5: Technology

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East Pacific Rise

To fully investigate a newly discovered area of the seafloor, as we have been attempting to do during the first three dives, is difficult. Alvin is our primary tool, but it can work on the bottom for only up to six hours a day, and the amount of area it can cover is limited by its comparatively slow top speed. Trying to completely document and sample animals that occur only in small vent habitats with unpredictable distributions on the otherwise huge sea floor in a grand total of eighteen hours is clearly impossible, especially when all we know of the inky-dark area are its topographic highs and lows. Yet if we could only use Alvin for three days to explore this new area, that is what we would do.

To improve our odds of getting done what we need to in the very limited time available, we have are very lucky to have use of a towed camera system that Dan Fornari, a scientist at Woods Hole Oceanographic Institute, developed. The last couple of nights Z and Jim and students from University of California at Davis and University of Chicago have guided this camera system for a total of 12 hours approximately 5 m off the seafloor over 2500 m below. Imagine lying on a raft in a 10 foot deep swimming pool trying to dangle a weight on a fishing line within a quarter inch of the bottom - but never, ever touching the bottom. They've essentially done that with the 12.5 foot-long, 750 pound camera system and the 274 foot long ATLANTIS. Admittedly they had a bit of electronic help. The camera system has real-time altimeters that tell people on the ship its height over the bottom. In addition, sensors near the camera provide data on temperature and salinity in real time to computers on the ship. The photos, however, can only be accessed after the system is on the deck. Although my geologists are pretty tired, they operated the camera system flawlessly, taking an image every 15 seconds. The computers on-board the ATLANTIS have 4225 new images of the seafloor thanks to their efforts.

We examined as many of the downloaded images, each depicting a 6 by 4 m area of the seafloor, as possible as we planned Saturday's dive. The pictures told us what areas had bare rock, and to our delight, that tube worms were present with the medusae. The jpg with this email is one such image, looking down from above. The Stauromedusae are on the left - they are small and a little dark, so might be hard to see. Tube worms are in the upper right and cloudy fluid rises from a fissure in the lower left.

Based on this photographic evidence of the co-existence of Stauromedusae and typical tube worms, we sent Stephane, Beth and pilot Anthony Tarantino on our third dive with a mandate to collect at these new vents and become the first humans ever to set eyes on this part of our planet. After they arrived back on-board the ATLANTIS about 5 PM with tube worms, Stauromedusae and other animals, Stephane looked at some of the images. He immediately recognized the one I'm sending you, as it shows the area where they collected the tube worms and water. Specifically they collected the tube worms marked by the 1 on the photo and took a water sample at 2. Amazingly, they found this very site, so well-imaged by our towed camera after searching for a collection site from 9:30 to noon.

Although this might seem to be an incredibly lucky coincidence, they report that the entire field of exceptionally dense animals extends only across an area slightly larger than that seen in the photo. The incredible luck is not that we a picture of the area before sampling, but that they could find such a small area at all. We're a little disappointed that they didn't find more, larger fields or stunning smokers belching out high temperature fluids, but Meg Daly's enthusiasm for being the first cnidarian expert to touch these stauromedusae more than makes up for it. Meg estimates these animals are about 20 times the size of most other stauromedusae, which tend to live more or less solitary lives. We all wonder why they grow so big here and how they deal with living so close together. We hope the specimens we collected will help answer these questions.

During the expedition, email questions for Dr. Voight and her team to expeditions@fieldmuseum.org. Selected emails will be sent to the ship and video answers to these questions will be posted periodically on the expeditions@fieldmuseum website.