Last month Tobias Vonnahme, Christine Dybwad and Ulrike Dietrich started their project “Microbial communities and fluxes in the cryosphere. Controls and connectivity on glaciers and sea ice, Billefjorden” on the sea ice in an Arctic fjord on Svalbard. The aim of the project is to understand how sea ice and different types of glaciers impact the ecosystem and fluxes in the system. Billefjorden is the perfect fjord for this study, due to its seasonal ice cover and two very different bays, one influenced by the tidewater outlet glacier Nordenskiøldbreen, and one by the land terminating glacier Hørbyebreen.
Thanks to the Arctic field grant and support from the Centre of Polar Ecology from the Czech Republic it was possible to stay one week in Billefjorden for sampling different locations on the sea ice. Marie Sabacka, Eva Hejdukova, and Josef Elster joined us in the field and made our ambitious sampling program possible while we could show them how to work on sea ice.
Our first station was close to the ice edge with some walrusses on an ice floe nearby. The sea ice was thick (70 cm) and covered by photosyntetically active (Quantum yield of 0.6) sea ice algae (Mainly Nitzscia frigida and Pleurosigma) on a skeletol layer at the bottom. CTD profiles showed two different water masses with temperatures between -1.5 and -2°C. No Chlorophyll maximum could be found in the water column, but both phytoplankton and zooplankton net hauls were filled with the arctic copepod Calanus glacialis (mostly male), and a few other arctic species, such as Clione, Krill and Pteropods. Overall the ice edge appeared to be a typical sea ice ecosystem.
The second main station was close to the glacier front of Nordenskiøldbreen. The ecosystem was quite similar to the ice edge, but we found higher biomasses of sea ice algae including filaments of Melosira arctica. The CTD profile was lacking the two water masses as at the ice edge, but a fresh surface layer indicating glacial outflow
could be seen and got more clear closer to the glacier.
Reduced stations close to the glacier indicated a high spatial variability in terms of salinity and ice properties. The southern bay had strong indications of glacial meltwater impacts with salinities between 6 and 10 and high algal biomass in the sea ice between 5 to 15 cm from the ice-water interface, instead of a densely colonized skeletal layer. Despite some earlier doubts that Nordenskiølbreen is truly terminating in the sea, we found water depths of 20-40m very close to the glacier and a clear layer of freshwater down to 6 m depth.
Further reduced stations in a transect along Billefjorden showed that the deep stratification of the ice edge gets shallower towards the glaciers and disappears about 6 km away from the ice edge.
Besides the fjord sampling, we also had a look on the glacier for understanding where the biomass, nutrients, and organic material in the fjords may come from. We sampled the upper 1-2m of Nordenskiøldbreen and frozen-in cryoconite holes, sediment filled holes, which are known to be a hot spot of life on glaciers. Due to earlier findings of distinctive cryoconite communities dominated by cyanobacteria further away from the coast and communities dominated by desmids and snow algae close to the glacier front, those two sites were sampled. On the southern part of the glacier, we found glacial outflow water, which may be a source of nutrients even in winter.
Overall, the field work was a full success and we are coming back to Tromsø with lots of samples, which will give us a deeper understanding of the ecosystems and connectivity of the different systems in Billefjorden. Besides our own sampling we managed to get some samples for cultivation and potential use for wastewater treatment for SLU, some mercury and fatty acid samples for understanding the food web structure and impact by heavy metal pollution for Akvaplan, and some zooplankton and Ctenophora for NTNU. In July we will return to Billefjorden for continuing our study in a system without sea ice and much higher inputs from glacial meltwater.
We are very thankful for the support from Maja Hatlebakk, and Janne Søreide from UNIS with some essential equipment, Jason Roberts for an emergency delivery of a Niskin bottle to Billefjorden, the field inspectors and advisors of Sysselmannen for the very quick response to our application for permits and logistical advice, and Piotr Petrovitsch and Trust Arktikugol from Pyramiden for some logistical help in the field.