April 14, 2008
Gulf of Mexico Coral Expedition – Part Two
BY: Margot
After several hours of transit we arrive at the next dive site for the ROV. ROV stands for remotely operated vehicle, the workhorse of deep seafloor research and the primary focus of this cruise. ROVs are robots that perform similar tasks to the Mars Rover while exploring remote frontiers, though the technology was originally developed for less glamorous tasks like maintaining underwater cables or inspecting oil platforms. As we approach the dive site, everyone switches abruptly into action. The crew lifts the ROV (a Phantom S2) and dead weight (which looks like a diver’s air tank) over the side with a crane and then lowers them both into the water. The weight keeps the robot aligned with the ship to prevent it being dragged behind like a tail.Meanwhile, the scientific party sets up in the main lab, which is set up like a roomy airplane cockpit. Surrounded by screens large and small, the work begins. In the driver’s seat is one of the ROV pilots, who alternates with the other between driving and tending the cables over the side. If you, your child, or someone you know addicted to video games, perhaps you have a future as an ROV pilot. A black control panel with an array of metal levers and two small joysticks surround a small 4-inch screen. The pilot scrutinizes live video feed on this screen and constantly makes adjustments with the joysticks to control the ROV’s orientation and depth with four thrusters pointed in different directions. It’s clear that this is extremely difficult, yet we manage to spend 90 percent of the time suspended just above the bottom to see everything and get good film without breaking or touching this fragile seascape. The pilot also wears a headset that connects directly to the bridge to be able to request course changes for the ship. Today the ROV pilot mostly asks the captain to slow down, as the filming works best at less than 1 knot. On either side of the ROV pilot are scientists who identify fish and coral that fly by on the large screen in front of us. The film is recorded simultaneously on DVD and video tape with running commentary dictated into the microphone that goes something like “bigeye… almaco jack… soft coral… sponges… sharp-nosed puffer…” interspersed with questions like “What do you think those spiky things are?”The first dive we visit a yet-to-be-explored area that looks like it might be interesting from the maps. Previous cruises have mapped out what could be a low-lying ridgeline of hard bottom covered in coral. We hover rapidly over the seafloor, stopping for still photos every four minutes to get an unbiased sampling, and stopping for anything we think looks interesting or appealing. The start of the dive is sandy shell hash, with not a lot visible from the surface. Then more and more frequent clumps of living hard bottom habitat go by, each a small furry grey island bedecked with a brightly colored sea fan, sponge, or fish. As the ROV approaches, the fish seem to look on with curiosity and then flee into a nearby hole or crevice at the last minute. The second dive is also in an unexplored ridge that is being considered for protection by the Gulf of Mexico Fishery Management Council. This ridge is actually a submerged shoreline from before the last ice age, flanked by drowned shallow-water coral reefs from the same era. These features sank away from the sunlight with sea level rise and now provide a platform for vibrant deep sea coral gardens and living seafloor to grow on. Almost the entire area is sprinkled with lavender-grey sea fans, with others in yellow or purple. Regular appearances of tall, spiraling black corals lend a Dr. Suess feel to this low-lying forest. This area is also marked by perfectly round holes about a foot deep that look almost man-made, that we think are solution holes where the hard seafloor has dissolved due to fluctuations in acidity. We see many fish of different species, including scamp grouper, amberjack, angelfish, and a cluster of butterflyfish. It’s really funny to watch the bigger fish try to hide in small holes. Sometimes they bury their heads like an ostrich and hold still, as if we couldn’t see the other half of their body and tail. We wait for a few seconds for them to reemerge, before we are forced to move on and keep with the movement of the ship.
