Comparative Analysis Multispatial Imagery for Coral and Seagrass Distribution Mapping

Coral and seagrass are essential components of the benthic community found in coral reefs, playing a crucial role in maintaining ecological balance. Over time, both have significantly declined on Yoron Island, located in the central Ryukyu Arc, southwestern Japan. Remote sensing has enabled the monitoring of distribution maps for coral and seagrass. While high-resolution imagery, such as aerial photographs, the accessibility and availability of aerophoto data are limited and regulated, making it necessary to use alternative data sources that are more readily available and consistently updated. However, open-access imagery generally has lower resolution compared to aerophoto. The objective of this study is to assess and compare the spatial distribution of coral and seagrass using different types of imaging. To achieve this, Landsat-8 and aerophoto imagery from 2010 and 2020 were utilized. Both datasets were processed using the ISODATA unsupervised classification technique to generate benthic maps. The results revealed differenced in benthic composition. In 2010, there was a 17.5<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> discrepancy in coral area, and seagrass was not detected in the Landsat image despite being identified in the aerophoto. In 2020, the difference in coral area had decreased to 4.1%, while seagrass coverage was zero in both images. Although some changes were observed, they were not statistically significant. Therefore, it can be concluded that Landsat-8 has potential for coral and seagrass mapping.