CORAL REEF HABITAT CHANGING ASSESSMENT OF DERAWAN ISLANDS, EAST KALIMANTAN, USING REMOTE SENSING DATA MARLINA NURLIDIASARI' AND SYARIF BUDHIMAN2 Abstract Coral reefs in Dcrawan Islands are astonishingly rich in the marine diversity. However, these reefs are threatened by humans. Destructive fishing methods, such as trawl, blasting and cyanide fishing practise, are found to be the main cause of this degradation. The coral reefs habitat reduction is also caused by tourism activities due to trampling over the reef and charging organic and anorganic wastes. The capabilities of satellite remote sensing techniques combined with field data collection have been assessed for the coral reef mapping and the change detection of Derawan Island. Multi-temporal Landsat TM & ETM images (1991 & 2002) have been used. Comparison of the classified images of 1991 and 2002 shows spatial changes of the habitat. The changes were in accordance with the known changes in the reef conditions. The analysis shows the decrease of the coral reef and patchy seagrass percentage, while the increase of the algae composite and patchy reef percentage. Keywords : Coral Reef, Change Detection, Landsat-TM, Derawan I. Introduction and storm events and a rise of the seawater temperature. The health of the world's coral reefs is Information on the health of coral reefs in serious decline. Approximately 11 status is crucial for their conservation and percent of coral reefs with a high level of sustainable utilization. Unfortunately, in marine diversity are under threat, including most cases only a small amount of this reefs in the Philippines, Indonesia, information is available. The International Tanzania, the Comoros, and the Lesser Coral Reef Initiative (ICRI) Framework for Antilles in the Caribbean (Bryant et. al., Action emphasizes the needs of research 1998). Principally, human activities are the and monitoring of the coral reefs status. main cause of the coral reef degradation. Particularly the reefs in tropical ecosystem These include destructive fishing methods, because reefs in this area are still not well over-fishing, inappropriate inland understood as compared to the temperate management; human and industrial waste system (ICRI, 1995). disposal, coral mining and even careless Coral reefs in Derawan Islands are diving activity. Global wanning may also astonishingly rich in the marine diversity. enforce reefs stress, such as increased flood The high diversity of corals and fishes, the 1 Alumni of International Institute for Geo-Information Science and Earth Observation ITC, The Netherlands, email: ihoo.com orpurwucliiaialumni.ilc.nl 2 National Institute of Aeronautics and Space - I.APAN, Remote Sensing Application and Technology Development Center email: sbudhimanftyyahno.com or biulhmi,mm•alumni.ifc.nl REMOTE SENSING ANE) EARTH SCIENCES September 2005 Volume 2 32 presence of turtles and Kakaban salt lake variables, but also to determine make Dcrawan Islands one of the most ecologically meaningful changes (Reese famous diving sites. One of the outcomes and Crosby, 2000). of the "World Heritage Marine Diversity" The objective of the study was to Workshop, in Hanoi 2002, stated that the assess the coral reef habitat change by Derawan islands area has a high priority to comparing classified images of Landsat of be nominated as World Heritage Site. 1991 and 2002 for coral reef habitat There are about 120 areas in the world mapping and change detection of Derawan identified as potential sites of outstanding Island using multi-temporal Landsat TM & universal values. Within those, 25 sites ETM images (1991 & 2002). ranking in Southeast Asia, Dcrawan islands area is among the top seven (UNESCO, II. Mcthododology 2002). This study focuses on the coral reefs of However, these reefs are threatened by Derawan Island and Masimbung reef and humans. WWF Indonesia (2002) reported Tubabinga reef in the southern part of there arc 4 main threats in Derawan Derawan Island. The Derawan islands Islands: 1) Habitat reduction, 2) Fisheries region is a sub-district (Kecamatan) of the activities, 3) Tourism and 4) Policy. East Berau district of the East Kalimantan Kalimantan once had approximately Province, Indonesia. Geographically, it is 950,000 ha of mangrove-nipa forest situated between 118"09'53"-118°46'28" formation and only 266,800 ha left in 1980 East and the 02°25'45"-02°03'49" North. (Mac Kinnon, et.al cited in Jompa and Pct- The islands of Derawan, Rabu-Rabu, Soede, 2002). These mangroves have been Panjang, Samama and Sangalaki are part of converted or degraded due to logging, the the Berau barrier reef. The two up lifted making of fishponds, human settlements atolls are Maratua, with an open lagoon and industrial facilities. As a result, the and Kakaban, with a closed lagoon (Figure mangrove function as the barrier for lc). erosion and as a filter of sediment also The islands are