Taxonomic variability in coral bleaching on a remote, uninhabited island in the western Pacific.

Farallon de Medinilla (FDM) is an uninhabited island approximately 2.8 km in length, located near the middle of the Commonwealth of the Northern Mariana Islands archipelago, 278 km north of Guam, and 83 km north of Saipan, the closest inhabited island. FDM has been used by the United States (US) Department of Defense as a live and inert training and testing range for the US Navy since 1971. The conditions have created, to some extent, a de-facto marine protected area at FDM. The island is comprised of limestone that forms plunging cliffs on all sides,located within one of the most active typhoon regions in the world, and is routinely subject to extreme waves and strong currents. A dive survey was conducted during five days from 27 September to 1 October 2017, when the training range was closed. The survey protocol was designed to quantify the status and diversity of the coral communities around the island, and included in-situ rapid assessment combined with collection of scaled and geo-referenced photographs that could be analyzed post-survey and archived. Approximately 89 unique taxa of scleractinian corals were identified at FDM in imagery captured during the 2017 survey. Approximately 77% of corals in photoquadrats were either completely bleached, pale, or mottled at the time of the survey; these states reflect physical stress in corals and are typically caused by warm water events. Pocillopora spp., Astreopora spp., and L. purpurea corals suffered the highest rates of bleaching, while Favia spp., Porites spp., and one Favitessp. exhibited the lowest levels of bleaching. Significantly fewer corals were bleached from deeper and more exposed portions of the island, compared with shallower and more protected areas, respectively. The variable responses of corals captured during this survey event, and comparisons to fourteen prior surveys conducted between 1997 and 2012 will be presented to predict possible changes to the coral community in response to ocean warming at this remote, access-restricted island located in a highly dynamic oceanographic environment.