Spatial modelling of coral reefs habitat under climate scenario in coral triangle area of East Java

Coral reef ecosystems within the Coral Triangle (CT) represent global biodiversity hotspots but are increasingly threatened by climate change and anthropogenic pressures.This study was purposes to assess the current and future condition spatial distribution of coral reef habitat suitability in the Kangean Archipelago, East Java, Indonesia, located at the westernmost boundary of the CT areas.Coral reef occurrence data were integrated with ten key oceanographic and biogeochemical variable using a maximum entropy (MaxEnt) modelling framework.Habitat suitability was evaluated under present environmental conditions and projected climate conditions for 2050 based on the low-emission Shared Socioeconomic Pathways (SSP) 1-1.9 scenario from Intergovermental Panel of Climate Changes (IPCC) Sixth Assessment Report (AR6).Model performance was robust, achieving an area under the curve (AUC) value of 0.775.The results identified four primary drivers of coral reef habitat suitability based on their relative importance: seawater pH (21.1%), current velocity (16.7%), sea surface temperature (15.6%), and chlorophyll-a concentration (14.6%).Under current conditions, areas classified as very suitable and suitable cover a total of 31,521.14ha (7.98%) and 58,772.96ha (14.89%), respectively.These areas are primarily distributed around Raas Island, eastern Kangean Island, and the Sepanjang Archipelago.However, future projection reveal a pronounced decline in habitat suitability, with more than 90% of the study area shifting to the not suitable category by 2050, even under this optimistic climate scenario.These findings highlight the high vulnerability of coral reefs in East Java to climate-driven oceanographic changes and emphasize the urgent need to prioritize remaining suitable habitats as climate refugia within marine spatial planning and adaptive conservation strategies.