Ecological Roles of Herbivorous Fishes in Coral Reef Ecosystems

Herbivorous fishes are central architects of coral reef ecosystems, exerting top-down control on algal communities and facilitating coral recruitment and growth. Through grazing, scraping and excavating behaviours, these fishes remove macroalgae, trim algal turfs and generate settlement space for coral larvae, thereby maintaining the dominance of reef-building corals. Bioerosion by excavating species produces biogenic sediment, which contributes to reef framework renewal and shoreline stabilisation. Variation in species identity, body size and functional traits mediates the balance between algae suppression, sediment production and net reef accretion. Diverse assemblages of browsers, scrapers and excavators act synergistically: browsers nip fleshy macroalgae, scrapers remove turf and epilithic algal matrices, and excavators penetrate reef substrate, promoting reef renewal. The co-occurrence of distinct functional groups enhances benthic states by limiting algal overgrowth and fostering coral calcification. Conversely, loss of functional diversity or skewed community composition can precipitate algal phase shifts, reduce structural complexity and undermine reef resilience to warming, bleaching and storm events. Management strategies that protect key herbivore species, safeguard size structures and maintain fine-scale community composition are thus indispensable for sustaining ecosystem services and global reef health.

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Ecological Roles of Herbivorous Fishes in Coral Reef Ecosystems publication trend

The graph below shows the total number of articles in ecological roles of herbivorous fishes in coral reef ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Grazing: The removal of algal biomass by fishes that nip or crop algae from reef surfaces.

Scraping: A feeding mode in which fishes use teeth to remove algal turfs and biofilms, leaving minimal substrate scars.

Excavation: The consumption of substrate and associated algae by fishes, creating deeper scars and contributing to bioerosion.

Bioerosion: The mechanical breakdown of reef carbonate framework by grazing organisms, resulting in sediment production.

Macroalgae: Large, multicellular algae that compete with corals for space and light on reef substrates.

Benthic state: The ecological condition of the reef floor, encompassing coral cover, algal cover and substrate complexity.

Functional diversity: The range and value of functional traits represented within a fish assemblage, reflecting roles in ecosystem processes.

References

1. Co‐occurrence of herbivorous fish functional groups correlates with enhanced coral reef benthic state. Global Ecology and Biogeography (2023).
2. Incorporating parrotfish bioerosion into the herbivory paradigm of coral reef resilience. Conservation Letters (2024).
3. Site-Level Variation in Parrotfish Grazing and Bioerosion as a Function of Species-Specific Feeding Metrics. Diversity (2020).