By Fokje Schaafsma |

A kittiwake managed to grab a nice snack: a polar cod. Photo: Peter Gege

On Friday the 23th of June, RV Polarstern left Svalbard for the SiPCA expedition to the Arctic Ocean. SiPCA stands for Survival of Polar cod in the Arctic Ocean. The main aim of the expedition is to learn more about the life of Polar cod, which is a species that is widely distributed in the northern seas. Young Polar cod is found right underneath the sea ice, and we would like to know more about how important the sea ice is for their survival. But although this fish has a central place during this expedition, there are also people on board that focus on other things, for instance the atmosphere.

Usually, the people on board start by unpacking their stuff, and getting their working spaces and gear ready. But one team set to work as soon as the ship started moving. Bram, Suse and Elisa, also known as the bird and mammal team, immediately headed off to the upper deck of the ship to start counting sea birds and mammals. This will not only tell us more about their distribution, of which there is limited knowledge in general, it will also give insight in how the distribution of different species is related to the sea ice and the distribution of the Polar cod, a big part of the menu of many. Although we have only left a couple of days ago, they already enthusiastically have been telling us about their observations, including whales, seals, walruses and polar bears.

A bright blue melt pond appeared on the ice. Photo: Susanne Kühn

Other work started off with taking water samples, followed by a sea ice station. During this station the ship remains stationary next to a large ice floe. Many people will get off the ship to make the ice their new working space where they do all sorts of measurements and collect many samples. Water, sea ice, snow, a bit of everything is taken to learn more about the properties of the ice floating in the north. The melt ponds that are found on the Arctic sea ice are also investigated. These melt ponds occur when first the snow and then the ice on top starts to melt, and usually have a bright blue colour. This colour darkens as the ponds deepens and reflect much less light than the surrounding snow and ice, which accelerates its melting. The melt ponds often contain living organisms and change the sea ice habitat drastically during the transition from spring to summer. The occurrence of melt ponds distinguishes the Arctic sea ice from the Antarctic: In the south the ice carries more snow, isolating it from the atmosphere and pressing it under water, and it drifts away from the continent where the warmer sea water causes the ice to melt from the bottom.

A lot of other work will be done during the coming three weeks. At the moment it is time to try out different fishing trawls to hopefully find the much wanted Polar cod.