Mapping and assessing the coral reef health in Kadatua, Liwutonkidi and Siompu Islands, South East Sulawesi, Indonesia

Abstract

The quality and quantity of coral reefs contain essential ecological functions to provide goods and environmental services for the livelihood of local communities. However, coral reefs continue to suffer in most of Indonesia’s remote reefs. This study aims to map and monitor the health coral reef in five sites of south Buton Regency, the Kadatua (BTNC-13 and -14), Liwutonkidi (BTNC-C), and Siompu Islands (BTNC-D and -17) using the effective and efficient remotely sensed Landsat-8 OLI (operational land imager) satellite and intensive field survey data using Line intercept transect (LIT) method, then use the result to assess the coral health index (CHI) of the study sites. The results of the mapping using Landsat-8 OLI data classified five groups of benthic habitats: algae, corals, seaweed, rubble, and sand, after following the standard image processing procedure and utilizing sun-glint, water column correction and maximum likelihood classification. Meanwhile, the intensive LIT survey resulted in information on the percent live coral cover that was in the range of moderate conditions (25 –≤ 50%), but the site of BTNC-17 was in bad condition (< 25%). The resilient condition of coral reefs in all sites was good, which is indicated by the low cover of fleshy seaweed but the low biomass of herbivorous and carnivorous reef fish. Thus, the CHI, in general, was in moderate condition (CHI 5 and 6). However, a comparison with CHI data from 2016 showed that the coral condition in study sites tends to decline. Several efforts to improve the CHI and to ensure the long-term health and resilience of coral reef ecosystems are suggested. The findings of this study can be used as a benchmark and indicator to monitor the progress or the decline of the coral reef environment in the future at five study sites