October 11, 2012
Polarstern Has News About Arctic Sea Ice
Alan McStravick for redOrbit.com — Your Universe Online
The Polarstern expedition has disconcerting news about our rapidly receding sea ice.The Polarstern, an ice-breaking research vessel, returned to the port of Bremerhaven two days ago. The Polarstern, operating on behalf of the Alfred Wegener Institute, was conducting research into the retreat of sea ice and the impact it will have on the Arctic Ocean and its ecosystems over the last two months. In all, 54 researchers and technicians representing 12 countries were aboard. The voyage covered 12,000 kilometers, or approximately 7,500 miles, and conducted research and collected data from 306 Arctic stations. Nine of these were ice stations where the Polarstern moored to an ice floe to examine the ice, the water beneath it and the bottom of the sea.
The crew was able to utilize several new technologies to record, through both film and photograph, life in and below the ice to a depth of almost 3 miles. A primary focus of the voyage had to do with measurements concerned with responses to the rapid retreat of the sea ice this summer. They were able to determine the ice in the area of investigation had declined further than had previously been reported.
In the summer of 2011, the Polarstern had encountered what is termed as ℠multiyear´ ice in the Siberian shelves that include the Laptev Sea. Prior to this most recent expedition, in July of this year, this area was free from ice. This means the volume of ice has been greatly reduced through melt which increases the fresh water content of the sea surface. “The Arctic of the future will consist of thinner sea ice which will therefore survive the summer less frequently, will drift more quickly and permit more light to penetrate the ocean. This will lead to great changes in composition of sea life,” according to the head of the expedition Dr. Antje Boetius, manager of the Helmholtz-Max-Planck Research Group for Deep-sea Ecology and Technology at the Alfred Wegner Institute.
Also utilizing a new type of under-ice trawl, researchers were able, for the first time, to conduct large-scale investigations of the communities living directly on the lower side of the Arctic pack ice. Speaking on this advancement and the importance of the sea ice as a habitat, Dr. Hauke Flores, head of the Polar and Marine Research group said, “We had a polar cod in our net almost every time. This species is particularly adapted to life below the ice; it does not occur without ice.”
Sea ice physicists had some new toys, too. They used an under-ice robot to measure and record light incidence and the distribution of algae on the lower side of the ice. Their detection of the diatom Melosira artica in high concentrations under first-year ice helped in their understanding that the Arctic is not a desert, but has a thriving bio-diverse community. Through collected photos, researchers learned this algae would simply drop to the bottom of the sea as a result of the melting ice.
What is particularly interesting about the team´s findings is how the rapid changes in the Arctic are not restricted to the sea surface. They found water from the Atlantic Ocean flowing into the Arctic at significant depths. The incoming water was found to have an elevated temperature and salinity. The influx from the Atlantic, in combination with the under-ice algae that had fallen to the seabed, allows for frequent accumulations of sea cucumbers, sponges, feather stars and sea anemones.
With warm temperatures, the retreat of the ice and the greater light availability, the seasonality of the Central Arctic is shifting. By collecting anchored sediment traps, they have determined that the production and export of algae is occurring far earlier when compared to previous years. Also, due to the extremely thin ice cover, the Polarstern had no trouble in navigating much further north this late in the year. The sea ice physicists took advantage of this fact to collect important data at the start of the freezing period. The reason the measurements of the new thin ice are important is because this form of sea ice will occur with far more frequency in the future.
The Alfred Wegener Institute regularly conducts research in the Arctic, Antarctic and the high and mid-latitude oceans. They are one of 18 research centers of the Helmholtz Association, which is the largest scientific organization in Germany.