Marine habitat mapping: using ALOS AVNIR-2 satellite image for seagrass beds at Rabbit (Koh Tonsay) Island, Cambodia

The coastline of Cambodia stretches along the Gulf of Thailand including 69 islands. It supports rich diversity of marine species. Distributions of habitats including mangroves, coral reefs and seagrass beds along the pristine Cambodian coast still remains unknown compared to neighboring countries, Thailand and Vietnam. Cambodian seagrass beds form habitats with rich biodiversity and economical value through marine ecosystem services playing as a key role against climate change by reserving large amount of carbon. However, the general status of these seagrass habitats is poorly researched and documented. Satellite image of Advance Visible and Near Infrared Radiometer type 2 (ALOS AVNIR-2) with high resolution (10×10m) provides good information for seagrass habitat mapping. Study site was selected around Rabbit (Koh Tonsay) Island with area of 2 km2. The objectives of this study are (1) to know spatial distribution of seagrass beds around this island by ground survey and (2) map seagrass beds using the ALOS AVNIR-2 image with ground truthing data. Ground truth survey was conducted in June 2011. Surveys along three transect lines revealed 8 species of seagrasses belonging to Hydrocharitaceae (4 species) and Cymodoceaceae (4 species) around the island. We analyzed ALOS AVNIR-2 taken on 22 December 2009 to map distribution of seagrass beds around Koh Tonsay Island. Results showed that remote sensing using ALOS AVNIR-2 data provides a practical tool for mapping seagrasses beds around the island and information for future management and conservation of seagrass beds in Cambodia.

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