Clara Hoppe
Appearances
Short Wave
The Algae That Thrive in Arctic Darkness
And because you're only seeing what you see with your little headlamp, you see very, very little and you feel very small.
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The Algae That Thrive in Arctic Darkness
The most intriguing and beautiful group of organisms we found are diatoms. They are a group of microalgae that... built these little boxes out of glass, out of silica, that they use as grazer protection.
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The Algae That Thrive in Arctic Darkness
When there's absolutely no light, we can be sure that there is no...
Short Wave
The Algae That Thrive in Arctic Darkness
So the traditional thinking was very much when there is no light, there can't be active light. So what people have assumed is happening is that these cells hibernate. So they are in a resting stage. Some of them form actual resting spores that are very durable. And then they can overwinter, for example, in the sea ice.
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The Algae That Thrive in Arctic Darkness
So those resting stages can be frozen into the sea ice in the fall and then be stuck in the sea ice and then get released in the spring when the sun comes back. That was a very traditional way of thinking of microalgae up there in the high north. Is it almost like hibernation?
Short Wave
The Algae That Thrive in Arctic Darkness
So the light comes back and the light serves as a cue to emerge from this resting stage, from their little cave. And then they can continue photosynthesizing and dividing. And there are algae, microalgae that actually do that. It's just that it's not all of them.
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The Algae That Thrive in Arctic Darkness
The sky looks like cotton candy the whole day because you have a sunrise that doesn't stop. It's just a full day of sunrise or sunset.
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The Algae That Thrive in Arctic Darkness
So when we looked at them in the microscope, we saw that they were active vegetative cells so they were loaded with chlorophyll so the chlorophyll is the pigment that is used for photosynthesis and it's a big costly compound in the cell so we would have expected that they wouldn't invest energy into into this pigment in a period where they can't use it okay that makes sense
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The Algae That Thrive in Arctic Darkness
So seeing them so ready to photosynthesize suggested to me that You know, they were in this physiologically active stage and not in this resting stage.
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The Algae That Thrive in Arctic Darkness
So on a weekly basis, we sampled the microalgae in the water column. So in the water under the ice and then in the ice itself. So we took water samples and we drilled cores out of the ice flow to study which algae are there and in which physiological state.
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The Algae That Thrive in Arctic Darkness
Yeah. So the water sampling initially happened mostly at a hole next to the ship, which was very convenient because then the samples were directly on the boat. But then in beginning of March, we had a lot of dynamics in the ice and And it destroyed our hole. So we couldn't sample anymore. And then we moved to Ocean City, which existed throughout the whole winter.
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The Algae That Thrive in Arctic Darkness
But it meant us dragging hundreds and hundreds of liters of water over the flow of... up the gangway and into the labs. So it was really, you know, us pulling those buckets and buckets of water on little pulkas, little sledges behind us through the snowstorm to the boat. So it was a lot of physical work involved getting those samples.
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The Algae That Thrive in Arctic Darkness
Well, at least you can do it in the cold. You know, if people that work in the tropics have to do that in like hot human conditions. So I much rather do that at minus 20. Absolutely.
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The Algae That Thrive in Arctic Darkness
So the biggest finding for me was the super early increase in the biomass and activity of these microalgae. So we found just a few weeks after the first sunrise, we found the biomass of the microalgae increasing both in the water column and the sea ice. So the microalgae were growing.
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The Algae That Thrive in Arctic Darkness
So the polar night is the period between the last sunset in fall and the first sunset in spring, during which the sun never rises in the Arctic for several months.
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The Algae That Thrive in Arctic Darkness
Because it's several orders of magnitude lower than what people usually assume. For example, what is put into those big global ecosystem and ocean models. And if this light level is really several orders of magnitude lower, that means that there is a lot more productivity in parts of the oceans that we thought wouldn't be productive.
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The Algae That Thrive in Arctic Darkness
I mean, they must be incredibly efficient. They must transfer all that energy that comes in into biomass production. And I guess to some extent, we need to solve the riddle of what they actually do to survive the polar night, the proper darkness. But there seem to be a range of different mechanisms that allows them to survive the polar night. And those mechanisms...
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The Algae That Thrive in Arctic Darkness
don't respond to the increase in light, but they may give them some background energy that allows them to then start growing as soon as the light comes back.
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The Algae That Thrive in Arctic Darkness
So phytoplankton, even though they do photosynthesis, they are not... only plants in a traditional way we call them mixotrophs so they while they do photosynthesis they can also eat like an animal oh so some species can do something we call phagotrophy which is basically
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The Algae That Thrive in Arctic Darkness
eating bacteria or other small phytoplankton cells and then other species can do or probably most species can do something we call osmotrophy which is taking up dissolved organic compounds from the seawater so dissolved sugars or amino acids or something like that They're like omnivores. They like eat plants and meat or something.
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The Algae That Thrive in Arctic Darkness
I think they do whatever they can to like, you know, fill up their energy reserves.
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The Algae That Thrive in Arctic Darkness
I think it's mostly shaped a feeling of not knowing. I mean, if you have those paradigms and then you realize that they can't really explain your observations, then you are in this, what is, you know, the magical science world. where you are like, whoa, I don't understand this at all. And there's so many things I want to study and find out.
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The Algae That Thrive in Arctic Darkness
So it's really, you know, the beginning of solving this riddle is understanding that it's a riddle. So you start thinking about a lot of different things that you haven't really been thinking before. And that's really the most fun.
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The Algae That Thrive in Arctic Darkness
When it's really dark, it's really a black and white world, I would say, where you see some gray shades of things and you see stars and the moon. It's really quiet here. There's wind, there's instrument noise, there's ship sounds and snowmobiles, but like natural sounds, it's probably mostly the wind and the snow moving. It's a very big, dark world.