Fish aggregations and biogeochemical hot spots across regional environmental gradients

海洋生态系统的消费者在自上而下的生态系统调节中的作用早已得到承认，但他们通过自下而上的途径（如营养供应）产生的影响往往没有得到充分认识，也没有被纳入沿海生态系统动态模型。然而，当消费者聚集时，来自消费者的营养供应可能是一个调节因素，例如结构复杂的栖息地周围的鱼类。研究这种自下而上的机制途径对于更全面地了解海草生态系统至关重要，海草生态系统在全球范围内很重要，也受到威胁。这项研究将解决以下问题：（1）集中营养供应消费者的结果在海草床明显的生态地球化学热点？以及（2）在营养物质可获得性和捕捞压力各不相同的区域环境背景下，消费者对生态系统过程的影响如何变化？研究所将在加勒比三个地理区域（巴哈马、伊斯帕尼奥拉岛和格林纳达/圣文森特/格林纳丁斯）的多个地点进行试验。这些实验将利用人工珊瑚礁，模仿自然的补丁礁栖息地，集中在高密度的动物。反映生态系统过程的响应变量（例如，海草营养成分、海草生物量、初级生产者多样性），并与对照地点（没有珊瑚礁的海草地点）进行比较。生态系统过程可能受到影响的空间范围，即，与人工鱼礁的距离，将被量化，并用于检测生态系统响应的生态阈值。预测变量，包括环境养分供应、鱼类密度和鱼类放牧率的措施，将用于说明消费者介导的养分供应的相对重要性。分层实验设计和双管齐下的分析将表征环境梯度之间的关系，发现和内的地理区域，促进一个概念框架，需要预测何时，何地，以及为什么消费者介导的养分供应是一个重要的控制生态系统过程中的海草床。更广泛的影响：该项目旨在通过广泛整合研究和教育工作，最大限度地扩大在区域、国家和地方各级的影响。整个计划是与大自然保护协会合作设计的，PI在加勒比咨询委员会任职。大自然保护协会是加勒比海挑战的最前沿，该挑战旨在到2020年保护20%的海洋栖息地。所有计划中的研究地点都是作为加勒比挑战倡议一部分的现有或拟议的海洋保护区的一部分。研究数据将为监测计划、管理战略和保护措施的优先次序提供信息。在设计地方和国家两级的外联举措时，将敏感地考虑到当地的环境和社会机遇与挑战。例如，在巴哈马，PI将帮助在阿巴科岛设计和开发一个新的中心，旨在支持研究、教育和保护活动：ACRE（阿巴科保护研究教育中心）。&将扩大"阿巴科科学家"外联网站，继续为向公众快速传播信息提供平台。重点将放在培训在科学领域代表性不足的少数民族学生，在综合科学，教育和跨文化融合模式内提供经验。

Consumers in marine ecosystems have long been acknowledged for their role in top-down regulation of ecosystems, but their influence through bottom-up pathways such as nutrient supply is often underappreciated and has not been integrated into models of coastal ecosystem dynamics. Yet, nutrient supply from consumers may be a regulating factor when consumers aggregate, such as fishes around structurally complex habitat. Examining this bottom-up mechanistic pathway is essential for a more holistic understanding of seagrass ecosystems, which are important and threatened globally. This study will address the following questions: (1) Does concentrated nutrient supply from consumers result in distinct biogeochemical hot spots in seagrass beds? and (2) How do consumer effects on ecosystem processes vary across regional environmental contexts where nutrient availability and fishing pressure vary? The PIs will conduct experiments at multiple sites within three biogeographic regions in the Caribbean (The Bahamas, Hispaniola, and Grenada/St.Vincent/Grenadines). The experiments will utilize artificial reefs that mimic natural patch reef habitats that concentrate animals at high densities. Response variables reflecting ecosystem processes (e.g., seagrass nutrient content, seagrass biomass, primary producer diversity) will be measured at reef sites and compared with control sites (seagrass sites without reefs). The spatial extent over which ecosystem processes may be affected, i.e., distance from artificial reef, will be quantified and used to detect ecological thresholds in ecosystem responses. Predictor variables, including measures of ambient nutrient availability, fish densities and fish grazing rates, will be used to contextualize the relative importance of consumer-mediated nutrient supply. The hierarchical experimental design and two-pronged analysis will characterize relationships across environmental gradients found among and within the biogeographic regions, facilitating a conceptual framework needed to predict when, where, and why consumer-mediated nutrient supply is an important control of ecosystems processes in seagrass beds. Broader Impacts: The project is designed to maximize broader impacts at regional, national, and local levels through extensive integration of research and education efforts. The entire program is designed in partnership with The Nature Conservancy, for which the PI serves on the Caribbean Advisory Board. The Nature Conservancy is at the forefront of the Caribbean Challenge, an effort to protect 20% of marine habitats by the year 2020. All of the planned study sites are part of current, or proposed, marine protected areas as part of the Caribbean Challenge initiative. Data from the research will inform monitoring plans, management strategies, and prioritization of conservation measures. Outreach initiatives at local and national levels will be designed with sensitivity to local environmental and social opportunities and challenges. For example, in The Bahamas, the PI will help design and develop a new center on Abaco Island intended to support research, education and conservation activities: ACRE (the Abaco Conservation, Research & Education Center). The outreach website "The Abaco Scientist" will be expanded, continuing to provide a platform for quick dissemination of information to the general public. Emphasis will be placed on training minority students under-represented in the sciences, providing experiences within an integrated science, education, and cross-cultural integration model.