Easter Microplate Expedition
March 22, 2005 Day 11
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Alvin dive# 4088, 38°S:
Today cleared to be a beautiful day, warm in the sun though the wind was a little nippy. The swells are long rollers coming from the south. A perfect day for the second dive of the expedition.
The observers were Cindy and Michel, and the pilot was Tony. The dive started at "Sebastian's Steamer", where they collected a small sulfide structure that was venting clear shimmering fluid and had alvinellids attached to it. Nearby, they drove through diffuse milky-white flow and collected some water and bacteria with Niskin bottles. They named the site "Pâle Etoile", or pale star in French after a poem that Michel brought with him for Cindy to memorize. In this diffuse flow area were numerous brachiopods. These animals, and the megafauna in general that live away from focused venting, are found here at 38°S at the highest densities Cindy had seen anywhere on the East Pacific Rise (EPR): crinoids, sponges, predatory tunicates, and even urchins, which haven't been seen before on the EPR.
The first mussels they encountered were on an old sulfide mound; one more mussel site was found on the dive on more level ground, and they collected a cluster with associated fauna using a mussel pot. Two crab traps were deployed at "Sebastian's Steamer", with "surf and turf" leftovers as bait. They are to be picked up tomorrow, but crabs were already attracted to the traps before the sub left the site. Dead clam shells were seen, but no live clams.
There were lots of recent, glassy lava flows, collapsed lava pillows, and a large tectonic fracture (not an eruptive fissure) that they followed for much of the 1800m transit, but they collected no rocks. Both observers were biologists, and with it taking nearly 1/2 hour every time the sub sits down to do anything, the priority today was to spend the dive time collecting biology.
The rest of the science party spent the day finishing up samples collected yesterday, and the evening working on the newly collected samples while they were fresh. Yesterday was the Fall Solstice for us here in the Southern Hemisphere. Our days will begin to be shorter. I find that to be ironic, because also yesterday the dive program began, and our days have become considerably longer!
The science party crowds around the Alvin's science basket to bring the samples into the lab.
Shannon emptying the bio-box from the science basket after the dive.
"With a little love and luck, we will get by..." (Jimmy Buffett )
Maybe I should say a little SCIENCE and love and luck ... it certainly takes a lot of all of those to find good stuff on the seafloor. Cindy and Michel dove in Alvin today, and managed to finally use our mussel pots! Well, one of them anyway. The mussels DO exist here, although not in large quantities. Hooray... our sample was small, but the bright side was that Team Van Dover got a little sample processing practice that way. It must be frustrating to dive to a new site like this, because there are so many fascinating wonderful animals all around to collect, but only so much space on Alvin's science basket. I really hope that I can do a good job helping on my dive, which just might be very soon! The sun has come out again, and let me tell you, it is gorgeous out here! Wish us some more love and luck for the upcoming dives!
Left image: Mussels are cleaned of juvenile recruits, parasites, and other fauna, and dissected after the dive. Right image: Nerida and Greg examine specimens through microscopes. The image of a snail from Greg's scope is projected on the computer screen just beyond. The dissections continue at the table across the lab.
Left image: Microscopic image of the underside (mouth to the left) of Peltospira, a small (3mm) limpet found on "Sebastian's Steamer". Right Image: Microscopic image of a juvenile Alvinella pompejana (1cm long). The white "hairs" are symbiotic bacteria. Photos by Greg Rouse, South Australian Museum.
All underwater photos were taken with the submersible Alvin, and are courtesy of Woods Hole Oceanographic Institution.