December 19, 2003
|Peter Countway, Ph.D. Student, University of Southern California|
Letise Houser, Shipboard Education Coordinator
The day started with a bit of anticipation from everyone, all anxiously awaiting the launch of the 18th and final dive of Extreme 2003! The basket was loaded and ready to go, and it included two Extreme Experiments. Alison and Liz were today’s observers, both taking their second dives of the expedition. My vantage point, this time, was from Top Lab where Atlantis communicates with Alvin throughout the duration of any dive. I was unable to actually see the launch, but could hear all of the verbal exchanges between the parties involved. There was quite a checklist of steps that different parties — Bridge, Avon, Top Lab, Doghouse, Main Deck, and Alvin — have to complete before Alvin is lifted off the deck and deployed into the water. Then, there was yet another checklist once the sub was actually in the water and detached from the ship, before it could dive. Finally, everything was in order and completed, and Alvin began to descend — “Sub submerged. Roger that, Alvin submerged.”
I spent the next part of my morning working out, of all things. I am ashamed to say that I have only exercised about four times during the entire three weeks, due to the erratic nature of my schedule. So, I guess I’ll just call it a “vacation!” : ) I’ll get back into a regime once I return to Delaware, if not while home in Chicago for the holidays (doubtful). I not only have to stay in shape for myself, but also to keep up with the track athletes that I help coach during the year — Track and Field, Cape Henlopen High School (Lewes, DE).
I finished my workout by about 10 am, and then began some preparations for today’s posting. Part of that time, I did some work out in the sun, since these are the final days that I have in this tropical weather before facing the wintry conditions in the Midwest and on the East Coast of the U.S. Burrrr! I don’t even want to imagine it. It was such a beautiful and sunny day that I got distracted often just watching my surroundings. The sea surges still seemed high, but they were smooth and calming, instead of the crashing waves we saw only days ago. The wind wasn’t very strong either — a welcome breeze that merely tickled the surface of the water, causing small, shimmering ripples. In addition, my attention was lured by the life around me. There was a seagull walking on the deck near where I was sitting (see picture in Neat Stuff). This bird has been taxiing on the ship for the last several days and seems to have become quite comfortable around us. Then there was a turtle (see Neat Stuff) that was spotted swimming on the starboard (right) side, causing several people to come out to see it. Initially, a bird was riding on its back, but it eventually flew away, leaving the turtle less inhibited. This is at least the fourth time that a turtle has been seen nearby since the beginning of the cruise.
After a short while of “working” on the back deck, it was already time for lunch. I opted for tuna salad and crackers, vegetable spring rolls, and some soup. Then, I needed to find something to do to pass the time until today’s science seminar. Since I had less than two hours before the seminar was scheduled to begin, I couldn’t watch a full movie. Instead, I watched a few 30-minute episodes of a cable series that we have on DVD here. By the end of the third episode, it was about 1:35 p.m. (1335) and almost time for the seminar.
Upon arrival to the seminar, several of us received a cool surprise from Pat Hickey, Alvin Expedition Leader. All the first-time Alvin divers were given a nice certificate commemorating the occasion — citing name, dive date, depth of dive, dive number, latitude and longitude of site, and cruise number, signed by the respective Alvin pilot, Craig (Chief Scientist), and Pat. I feel so special! : ) I can’t wait to frame it and find a place to hang it.
Once all the certificates were distributed, Dr. Tara Harmer presented today’s seminar: “Stalking the Wild Symbiont: Free-living Riftia pachyptila Symbionts at Deep Sea Hydrothermal Vents.” Her research is closely linked with that of Dr. Colleen Cavanaugh’s in trying to learn more about the bacteria that have a symbiotic relationship with that species of deep-sea tubeworm. She also had several props to pass around to complement her discussion, which included worm tubes and FRIES (sampling apparatus she uses).
As usual, the end of the seminar meant the beginning of the science meeting. Before it was completed, it was announced that the sub was off the bottom and beginning its ascent, with an expected surface time of 4 p.m. (1600). That didn’t leave much time after the meeting, so people began to gather out on the deck earlier than usual to see the final recovery. The scientists had to get ready to empty the basket as soon as possible today. Usually the sub is transported back into its hangar and secured before the scientists can retrieve any samples. Today, however, the sub was stopped mid-deck for a “skin party.” Since it was the final dive, Alvin was stripped of its “skin” — the metal panels covering the hull and external operating parts of the sub (see Neat Stuff). The Alvin group used soap, water, and scrub brushes to clean the sub from top to bottom, inside and out. Though it was still work, it almost seemed like a celebratory occasion for them. At the same time, the deck crew also washed Avon (the deployable boat).
Due to the early recovery of the sub, there was still plenty of time between the “skin party” and dinner, which was worth the wait. It was ‘Za Night again, but Larry was the pizza maker this time. He made some unbelievable options; my choices were white sauce, onion-green pepper-red sauce, and spinach-feta-tomato. He had them coming “hot and fresh” out of the oven every three minutes like clockwork. The man could open his own pizzeria, no doubt! He would definitely have lots of happy customers.
