dr. FL (Fokje) Schaafsma

Microbial communities within sea ice are presumed to be a major carbon source for the pelagic ecosystem covered by ice. Also, the ice-water interface constitutes an important habitat for many organisms, including e.g. Antarctic krill  and polar cod as key species. Highest densities of top predators are strongly associated with sea ice where primary production measurements suggest low productivity of the water column underneath, further indicating the importance of sea-ice algae as a food source. Climate warming can cause changes in extent, thickness and seasonal persistence of sea ice and can therefore have consequences for ecosystem functioning in polar regions. Understanding sea-ice food webs can help the development of policy for conservation and fishery, considering future changes.

To investigate the importance of sea ice in the life of species, biological sampling at the under-ice and open water surface is done with the worldwide unique Surface and Under Ice Trawl (SUIT), which was hindered in the past by the inaccessibility of the sea ice underside. With these samples, the abundance, distribution and biomass of species in the surface waters can be investigated.

To get a complete image of polar ecosystem with and without sea ice, environmental variables such as temperature, salinity and light availability are measured. These measurements are done using sensors that are attached to the SUIT frame, and are thus measured simulateously with sample collection. In addition, the distribution of animals in deeper water layers, and of birds and mammals are investigated in order to find relationships between de location of various animals and environmental properties. This is further studied by looking at e.g. the diet of various species or the energy flow between trophic levels.

Additional information, news and results can be found in the dossiers:

Antarctic: www.wur.eu/antarctica

Arctic: www.wur.eu/arctic