Priority coral conservation areas under global warming in the Amami Islands, Southern Japan

Coral reef ecosystems are highly sensitive to climate change. The Amami Islands in Southern Japan were selected as the study area. It is important to select areas that should be given priority for conservation and subsequently direct resources there. The objective of this study was to identify locations with low bleaching potential against future increases in water temperature, as well as high larval recruitment from other areas and high larval supply capacity to other areas based on connectivity. We simulated the coral bleaching rate and larval connectivity under historical (2000s) and future (RCP2.6 and RCP8.5 in the 2090s) climate conditions using a high-resolution (1/30 degrees x 1/50 degrees) future ocean regional projection dataset. From the model simulation, coral bleaching did not occur in most areas in the 2000s. However, the bleaching frequency would increase significantly under RCP8.5 in the 2090s, and it is projected that mass coral bleaching events will occur in more than half of the years of that decade. Larval dispersion simulation shows that some particles released from the Amami Islands remain in the same area. However, fluctuations in both the sink strength and the source strength among the islands were larger than those within each island, and differences in connectivity between scenarios were not apparent. Grid cells that have a low bleaching rate and high potential for a larval sink and source under each scenario were selected. Since our results can identify priority conservation areas, it is important to conduct conservation and/or adaptation strategies according to the specific characteristics of each island.