To “top” it off, so to speak, there was chocolate-chip ice cream for dessert. I put a scoop in a cup, and brought it back to my workstation with me. I had a lot of work that I needed to get done, now that the expedition is coming to an end, so I wanted to get to it. We’re all starting to wrap up everything as Atlantis steams toward shore. Our commute back to Manzanillo will take about a day and a half, getting us in port by Sunday (Dec. 21) morning. There’s plenty to do before then, though.
My day began after dinner on the 18th. For the most part, I’ve been working at night, using the CTD (Conductivity/Temperature/Depth) sensors to profile the water column over areas of hydrothermal vent activity. The CTD sensors are surrounded by 24 Niskin water-sampling bottles mounted in the center of a circular steel frame (to protect the sensors and sample bottles). The Niskin bottles are approximately 1-meter tall, forming a ring around the sensors just inside the perimeter of the steel frame. Before sending the CTD rosette (the electronics, Niskin bottles, and frame) overboard, the "Niskins" are rigged in the open position, with closures at the top and bottom of each bottle tied into a "firing" mechanism in the center of the rosette. The CTD sensors and bottle-firing mechanism on the rosette are connected to a computer on the ship through 8,000 meters of cable!
Once deployed, the CTD is controlled from an instrument station in the computer lab. The CTD sensors send real-time water column data back to the ship where it is displayed on a computer monitor. The water column features typically displayed on the monitor include temperature, pressure (depth), salinity, fluorescence (from phytoplankton), and a measurement of the transmittance of light through the water. The real-time data allows us to decide which depths are of interest for collecting a water sample in a Niskin bottle. The goal of the CTD cast on the night of the 18th was to create a profile of the water column above a hydrothermal vent and collect samples at particular water column features for analysis of the microbial community (back on land).
The water temperature at the surface was 29° Celsius. At 2,400 meters below the surface, the temperature dropped to 1.9°C. In most areas of the deep sea, physical properties like temperature and salinity change very little on the scale of several tens of meters. Just below 2,400 meters, there was a sudden drop in light transmittance (indicating more particles in the water column). The drop in transmittance was coupled to anomalies in temperature, salinity, and turbidity. This is the feature we had been hoping to find, water from the buoyant hydrothermal vent plume! The goal was to collect water from below, within, and above the plume for the purpose of characterizing the genetic diversity of the microbial community.
We knew that this area was characterized by tall geological features rising off the bottom, so it was very important not to get our sampling gear too close to the bottom. A “pinger” mounted on the CTD allowed us to monitor the position of the sampling gear with respect to the seafloor. Most of the hydrothermal chimneys in this area are fairly narrow features so we stayed approximately 50 meters off the bottom, just in case there was a chimney in the vicinity that we couldn’t detect. The R/V Atlantis has a dynamic positioning system, which allows us to hold a position over the seafloor within a few tens of meters. This feature is of great benefit to “plume profiling” work, as it would be fairly easy to drift out of the plume.
After firing Niskin bottles across the vertical plume gradient (a layer of water approximately 200 meters thick), we brought the CTD back up through the water column, stopping to collect additional samples at 1500, 1000, 500, 200, and 50 meters. I will be studying the genetic diversity of the eukaryotic microbes (protists) present in the samples, while other researchers will examine the bacteria, archaea, and viruses. Once the water returned to the deck of the ship, I began the long process of filtration to collect the various microbes for subsequent DNA extraction. This process involved several stages of filtration to remove zooplankton (which might interfere with my analysis of protistan diversity) and to finally collect all protists in the size range of 0.7 to 80 micrometers in diameter. Twenty liters of seawater were collected (two Niskin bottles fired) for each depth because biomass is typically low in the deep sea, and I wanted to ensure that I would be able to extract enough DNA for my analyses back at USC.
After working all night, I finally finished filtering my last sample at 2:15 pm today, just in time to make it to the science meeting at 2:30. Alvin was scheduled to surface at 4 p.m., after which we’d begin to steam back to Manzanillo. I really wanted to see the recovery of the last dive, but I could barely keep my eyes open and my bunk was calling. Falling asleep was nearly instantaneous. The next thing I knew, it was 8:30 p.m. That was the best five hours of sleep I’ve had in a very long time! Now begins the task of breaking down my lab bench and packing up all of my sampling gear. Additionally, there will be lab reports to write tonight, as well as collection of data and images from our various sampling efforts. All in all, it has been a great cruise. The captain and crew of the R/V Atlantis and the DSV Alvin group have been incredibly supportive of our scientific endeavors and it has been a real pleasure sailing with them. Dave Sims and Chrissy van Hilst (the SSSG techs on this cruise) were very supportive of all of the nighttime CTD operations — thanks to both of you, and thanks for the music education, Dave! As the only representative from USC on this expedition, I’ve enjoyed getting to know (or in some cases getting reacquainted with) the other members of the science party and finding out about their research projects. This cruise has definitely been an experience of a lifetime, and I look forward to returning to the deep-sea hydrothermal vents. However, right now, my thoughts have turned to returning to Los Angeles to see my wife, Becky (who I miss very much), and spending time with friends and family over the holidays. It’s time to start packing!
|Copyright University of Delaware, November 2003|