Easter Microplate Expedition
April 1, 2005 Day 21
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Alvin dive# 4096, 23.5°S
Dan and Caren were the observers and Tony was the pilot. They returned to the same site as dive# 4095, and quickly were in the same highly fractured terrain. They found the same sets of chimneys: a diffusely venting set, and a second set with large edifices and lots of small turrets (see photo on March 31). The prize sample today was a chunk of old sulfide chimney that had numerous small mussels attached to it. Otherwise the only mussels seen were shattered shells in presumed octopus middens (piles of mussel shells below octopus perches). Consistent with yesterday's observation that tubeworms used to be present here but are now gone, there was only one, empty Riftia tubeworm tube. Several glassy lava "pillow buds" were collected (several cm long), which are from small breakouts in pillow lava flows.
Left image: Octopus on crevasse wall. The mantle (head) is about the size of a grapefruit. Right image: Brisingid stars on top of a dead chimney at 23.5oS. And look! There's a vent kitty prowling for dinner! Happy April Fools Day!
Yesterday's dive was my first, and it was something I will never forget. I was a little apprehensive, but also really looking forward to the whole experience. It felt quite strange to descend past the 42 meters allowed for recreational SCUBA diving. I really never thought I would go deeper than this. But we descended right down to 2600 meters, and it was an amazing feeling when the bottom first came into view. It really felt like an ancient, quiet place, but according to the geologists, this is not at all the case! And on closer inspection, big lava flows and the rifts tell us that it was recently quite an exciting (and perhaps dangerous) place to be living. The topography of the seafloor here was very complex, with deep fissures and sheer canyon walls. It was really exciting to be "flying" through this terrain. We found some old extinct chimneys and sampled some other basalt areas before continuing exploration. In these areas there were many sea cucumbers and stalked crinoids, and occasionally giant anemones. They really were huge, over one meter across if the tentacles were extended, definitely falling into the sea monster category! Then we found a patch of several active smokers, belching black "smoke" into the surrounding water. Here, and interspersed with the extinct chimneys was were many animals lived. We did not see the usual mussels or tubeworms, but could see where some tubeworms had lived here at some time in the past. But there were many seastars, smaller anemones, octopus, gastropods, worms, fish, shrimp and crabs and bacterial mats. It was an amazing place.
Alvin, the chase boat, and two swimmers during today's recovery. Photo by Mark Spear,
"Mother mother Ocean, I have heard you call..."-Jimmy Buffett
I'm starting to realize that the cruise is over in a few days, and it's a sad thought! It is so thrilling to see what crazy things live on the seafloor. We have taken Alvin further south than she's ever gone, we've discovered new vents, new animals, and new friends, and we've had the best view in the world the entire time. I could definitely get used to this life... except for missing everybody at home!
We have another cookout tomorrow, so that will be a much-needed break from the thesis writing and sample processing for everyone. Maybe we can get a dance party started this time-- this is of course another activity (like ping pong, showering, foosball, carrying a glass of water, yoga, standing on one foot, using a microscope, juggling, etc.) that is extra challenging on a moving ship. I plan to take lots more photos tomorrow to remember all of these fellow crazy ocean lovers after this trip ends!
All underwater photos were taken with the submersible Alvin, and are courtesy of Woods Hole Oceanographic Institution.