Sea ice, which is frozen sea water, consists of two phases: solid ice and brine. Brine fills an interconnected network of pockets of solid ice, and provides a habitat for ice algae. These microscopic algae, especially those living at the bottom of ice floes, are an important food source for Antarctic krill during late winter and spring. Krill are shrimp-like crustaceans that are in turn a key food source for penguins, seals and whales. Information on the biomass and distribution of ice algae is very scarce.
During SIPEX-2, we will study the biological properties of sea ice. This includes
- Phytoplankton and bacterial studies
- ROV and bio-optics
- Sea Ice Biogeochemistry
- Studies of adult krill
- Studies of larval krill
We will measure the amount of ice algae in two different ways. The classical method is to collect ice cores, melt these and then analyse the melt water for the abundance and biomass of algal cells. We will use this very accurate but time-consuming method at each ice station, but will be able to collect and analyse only a few ice cores per sampling site.
The second method to estimate ice algal biomass will involve an instrumented Remotely Operated Vehicle. We will deploy the vehicle (which is about the size of two large suitcases) through a hole in the ice and will pilot it via a 400m long fibre-optic tether.
We also intend to measure biogeochemical and biological sea ice parameters using ice coring surveys. And… we have several methods for catching krill, including CTD mounted light traps, the German MASMA pump, and in coordination with the ROV.
The krill studies will be repeated using the same approach next year on the German winter voyage WISKY with RV Polarstern on which Rob King, So Kawaguchi, Simon Jarman, Klaus Meiners and others will participate. In that way we can compare our results between regions and years. The overarching project, PolarTime, is an international project funded by the German Helmholtz Association and lead by the AWI (Bettina Meyer). It was designed to investigate the biological clock in krill with respect to their seasonal life cycle. The AAD are partners in the Polar Time project with both the krill group led by So Kawaguchi and molecular group led by Simon Jarman. Krill is used as model organism to study and understand biological rhythms and clocks in other polar pelagic key invertebrates.