Easter Microplate Expedition
March 29, 2005 Day 18
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Alvin dive# 4094, 31°S
Today marks the beginning of the second half of our dive series (dive 8 of 14), and there is exactly one week remaining to the cruise. This dive site was an overnight steam from the 32°S site of the last two dives. We are still on the East Pacific Rise, on a segment that also experiences super-fast spreading rates but is not as inflated as the 32°S region.
Right image: "Fred's Fortress," a tall black smoker chimney. A crab trap has just been deployed (it is about 15" long, for scale). Slightly below it is a clump of Tevnia tubeworms.
Today was Ana and my first dive in Alvin! It was very fun. We had a very experienced pilot, Pat, who has over 550 dives so we felt very safe. On the descent the sub lights are off and you can see different mid-water animals like jelly fish and salps bioluminescing as the sub bumps them. It was beautiful! We reached the bottom very quickly and began exploring. We landed at "Nolan's Nook" where there was diffuse venting everywhere. This was my first trip to a hydrothermal vent so I was in awe of the abundance of animals like macrourid fishes, sea cucumbers, sponges, anemones, urchins, bythagraid crabs, and gorgeous stalked and swimming crinoids! The geology landscape was also unlike anything I have ever experienced. It was as far as the eye could see of glassy lava that made a smooth surface like black pillows. There is a lot of pyrite down there too, so everything was sparkly, very beautiful. We meandered to the large vent "Fred's Fortress" where we took some samples of bacterial mat and water for our microbiologist from Cal Tech, Victoria Orphan. What a sight! A giant chimney of sulfide smoking away!
"Nolan's Nook" is a forest of tall lava pillars in a large, drained lava lake along the ridge axis. Fred's Fortress a large black smoker is right next door. A marker that reads Nolan's Nook (seen on end) was place on this spot in 1999 in honor of Nolan Dalpe, Bob Vrijenhoek's grandson. We were all happy to see it again right where we left it. Nolan who is now 6 years old was informed that we found Nolan's Nook, and he said, "That's neat, Opa!".
Left image: Stalked barnacle Neolepas, 2 cm long, taken from glassy sheet of lava. Right image: Branchipolynoe, 1 cm long, which is a worm that lives commensally inside the shells of mussels, one worm per mussel. Its amazing red color is probably hemoglobin. Photos by Greg Rouse, South Australian Museum.
We explored some more, there were not many animals living on the large "fortress" vent. We wanted to find the giant tube worms, Riftia, and some clams, but neither were there. We were able to collect the tubeworms, Tevnia and the mussels Bathymodiolus as well as some snails and limpets. We also got a chunk of rock that had a bunch of serpulid worms living on it, which made our resident polychaete expert, Greg Rouse, very happy. At the end of the dive we also collected a large lava pillar, which made our geologist from MBARI, Jenny Paduan, very happy because even as we were collecting people back on the shore were wondering how such things form. All in all it was an amazing experience and I feel very lucky to have the privilege to participate in such a cool adventure. At the end of the day we were very tired and sore from sitting in an awkward position for so long, but I would jump at the chance to do it all over again.
Casper the Ghost peeing for her record fifth time on the dive.
All underwater photos were taken with the submersible Alvin, and are courtesy of Woods Hole Oceanographic Institution.