situated in two decreases. Destructive fishing methods, different systems: a shelf reefs system, such as trawl, blasting and cyanide fishing which has developed as barrier reef, known practice, are found to be the main cause of as the Berau barrier reef, and tectonically this degradation. The coral reefs habitat uplifted atolls. The Berau barrier reef reduction is also caused by tourism system is found in the Northern part of the activities due to trampling over the reef and Berau delta, part of Mangkalihat Peninsula; charging organic and anorganic waste. and it extends about 60 km to the South. It Moreover, the unwise practice is located at the inner side of the 200 m iso- development decisions also contribute to depth at the margin of the Sunda shelf habitat degradation, such as stock collapse (Tomascik et al. 1997). and habitat reduction due to intensification Multi-temporal remote sensing satellite and industrial development (Ismuranty, data were used in the study. The Landsat-5 2002; Jompa and Pet-Soede 2002). TM, of June 1991 has been downloaded A monitoring program to detect from the Global Land Cover Facilities changes of the coral reef environment is achieved images data (http://glcfapp. essential to promote sustainable umiacs.umd.edu). The Landsat-7 ETM management. The monitoring has to be data, of July 2002 was obtained from the repeated over time at the same location. National Institute of Aeronautic and Space- An appropriate time scale is needed to LAPAN, Indonesia. Table 1 describes the study statistically changes in the main details of the available remote sensing data. REMOTE SENSING AND EARTH SCIENCES September 21 S Volume 2 33 Table 1. Available Remote Sensing Data Acquisition Path/ Number of Spectral range Sensor Resolution Row Time Bands (nm) Date (GMT) Bl=450-520 B2= 520 - 600 B3= ,630 - 690 Landsat- 16 June 30 m B4= 760 - 900 116/58 09:43 a.m. (Band 1-7) 5TM 1991 120m(B6) B5= 1550-1750 B6= 1040- 1250 B7= 2080 - 2350 Pan- 450 - 900 The fieldwork activities were carried Derawan Islands consisted of: ground out in October 2003 for one month, control points collection, habitat ground including one week secondary data truth points, insitu spectral data collection and research equipment measurements, water depth measurements preparation, and 3 weeks in Derawan and habitat data collection along the Islands (4 - 25 October 2003) for insitu transects (Figure lc). data collection. The field methods in REMOTE SENSING AND EARTH SCIENCES September 2005 Volume 2 34 Habitat transect data were collected to intercept; so there were 10 transect obtain more details of the coral reef quadrants along each line (see Figure la). conditions, such as live coral percentage, A digital underwater camera was used to the dominant species etc. A quadrate record the data in each transect quadrant transect technique was used to collect the (Figure lb). data. A 20 m line was placed parallel to Image processing activities as the coastal line. The data were collected at described in Figure 2 consists of: geometric three different depths; 10, 6 and 2 m, correction, atmospheric correction, water starting at the deeper part (10 m) until the column correction, habitat classification shallow part (2m). The transect quadrant (1 and change detection. x 1 m) was placed along this line, with 2 m 2.1 Geometric Image Correction to use infrastructural elements as ground It was difficult to find suitable ground control points. In the field, the corner of control points. The Derawan Island is only some jetties surrounding the island, corners a very small island, approximately 1 km of a helicopter base and sand pit in the east long and 0.5 km wide. The high spatial part of the island were collected as ground resolution of the panchromatic QuickBird control points. band (resolution 0.6 m) gave the possibility REMOTE SENSING AND EARTH SCIENCES September 2005 Volume 2 35 However, those points could not be Error (RMSE) of the geometric image used for the geometric correction of the correction. Landsat image, due to its relative low spatial resolution. Thus, for the geometric Table 2. RMS error of geometric corrected images correction of Landsat TM (1991) and Images Number Reso- RMSE Landsat ETM (2002), the geometric of points luiion corrected image of QuickBird was used as QuickBird 5 0.6 m 4.667 the master image. The two Landsat images panchromatic 10 were subset first to the same area as the QuickBird MS 2.4 m 0.468 Landsat ETM 12 30 m 0.557 QuickBird image. Table 2 gives Landsat TM5 7 30ni (1.544 information about the Root Means Square Table 3. Parameters of Landsat-5 TM 1991 and landsat-7 ETM 2002 images Sensor TM ETM Date of Acquisition 16 June 1991 8 July 2002 Bands 1-7 exclude b6 1-7 exclude b6 and pan Pixel size 30 m 30 m Factor scale 4 (default) 4 (default) Solar zenith angle 40.32 35,6 Calibration file Tm51991.cal Tm7-2002.cal Model for solar region Others.