HURL 2002

Wierd Sponges (9/14/02)
Posted by Rachel Shackelford

We finished our work at Brooks Bank yesterday. A total of three Pisces (sub) dives and six ROV (remotely operated vehicle) dives. All three Pisces dives were in the same area - Northeast Brooks. They overlap each other significantly so we effectively have sampled it in triplicate with two observations for each sample, which will lend a lot of confidence to the results. The ROV dives were scattered around the bank a bit more.

As I mentioned earlier, the Pisces dives take up the entire day, going into the water around 8:00 am or so in the morning and getting back to the surface around 4:00 or 4:30 pm in the afternoon. Once the sub is on deck, any samples that were collected are put in alcohol and then it is time for dinner. The submersible support crew goes to work making sure that everything is in order for the next dive. The oxygen bottle has to be filled, batteries charged, repairs made, new sodasorb (the stuff that soaks up carbon dioxide in the sub) loaded, etc. Meanwhile the ROV support crew has been making sure that it is ready to go. By about 7:00 pm or so, the ROV goes into the water. Once the ROV is launched everyone gathers in the tracking room. Three ROV pilots rotate positions every half hour; one sits at the control console and drives the vehicle with a joystick, another watches the sonar screen and controls the winch, the third gets to rest a bit and stays on hand as backup. Once the ROV package gets close to the bottom (we have to watch the depth closely so it doesn't go crashing into the ocean floor), the winch is stopped and the pilot carefully guides the vehicle out of its 'garage.' Several other people fill the room, directing the pilots to steer toward biological targets, challenging them to get as close as they can. Biologists gather around the TV screens trying to identify deep-sea organisms as the ROV flies over them. At the end of the dive, the pilot must guide the ROV back into its protective cage. The starting and ending points of each dive can be the most complicated and potentially dangerous for the ROV.

The ROV dives tend to be a bit shallower than the sub dives - 100 to 200 m vs. 200 to 400 m in the sub. The last ROV dive, however, was done at 600 m. This was one of the coolest dives yet. There were vast field of cylindrical white Symparella sponges; it looked like something out of a Dr. Seuss book or a Salvador Dali painting. We didn't see very many fish down this deep, but the few we did see were pretty neat. There were several different types of macrourids (rat tail fish) - a few of which we weren't able to identify. They may be new records for Hawai‘i, and at the very least, they are new records for the HURL database. We also saw a purple coral that no one was able to identify; we know of a similar-looking blue one, but this one was distinctly purple. It is fun to watch the biologists on board get giddy and excited when they see fish or coral that they can't recognize.

After cruising along the bottom for over two hours, the ROV pilots noticed an oil alarm. It looked like we might have an oil leak so we had to abort the dive. Everybody was satisfied with what we had seen, though. The ROV crew started bringing the vehicle back up to the ship, where they would diagnose and fix the problem. Something always seems to break or malfunction on these vehicles, but the crew can always fix it. They do an amazing job.