This station has proven to be very difficult for many members of the Science team. Our Yo-yo camera, a camera that bobs up and down taking pictures of the ocean floor, hit what we can only describe as a wall of rock and was mildly damaged. Luckily the video equipment was unharmed but the frame that it was mounted on was bent slightly. For the Geology and Microbiology groups it has proven difficult because the sediment here is very sandy and contains lots of rocks. This leads us to problems when we take core samples since the sediment is so loosely packed that it often falls out of the cores before we can secure them. For our Microbiology group this sandy sediment is troublesome because we have been unable to centrifuge adequate pore water out of our samples for the different analyses that we want to conduct on the sediments at each station. We have been able to collect the bare minimum data that we want from each sample and in some cases we had to try several centrifugations in order to obtain enough water to get even the 2 milliliters that we wanted.
Several of our megacores have come up with several empty tubes so there has had to be a fair amount of swapping priorities so that everyone can get as close to their desired number of cores as possible. Last night a megacore hit some rocks and several of the tubes were shattered and no cores took so we spent a good part of today taking apart the frame for the megacore and putting in new tubes to replace the broken ones. Hopefully tonight we can send it back down and get a few more successful cores. Another issue now is the drop in temperature; the sea has started freezing around us, which is not a problem for the ship but it is a problem for our cores. It is actually very beautiful to watch because it forms little circles of ice as it freezes called “pancake ice”. Those cores that we have been able to get are beginning to freeze before we can unload them and store them inside the ship. This makes loosing sediment less of a problem since it is more solid and won’t just fall out of the tubes, however, we now have to move faster when unloading the cores so that they do not freeze completely before we can sample from them. Hopefully the next station, which we should be transiting to tomorrow, will present us with fewer problems with our core and sample collection.
64° 44.08 S
60° 35.88 W
As we began our final day stationed in the Drygalski Inlet, we sent down a Blake Trawl to recover organisms from the seafloor. The water depth of this particular area was nearly 700 m. Craig Smith, a principal investigator from the University of Hawaii, and the team of benthic ecologists, collected these critters for identification, species counts, and morphological studies. The types of organisms range from handful-sized sea pigs to miniscule scaphopods.
Despite the -40°C wind chill, I was excited to help with the evening’s trawl. We sieved through buckets and buckets full of mud to try to recover as many creatures as possible. We geologists are sometime more fond of the rocks that the trawl carries up with it from the seafloor, typically granites and shales in this particular area.
Our time at this station is nearly over, and in these last 12 hours the science team intends to collect a CTD, a megacore, and, most exciting of all, a jumbo piston core. We spent the latter part of our shift preparing the length of the core (a maximum of 80 ft.) for its deployment. We inserted liners and made sure everything was ready. The actual deployment of the jumbo piston will occur during the day shift – I hope to wake to experience it.
After leaving this station, we will travel to a new site where we plan to take a jumbo kasten core, a megacore, and retrieve photos from the seep searcher.
The weather these last few days in the Drygalski has really kept us on our toes, from warm föhn winds to bitter cold temperatures. It is strangely satisfying to spend enough time in one area and become familiar with the landscape.
While we were located in the Drygalski Trough, we have had even further interruptions in our sampling in these past few days because of a storm that we encountered on Monday. With the storm, came an incredible increase in temperature as well as wind speed. While I was in the wet lab analyzing the percent oxygen, pH, and redox potential of a megacore the temperature increased from the more normal temperature of about 3oC to a balmy 12oC in only a few hours. All of the scientists flocked to the various decks to feel the warm air and see the swells of the ocean. Unfortunately for our group, the warmth was not as exciting because it meant our cores would warm up very quickly, when ideally they need to stay around 2oC. With the increase in temperature, there also came an increase in wind because of the storm. Warm westernly winds were coming over the peninsula at around 45 knots, much higher than we normally experience. This sudden increase in temperature and wind, as explained to me, is a phenomenon known as the Fohn Winds, which is a type of dry down-slope wind. It results from a warming of air that has dropped most of its moisture on the windward slope of a mountain range. This consequence of mixing dry air and moisture causes the air on the opposite side of the mountain, or downwind side, to warm. Where we were located in the Wedell Sea, we experienced a sudden increase in temperature because of winds coming over the mountain range on the peninsula, onto the downwind side. With the high winds, the captain would not allow any equipment to be deployed over the edge of the ship. Unfortunately that meant we had to sit and wait for the winds to die down, winds that were expected to last nearly 48 hours. The upside to all of this was that when the sun rose, we all were able to go outside and enjoy the beautiful colors of the sky and the landscape.
We have moved to a new station today which is right up against the Larsen A ice shelf. On our way to this station several members of the science team took a CTD survey (a water sample survey at different depths) to examine a warm water flow that was showing up around 350 meters deep. They believe that this flow is from the deep waters beyond the continental shelf that has made its way up to the area under the ice shelves and may be leading to the melting of the ice shelves. Our group decided to take bacterial samples from this warm flow as well as from one depth below and above it in order to characterize the bacteria in the water of both temperatures. If their hypothesis is correct then we should find different bacteria in the warm flow than in the cold water and those bacteria should remain constant through the entire survey. Taking these samples involved collecting two liters of water from the CTD for each depth and then filtering them through a small syringe filter which would catch any bacteria that were in the water. It took quite awhile to accomplish this since our largest syringe is only 60 milliliters and it requires a fair amount of pressure to get the water through the filter. Luckily one of the MST’s (Marine Science Tech) had a battery powered caulking gun, that she used for just that task, which made our job much easier on our hands.
At this station we will also be taking the same megacore samples that we took at the last station. Last night we brought up the first round of megacores and since we are no longer in the ice they were much more viscous than the more solid samples we had at the last station. This meant that we had to move fast in order to plug and cap the tubes before the mud slid out and was wasted. Once we collected the tubes from the array our group and the group under Craig Smith had to agree on which tubes we would split up between us for sampling. Since two tubes lost most of their mud this was a difficult task. Once we had sorted out our tubes we wrapped them in their Mylar blankets and stored them in the cold room to be processed later tomorrow. Since this is our second station we have gotten used to the procedures for processing our samples so we should be able to collect them faster now that the kinks have been worked out.