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Coral reefs not only endow the world with affluent, fruitful ecosystems and picturesque underwater locale, they also throw in a profitable advance esteemed at hundreds of billions of dollars. But their decline in recent years due to a multiplicity of intimidations from pollution to climate warming has created an alarming exigency to the hunt for new ways to weigh up their health. Challenging efforts are being taken by scientists to create a safer and healthier environment for them by finding out their most favorable conditions.
A new study by Scripps Institution of Oceanography at UC San Diego scientists has discovered that fluorescence, the glittering but poorly understood light produced by corals can be an effectual tool for gauging their health.
As described in the March 12 edition of Scientific Reports (a publication of the Nature Publishing Group), marine biologists Melissa Roth and Dimitri Deheyn illustrate groundbreaking research using fluorescence to analyze coral stress encouraged from cold and heat revelations.
In experimental studies conducted at Scripps, Roth and Deheyn tested the common Indo-Pacific reef-building branching coral Acropora yongei under a range of temperatures. Branching corals are vulnerable to temperature stress and regularly one of the first to show signs of suffering on a reef. Roth and Deheyn found that at the initiation of both cold and heat stress, corals swiftly show a turn down in fluorescence levels. If the corals are able to become accustomed to the new conditions, such as to the cold settings in the experiment, then the fluorescence proceeds to normal levels upon acclimation.
While the corals recovered from cold stress, the heat-treated corals ultimately bleached and remained so until the termination of the research. Coral bleaching, the loss of minute symbiotic algae that are vital for coral survival is a crucial peril to coral reefs and has been rising in rigorousness and degree due to climate alteration. In this study, the very onset of bleaching caused fluorescence to spike to levels that remained high until the end of the experiment. The researchers noted that the early spike was caused by the loss of “shading” from the symbiotic algae.
“This is the first study to quantify fluorescence before, during, and after stress,” said Deheyn. “Through these results we have demonstrated that changes in coral fluorescence can be a good proxy for coral health.”
Deheyn said the new technique improves upon current technologies for testing coral health, which include conducting molecular analyses in which coral must be collected from their habitat, as opposed to fluorescence that can be tested non-invasively directly in the field.
Corals are known to generate fluorescence through green fluorescent proteins, but little is known about the emitted light’s function or purpose. Scientists believe fluorescence could offer shield from damaging sunlight or be used as a biochemical defense generated during times of stress.
“This study is novel because it follows the dynamics of both fluorescent protein levels and coral fluorescence during temperature stress, and shows how coral fluorescence can be utilized as an early indicator of coral stress” said Roth, a Scripps alumna who is now a postdoctoral scientist at Lawrence Berkeley National Laboratory and UC Berkeley.
