OCE-PRF: Quantifying the genetic and epigenetic contribution to stress response in corals

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Overview: A combination of global and local stressors threaten the persistence of coral reef ecosystems. Atmospheric CO2 and global mean temperatures are expected to increase significantly. The rapid influx of atmospheric CO2 into the oceans will result in ocean acidification (OA), or a shift in the buffering capacity and chemistry of seawater leading to declines in pH and carbonate ions. Together, these stressors are predicted to result in mass coral bleaching, declines in coral calcification of more than 40%, and even extinction. It is thought that the current rate of climate change will outpace the potential for coral reefs to undergo necessary evolutionary adaptation. There is, however, enormous variability in the response of corals to stress and differential survival of species, suggesting that some corals possess mechanisms to better respond to climate change. These mechanisms include innovations related to genetic adaptation, rapid acclimatization through epigenetic mechanisms via parental effects, and the associated symbiotic communities (Symbiodinium, bacteria, fungi, and viruses). In corals, the overall contribution of these factors to resilience is understudied. The fellow's PhD research was the first to identify positive responses of coral offspring to OA and increasing temperature via trans-generational acclimatization (i.e., an epigenetic process). The fellow will employ novel experimental approaches to test hypotheses suggesting that there is a greater genetic, epigenetic, and symbiotic potential for corals to respond to and resist the adverse effects of increased temperature and OA than was previously thought. If true, the outcome of this research will have the potential to transform our understanding of coral response to environmental stress and to develop well-parameterized predictions of the future of coral reef ecosystems. The objectives of this research are to quantify the genetic, epigenetic, and symbiotic contributions to stress response in reef-building corals. Intellectual Merit: The oceans play an important role in human health through factors such as food production, economics, and regulation of atmospheric gases, climate, water supply, and protection from physical disturbances. Although coral reefs cover a small proportion of the ocean (1%), they generate vast revenue, valued in the hundreds of billions of dollars annually. By describing and quantifying potential genetic, epigenetic, and symbiotic processes of resilience and resistance this research will advance our understanding of the genuine threats that changing climate poses to coral reefs and the resulting economic, physical, and cultural consequences of the coral reef ecosystem resource loss. Broader Impacts: The fellow will be responsible for shared mentoring of PhD, MS, and undergraduate students. The proposed research will be disseminated broadly to the university and public community in Hawaii through existing connections to the public tour and education department at the University of Hawaii and the Waikiki Aquarium, and internationally through scientific conferences and publication in peer-reviewed journals, in addition to online video tutorials of experimental research and analyses. The host organizations are the University of Hawaii at Manoa's Hawaii Institute of Marine Biology (HIMB)and the James Cook University's (JCU)Australian Research Council Center of Excellence. Together they provide the ideal organizations located on coral reefs to perform the research, to broaden scientific participation, and to provide diverse international mentoring and prolific networking opportunities with world experts. The mentors include: (1) primary mentor and expert coral biologist Ruth D. Gates, PhD at HIMB; (2) expert in larval biology and quantitative genetics Robert J. Toonen, PhD at HIMB; and (3) international mentor and Super Science Fellow at JCU and expert in coral stress response and coral microbial associations, Tracy D. Ainsworth, PhD. Together these mentors provide world-class expertise in coral biology, genetics, symbiosis, and experimental design.