CAREER: Fish-Derived Nutrients in a Coral Reef Ecosystem-Impacts on Benthic Communities and Importance for Coral

Award Period
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Agency Name
National Science Foundation
Award Number
PI First Name
PI Last Name
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Area/s of Research
Ecology and Evolution


Dramatic changes in ecosystem function often follow changes to top-down and bottom-up forcing.

Importantly, alterations of both top-down and bottom-up processes may be mediated throughchanging the abundance of consumers. That is, in addition to altering primary producer abundance

through consumption, consumers may be a significant source of limiting nutrients via their

excretion. Despite the important role of both consumers and nutrients in influencing community

dynamics on coral reefs, the role of bottom-up forcing by fish excretion has generally been

ignored as a mechanism for altering benthic community structure.

Objectives: The goal of this proposal is to quantify how nutrients from fish excretion impact

coral reef community structure and how this effect varies across environmental context. Specifically,

I outline research to focus on three general sets of objectives that we will ask 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.

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.

I will address these questions with: (1) a field monitoring program (Objective 1), (2) mechanistic

nutrient enrichment experiments (Objective 2), and (3) coral restoration experiments (Objective


Intellectual Merit :

As compared to freshwater, terrestrial, and pelagic marine systems, benthic marine systems

have been ignored in as to the effects of consumers as critical sources of limiting nutrient.

Our research will address fundamental and untested questions of how nutrient excretion by

fishes impacts coral reef communities. Our data suggest that the ecology of reefs is critically

linked to the role of fishes as providers of limiting nutrients as fishes are one of, if not

the most important, sources of N on reefs. Although there has been significant work done on

how fish excretion affects individual corals, there has been little examination of the role

of fish-derived nutrients on scales relevant to reef communities. Our 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. Even in areas where fishing is light and nutrient loading low,

the impact of fish-derived nutrients may be changing as climate change and disease outbreaks

drive declines in coral cover. Thus, It is critical to the conservation of coral reefs for

us to understand how consumer-derived nutrients impact benthic dynamics.

Broader Impacts :

My proposed research and education activities are integrated around understanding the current

threats to coral reefs and how we can help mitigate these threats and restore corals. This

integration is evident in all aspects of my education program 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,

and (3) taking marine science to the masses with widely distributed videos. But, this integration

is strongest in my citizen science initiative with MarineLab. Here, we will fully integrate

MarineLab students into our research by having them collect several types of data on our coral

restoration plots. Thus, they will get an actual working knowledge of our research, marine

ecology, and coral restoration. Further, our 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, our work will be able to make significant contribution to educating managers

and restoration practitioners as to the processes that can help facilitate successful restoration