Researchers Use Fluorescence to Study Coral Reefs

The biological systems that convert sunlight to photosynthesis and produce growth for nearly all organisms "are exactly the same way," he adds. Excess energy that cannot be used by the organism has to go somewhere, and Ackleson thinks it probably goes into fluorescence.

Thus the type and intensity of fluorescence emitted by marine organisms may offer critical clues about the health of the organisms, but much research has to be completed before anyone can say that with certainty.

For several years now scientists funded by Ackleson's program in the Office of Naval Research have been developing sensors that will detect and even analyze undersea fluorescence, even while divers are still in the water. Much of the research has been carried out in the Bahamas, and off a Hawaiian island formerly used as a bombing range, trying to answer a few fundamental questions.

"Are there indications in the fluorescence that could tell us this coral is under stress for some reason?" he asks. "It could still come back, it's still healthy, but it's under stress. That's what we're trying to get from fluorescence.

"Our only way of managing coral reefs at the moment is to look at a disaster that has already occurred and try to do something about it," he says. "We're trying to come up with a technique that will tell us, look, if you don't do something about it right now, a disaster will occur."

Coral reefs are critical habitats for marine life around the world, and they protect many beaches from erosion and coastal storms, so saving them is far more important than just an effort to protect these unique marine animals. They are animals, by the way, not plants. They are made up of trillions of microorganisms.

Seeking Old Bombs

There is another practical reason why Ackleson's program has been embraced by the Navy. Fluorescence might help searchers locate missing objects in the sea. Like a bomb.

Searching is frequently done by underwater cameras, but images are usually so cluttered with stuff that is of no interest to the searchers that zeroing in on the missing object can be a real challenge. But if that object doesn't fluoresce — and a bomb or a mine wouldn't — flashing a fluorescent light onto the sea floor should make it stand out in a maze of fluorescing organisms.

That concept has been tested in the Bahamas and Hawaii with considerable success.

Ackleson will take the equipment next year to one of the mysterious deep sea vents where strange forms of life flourish despite the lack of sunlight. With no sunlight, the organisms have no pigment which is critical to fluorescing, so "we shouldn't see any fluorescence at all," he says.

"So if we do see fluorescence, won't that be exciting," he says, "because we will have to figure out why."

Like he says, it's a voyage of pure discovery. Lee Dye’s column appears weekly on A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.

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