Fluorescence could be measure of coral health

Fluorescence, a poorly understood light phenomenon displayed by marine corals, can be an effective tool for gauging their health, U.S. researchers say. Scientists at the Scripps Institution of Oceanography of the University of California, San Diego, are reporting research using fluorescence to test coral stress prompted by cold and heat exposures. Marine biologists Melissa Roth and Dimitri Deheyn tested the common Indo-Pacific reef-building branching coral Acropora yongei and found both cold and heat stress caused corals to rapidly display a decline in fluorescence levels. "This is the first study to quantify fluorescence before, during, and after stress," Deheyn said in a Scripps release Tuesday. "Through these results we have demonstrated that changes in coral fluorescence can be a good proxy for coral health." Because fluorescence that can be tested non-invasively directly in the field without having to remove coral samples for laboratory molecular analysis, it improves upon current technologies for testing coral health, he said. Corals are known to produce fluorescence through fluorescing proteins, but little is known about the emitted light's function or purpose, scientists said. It could offer protection from damaging sunlight or be used as a biochemical defense generated during times of stress, some marine scientists suggest.