Preconditioning to increased ocean temperature and acidification might buy corals time in the race to survive climate change, ARCS Scholar Alumna Hollie Putnam reported in the August 2015 Journal of Experimental Biology. The University of Hawai‘i integrative biologist demonstrated that adult corals exposed to warmer, more acidic water produced offspring that were better able to handle subsequent exposure to those conditions.
Putnam studies epigenetics, cellular and physiological phenotypic trait variations caused by external or environmental factors that switch genes on and off and affect how they are read (as opposed to variations caused by changes in the DNA sequence). Her laboratory studies provide the first evidence of rapid, trans-generational acclimatization in reef-building corals.
She exposed parental corals to ocean temperatures and acidification levels predicted by the Intergovernmental Panel on Climate Change. As expected, the harsh conditions negatively affected the health of the parental coral. However, the offspring of those corals appeared healthier when re-exposed to the harsher environment than did the offspring of parental corals exposed to ambient ocean conditions.
Putnam received the Sarah Ann Martin Award in Zoology from the ARCS Foundation Honolulu Chapter in 2012. She completed her PhD that year and is now an assistant researcher and National Science Foundation Ocean Sciences Fellow at the UH Manoa’s Hawai‘i Institute of Marine Biology. Putnam’s coauthor, Ruth Gates, was her PhD adviser and the ARCS Foundation Honolulu Chapter’s 2015 Scientist of the Year.
Coral reefs worldwide have suffered huge losses in diversity and abundance due to local stressors (such as overfishing, coastal development, pollution and sedimentation) and global stressors related to climate change, Putnam says. “Together these local and global stressors are placing an unprecedented strain on coral reef ecosystems. It has even been predicted that some corals may go extinct.” The reduced biodiversity affects reef-dependent goods and services from fisheries to tourism valued at hundreds of billions of dollars annually.
Whether the consequences of parental effects and potential for trans-generational acclimatization are beneficial or maladaptive, remains to be seen, Putnam and Gates write. “Our work identifies a critical need to expand currently proposed climate change outcomes for corals to further assess rapid response mechanisms that include non-genetic inheritance through parental contributions and classical epigenetic mechanisms.”