(Text: Ingrid Wiedmann)
The main sampling program of the ARCEx cruise started after few hours of steaming in van Mijenfjorden. This fjord has all the past years been ice-covered during winter and spring, but this year was special. Sea ice did not form before February/ March and covered only the very innermost part of the fjord. Thus, it was possible for us to reach the inner basin of van Mijenfjorden with R/V Helmer Hanssen and do a comprehensive sampling. We collected physical data, such as water temperature, salinity, density and water currents as well as a lot of water samples and plankton nets.
The water samples from depths between surface and 60 m were partly processed by our dear filtration team Emma and Sigrid (also known as “filtøsene”).
The amazing filtration team Sigrid and Emma (picture by Ingrid Wiedmann)
They spent hours to filtering water on paper filters and freeze them. Once back at the University of Tromsø these filters will be further processed and in this way, we get an idea about the amount of autotrophic biomass (= microscopic algae) in the water. This helps us to determine, if e.g., the grazers in the water have enough “food” available.
Looking deeper into the link between algae and grazers, our colleagues from the Norwegian Polar Institute also set up a major experiment. They collected 240 L of water and divided the water into 24 different bottles. Copepods, a small crustacean grazer living in the water column, was added to some bottles and all the bottles were put into different light conditions. In this way, Mar, Hanna, Philipp and Lasse can mimic different ecological situations and they will be able to get new insights into the importance of the algae composition and grazers in an Arctic, which is just about to turn from a seasonal ice-covered fjord to a year-round ice-free fjord.