Using a specially designed digital camera, called a tow system, as well as a robotic submarine, the researchers captured underwater images of the ocean floor. Where coral sites were found, the team used a remotely operated vehicle (ROV) to collect high-resolution images of the corals.
The researchers then compared images of new coral communities with previously collected data of a coral community affected by the 2010 spill. These older coral images served as a model "fingerprint" for gauging the impact of the spill on newly discovered coral.
"With the camera on board the ROV we were able to collect beautiful, high-resolution images of the corals," Fischer said. "When we compared these images with our examples of known oil damage, all the signs were present providing clear evidence in two of the newly discovered coral communities of the impact of the Deepwater Horizon spill."
Unlike other organisms whose remains sink to the ocean floor and quickly disappear, corals form a mineralized skeleton that can last for years after the organisms die, according to the researchers.