Revealing the changing trophic niches
of large herbivorous fish on modern coral reefs using an interdisciplinary approach
Funding: NSF Biological Oceanography
Summary
On coral reefs, herbivorous fish influence benthic community dynamics, playing a crucial role in the abundance of algae that compete with corals for space. These herbivorous fish species have diverse feeding behaviors, ranging from grazing small filamentous algae to removing large macroalgae and accessing endolithic resources by excavating the reef matrix.
The diversity of feeding adaptations likely promotes niche partitioning among herbivore species, facilitates species coexistence and contributes to the high herbivore diversity found in an ecosystem with limited food resources. Despite their important ecological role, our understanding of the trophic niches of reef herbivores remains incomplete. This is because current methods used to study herbivore feeding, such as behavioral observations and small-scale experiments, provide only a limited simplified view of the niche.
Objectives
In this project, we use a high-resolution tool – DNA metabarcoding of gut contents – in combination with other diet tracing methods and field observations, to ask the following questions:
- What is the degree of trophic niche partitioning among herbivorous species in three biogeographic regions: the Central Pacific, Tropical Eastern Pacific and the Caribbean. The detailed characterization of the trophic niches will provide insights into the breadth of resources controlled by herbivores through top-down forcing and the extent to which feeding redundancies exist among taxa.
- How do herbivore trophic niches change as fish communities are simplified and reefs become dominated by algae and cyanobacteria across a gradient of reef condition, from minimally to heavily impacted reefs.