Multi-colored fluorescence of reef-building corals is one of the most striking visual phenomena in the ocean. A number of observations indicate that fluorescent proteins play a major role in the interaction of corals with the environment, including responses to stress and symbiotic microalgae. However, the mechanism of action and the role of different colors remains obscure. Coral fluorescence thus represents a substantial gap in the basic knowledge of coral eco-physiology, directly relevant to understanding the factors contributing to the ongoing decline of coral reefs worldwide. This project will investigate morphological, physiological and molecular traits correlating with fluorescence, and will test specific hypotheses concerning functions of individual colors, in early life stages of the table coral Acropora hyacinthus, a major reef-builder of the Indo-Pacific. The expected results include advancement of the basic knowledge of coral biology, clarification of the molecular function of fluorescent proteins, and possible biomarker applications for reef management based on non-invasive optical methods. The results of the project will be published in open-access journals; all the data and materials will be made available promptly to the broad scientific community. The main subject of the project (why coral reefs are colorful) has considerable public appeal and represents a rich opportunity for outreach, which will include lectures and press releases to increase public awareness of global climate change, and presentations in schools to raise the interest of children from underrepresented groups to pursue science as an academic or professional goal.
Natural fluorescence of reef-building corals is one of the most fascinating visual phenomena in the ocean. We found that fluorescence of coral larvae is determined genetically and is linked to molecular and behavioral characteristics signifying the larva's potential to travel away from the home reef to colonize new habitats. Far-traveling red-fluorescent larvae stop cell division, up-regulate stress tolerance genes and down-regulate sensory genes, entering a form of protected hibernation to traverse large distances with ocean currents. When eventually selecting a good spot to settle, a larva makes a decision based on the proportion of green and red wavelength in the ambient light, which is essentially color vision without eyes – a sensory capability that was not previously recognized in corals. Larval fluorescence also refelcts stress: when conditions are less than ideal, red fluorescence declines. How exactly coral fluorescent proteins function within all these processes remains to be investigated. The ability of coral larvae to colonize and establish new reefs is the key for coral reef persistence during climate change. Because of this, our research has attracted considerable media attention: http://deepseanews.com/2011/02/red-means-go-coral-color-and-climate-change/ www.futurity.org/red-coral-go-green-coral-stay/ www.statesman.com/news/news/opinion/corals-color-decoded-at-university-of-texas-1/nRYHd/ The project also provided rich opportunities for training graduate and undergraduate training, as well as for outreach in the form of public lectures, presentations at K-12 school science club and at public outreach events at UT Austin.
