Dispatch 8: Life in the Arctic     Print

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Mengnan Zhao

September 25, 2015

Today was a day of preparation, since tomorrow would be big excitement – our first on-ice deployment! Several buoys will be installed in an ice floe and ice measurements will also be taken. We completed helicopter safety training several days ago, and all equipment was being assembled and tested for the final time.

Our CTD station and sampling was over by 9 pm tonight, and I was happy to use the extra time to talk with other scientists about their research. Two scientists on our cruise, David Walsh (Concordia University) and Deo Florence Onda (University of Laval) are studying the organisms living in the Arctic Ocean.

David Walsh’s research focuses on bacteria. Compared to elsewhere in the world’s oceans, relatively little is known about bacteria in the Arctic Ocean. As soon as the water samples are collected from the Niskin bottles, David filters them for bacteria of different sizes – the filtered samples will be analyzed in his lab at home. With knowledge of the genetic information of the bacteria, David and his colleagues will be able to assess whether the Arctic has her own exclusive species or how they are related to other oceans. David has been sampling bacteria in the Arctic since 2004, and now has the first long time series to evaluate changes in bacteria at different depth levels. With different bacteria species fixing carbon at different depths in different ways, his results will be key to understanding the carbon cycle of the Arctic.

Deo Florence Onda’s research concerns a (relatively!) larger life form – microorganisms. In general this region of the Arctic has been becoming more stratified in the past decade, with a fresh surface layer. Previous understanding was that the ocean was more weakly stratified (better mixed) and higher in nutrients; phytoplankton was a major food source for copepods (small crustaceans). Evidence suggests that things may be different now in this more stratified environment, in which the dominant phytoplankton are smaller, and are no longer a dominant food source for copepods. The diet of copepods is hypothesized to have shifted to ciliates (larger than phytoplankton) instead, thus changing an important link in the food chain. Confirmation or rejection of this hypothesis would be a significant advance in our understanding of the Arctic food chain and how it evolves as the system changes.