Abstract

Species overexploitation has simplified food webs worldwide, resulting in the degradation of ecosystems relative to their natural state. Fishes are the most important herbivores in many shallow coral reef environments, where they control algal successional processes and promote coral reef resilience. Nowadays, Rapa Nui (Easter Island) is suffering a severe decline in its nearshore fish populations due to overfishing. In this study, we used artificial underwater settlement plates with different levels of herbivore exclusion, and underwater visual censuses, for eight consecutive months to examine the functional role of herbivorous fishes in the coastal benthic community of Rapa Nui. Fishes effectively controlled fleshy erect algae growth along the west and north coast of the island. In total exclusion treatments, Codium spp. dominated settlement plates, showing a likely late successional stage when no herbivory occurred. Significant differences in fish biomass were observed across sites, suggesting a possible fishing gradient. The results of this study can help to inform various spatial and temporal management strategies to increase the protection of nearshore fishes at the recently created Rapa Nui multiple-use marine protected area.