Habitat Decline and Dugong Distribution Shifts in Relation to Seagrass Meadows at Libong Island, Trang, Thailand

ABSTRACT

Seagrass meadows are important feeding areas for dugongs ( Dugong dugon ); however, these habitats are disappearing rapidly throughout Southeast Asia. This study examined the spatial patterns of seagrass distribution, dugong feeding trails and dugong sightings around Libong Island, one of the most important dugong habitats in Thailand. Seagrass cover was mapped from 2022 to 2024 using drone‐based orthomosaics and Sentinel‐2 imagery, validated with ground‐truth surveys and classified with Random Forest. Dugong feeding trails were digitized from drone imagery, and sighting records were analysed using kernel density and nearest‐neighbour distance (NND) metrics. Results revealed strong site‐level variation in habitat use, with dugongs consistently concentrating their feeding activity within persistent, continuous meadows (DT, JH, SK and TJ) and showing reduced activity in patchy or less stable sites (LTC and MT) ( χ ²  = 230.72, df = 5, p  < 0.001 for seagrass; χ ²  = 107.46, df = 5, p  < 0.001 for feeding trails). Seagrass extent declined sharply from 3.56 km ² in 2022 to 1.16 km ² in 2024, with minimal persistence (< 0.3 km ²  year ⁻¹ ) and most patches either lost or newly colonized. Dugong sightings peaked in 2023 (127 records) but declined by 2024 (78 records), with high‐density hotspots disappearing and NND nearly doubling from 464 to 819 m, indicating weaker aggregation. These findings demonstrate that dugong foraging is highly dependent on large, continuous seagrass meadows and that rapid seagrass fragmentation results in a decreased local carrying capacity, more dispersed dugong distribution and greater susceptibility to habitat loss. Therefore, conservation measures should prioritize protecting and restoring the more permanent seagrass meadows to support dugong populations in the Andaman Sea.