Investigating Coral Reef Loss and Its Causes around Panggang Island, Seribu Islands, Indonesia

摘要

The growth of coral reefs is influenced by two factors that are natural and anthropogenic factors, which natural factor include salinity, temperature, light and solar radiation, nutrients, and depth. The objective of this study was to examine the changes in coral reefs area around Panggang Island and to know: whether oceanographic parameters such as temperature, chlorophyll-a, salinity. pH. brightness, hotspots, thermal stress. El Nino Southern Oscillation (ENSO). and Indian Ocean Dipole (lOD) influence the change. The method used in this research is remote sensing and field data observation. The image data used comes from Landsat 7 ETIVT (2001-2003) and Landsat 8 OLI / TIRS (2013-2016) for coral reefs. NOAA Coral Reef Watch Satellite Monitoring data (2013-2016) for Sea Surface Temperature (SST) and Aqua Modis data (2002-2003 and 2013-2016) for chlorophyll-a. Field data for seawater quality in April 2016 obtained from National Institute of Aeronautics and Space. Meanwhile. Ocean Nino Index and Dipole Mode Index downloaded from Jamstee and NOAA websites. The results showed that the average rate loss of coral reefs area around Panggang Island, during 2001-2016 is 10.74 ha /year. The highest coral reef loss occurs in the 2013-2014 (42.9 ha), this is due to thermal stress in December 2013 to April 2014 which reached -2.25°C / week. In 2014-2015 the coral reef area is increase by 37.3 ha. this is due to the coral planting activities in the study area. During 2013-2016 there is only one hotspot. so the phenomenon does not affect the change of coral width. ENSO and IOD didn't seem to affects the coral reef loss in the study area. According to field observation in April 2016. the parameters that meet the reef growth standards are chlorophyll-a and pH, while temperature, salinity, and brightness does not meet the coral reef standards.