Extreme Fieldwork on the Bloody Bay Wall main content.

Extreme Fieldwork on the Bloody Bay Wall

by AMNH on

From the Field posts

Museum Research Associate David Gruber, assistant professor at The City University of New York (CUNY), describes a diving trip in 2011.

We wanted to include a panoramic image of a magnificent coralscape in Creatures of Light: Nature’s Bioluminescence, and Bloody Bay Wall [off Little Cayman Island] was the perfect place.

But capturing Ansel Adams-like vistas are impossible under water, where sections of the light spectrum—especially reds—are absorbed within a meter. We need to get in very close to our subject and use flash photography to capture the reef ’s true color. We have to repeat this process hundreds of times over the wall face. Then, the small consecutive images are painstakingly stitched together to create a life-sized, true-color view.

Underwater photographer Jim Hellemn developed this process to create a 20-foot by 70-foot true-color image of the Bloody Bay Wall in 1999. Returning to the wall 12 years later (with the support of a National Science Foundation Connecting Research to Public Audiences grant) allowed us to overlay the images and really see the way a coral wall ages. Some of the corals are disappearing, some of the sponges have gotten huge, and some new things have taken up residence on the wall. It’s amazing.

We also wanted to apply Jim’s methods to photograph the coralscape at night to capture a phenomenon few people encounter in person or in photographs: marine biofluorescence. As you can imagine, capturing natural biofluorescence is even more of a challenge. Fluorescence on the reefs works a bit like those glowing posters where you need to shine a black light on them in the dark to see their glow. Corals have the same biological property: proteins in their tissue absorb light and then emit it back as biofluorescence. On our dives, we shine blue light—a specific wavelength of pure blue, using very sharp-edged filters, science-grade filters we equip so they can go under water—and the corals emit back in otherworldly green and red.

For this trip, we left at dusk, and descended down a vertical cliff that drops thousands of feet below the surface to start photographing. It’s a challenge. We can’t use any lights because we’re only interested in the light emitted by the corals and reef-dwelling organisms, which makes it difficult to see if we’re in the right focus frame. So we use a red laser to give our lenses something to focus on. We often also use a measuring stick to keep the camera lens at a set distance from the wall so our images will have the same focus distance. We’re under water, breathing through a regulator, and it’s totally dark except for the red focus point. John [Sparks] swims alongside, guiding us across the wall, making sure we don’t drop down too deep. And then we shoot. Shoot, shoot, shoot. The results are cool and unveil a hidden beauty—you’ll see them in the exhibition.

Don’t miss the Bloody Bay Wall interactive exhibit in Creatures of Light.

A version of this story originally appeared in the Spring issue of Rotunda, the Member magazine.