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、对重要鱼类物种的过度开发以及过量营养物质的富集化。这些威胁可能会导致珊瑚和鱼类的减少，海藻的增加，将珊瑚礁变成海藻礁。理解人类调节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上重要的营养循环。研究人员先前的研究表明，鱼类可能是珊瑚礁上最重要的氮和磷来源之一，通过它们每天的排泄物。这些从鱼中提取的营养物质可能有助于珊瑚更快地生长，但如果珊瑚被气候变化或疾病等其他过程杀死，也可能有助于海藻更快地生长。然而，来自人类来源的营养物质，如农业径流或污水排放，可能对珊瑚有害，因为这些营养物质通常与鱼类排泄物中的营养物质类型不同。这位研究人员试图了解鱼类来源的营养物质与人类来源的营养物质的不同影响如何影响珊瑚生长、海藻生长，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，其中包括：(1)培训研究生和本科生；(2)在FIU和MAST@FIU之间建立伙伴关系，对未被充分代表的少数群体进行海洋生物学方面的教育；(3)通过广泛传播的视频向大众宣传海洋科学；(4)创建公民科学倡议，使有兴趣的海洋生物学学生参与帮助监测一些实地实验。此外，这项工作将产生关于珊瑚礁恢复科学的迫切需要的信息。珊瑚礁的恢复是一个不断发展的领域，但许多恢复努力在了解保持珊瑚礁健康的生态过程方面缺乏坚实的基础。因此，这项工作将能够对管理人员和恢复从业者作出重大贡献，使他们了解有助于成功恢复工作的过程。这项研究将解决鱼类排泄营养物质如何影响珊瑚礁群落的基本和未经检验的问题。先前的数据表明，珊瑚礁的生态与鱼类作为限制性营养物质提供者的作用密切相关，因为鱼类即使不是珊瑚礁上最重要的氮源，也是其中之一。由于全球对珊瑚礁的威胁，这项研究不仅在范围上是独特的，而且也是及时的。由于过度捕捞减少了重要的鱼类(以及它们作为营养物质提供者的角色)，人为的营养物质负荷增加了潜在有害营养物质的丰度，珊瑚礁的营养状况可能正在恶化。该项目的目标是量化来自鱼类排泄物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不同的环境背景下变化。具体地说，研究人员概述了将在美国佛罗里达群岛的珊瑚礁实现的三套一般目标：(1)评估鱼源性营养素如何影响珊瑚礁内外的海底群落结构、珊瑚生长和健康，以及这种影响随非生物环境的变化而变化；(2)测试单个珊瑚和藻类的生理和生长如何响应鱼类排泄物的不同营养来源；以及(3)研究鱼源性营养素如何影响珊瑚恢复，以及如何设计修复计划，以充分利用鱼源性营养素对珊瑚生长的重要作用。这些问题将通过：(1)现场监测计划(目标1)，(2)机械性营养丰富实验(目标2)，和(3)珊瑚恢复实验(目标3)来解决。

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).