Coral Reef Recovery Potential on Gelasa Island, Indonesia: Integration of Benthic Conditions, Fish Biomass, and Coral Reef Health Indice

Abstract

Assessing the recovery potential of coral reefs requires indicators capable of distinguishing habitat conditions from the functional responses of reef fish. This study evaluated the recovery potential of coral reefs in Gelasa Island, Central Bangka Regency, through an integrated assessment of benthic conditions, target fish biomass, and the Coral Reef Health Index (CRHI). Data were collected in March 2024 at four stations using the Underwater Photo Transect (UPT) method to assess benthic conditions and the Underwater Visual Census (UVC) method to measure fish length. Mean live coral cover reached 54.90%, ranging from 36.27% to 76.67%. Other benthic components included dead coral with algae (20.60%), rubble (20.20%), and fleshy seaweed (0.97%). Target fish biomass ranged from 6.30 to 61.55 kg/ha with the highest value recorded at ST1 and the lowest at ST3. ST3 had the highest live coral cover but the lowest target fish biomass, whereas ST1 showed the opposite pattern despite having a relatively high rubble cover of 43.33%. Based on the operational application of the CRHI, the mean index value was 5.5, with ST1–ST3 obtaining a score of 6 and ST4 obtaining a score of 4. Overall, the coral reefs of Gelasa Island have moderate potential for natural recovery but cannot yet be categorized as undergoing good ecological recovery, as biological responses, particularly target fish biomass, remain limited and do not consistently correspond with benthic conditions. Coral reef recovery is still ongoing and should be supported by long-term monitoring that integrates benthic and biological indicators.