As clean as mud – first samplings on the expedition

Quelle: blogs.helmholtz.de/polarstern/en/

3 June 2015
A. Fong, M. Kędra, and C. Mӓrz

Beyond 80°N, the seascape is dotted with thick ice floes and sometimes you can’t see where the ice ends and the sky begins. It’s beautiful. The waters are calm except for the wake and churning ice left by the Polarstern. A tiny trail of muddy water is all we leave behind as we head northeast towards deeper waters.

Although we are experiencing 24 hours of light, the seafloor below is permanently surrounded by darkness. Nevertheless, very diverse animals live here. Despite many studies in the Arctic Ocean, we still know very little about the full diversity of Arctic life. Many new species of these hardy and fascinating creatures are waiting to be discovered. But the Arctic is rapidly changing. We need to know who is there, how abundant, and what their functions are in the ecosystem. Only then will we know how climate change will affect these communities.

Benthic organisms, the ones that live in or on the sediments, rely on food from above. Where does this food come from? Within the water and sea ice above are tiny algae, which use the sun’s energy to grow. As they grow and die, some of these algae sink all the way to the seafloor and provide food to the benthos while the others are grazed in the water column. The well being of life on the seafloor depends on the balance between the food sinking to the bottom and food being used by organisms in the water column.

This delicate balance is likely to change in the future due to changes in sea ice extent and thickness. Since sea ice is the most characteristic feature of the Arctic Ocean, it is our mission to understand how changes in sea ice will affect ecosystem functions. Benthic studies are one component of the TRANSSIZ program, and allow us to study linkages between the sea ice, water column, and seafloor.

Impressions