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Special Feature: ASPIRE: The Amundsen Sea Polynya International Research Expedition

Collection launched: 15 Jul 2014

Understanding the climate-sensitive processes supporting the Antarctic's most productive marine ecosystem

The Amundsen Sea is a place on Earth about as far as you can get from human civilization. Satellites reveal it to be the most productive region of coastal Antarctica. Nearby glaciers and ice sheets are melting rapidly. Between November 2010 and January 2011, the U.S. Research Icebreaker Nathaniel B. Palmer was joined by the Swedish Icebreaker Oden for the Amundsen Sea Polynya International Research Expedition (ASPIRE). Scientists on the NBP focused on understanding the climate-sensitive dynamics of the open water region, known as a “polynya,” while the Oden investigated the disappearing sea-ice ecosystem nearby. Here we report our findings from this extraordinary place.

Additional articles under review

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Patricia L. Yager Explains the Significance of the ASPIRE Special Feature

Please describe the focus of the ASPIRE Special Feature. The Amundsen Sea hosts the most productive polynya in all of coastal Antarctica, with its vibrant green waters visible from satellites. It is also one of the global regions most vulnerable to climate change, experiencing rapid losses in both sea ice cover and nearby ice sheets.

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Adelie Penguins (Pygoscelis Adeliae)
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Amundsen Sea Polynya
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Adelie Penguins (Pygoscelis Adeliae) are the most commonly seen penguin in the Amundsen Sea region. They feed on the krill associated with the sea ice. Here, we encountered a group of them as we were breaking through the sea ice pack near the Thwaites Iceburg Tongue on December 31 (Photo credit: P. Yager)
Amundsen Sea Polynya. This image was taken from the pack ice as we first approached the open waters of teh Amundsen Sea Polynya. Polynyas are recurring areas of open water surrounded by sea ice. (Photo credit: P. Yager)
Calm Amundsen Sea. When the wind stops blowing, which happens only occasionally in the austral summer, the polynya surface can become like glass. Here, you can see how, no longer pushed around by the wind, the sea ice can then spread out. The golden brown color in the ice floe is ice algae, typically diatoms which have golden brown pigments in addition to chlorophyll. If you look carefully in the dark areas of the photo, you can see 'grease ice', which is the first steps of new sea ice formation. Air temperatures are still below freezing at this time of year, so when it gets calm, new sea ice crystals can form. (Photo credit: P. Yager)
Sea Ice in the Amundsen. Phytoplankton are very abundant in the surface waters of the central polynya. Here, a large floe of sea ice was blown into the otherwise open region, providing a nice backdrop for seeing the green color of the water. (Photo credit: D. Munroe).
Amundsen Sea Wildlife. Adelie penguins and a crabeater seal on the sea ice floes near the open polynya waters and Thwaites Iceburg Tongue in the distance. (Photo credit: P. Yager)
Collecting Sea Ice Algae. The marginal ice zone, on the edges of the polynya, is a very productive part of the polar ecosystem because of the sea ice algae there. Here, postdoctoral fellows, Tara Connelly (left front) and Rachel Sipler (right front), Emily Roglsky (back right), and Sandy Aylesworth (standing back left), are collecting organic-rich nutrients from the slushy sea ice flow near the ship. The ice was too thin to stand on, so the Palmer crew used a crane to lower them over the side of the ship in what is usually called the 'man basket.' We renamed it the 'woman basket' that day. (Photo credit: P. Yager)
The Conductivity-Temperature-Depth Sensor (CTD). with its 'rosette' of 24 10-liter Niskin bottles, is one of the main oceanographic instruments for studying the open waters of the polynya. As the ship holds position on station, it is lowered by a winch slowly through the entire water column and then returned to the surface. The CTD sends data back to the ship in real time, and the Niskin bottles (which go into the water open) are closed at points of interest on the way up to collect water samples. (Photo credit: K. Esswein)
Floating Sediment Trap Array. One of the questions of ASPIRE had to do with the fate of the very high algal productivity in the surface water of the polynya. To capture particles sinking to the deep, a floating sediment trap array, pictured here, set free from the ship while attached to a buoy with a locating transmitter, was deployed to depths of 60, 150, and 300 m for several days. When brought back to the surface, we could see that a great deal of material was indeed sinking below the polynya surface, likely providing food to deep dwelling zooplankton and benthic organisms. (Photo credit: P. Yager)
