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The first dive.

t has been two years since any of the scientists on board have visited this site, and at mid-ocean ridge hydrothermal vents things can change overnight. These systems are largely geologically driven — the fauna is very sensitive to changes in the chemistry of the water bathing it, and, of course, to the not-infrequent volcanic eruptions. During the first dive, one of the major goals was to visit as many of the individual vents as possible, to see how they had changed and to explore for new areas of hydrothermal activity. I had visited all of these sites in the late nineties. Graduate student Breea Govenar and I made the dive on Wednesday, December 12. Our impressions follow.

C. Fisher:

ven expecting to see dramatic changes, all I can saw is Wow! The first site we visited, Tica, used to be populated by a few small Riftia (tubeworms), and now hosts one of the largest and most impressive stands of tubeworms I've ever seen: thousands and thousands of individuals in a clump four to five meters in diameter and at least that high. Another site we visited, Riftia Fields, was so named because of the many clumps of thriving tubeworms there. Now, only a few sickly looking clumps remain among many dead and empty tubes. But the area has been settled by hundreds of anemones and invaded by numerous galatheid crabs and large vent fish. Two of our other study sites, East Wall and Biovent, used to be populated by a fairly even mix of mussels and free-standing tubeworm clumps. Now mussels cover the landscape with the occasional tubeworm plume sticking out of the top of a mound of mussels. Despite the distractions of the dramatic changes in a dynamic environment, we managed to make a few collections for shipboard analyses and to deploy two arrays of thermistors to record the temperatures of waters bathing the groups of tubeworms and mussels we chose for intensive study over the next few weeks. Unfortunately, our batteries and time ran out just as we began to head north into unexplored territory, so that adventure must await a future dive.

Breea Govenar:

esterday was my first dive in ALVIN, the first dive of this cruise, and the first cruise I have been on — an unusual and wonderful combination of "firsts"! In the tiny sphere (only about six feet in diameter) of the sub was Chuck on the port side, me on the starboard side, and the pilot in the middle. Each of us has a porthole that is about six inches in diameter. From there, a whole other world came into view. It took 1.5 hours (total dive is eight hours) to descend to the bottom (2500 meters, or 1.5 miles) and another twenty minutes to glide over to the vents. It is an amazing feeling to see the actual bottom of the ocean, but then it is even more exhilarating to see the animals that we study. I was the first of the three of us to spot the tubeworms — big (over two meters long and 2 inches around) white tubes with bright red fleshy plumes. I couldn't even stammer out what I was observing . . . "uh, there are . . . there are . . . Ohmygosh! There are tubeworms!!!" Chuck thought I was going to pee my pants. After I got adjusted to the magnificence of the site, we continued with a very successful dive. We visited six different sites, made two collections, deployed temperature probes and took water samples at our study sites. Then on the ascent, I started to get a very bad headache. I asked for aspirin while we were having lunch, but by then I was totally nauseous. By the time they started talking about what they might do to me when we got back to the boat (they always haze first-time divers), talking about mixing oatmeal and Jell-o — I asked for a bag and lost my lunch. I was pretty miserable for most of the two-hour ascent, but I assured Chuck that I would be ready to dive again and again over the next few weeks. While we were on the bottom, the pilot let me drive a little bit, and I dropped the weights and called up to the boat on the mic to begin the ascent. On board, everyone was waiting for us. I thought my friends were opening their arms to hug me . . . but each of them dumped big buckets of ice cold water all over me and threw me in the pool. I took a few victory pictures and headed in for a shower. After dinner, I was up until 12:30 a.m. sorting samples and entering data.