Integrative Geospatial and Geochemical Approach for Mapping and Analyzing Coral Reefs in Pangkor Island

This study integrates geospatial mapping and geochemical analysis to evaluate coral reef health at Teluk Segadas and Pantai Pasir Giam of Pangkor Island, Malaysia. A drone-based survey captured 603 aerial images across Teluk Segadas and Pantai Pasir Giam, processed through structure-from-motion (SfM) and object-based image analysis (OBIA) to classify benthic habitats. Results focusing on shallow water revealed coral dominance at Teluk Segadas (63%) compared to sediment dominance at Pantai Pasir Giam (54%), with the overall classification accuracy exceeding 70%. Coral and sediment samples were analyzed via X-ray fluorescence (XRF) spectrometry, detecting 15 elements. Calcium (Ca) was the major constituent (>270 ppm), while sodium (Na) and magnesium (Mg) were consistently abundant. Heavy metals, including copper (Cu), iron (Fe), nickel (Ni), and manganese (Mn), were enriched at Pantai Pasir Giam, likely reflecting anthropogenic inputs from tourism and human population density. An integrated geospatial and geochemical map demonstrated that Teluk Segadas supports healthier reef conditions, whereas Pantai Pasir Giam exhibits stress from elevated toxic elements. This study provides the first important geological assessment of coral characterization on the reef system in Pangkor Island, and the resulting spatial map is useful for future reef management as a reference to identify vulnerable reef areas and prioritize conservation efforts.