Coral cover, biomass, and composition of herbivorous reef fishes as indicators of coral reef health in the Padaido Marine Tourism Park, Indonesia

Marine Protected Areas play an essential role in conserving coral reef ecosystems by maintaining biodiversity, sustaining fisheries, and supporting ecosystem resilience. Herbivorous reef fishes are recognized as key ecological indicators because they regulate macroalgal growth and facilitate coral recovery. This study evaluated coral cover, environmental conditions, herbivorous reef fish composition, abundance, and biomass in the Padaido Marine Tourism Park, Indonesia. Field surveys were conducted from August 2021 to June 2022 using the Underwater Photo Transect (UPT) method to assess coral cover and the Underwater Visual Census (UVC) method to quantify herbivorous reef fishes. Environmental parameters, including temperature, pH, salinity, and water transparency, were measured at each sampling station. A total of 84 herbivorous fish individuals representing 26 species from three families (Acanthuridae, Scaridae, and Siganidae) were recorded. Live coral cover ranged from 24.93% to 37.13%, indicating poor to fair reef condition. Herbivorous fish abundance varied from 614.28 to 1,657.14 individuals ha⁻¹, whereas biomass ranged from 14,515.76 to 50,609.04 kg ha⁻¹ among stations. Spatial variation in herbivorous fish communities generally corresponded with differences in coral reef condition, highlighting the importance of habitat quality in maintaining reef fish assemblages. The dominance of Acanthuridae, together with the presence of Scaridae and Siganidae, indicates that essential herbivorous functional groups remain within the protected area despite moderate reef degradation. These findings demonstrate that herbivorous reef fish communities provide valuable ecological indicators for evaluating coral reef health and support adaptive zoning, long-term ecological monitoring, and conservation management within the Padaido Marine Tourism Park.