Vulnerability and habitat suitability changes of Acropora spp. in Wakatobi National Park due to the pressure of climate change

Coral reefs in Wakatobi National Park, located within the Indonesian Coral Triangle, are a vital marine ecosystem with significant ecological and economic importance. However, they face increasing threats from direct human activities and climate change. This study aims to predict the habitat suitability of the dominant coral species, Acropora spp., in Wakatobi National Park under various climate change scenarios projected for 2050. A Habitat Suitability Model (HSM) was developed using the Maximum Entropy (MaxEnt) approach. Occurrence data for Acropora spp. were obtained from the Global Biodiversity Information Facility (GBIF), while current and future environmental variables (based on Representative Concentration Pathways/RCP 2.6, 6.0, and 8.5) were obtained from Bio-Oracle 2.2 and the Global Marine Environmental Dataset (GMED). These variables included sea surface temperature, salinity, surface water velocity, dissolved oxygen, euphotic layer depth, pH, primary productivity, and chlorophyll concentration. The results forecasted changes in the suitable habitat area for Acropora spp. Currently, 578.5 km2 of coastal waters are classified as “suitable” habitat, with 69.7 km2 designated as “very suitable.” However, under the 2050 RCP projections, a significant reduction is expected. “Very suitable” zones are projected to disappear entirely, while the “suitable” area is anticipated to decrease, from 487.9 km2 (RCP 8.5) to 550.6 km2 (RCP 2.6). The most pronounced reductions are expected around Kaledupa Island and the northern part of Tomia Island. Chlorophyll concentration was identified as a key factor influencing optimal habitat for Acropora spp. Since chlorophyll levels are often linked to nutrients from anthropogenic runoff, the combination of nutrification and climate change are likely to significantly affect Acropora spp. Therefore, wastewater management is a crucial priority to enhance their resilience and reduce its vulnerability to climate change.