个明确解决大型鲨鱼在构建海洋社区中的作用的项目。 该项目将资助一名博士生和一名博士后研究员。佛罗里达国际大学是一所为少数民族服务的机构，许多本科生也将参与实地和实验室工作。 本科生也将从俄亥俄州和密歇根州的小型文理学院招募。最后，将通过网站、电视纪录片和公开讲座向公众传播成果。