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