MEPS 634:225-229 (2020)  -  DOI: https://doi.org/10.3354/meps13172

ABSTRACT: Coral reefs are increasingly shifting to algal dominance after disturbances. While herbivory that controls algal biomass may influence the stability of coral versus algal states, most reefs are overfished. Despite this, little is known about the contribution of smaller fishes to herbivory, especially in algal versus coral post-disturbance habitats, where differences in structural complexity may also influence herbivory. After coral loss driven by a predator outbreak in Mo’orea, French Polynesia, the benthic community comprised a mosaic patchwork of remnant coral, the brown macroalga Turbinaria ornata on the reef flat, and turf algae (<1 cm filaments) along the reef slope. We partitioned fish herbivory by size by deploying palatable macroalgae within cages with variable opening sizes in coral versus algal habitats on a reef flat and a reef slope. Herbivory was ~2× higher in Turbinaria habitats than coral habitats on the reef flat, while herbivory in turf and coral habitats on the slope were similar. The only measurable herbivory in coral habitats on the reef flat occurred in open treatments that allowed access by the biggest fishes, while smaller fishes were more important in Turbinaria habitats, evidenced by consumption of algae in cages with smaller openings. Equal or higher herbivory in algal habitats compared to coral may indicate an important feedback post-disturbance, and contribute to the rapid recovery of Mo’orean reefs.

KEY WORDS: Coral reef recovery · Herbivorous fish · Herbivory · Macroalgae · Phase shift