Effects of Predator Diversity on the Strength of Trophic Cascades in an Oceanic Benthic Ecosystem

智力优势。 由于过度捕捞、人类活动对栖息地的破坏以及可能的气候变化，世界海洋中捕食者的多样性急剧减少。 然而，对于大多数生态系统来说，捕食者的多样性和丰富度对生态系统功能的重要性仍然是未知的。 顶级捕食者最普遍的社区范围内的后果之一是营养级联（TC），其中食草动物受到抑制，这使植物免于消费，从而提高植物生产力。 最近的研究表明，捕食者的多样性可能会减少，增加，或对营养级联的强度没有影响。 少数，到目前为止，实验测试捕食者多样性对级联强度的影响排除了广泛的概括预测理论的发展至关重要。 这种研究是有限的，缺乏实验现实主义，由于数量很少的捕食者物种，可以在简化的中型生态系统中进行操作。 如果没有更真实的物种数量，就不可能将结果外推到经历捕食者多样性损失的自然生态系统。 为了应对这些挑战，并更好地了解海洋生态系统中捕食者多样性的现状和变化水平的后果，将对捕食者多样性及其草食性海胆猎物的自然水平进行一系列实验操作。 这些假设检验了对底栖藻类的最终影响，作为衡量加拉帕戈斯海洋保护区海洋底栖生态系统级联强度的一个尺度。 由于多年来作为联合国教科文组织世界遗产的工业捕鱼保护，以及作为GMR的地方保护保护，有各种各样的高营养级捕食者，如大鱼和鲨鱼。 同样，捕食海胆的中级鱼类和无脊椎动物也具有高度多样性，这为测试和发展捕食者多样性和生物多样性生态系统功能理论创造了一个不寻常的机会。 在这个项目中解决的首要问题是：如何自然发生的大范围的海洋捕食者多样性的影响力的营养级联？环境变化和保护如何影响这些过程？第一个问题将在操纵水平（营养水平内;海胆食草动物）和垂直（跨营养水平;捕食者）消费者多样性的实验中得到解决，并在另一个实验中操纵掠食性鱼类和无脊椎动物公会的多样性。 实验采用开放式围栏处理，其中含有海胆，但允许鱼类和无脊椎动物捕食海胆。 为了记录鱼类和无脊椎动物捕食者丰富度的自然水平，它们遇到了处理，消耗了海胆并相互作用，整个实验布局将被视频记录长达几周。 延时摄像机/照明系统能够在不影响捕食者行为的情况下进行昼夜成像。 一个简化的操作，以衡量捕食者多样性对级联强度的影响，将复制和视频记录在16个网站-代表不同水平的上升流和保护-把机械的理解，从详细的实验中收集到的地方网站到一个更广泛的（中尺度）的背景。更广泛的影响。 预计拟议的教育研究的几个主要影响将超出对养护和基于生态系统的管理的影响。 例如，该计划将为一名研究生和两名本科生提供实验生态学，潮下群落生态学，统计学，海洋保护区科学，科学写作和口头陈述技能的实践培训。 PI致力于教育和公共宣传活动，超越了捕食者和食物网获得的信息的典型用途，用它来加强他在布朗大学的大型本科生生态学课程的讲座。这些推广活动之一是通过与布朗大学教学硕士（MAT）项目主任合作，每年为一名MAT学生提供科学实习机会，以帮助培养下一代教师领导者。 将与MAT实习生分享从延时录像中获得的关于食物网、魅力十足的加拉帕戈斯巨型动物生态学和海洋捕食者活动图像的一般信息，以启发他们为小学和高中学生制定课程计划。 总之，拟议研究的更广泛的教育影响将是加强全球训练有素的生命科学博士生队伍，帮助本科生为海洋生态学研究生院做好准备，加强对下一代K-12教师的培训，并加强对最紧迫的环境问题之一的理解-过度的生态系统后果，捕获顶级捕食者和随之而来的海洋捕食者多样性的丧失。

Intellectual Merit. Predator diversity has decreased dramatically in the world's oceans due to overfishing, anthropogenic habitat destruction and possibly climate change. Yet, still unknown for most ecosystems is the importance of predator diversity and abundance for ecosystem functioning. One of the most pervasive community-wide consequences of top predators is the Trophic Cascade (TC), where herbivores are suppressed, which releases plants from consumption, thus increasing plant productivity. Recent studies have shown that the diversity of predators may reduce, increase, or have no effect on the strength of trophic cascades. The small number, to date, of experimental tests of predator diversity effects on cascade strength precludes broad generalizations vital to the development of predictive theory. Such research is limited by the lack of experimental realism due to the small number of predator species that can be manipulated in simplified mesocosms. Without more realistic species numbers, it is impossible to extrapolate results to natural ecosystems that experience losses of predator diversity. To meet these challenges, and to better understand the consequences of present and changing levels of predator diversity in marine ecosystems, a series of experimental manipulations will be conducted on natural levels of predator diversity and their herbivorous sea urchin prey. The hypotheses test the ultimate effects on benthic algae, as a measure of cascade strength in oceanic benthic ecosystems of the Galapagos Marine Reserve (GMR). Because of years of protection from industrial fishing as a UNESCO World Heritage Site, and of local conservation protection as the GMR, there are diverse guilds of higher trophic level predators, such as large fish and sharks. Likewise, there is high diversity of intermediate-level fish and invertebrates that prey on sea urchins, creating an unusual opportunity for testing and developing predator diversity and Biodiversity Ecosystem Functioning theory. The overarching questions addressed in this project are: How do naturally occurring large ranges of oceanic predator diversity influence the strength of trophic cascades? and How does environmental variation and conservation protection influence these processes? The first question will be addressed in experiments manipulating both horizontal (within trophic level; urchin herbivores) and vertical (across trophic level; predators) consumer diversity and in another experiment manipulating the diversity of predatory fish and invertebrates guilds. The experiments employ open fenced treatments containing urchins but allowing access by fish and invertebrate predators of the urchins. To record natural levels of fish and invertebrate predator richness encountering the treatments, consuming the urchins and interacting with each other, the entire experimental layout will be video-recorded for up to several weeks at a time. The time-lapse cameras/lighting system is capable of day and night imaging without affecting predator behavior. A simplified manipulation to measure the influence of predator diversity on cascade strength will be replicated and video-recorded at 16 sites -- representing different levels of upwelling and conservation protection -- to place the mechanistic understanding gleaned from detailed experiments at local sites into a broader (mesoscale) context. Broader Impacts. Several major impacts of the proposed research on education are expected beyond the implications for conservation and ecosystem-based management. For instance, the program will provide hands-on training for one graduate student and two undergraduates in experimental ecology, sub-tidal community ecology, statistics, marine reserve science, scientific writing and oral presentation skills. The PI is committed to educational and public outreach activities beyond the typical use of the information gained on predators and food webs by using it to enhance lectures in his large undergraduate Ecology class at Brown University. One of these outreach activities is to help train the next generation of teacher leaders by collaborating with the Director of the Brown University's Masters in Teaching (MAT) program to offer a science internship for one MAT student per year. The general information on food webs, ecology of charismatic Galapagos megafuana and images of marine predators in action obtained from the time-lapse video would be shared with the MAT interns to inspire their lesson plans for elementary and high school students. In summary, the broader educational impacts of the proposed research will be to enhance the workforce of globally trained doctoral students in the life sciences, help prepare undergraduate students for graduate school in marine ecology, augment the training of the next generation of K-12 teachers and enhance the understanding of one of the most pressing environmental issues -- the ecosystem consequences of over-harvesting top predators and concomitant loss of predator diversity in the sea.