Detection of Coral Bleaching on Sekisei Lagoon Using Multispectral Sensor Data

Coral reefs support enormous diversity of species and economical values for human being. However, they are seriously declining at an alarming rate in all tropical oceans. In 2007, one of environmental negative impacts, sea surface temperature rise, was triggered massive coral bleaching and consequential coral mortality in Japan. This study aims to detect massive coral bleaching with change detection by multispectral sensor images and validate the results based on reference materials at a study area - Sekisei Lagoon. It is located between Iriomote-island and Ishigaki-island in Okinawa, is the most abundant coral reef species in Japan. To detecting coral bleaching uses bottom-typed index by Lyzenga (1978) generates constant index values from same habitats without affect by the water depth. After processing several corrections of data products, bleaching areas are extracted with change detection from different time periods. The results are spatially and temporally validated with referenced materials though a report and a websites under the Ministry of Environment in Japan. As a result, the results are determined to detect coral bleaching by the process.