RAPID collaborative proposal: Will corals recover from bleaching under ocean acidification conditions?

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Following the second hottest month on record since the 1940s, water temperatures near the main Hawaiian Islands reached 30 °C in October 2014. The result of this 2 °C increase above normal temperatures has been a severe bleaching event across the Hawaiian Archipelago. In Kaneohe Bay, 75% of the dominant coral species are bleached. Bleaching is a stress response whereby corals lose their symbiotic algae and turn white. Prolonged bleaching can lead to disease, decreases in coral growth and reproduction, and even death. In addition, rising atmospheric levels of carbon dioxide cause the oceans to become more acidic and potentially less hospitable to coral reefs. By the end of this century, seawater is predicted to be twice as acidic as it is today. The current bleaching event in Hawaii provides a rare opportunity to test the ability of corals to recover under the acidic ocean conditions expected by the end of this century. This research compares the recovery rate of bleached corals in normal seawater to those exposed to more acidic seawater. The results will inform which species or reef regions are more resilient to global change conditions and thus better targets for protection. The results will be particularly relevant to management of the Papahanaumokuakea Marine National Monument and World Heritage site. It will also provide critical data input for models that project the persistence of reefs in the future. Educationally, the research will provide a dynamic learning and training environment for students and a post-doctoral researcher. Minority students will be recruited and trained in marine science providing them with excellent career options in STEM disciplines. Results will be broadly disseminated through publications, classroom visits, public outreach and online media. Coral reefs are among the most diverse ecosystems on the planet, housing an estimated 25% of marine species. Massive coral bleaching poses a substantial threat to the integrity of coral reef habitats, and is predicted to be the major source of mortality for reefs under future climate model scenarios. Although previous work on the recovery of corals from bleaching sets the groundwork for this project, it remains to be seen how recovery from bleaching will be impacted by climate change and ocean acidification. This project takes advantage of the natural difference in baseline temperature and seawater acidity conditions between Kaneohe Bay and Waimanalo Bay, HI. Both these sites are impacted by the massive bleaching event. This research will test the recovery rate of bleached corals in normal seawater to that of bleached corals exposed to more acidic seawater. Three questions will be addressed: 1) Will ocean acidification slow rates of recovery from bleaching?; 2) Does zooplankton feeding minimize the impact of bleaching?; and 3) Do corals acclimated to warmer, more acidic conditions (Kaneohe Bay) recover more quickly than corals at present day mean oceanic conditions (Waimanalo Bay)? The project integrates techniques across the disciplines of ecology, physiology, evolution, and genomics. The research will help to identify characteristics of resilient coral species or populations that are more likely to survive bleaching events in the future.