Award: OCE-1418673

Guam experienced island-wide bleaching event in 2013, an event that was unprecedented in recent decades. The severity and extent of this event was linked to extended high sea surface temperature and a delay in the onset of the rainy season. Initial surveys indicated that the impacts were broad in both geographic extent and species affected. To assess the resilience of GuamÆs coral reefs, we evaluated patterns of mortality and recovery from this event as they relate to exposure to water flow (i.e., windward vs leeward sides of the island) and genetic make up of the zooxanthellae and coral host. To these ends, we carried out repeated surveys and sampling along permanent transects and permanently marked individual colonies at 11 sites (five with deep/shallow pairs and one shallow only). Our work suggests that the impact of the bleaching event was not particularly severe: mortality rates of among initially bleached colonies was approximately ~12%; in contrast, mortality among those without any obvious signs of bleaching was 4.5%. Physiological measurements indicate that corals were stressed even towards the end of the bleaching event (Jan 2014) but that that there was notable improvement over the course of the year. We did not find evidence of spatial or genetic patterns in the impacts of the bleaching event. The recovery from bleaching on Guam suggest that these reefs are resilient; however, it is unclear if these reefs will continue to recover from bleaching events as they become more frequent and severe. Last Modified: 12/18/2015 Submitted by: Kiho Kim