Hard coral cover in the Halmahera waters: Spatial distribution and environmental factors

Abstract

Differences in the geographical location and geomorphology of small islands contribute to variations in aquatic environmental factors, spatial distribution of corals, and percentage of hard coral cover. This study was conducted in the open waters of the Termadoreh Islands in the middle of the Maluku Sea, and the semi-enclosed waters of Buli Bay. This study aimed to examine the distribution of hard coral cover in the Halmahera coral ecoregion with respect to differences in geographic location, geomorphology and water quality. This study found that the spatial distribution of hard corals differed among sites. Spatially, the total area of shallow water habitat at the study site showed the largest area of coral habitat in Termadoreh, at 1313.99 ha. Hard coral cover and coral diversity differed between sites and depths. Higher hard coral cover was found on the coral islands of Teluk Buli and lower on the volcanic islands of the Termadoreh Archipelago. The highest percentage of hard coral cover per site was found on Maitara Island (site MaT05) at 71.60%, and the lowest percentage of cover was found on Tidore Island (site TiT08) at 14.9%. An optimal temperature, salinity, and brightness parameters support the high percentage of hard coral cover. The highest coral diversity value in the Termadoreh Islands correlated with water brightness. This study is important for recording the conditions of hard corals in the Halmahera reef ecoregion. The results of this study provide data on the benefits of a coral reef management plan for the Halmahera coral ecoregion. We also provide recommendations regarding the life forms of hard corals that are appropriate for making coral seeds to restore and rehabilitate coral reef ecosystems at the research sites.