056B62A6-E55A-5FE8-D80F8936F8E66C9D
A2977AF3-EE97-8808-05813B5D9A3A2DEE

2010 Expedition to Antarctica

Week 7

Monday - Wednesday, February 8 - 10

For the past few days, we have continued our biological survey of a small area to the southwest of Lockyer Island. We have conducted several mega-core, yo-yo camera, and CTD deployments as well as dragged a trawl on the seafloor to bring up and document benthic organisms. The trawl proved to be a large success, having collected a range of Antarctic benthic feeders, including several examples of an organism aptly called a sea pig, a certain kind of sea cucumber. The trawl also brought up several species of Antarctic fish, brittle stars, an octopus, and a number of other creatures. University of Hawaii post-doctoral fellow Laura Grange commented that she had observed relatives of these organisms elsewhere, but had never seen varieties this large in size. Helping to document the species collected in the trawl, National Geographic photographer Maria Stenzel photographed some of the organisms in collaboration with the biologists.

In addition to sampling and processing the trawl catch, others were hard at work collecting and sampling mega core sediments. Orchestrated by University of Hawaii professor Craig Smith and Grange, the mega-core deployments have been a smooth operation, recovering an average of ten cores per deployment. Back in the aquarium room, adjacent to the back deck, Grange, Smith, and helpers have been sampling each of the mega-cores in 1-cm intervals for a range of analyses, including macro-fauna, bioturbation, and chlorophyll. Also claiming a core from each deployment, University of Southern Illinois professor Scott Ishman samples the cores for foraminifera analysis. Hamilton College professor Mike McCormick has also been hard at work in the 1-degree Celsius cold room to process the mega-core sediment in an anoxic environment to evaluate the microbiology and geochemistry of the sediment. One of his interests in the core is documenting the change in chemistry that is occurring from the top of the core to a few centimeters below the top in the oxidation layer, which is marked by a darker sediment layer. 'Oxidation' is a chemistry term that describes a reaction in which electrons are being donated. One common oxidation reaction is the formation of rust (an iron oxide) when iron is exposed to oxygen. Graduate student Sun Mi Jeong and post doctoral fellow Caroline Lavoie have been instrumental in helping McCormick process the sediments in the cold-room. Other news off the ship include the successful transfer of the LARISSA ice team and their drilling equipment from Site Beta to Rothera Station on Monday. Additionally, as of Tuesday, the glaciologists are 95% complete with their AMIGOS installation on Flask Glaier and will be looking to move to Leppard Glacier next to install a GPS system.
 

Thursday, February 11

Welcome back, Dr. Greg Balco, Doug Fox, and Barry James! On Monday of this week, helicopter pilot Barry James transported Balco and Fox to the Sjogren Glacier to collect glacial erratics for exposure dating. Unfortunately, during their return after a successful day on the glacier, visibility decreased and forced a landing on the southwest side of James Ross Island at Inoceramus Point. The three have been camping out safely and securely on the island for three nights, making use of the survival kit stowed at all times on the PHI helicopters. The kit included items such as tents, sleeping bags, freeze-dried food, and a cooking stove, among other useful items. We had been maintaining contact with them via iridium phone every two hours for updates as we awaited the weather to clear. Thanks to their patience and the help of helicopter pilot Chris Dean, we made a safe recovery of the three this afternoon. We are all thankful and excited to have the rest of our team back on the ship, and Captain Joe sounded the ship's horn upon their return in celebration.
 

Friday - Sunday, February 12 - 14

Following the three ice campers' return to the Palmer on Thursday afternoon, helicopter pilots Barry James and Chris Dean as well as the two helicopter mechanics Randy Perrodin and Jay Cox successfully returned the second helicopter from James Ross Island to the Palmer. With our team back on the ship as well as the two helicopters safely nestled in the hanger,
the Palmer started north through the thick ice.

Since the break-up of the Larsen B Ice Shelf in 2002, we have been observing changes in the sea ice in the Weddell Sea. Immediately following the break-up, a surge of tabular ice bergs flushed the region, but this ice is now long gone. The tidewater glaciers, however, are continuing to surge, "spewing thousand of large pinnacle and irregular ice bergs of large
draft into the mix," says Dr. Eugene Domack. These bits of ice have joined into the seasonal pack ice, producing what Dr. Eugene Domack loosely calls a "super ice." This super ice is being circulated clockwise in the Weddell Gyre as it is being influenced by surface winds as well as water currents below the ice. This assemblage of currents and recent low pressure weather systems has pushed the "super ice," pack ice, and multi-year ice floes into what was once open water in middle January, which has ultimately shaped our decision to leave the area.

Before cutting our way though the ice in Admiralty Sound to head north, we deployed an oceanographic mooring, an event orchestrated by Lamont Doherty scientist Bruce Huber. The device will hang vertically in the water column for two years, we will retrieve the mooring during the next leg of the Larissa project in 2012. The mooring will record a suite of oceanographic information, such as water currents and temperature, as well as collect suspended sediment in the water column over the course of its deployment. Suspended sediment in the water column will be caught with the yellow funnels (the sediment traps) that bear the Hamilton College logo (see pictures).

Over the past few days, we have been transiting around James Ross Island through Admiralty Sound and into the Antarctic Sound. Last night, as we entered the Antarctic Sound, we stopped to conduct an ROV survey of Jun Jaygue, a volcanic cone, and to deploy a whale bone lander, prepared by Duke University graduate student David Honig. Based on previous work, we know that Jun Jaygue has had recent eruptive activity, and we were interested in determining whether the area is host to active hydrothermal vents. After a multi-hour dive, we did not observe venting activity, but we did see a productive benthic environment and ice berg scouring on the plateau of the cone. Ice berg scouring occurs when ice bergs scrape the seafloor, leaving large, distinguishing scars in the surface sediment.

After successfully moving out of the ice and conducting an ROV dive and a whale bone lander drop, we are transiting to Hughes Bay and Brailmont Cove on the western side of the Peninsula. Hughes Bay offers a key staging area for helicopter operations to Cape Framnes, where we hope to install another GPS station. Our position in the bay also allows us to deploy the bedrock seismic station at Spring Point. Spending our last two weeks in the west will also provide additional sampling opportunities for both the geology and biology teams. We also heard word from Ted Scambos and the glaciology team that they too are in transit to Leppard Glacier to install another AMIGOS.

— Commentary and photos provided by Kimberly Roe '08