Tracking coral loss in the Spermonde Archipelago of Indonesia: 32 years of satellite monitoring from 1990 to 2022

Abstract

ABSTRACT An alarming amount of damage has occurred to coral reefs in Indonesia, with the causes of such damage either from human activities (anthropogenic causes) or natural processes. This study investigated the long-term dynamic changes in coral reef habitats in eight selected islands in the Spermonde archipelago, Indonesia, using remote sensing and historical information. A series of Landsat images recorded in different years (i.e. 1990, 1996, 2002, 2008, 2013, 2016, 2018, 2019, and 2022) were used to map the benthic habitats of each island (i.e. live coral, dead coral, seagrass, sand, rubble, mix bottom). The analysis estimated a total of 303.47 hectares or 76.26% loss of live coral in studied islands since 1990. In contrast, there was a substantial increase in dead coral algae and rubble, estimated at around 108.63 and 101.91 hectares, respectively. Strong and similar negative coefficient determination between live coral cover with both dead coral algae (R2 = 0.96, Y = -2.95) and rubble (R2 = 0.94, Y = -2.85) suggested that human activities (e.g. destructive fishing activities, damage from anchors, coral mining) and natural processes (e.g. sedimentation, coral bleaching, coral diseases, and coral predation) played comparable roles in coral reef degradation in Spermonde Archipelago. Furthermore, this study revealed that destructive fishing occurred on the island regardless it was inhabited or uninhabited and was influenced by the extent of its live coral cover. This study overall highlighted the ongoing degradation and factors contributing to coral loss in the Spermonde archipelago. Further research and monitoring efforts are necessary to understand the mechanisms driving the decline in live coral and the factors contributing to increases in dead coral algae and rubble. This knowledge will aid in developing targeted conservation strategies and management plans to protect the coral reef ecosystem in the Spermonde Archipelago and other affected regions in Indonesia.