Healthy Glow

A coral’s fluorescent glow could provide clues to its health, giving scientists a better way to identify corals in danger of bleaching.

Global warming, pollution, and other threats have put corals around the world in jeopardy. The most visible sign of the organisms’ distress is bleaching, which can severely damage or kill corals. Scientists can try to monitor the problem by keeping an eye on coral color, but these observations “cannot give any indications of coral health until the bleaching process has been initiated, and most often already well underway,” a research team writes in Scientific Reports. Invasive techniques, such as taking samples of corals, aren’t ideal either.

The authors wondered if the corals’ fluorescence could offer any hints. Corals make fluorescent proteins, but scientists don’t know exactly why.

The team exposed the coral Acropora yongei to two stressful conditions: a 5-degree Celsius increase or decrease in temperature. After five days, green fluorescent protein levels were 35 percent lower in heated corals and 65 percent lower in chilled corals. At a result, the green fluorescence from both sets of corals dimmed.

The study suggests that fluorescence “could be used as an early indicator of change in health,” the authors write. The heated corals also started to fluoresce more intensely after the initial period of stress, probably because the loss of symbiotic organisms allowed more light to shine through. Roberta Kwok | 18 March 2013

Source: Roth, M.S. and D.D. Deheyn. 2013. Effects of cold stress and heat stress on coral fluorescence in reef-building corals. Scientific Reports doi: 10.1038/srep01421.

Image © e2dan |