What can Arctic microbes tell us about climate change?

Dr. Stefan Thiele tries to live his ethos surrounding sustainability. He eats mostly vegan and limits the amount of plastic he uses in daily life. As a microbial ecologist in the Department of Biological Sciences at the University of Bergen, in Norway, he’s tried to make changes in the lab, where plastic is intrinsic to many kits and instruments, and the ultra-low temperature (ULT) freezers are colder than they need to be. Raising a freezer’s temperature from –80 to –70°C, he says, can reduce a freezer’s energy use by as much energy as an average American household consumes in a year without harming any samples. And though he already has a master’s degree in microbial ecology and a Ph.D., he’s studying for a second master’s degree in sustainability in the little free time he has.

Thiele’s love of nature drives him to explore it. Bergen has 238 rainy days a year, but that doesn’t stop him from hiking the trails winding through the country’s stunning landscape. In this way, Thiele, a native of northern Germany, has adopted one of Norway’s most cherished traditions. “Everybody is on the trail on Sundays,” he says.

That love of nature also drives him to want to protect it. “I always felt we should do something for the world,” he says. “Nature is so beautiful. Why would we destroy it?”

Climate change is the most profound threat to nature. Perhaps no region has seen its impact as much as the Arctic – a region that is still in many ways mysterious. It’s there that Thiele is studying the microbial communities of the Arctic’s sea water, sea ice and sediments to understand how climate change is affecting the smallest organisms of the polar region. His challenge is fourfold: find the organisms, identify them, reveal their behavior and reveal how they change over time. And all this in some of the harshest working conditions in the world.

Nansen legacy project overview

Thiele’s work is part of the Nansen Legacy, a six-year research project (2018–2023) aimed at creating a holistic snapshot of the northern Barents Sea and Arctic Basin in this period of rapid climate change so that Arctic scientists of the future have a baseline to compare their own research to. Named after the Norwegian explorer, scientist, diplomat and Nobel Peace Prize winner Fridtjof Nansen, the project’s overarching goal is to enable the long-term sustainability of the Arctic. 

Its microbes are among its least known elements. “I'm looking into sediments to try and see how the warming of the ocean will affect the microbial communities,” Thiele says. “For the same reason, I’m looking into the water column – both the surface waters and deep waters, which are very different. In the surface waters, you have light, and in the depths, it's dark.”

Thiele has made multiple fieldwork voyages aboard the Kronprins Haakon in different seasons to ferret out the differences. “What does the community in the sea look like in summer versus in winter? Or is there a difference between different ice communities in summer and winter? And in the sediment, if the water warms, does that have an effect?”

Taking water, ice and sediment samples

The scientists on board are highly collaborative. They collect and process sea, ice and sediment samples for each other from seven field stations across the Barents Sea. “For example, I'm taking samples for colleagues taking viral samples, and they are taking samples for particle nutrition analyses,” Thiele says. “And the samples that I will get in the end are taken in the next lab by the people responsible for DNA sampling.”

QIAGEN toolkits are present throughout, especially the DNeasy PowerWater and PowerSoil (Pro) Kits.

Thiele has most recently spent time aboard the Kronprins Haakon to collect samples that will answer questions about microbial shifts during different seasons. “What does the community in the sea look like in summer versus in winter? Or is there a difference between different ice communities in summer and winter? And in the sediment, if the water warms, does that have an effect?”.Using a Sterivex filter, “We spend hours and hours filtering huge amounts of water.”

Their lab is in Longyearbyen, the largest settlement in Svalbard, a nine-island archipelago dominated by glaciers, tundra, snowy mountains and fjords. It’s there that a technician does DNA extraction for the water and ice samples using QIAGEN’s DNeasy PowerWater Sterivex Kit. “You have this plastic tube and the filter system is inside, so you can either crack it open, but that's not really favorable, or you can work in the filter itself. And for this work, the DNeasy PowerWater Sterivex Kit is actually perfect, because it is made to do exactly that.” 

Initial findings

“We run into problems with low cell densities,” he says. “Imagine you get an ice core of about 14 centimeters in diameter and then maybe 20 centimeters long. If you melt it, it boils down to about a liter of water, and the cell densities in the ice are not that high. We run into the problem of low DNA yields. So in that case, the DNeasy PowerWater Kit is absolutely perfect for us, because it ensures that we get a lot of DNA out of these samples.”The sediment samples are shipped directly from the Kronprins Haakon to his lab in Bergen, where they do DNA extraction using the DNeasy PowerSoil Pro Kit. “It’s very good for sediments for the reason that it has the inhibitory removal technology, so there are no unwanted carbon sources in there, like humic acids. All these things are filtered out, and we get a very clean sample that we can use then for preparing the libraries for sequencing.”

Each ship voyage yields hundreds of samples – about 50 for sediments and 250 for water and ice.

Thiele now has some initial results from the 2018 and 2019 field seasons. “We already found something very interesting,” he says. “2018 was a year with very little sea ice, while 2019 had a lot of sea ice. If we look at samples from roughly the same time of the year, we have vastly different communities based on their response to algae blooms.”

The algal blooms came earlier in 2018 than in 2019, indicating that “less sea ice will lead to earlier phytoplankton blooms,” he notes. “With these phytoplankton blooms comes carbon cycling and bacterial succession – so we will have a shift in the ecosystem based on how much ice we get. These longer blooms could lead to more carbon going into the system, but we can also imagine that the nutrients are running out, because the bacteria are not fast enough to replenish the nutrients, or there's just too much algae, or the bacteria also use the nutrients. So at some point, the nutrients will run out of the system. And that is a pretty bad thing. The system collapses at some point.” 

The future

While there’s much analysis still to do, Thiele says he may have an opportunity to join another Arctic research ship on a mission to collect more samples. He’d like look at the interactions between eukaryotic hunters and the bacterial prey they feed on. “There are a lot of small predators out there that are eating bacteria. I would like to see how this predation changes the microbial community – which microbes are eaten preferably, and which not? And why not?” 

In the meantime, Thiele’s pursuit of a second master’s degree in sustainability incorporates natural sciences, economics, politics and law. This broader knowledge helps him explain to people who think it’s too late to stop climate change that environmental doom is not inevitable. 

“I believe that the moment we stop thinking about the climate, that we stop caring about it, that's the moment when we've lost. And we have to be very quick to act, because otherwise we are losing the race,” he says. “But I think everybody can do small things. Everything counts. And as long as we do that, there's still hope and a chance for the climate.”