Terra Nova: part 2

VSLAM in action on Terra Nova. Left panel shows the 
ROV video; right panel shows the poitn cloud. 

Another day, another night, another night shift. I settled into my designated place, right behind the ROV team, where I could see the screens and take notes without interfering with the pilot. The ROV descended to the seafloor and approached Terra Nova. When the pilot felt comfortable, he called to a colleague at the back of the room: "Slam it!"

No, that was not a command to smash equipment. We've been using a software called VSLAM to make 3D models of our target shipwrecks, Quest and Terra Nova, in real time. As the ROV's camera records photo after photo, the images are fed into VSLAM, and a point cloud showing the structure of the wreck materializes on the screen. VSLAM is an incredibly useful tool - because the point cloud is made in real time, it's easy to identify gaps in the model and back-track to cover them. As the model slowly comes together, we can get a sense for the 3D structure and scale of the wreck. The ROV's camera can only see a limited field of view at a time, so the 3D model provides important context. Once finalized, the 3D models will be an impactful data product for archaeology and biology alike. 

Terra Nova had many of the same species as Quest, which surprised me a bit at first. The two shipwrecks are separated by almost 10 degrees of latitude. Yet, the Labrador Current brings cold water from the central Arctic southward into the Labrador Sea. The bottom water temperature was actually quite similar at both sites. On Terra Nova, we saw redfish and wolf fish, just like Quest. There were pink anemones everywhere, just like on Quest. The biggest difference was that Terra Nova had no soft corals. In their place were myriad sponges. 

Western Atlantic shipwrecks that I have had the opportunity to study

The sponges were large, textured, and white-yellow in hue. Some had siphons sticking up from their bulbous surface. Others looked like flowers, and still others were encrusting, lying flat on the ship's hull. Some of the sponges reminded me of species I had studied in the Fram Strait. I wondered if Terra Nova's location near Greenland put it in closer contact with larvae of Arctic species. 

As I think back to other shipwrecks I have studied in the western Atlantic, they all seem to have species that play similar roles. Every set of shipwrecks has an abundant anemone. Each one has a range of filter feeders, such as sponges or soft corals. At every set of shipwrecks, there have been structure-oriented fishes (e.g., rockfish) and pelagic fisheries species - amber jack in the Gulf, cod in the Labrador Sea. Each shipwreck has its own unique history, but the biology seems eerily consistent. I'm beginning to wonder if there are a certain set of functions - ecological niches - that must be filled, and the only question is which species will fill which niche. 

I have a lot of work ahead of me, not just documenting what lives on Quest and Terra Nova but also placing their communities in a larger, ocean-scale context. I can't wait to get started.