Changes in sea ice thickness and extent also have direct consequences for the eco-system of the Arctic Ocean. The reason is that the marginal ice zone is sort of like a "Garden of the Arctic Ocean". Due to the melting of sea ice, algae are released from the ice into the sea. In addition, the freshwater in the ice mixes with the seawater. Since the former has a lower density than seawater, a stable stratification of the surface water occurs. As a result, the algae remain in the topmost, light-flooded water layer and start to grow. So-called algal bloom results. These algae, in turn, form the beginning of the Arctic food webs. Currently it is scientifically controversial, however, whether the Arctic Ocean will become "more productive" because of the decline in ice and the related increase in light.
Scientists like Dr. Ilka Peeken therefore investigated the biology of the algae not only in the sea ice, but also in the melt ponds and in the water column under the ice. The initial results point to regional differences: in the Atlantic part of the central Arctic the algae biomass and carbon intake, both in the ice and in the melt ponds and water column, were significantly higher than in the Pacific section.
This applies similarly to the climate-relevant trace gas methane, which may form during algal bloom. Measurements by the biogeochemists headed by Dr. Ellen Damm showed that the formation and release of the greenhouse gas are influenced by which region of the Arctic Ocean is seasonally ice-free. In addition, the researchers succeeded for the first time in verifying how much methane is oxidised to carbon dioxide in the ice.
The scientists now want to compare these and many other snapshots of the situation in summer 2011 with their results from 2007 as well as with data from the two Arctic long-term observatories of the Alfred Wegener Institute in the Fram Strait. The so-called "mooring" and the deep-sea observa
|Contact: Sina Loeschke|
Helmholtz Association of German Research Centres