Coral Reef Habitat Mapping: A Case Study In Mensanak Island- Senayang Lingga, Riau Province, Indonesia I Nyoman Radiarta, Nitin Kumar Tripathi and Frederic Borne Space Technology Application and Research Program (STAR) K.R. Jensen Integrated Tropical Coastal Zone Management Program Asian Institute of Technology P.O. Box 4, Khlong Luang Pathumthani 12120, Thailand Tel: 66-2-524 6392, Fax: 66-2-524 5597 Correspondence: Email: nitinkt@ait.ac.th; st017032@yahoo.com Introduction Coral reefs are important resources for the great many tropical country. Reefs and their habitat associated sandy beaches are important attraction to tourist, major sources of income of tropical countries. Indonesia is the larges tropical archipelagic nation in the world, with a coastline stretching 0ver 95,000 km around more than 17,000 islands. An expensive group of coral reefs protect these islands. Indonesia has approximately 51,000 km2 coral reefs (Burk et al., 2002), this number does not include reef in remote areas that have not been mapped. For the management of specific coral reefs resources, it is first necessary to identify the reef to be managed A monitoring program can be provide information on the diversity of site, condition of particular habitats and changes in environment. Dealing with the monitoring program of coral reefs, the conventional methods are commonly used for mapping and monitoring of coral reef habitats. Topographic maps, nautical charts and direct observation are the conventional ways for surveying and mapping coral reefs. All the conventional methods mention above still have the limitation especially by using those methods may not be practical for monitoring large or remote coral reef ecosystem accurately. Other thing this is expensive, cumbersome and logistically and also time consuming. With respect to this situation, remote sensing may provide the most feasible mean for monitoring and management of coral reefs, particularly for insular (archipelagic) countries. Remote sensing can identify a number of environmental variables associated with habitat that are potential indicators of resources distribution and abundance such as coral reefs, algae and sea grass. Many researchers ( Khan et al., 1992; Luczkovich et al., 1993; Zainal et al., 1993) have examined the usefulness of Landsat data for inventory and mapping of coastal habitats such as coral reefs, however most of them used the oldest Landsat series such as Landsat MSS and Landsat TM (4 and 5). In this present study, Landsat 7 ETM+ has been used for investigating coral reef habitats. GIS technique and field data also considered in this study. Water column correction algorithm has been employed to enhance the image (Green et al., 2000; Mumby et al., 1998). This algorithm has not been widely adopted in term of mapping shallow water (Mumby et al., 1998). In addition, band ratio and principal component analysis also applied in this study. In order to classify reef habitats from the image, unsupervised classification using K Mean class was undertaken to identify reef habitat base on water column correction image. An error matrix was used for additional interpretation of classification accuracy within and between each reef habitats. Study Area The study area is located around three major islands (Mensanak, Medang and Benan Islands) and several smaller islands in Riau Archipelagos, Riau Province. False Color Composite (FCC) 421 (Figure 1) shows the study area. It stretches from latitudes 0°20' - 0°30' North and longitudes 104°20' - 106°35' East. This area is situated approximately 120 km Southeast of Singapore. The study area is one of the Coral Reef Management Program (COREMAP) areas. Major habitats in this area are representative of the general environmental in the Riau Archipelagos. Therefore the findings of this study could be useful for large mapping of coral reef habitats along the islands.  Figure 1. The study area as shown in FCC 421 using Landsat 7 ETM+
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