CAREER: Fish-derived nutrients in a coral reef ecosystem - impacts on benthic communities and importance for coral restoration

珊瑚礁目前受到各种人为威胁的威胁，包括气候变化、珊瑚疾病、过度捕捞重要鱼种和过度富集营养物。这些威胁可能导致珊瑚和鱼类减少，海藻增加，使珊瑚礁变成海藻礁。了解人类介导的变化如何影响珊瑚礁生态的一个重要方面是了解鱼类如何影响珊瑚礁的重要营养循环。研究人员先前的研究表明，鱼类可能是珊瑚礁上氮和磷的最重要来源之一，通过它们的日常排泄物。这些鱼类来源的营养物质可能有助于珊瑚生长得更快，但如果珊瑚因气候变化或疾病等其他过程而死亡，也可能有助于海藻生长得更快。然而，来自人类来源的营养素，如农业径流或污水排放，可能对珊瑚有害，因为这些营养素通常与鱼类排泄物中的营养素不同。研究人员试图了解鱼类来源的营养素与人类来源的营养素的不同影响如何影响珊瑚生长，海藻生长，并最终影响珊瑚礁生态系统的健康。这项研究还将促进一些培训和外联机会，包括：（1）培训研究生和本科生，（2）在FIU和MAST@FIU之间建立伙伴关系，MAST @FIU是一所新的科学和技术磁铁高中，为代表性不足的少数群体提供海洋生物学教育，（3）通过广泛分发的视频将海洋科学带给大众，以及（4）创建一个公民科学倡议，让感兴趣的海洋生物学学生参与帮助监测一些实地实验。此外，这项工作将产生急需的关于珊瑚礁恢复科学的信息。珊瑚礁的恢复是一个不断发展的领域，但许多恢复工作在理解保持珊瑚礁健康的生态过程方面几乎没有坚实的基础。因此，这项工作将能够作出重大贡献，教育管理人员和恢复从业人员的过程，可以帮助促进成功的恢复工作。这项研究将解决基本的和未经测试的问题，如何营养排泄鱼类影响珊瑚礁群落。以前的数据表明，珊瑚礁的生态是至关重要的关系到鱼类作为有限的营养物质供应商的作用，因为鱼类是一个，如果不是最重要的，氮的来源对珊瑚礁。这项研究不仅在其范围上是独一无二的，而且由于全球对珊瑚礁的威胁，也是及时的。由于过度捕捞使重要的鱼类（及其作为营养提供者的作用）消失，人为营养负荷增加了潜在有害营养物质的丰度，珊瑚礁上的营养状况可能正在恶化。该项目的目标是量化鱼类排泄物中的营养物质如何影响珊瑚礁群落结构，以及这种影响如何在环境背景下变化。具体而言，调查员概述了研究，重点是三个一般的目标，将在美国佛罗里达群岛的珊瑚礁接近：（1）评估鱼类产生的营养物质如何影响珊瑚礁内外的底栖生物群落结构和珊瑚生长及健康，以及这种影响如何随非生物环境而变化，（2）测试个别珊瑚和藻类的生理和生长对鱼类排泄物和人为营养负荷中不同营养源的反应，及（3）研究鱼类营养素如何影响珊瑚复原，以及如何设计复原计划，以利用鱼类营养素对珊瑚生长的重要性。这些问题将解决：（1）现场监测计划（目标1），（2）机械养分富集实验（目标2），和（3）珊瑚恢复实验（目标3）。

Coral reefs are currently imperiled from a variety of human-induced threats from climate change, coral diseases, overexploitation of important fish species, and enrichment with excessive amounts of nutrients. These threats can result in the decline in corals and fishes and the rise in seaweeds, turning coral reefs into seaweed reefs. One important aspect of understanding how human-mediated changes impact the ecology of reefs is to understand how fishes impact important nutrient cycles on reefs. The investigators prior research suggests that fishes may be one of the most important sources of nitrogen and phosphorus on reefs via their daily excretions. These fish-derived nutrients may help corals grow faster but could also help seaweeds grow faster if corals are killed by other processes such as climate change or disease. However, nutrients from human-derived sources such as runoff from agriculture or sewage discharge can be harmful to corals as these nutrients are often of different types than those in fish excretions. The investigator seeks to understand how the different effects of fish-derived vs. human-derived nutrients impact coral growth, seaweed growth, and, ultimately, the health of coral reef ecosystems. This research will also facilitate a number of training and outreach opportunities including: (1) training graduate and undergraduate students, (2) creating a partnership between FIU and MAST@FIU, a new science and technology magnet high school, to educate underrepresented minorities in marine biology, (3) taking marine science to the masses with widely distributed videos, and (4) creating a citizen science initiative that will get interested marine biology students involved with helping to monitor some of the field experiments. Further, this work will generate much needed information on the science of coral reef restoration. Restoration of reefs is a growing field but many restoration efforts have little solid grounding in understanding the ecological processes that keep reefs healthy. Thus, this work will be able to make significant contribution to educating managers and restoration practitioners as to the processes that can help facilitate successful restoration efforts.This research will address fundamental and untested questions of how nutrient excretion by fishes impacts coral reef communities. Prior data suggest that the ecology of reefs is critically linked to the role of fishes as providers of limiting nutrients since fishes are one of, if not the most important, sources of N on reefs. This research is not only unique in its scope but also timely due to the global threats to reefs. As overfishing removes important fishes (and their role as nutrient providers) and anthropogenic nutrient loading increases the abundance of potentially harmful nutrients, the nutrient regimes on reefs may be changing for the worse. The goal of this project is to quantify how nutrients from fish excretion impact coral reef community structure and how this effect varies across environmental context. Specifically, the investigator outlines research to focus on three general sets of objectives that will be approached on reefs in the Florida Keys, USA: (1) Assess how fish-derived nutrients influence benthic community structure and coral growth and health both across and within reefs and how this influence varies with abiotic context, (2) Test how the physiology and growth of individual corals and algae respond to the different nutrient sources in fish excretion vs. anthropogenic nutrient loading, and (3) Examine how fish-derived nutrients impact coral restoration and how to design restoration programs to take advantage of important of fish-derived nutrients for coral growth. These questions will be addressed with: (1) a field monitoring program (Objective 1), (2) mechanistic nutrient enrichment experiments (Objective 2), and (3) coral restoration experiments (Objective 3).