Saturday, June 30, 2012

Scientist at Work Blog: Glowing Wildly on a Moonless Night

David Gruber, an assistant professor of biology at Baruch College and research associate at the American Museum of Natural History, is leading a National Geographic Society/Waitt Institute expedition exploring bioluminescent and biofluorescent marine animals in the Solomon Islands.

Saturday, June 23

Storm clouds hang ominously over Mount Rano as the darkness of night descends, jeopardizing a valuable night of research. We have been waiting out the storm and unable to set up on the reef while there is still daylight. Earlier in the day, we mused about the efforts to pull this expedition off: more than a year of planning, specialty parts machined, traveling for three days on a journey involving five flights and one boat ride, and safely shipping 23 bags to a remote location. The last thing we want is to be dry-docked.

After two hours of torrential downpours and strong winds that have churned up the normally placid waters, the weather breaks and we confer with our local guides about the possibility of diving. We rely on the navigational knowledge and skills of our guides, who can slip in and out of dark lagoons and reef breaks with ease.

Tonight, Rubin Napao is our driver and guide. Rubin is a 33-year-old fisherman from a nearby island and one of the few locals who also scuba dives. Rubin drives the 17-foot boat with one hand on the outboard throttle and occasionally uses the other hand to shine a flashlight, seeking a few sporadic markers for reference or watching for shallow coral heads in our path. The moonless night and lack of artificial light make the sea pitch black.

Inside the boat, we are huddled low, holding onto our equipment so it does not become unfastened. At the first intended site, we encounter strong winds and a surging current that makes it too hazardous to dive with our cumbersome scientific equipment. Rubin drives the boat farther into darkness with waves crashing over the boat?s narrow gunwales. Within 15 minutes, he brings us to a sheltered lagoon and we anchor about 50 meters off a palm-covered island. We assemble our gear.

We have two tasks for tonight. We plan to continue our search for biofluorescent creatures using our high-intensity blue lights. Later, we will perform the first test of our underwater low-light color camera. Dan Tchernov and I are holding the blue lights and navigating to diverse biofluorescent areas, Ken Corben is filming with the RED Epic camera, Vincent Pieribone is testing the underwater bioluminescent camera and John Sparks and Robert Schelly are collecting nocturnally active fish. We have also given Rubin a yellow visor so he can witness the biofluorescence stimulated by the blue lights. We will be doing two dives, each for an hour.

One by one, we shout ?Diver in!? and splash into the inky water. The bright blue lights, battery packs and camera systems are then handed down from the boat, and we begin our descent. With yellow filters over our masks, the reef erupts into vivid green and red patterns. The fluorescent glow comes primarily from the stony corals and anemones, some of which glow wildly under our custom-made spectrally pure blue light source; others, curiously, exhibit no photic response.

We wander around the reef and hover over an anemone a meter across, with several resident clown fish. The anemone is a bright extraterrestrial green, but under our lighting, the orange clown fish are black silhouettes against their glowing host. As we descend down the reef, we encounter a strange moving fluorescence. Ken Corben, our cinematographer, follows the glowing motion and nestles into a sandy patch to focus the image. As my eyes adjust, I see the moving fluorescence is coming from a common reef fish, a bream (family Nemipteridae). The fish is dazed by our bright blue light (definitely a Roswell-like alien encounter for this fish), and I can see its green fluorescent racing stripes across the top of its head and cheeks. Some shallow reef fishes are known to exhibit red fluorescence, but green fluorescence was virtually unknown until very recently.

Source: http://feeds.nytimes.com/click.phdo?i=70e20b6fcd9a33cc93dfface3a59eaf0

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