The Dark Story on Sea-ice Microorganisms
Andrea Niemi has spent most of her young working career, from high school to her current biologist position, working with Fisheries and Oceans Canada.
One of the projects she has been associated with is the recently completed Circumpolar Flaw Lead System Study, a Canadian-led multidisciplinary multinational project that brought together over 200 scientists from 15 countries for a climate change examination of the Canadian high Arctic. The study enlisted the services of the Canadian icebreaker CCGS Amundsen that was used as a research platform. Its participants were studying the whole of the Arctic ecosystem – from sea-ice physics to the weather to mammals to the smallest of life forms.
Dr. Niemi's role was with DFO's Marine Productivity Laboratory. Her area of study was examining arctic sea ice and the microscopic life (algae and bacteria) that live on its underside.
Noted Niemi, "I went up for one leg of the study, during the dark winter period (Dec 07-January 08). DFO flew us out of Inuvik and out to the icebreaker which was just below Banks Island. The researcher group would move the ship into a big pan of ice and then just let it freeze in. Our group would drift with that pan of ice as long as it was possible."
The icebreaker Amundsen, operated by the Canadian Coast Guard Service, working as part of the Circumpolar Flaw Lead System Study, here stopped in a pan of ice with work going on around it. The picture shows the winter dusk sunlight.
She and her colleagues used ice-corers to take samples of the ice. These researchers then cut the ice cores into 10-centimeter sections to examine what was in the ice and get a profile from the top all the way down to the bottom. Niemi points out that the bottom section, where the ice is still growing, is really the most important habitat for the microorganisms living there.
Scientists collecting newly formed sea ice that has formed in a lead (crack in the ice). The crane on the front of the Amundsen is hanging the basket just above the new ice. In this picture you can see the thicker (older) ice next to the new ice, which is a common feature in the "flaw lead" area of the Beaufort Sea.
The ice can have a very diverse micro-community. In the springtime when the sun is back, there's a full-blown algae bloom on the bottom of the ice, and with very high concentrations of algae in the bottom 10 centimeters.
Sea-ice biology has been studied quite a bit. But almost all the work has been done in the spring because that's when there's the most growth. As fall and winter approaches a whole new set of questions comes up. As Niemi puts it, "If you're an alga cell, protist or some bacteria, which get incorporated into the ice in the fall, you need to survive extreme conditions during the dark, cold winter period. If you do survive then you become the founding members of the spring community. But, of course, if you're an alga, there's no light over winter. The question is how and who survives over this winter period to help initiate the springtime production in the ice?"
It's pretty tough to survive in the ice for four months with no sun and very cold temperatures. It's a bit of a mystery about how all these different species show up in the spring. Did the microorganisms really overwinter in the ice or where did they come from and how did they do it?
"Sea ice microorganisms Aniemi". This photo shows a diverse assemblage of sea ice microorganisms. The red containing cells are Algae (some are in a chain), the little blue dots are bacteria and there's one big flagellate with the tail (a single-cell animal).
"Ice algae Aniemi" shows an example of some of the different types of algae cells that live in the ice. In these types of pictures, any cell that has red in it is an algae cell. All the little blue dots are bacteria.
Dr. Niemi found that some of the cells actually coat themselves with a gel-like substance that can help protect them from freezing and perhaps make a better environment around themselves. Researchers also think that some of the microorganisms actually change into protective structures like a cyst or a spore. Changing their morphology, their shape and their structure, may help them hibernate over the winter.
All of which raises the broader question of how and in what sense is the fate of such minuscule microorganisms important?
Replies Niemi "Scientists need better measurements of primary (algal) production in the Arctic and production associated with the sea ice is an important component. It can contribute up to 25% of total Arctic primary productivity. So understanding the complete annual cycle of sea-ice biology is important for predicting how sea ice productivity could respond to climate-driven changes to when and how much sea ice forms. Even though they're small, algae and bacteria together have the greatest biomass in the Arctic Ocean. They respond quickly to climate change or other stressors and changes to them can have effects all the way up to marine mammals."
And she adds, "This current work fits with previous research to help us understand the big picture of sea-ice biology in the changing Arctic. Funding and research opportunities come under different headings but the work is not standalone. The lessons learned in one study apply and can be compared and added to other studies, and in this way DFO can build databases."
Dr. Niemi and her colleagues expect to publish their dark winter Arctic ice microorganism findings this fall.
- Date Modified: