A year in the high Arctic -What happens to small planktonic organisms during the long and dark polar winter?
Daniela Freese, PhD Student at the Alfred Wegener Institute (DE
The high Arctic is considered to be a harsh environment and after spending one year on Svalbard,I am certain that surviving in the most northern places in the world is certainly a challenge for the people living there. But how do small animals drifting in the waters surround ing Svalbard cope with extremely low temperatures,constant darkness and resulting low food availability during polar nights in winter?In order to answer this question,I moved all the way to Longyearbyen,the northern most city in the world. It is located on Svalbard (78oN), an island archipelago,which counts less people than polar bears.
I am aPhD student at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Bremerhaven, Germany, and at the University Centre in Svalbard (UNIS). As part of the Norwegian project CLEOPATRA II(CLimate Efects on planktonic food quality and TRophic transfer in the Arctic margin a lice zone),I investigate how a small zooplankton species, the copepod called Calanusglacialis, which lives in Arctic shelf regions, copes with the strong seasonal changes of their environment. In CLEOPATRA II, we seek to assess if Calanus follows a similar strategy as insects in diapause to survive during polar winter. Many insects respond to continual harsh environmental conditions with a diapause-a state of arrested development.
Until now,we do not know whether Calanus also enters a true diapause from which it cannot a wake before spring or whether it is able to respond flexible to environmental changes. Answering these questions will help to estimate their survival success in a changing environment and there with, the consequences of climate change in the Arctic marine food web.
Up to date we have very limited knowledge on how these copepods survive during winter, since high Arctic regions are hard to access during that time of the year. In CLEOPATRA II,we stepped up to the challenge and went out sampling in the high Arctic fjord Billefjorden every month.We tracked C. glacialis by zodiac in summer and by larger research vessels in winter, nothing but darkness and snow storms raging around us. When the fjord was completely ice-covered,we ever found our way to Billefjorden by snow mobile. The snow mobile tracks led us through the barren and stunning nature of Svalbard glaciars and moraines, until we finally reached the fjord after several hours. After drilling a hole in to the ice,we lowered our plankton nets to sample C. glacialis. The living individuals were brought back to the laboratories of UNIS, where we either placed them in experiments or stored them for further analysis.We figured out that for several months during the harsh Arctic winter C. glacialis migrates down into deeper water layers and depresses its metabolism ,which enables it to overwinter at low energetic costs.Our findings contribute to a better understanding on the role of marine organisms in the Arctic.