Fish Larva. Onboard ASPIRE, a Multiple Opening / Closing Net and Environmental Sensing System (or 'MOCNESS') was deployed to collect zooplankton in the waters of the polynya. Some of the animals it collected were fish larvae, as shown here. (Photo credit: S. Kjellerup).
The Thwaites Iceberg Tongue . (in the distance) sits on the eastern edge of the Amundsen Sea Polynya, separating it from the Pine Island Polynya (PIP). It is an important part of the ice-ocean interactions that impact the Amundsen Sea Polynya formation. The productive marginal ice zone on the eastern edge of the polynya is shown here in the foreground. (Photo credit: P. Yager)
Ice Algae, typically golden-brown diatoms, are very important to the Amundsen Sea ecosystem. They are the base of the sea ice food web, which includes krill, Adelie penguins, crabeater seals, minke whales, and orca whales, and are also an important component of the carbon cycle in the region, helping to draw down CO2 from the surface waters before the sea ice melts. (Photo credit: P. Yager)
Pack Ice North of Amundsen Sea Polynya. The large region of sea ice north of the Amundsen Sea polynya hosts a productive food web based on ice algae, typically golden brown diatoms, that provide food for the ice-associated krill. While not thought to be as productive as the open waters of the polynya, this sytem is hard to characterize over large areas since satellites cannot see the algae so easily as in open water. (Photo credit: P. Yager)
Icebergs are pieces of the ice sheet that have broken off and are adrift in the polynya waters. They can be over 100 feet (30 m) tall and reach down into the ocean several hundred meters, providing a 'stirring' mechanism for the upper surface waters as they drift northward. Much thinner sea ice (1 - 3 m) can freeze around them as shown here. (Photo credit: K. Lowry)
The Bridge of the U.S. Research Icebreaker Nathaniel B. Palmer looks out over a serene evening view of the ice floes of the Amundsen Sea. (Photo credit: K. Esswein)
Nathaniel B. Palmer (NBP. Fondly called the 'NBP', the U.S. Research Icebreaker Nathaniel B. Palmer was built in 1992 to be capable of breaking 1 m of ice at 3 kts. It continues to be the premier ocean-going platform for the US Antarctic Research Program. (Photo credit: P. Yager)
The Thwaites Iceberg Tongue is a nearly impenetrable section of ice sheet that separates the Amundsen Sea Polynya from the Pine Island Polynya. ASPIRE wanted to collect some moorings in the PIP for Stan Jacobs' team, so we had to try to cross through the Thwaites; we tried several times and were not successful. Some years, it is more impenetrable than others. (Photo credit: P. Yager)
U.S. Research Icebreaker Nathaniel B. Palmer Meeting Swedish Icebreaker Oden. As part of the two-boat operation in the Amundsen Sea, the U.S. Research Icebreaker Nathaniel B. Palmer met up with the Swedish Icebreaker Oden on December 21, 2010. Here, as seen from the bridge of the NBP, the Oden parked itself against the sea ice, and then shortly thereafter, the NBP nudged over closer and tied up to the Oden so that we could exchange personnel and some equipment. Fortunately, it was a beautiful, calm evening, making the exchange smoother and successful. (Photo credit: P. Abrahamsen)
The Dotson Ice Shelf, about 30 miles (50 km) wide, is located in the southeast corner of the Amundsen Sea Polynya between the Martin and Bear Peninsulas. It was a focus of the ASPIRE project that we called 'the iron curtain' because we were testing the hypothesis that some of the iron supply to the productive polynya comes from the melting ice sheet. (Photo credit: P. Yager)
Sediment Trap Buoy. In the very productive central open water polynya, we deployed the floating sediment trap array (see other photo above) for three days to collect particles sinking to depth. On Day 2, we could tell from the transmitter that the buoy was behaving strangely, so we went to retrieve it earlier than planned. When we located it, the buoy had been caught up in a drifting ice floe. The white sea ice and the orange buoy provided the perfect color contrast to the immense bloom of phytoplankton going on there. (Photo credit: D. Munroe)
The Amundsen Sea Polynya International Research Expedition (ASPIRE) Team onboard the RVIB Nathaniel B. Palmer included Captain Yuri Magrabe (front left) and his crew, Raytheon Polar Services Marine Specialists and Technicians, and scientists from around the world. Collaboration among all the team members was really exceptional, contributing significantly to the great success of ASPIRE. (Photo credit: D. Munroe)

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