CAREER: Does predator intimidation help structure a pristine seagrass community through multiple indirect pathways?

职业：捕食者的恐吓是否有助于通过多种间接途径构建原始海草群落？

• 批准号: 0745606
• 负责人: Michael Heithaus
• 金额: $ 72.52万
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745606&HistoricalAwards=false
• 关键词: CAREER; Does; predator; intimidation; help

A recent synthesis suggests that the role of grazing in seagrass ecosystems is generally under-appreciated and that our understanding of these critical marine communities would be greatly enhanced by long-term experimental studies that determine the impact of grazing by multiple guilds, especially megagrazers (green turtles, sirenians) that have declined dramatically in most coastal systems. Furthermore, given the steep declines in populations of marine predators, an understanding of how upper trophic levels structure spatio-temporal patterns of grazer impacts is needed to be able to predict how anthropogenic changes to marine environments will influence seagrass ecosystems. A predictive framework of community ecology in general has been hampered in part because non-lethal effects of predators, both direct and indirect, often are overlooked. Behaviorally mediated indirect species interactions (BMII) occur when a predator causes a change in the behavior of its prey that is transmitted to lower trophic levels. While BMII appear to be important in shaping community dynamics, most studies of BMII have been carried out in small-scale experiments, and have not considered that top predators might initiate multiple BMII that could either attenuate or amplify their indirect effects in natural communities. In this study, Dr. Heithaus will expand on previous investigations on one of the world's most pristine seagrass ecosystems (Shark Bay, Australia) to determine whether multiple BMII initiated by tiger sharks attenuate or amplify their indirect effects on seagrass communities. During previous NSF-funded research, the results show that tiger sharks can indirectly influence seagrass communities through two parallel non-lethal pathways rather than just one. In the first, well-established three-step BMII, tiger sharks cause shifts in megagrazer foraging locations, shielding seagrasses in dangerous microhabitats when sharks are present. In a second possible BMII, tiger sharks cause shifts in piscivore (dolphin, cormorant) microhabitat use that could result in enhanced grazing by herbivorous fishes in the microhabitats that megagrazers have abandoned. Depending on the nature of herbivorous fish interactions with seagrasses, these BMII could result in attenuation or amplification of tiger shark impacts on seagrass communities. In this new award, further monitoring visual and video surveys, experimental herbivory trials, underwater video monitoring, and turtle-borne video cameras will be used to determine whether and how spatiotemporal patterns of grazing vary. Experiments, in the field, will be employed using two types of exclosure and seagrass transplants to determine the relative importance of the BMII initiated by tiger sharks and whether they result in attenuation or amplification of shark effects on seagrass communities. This project will support some of the most comprehensive long-term studies of a relatively pristine community of highly interactive marine species (sharks, turtles, sea cows), extending the datasets to 15 years. This will enable Dr. Heithaus and collaborators to address new questions about how patterns of abundance are influenced by large-scale oceanographic and climatic factors. The project will also develop a broad education and outreach program that is integrated into the research program. This includes: 1) 5th-8th grade biology teacher research experiences in Shark Bay, 2) graduate student interactions with middle school students, 3) talks by graduate students and the PI at schools and regional and national science teacher conferences, 4) the development of lesson plans based on species in Shark Bay, 5) the development of DVDs for use in secondary school classrooms, 6) the development of video labs, 7) video content for National Geographic's online and on-demand channel - NGC Wild, 8) research experiences for undergraduate and graduate students, and 9) the enhancement of an educational website.

最近的一项综合报告表明，放牧在海草生态系统中的作用普遍未得到充分重视，通过长期的实验研究，确定多个行业，特别是在大多数沿海系统中急剧减少的巨型龟（绿色龟、海妖）放牧的影响，将大大增进我们对这些重要海洋群落的了解。此外，鉴于海洋食肉动物的数量急剧下降，需要了解上层营养水平如何构成食草动物影响的时空格局，以便能够预测海洋环境的人为变化将如何影响海草生态系统。一般来说，群落生态学的预测框架受到阻碍，部分原因是捕食者的非致命影响，无论是直接的还是间接的，往往被忽视。行为介导的间接种间相互作用（BMII）发生在捕食者引起其猎物的行为变化，并传递到较低的营养级。虽然BMII似乎是重要的，在塑造社区动态，BMII的大多数研究已经进行了小规模的实验，并没有考虑到顶级捕食者可能会启动多个BMII，可以减弱或放大其间接影响的自然社区。在这项研究中，Heithaus博士将扩大以前对世界上最原始的海草生态系统之一（澳大利亚的Shark Bay）的调查，以确定由虎鲨发起的多个BMII是否会减弱或放大它们对海草群落的间接影响。在之前的NSF资助的研究中，结果表明，虎鲨可以通过两种平行的非致命途径间接影响海草群落，而不仅仅是一种。在第一个，完善的三步BMII中，虎鲨引起了巨鲨觅食地点的变化，当鲨鱼出现时，在危险的微生境中保护海草。在第二种可能的生物多样性指数中，虎鲨引起食鱼动物（海豚、鸬鹚）微生境使用的变化，这可能导致食草鱼类在巨型剃刀已经放弃的微生境中吃草。根据草食性鱼类与海草相互作用的性质，这些生物多样性指数可能导致虎鲨对海草群落影响的减弱或放大。在这个新的奖项，进一步监测视觉和视频调查，实验性草食动物试验，水下视频监测，和海龟携带的摄像机将被用来确定是否和如何放牧时空模式的变化。 实验，在现场，将采用两种类型的围隔和海草移植，以确定相对的重要性，生物多样性指数发起的虎鲨，以及它们是否会导致鲨鱼对海草群落的影响衰减或放大。该项目将支持对一个相对原始的高度互动的海洋物种（鲨鱼、海龟、海牛）社区进行一些最全面的长期研究，将数据集延长到15年。这将使Heithaus博士和合作者能够解决有关大规模海洋和气候因素如何影响丰度模式的新问题。该项目还将制定一个广泛的教育和推广计划，纳入研究计划。这包括：1）5 - 8年级生物教师在鲨鱼湾的研究经验，2）研究生与中学生的互动，3）研究生和PI在学校和区域和国家科学教师会议上的谈话，4）基于鲨鱼湾物种的课程计划的开发，5）DVD的开发用于中学教室，6）视频实验室的开发，7）国家地理在线和点播频道- NGC Wild的视频内容，8）本科生和研究生的研究经验，以及9）教育网站的增强。