Accent: Climate change is impacting the world’s tiniest organisms

·7 min read

A PhD student in the Boreal Ecology program at the Vale Living with Lakes Centre is studying how the large scale impacts of climate change can affect microscopic organisms in the Hudson Bay lowlands.

Working in the far north of Ontario and Manitoba, Adam Kirkwood is examining how permafrost thaw is changing the activity, composition, and abundance of microbial communities.

These microbes play an important role in processing different chemical elements in the environment. For example, they can break down carbon to produce greenhouse gases like methane or transform inorganic mercury into its more toxic, organic form.

By collecting samples and using molecular techniques like DNA sequencing, Kirkwood’s research highlights how climate change is altering the way that these organisms behave.

“The Hudson Bay lowlands is the world’s second largest northern peatland. It has an area of 372,000 kilometres squared, which is almost the same size as the province of Newfoundland and Labrador,” said Kirkwood.

“It’s a really big peatland that stores a lot of carbon, which is the element that is the main constituent of greenhouse gases like carbon dioxide and methane. It also stores a lot of metals like mercury.”

The area is also very cold. This means that it has permafrost, which is any ground that remains completely frozen throughout the year.

“This permafrost has captured and stored all of this carbon and mercury, which means it hasn’t been cycled like it would somewhere like Sudbury where the ground freezes and thaws each year,” he said.

“Now, with climate change, this area is getting warmer and the permafrost is starting to thaw. That means that this carbon and mercury is becoming available for decomposition by microbial communities.”

These microbial communities are groups of microorganisms that live together in the same space. Communities are made up of tiny microbes like bacteria that interact with each other and different elements in the ecosystem.

“As the permafrost thaws in the Hudson Bay lowlands, it creates very unique environments and each of these different environments will have different habitats for microbial communities,” said Kirkwood.

“These permafrost thaw environments are very warm, and they have a lot of moisture. This creates suitable habitats for microbes called methanogens, for example, which decompose carbon and produce methane that is released into the atmosphere.”

Studying the behaviour of these methanogens was the focus of Kirkwood’s master’s thesis. For his PhD, he has turned towards microbes that play a role in processing mercury.

“Inorganic mercury is stored in the soils, and as the permafrost thaws, microbes now have access to this mercury. They take in this inorganic mercury, and though the microbe’s metabolic processes, its byproduct is the organic version – methylmercury,” said Kirkwood.

“It’s taking mercury from the ground and converting it into another kind of mercury, but that mercury is highly toxic.”

Once this mercury gets into the water and other aquatic ecosystems, he added, it can move up the food chain, and when it is consumed by humans, it can have negative health consequences.

This phenomenon has big implications for nearby communities that rely on subsistence fishing from their traditional territories.

“In the Hudson Bay lowlands, particularly around Attawapiskat and other communities, there has been a lot of focus on studying methylmercury in fish,” said Kirkwood.

“They have found that there is a significant amount of methylmercury in different types of fish, but we are interested in learning where this mercury in the water is coming from.”

The environment in the Hudson Bay lowlands, he added, is fairly pristine. There aren’t that many human-caused sources of mercury in the area, like from mining operations, for example.

“I am interested in kind of teasing out the linkages between the land and the water and whether this increase of mercury in the fish is coming from the land as a response to climate change,” he said.

Kirkwood will travel to far north communities to extract soil and permafrost samples – some of these samples will be sent to Western University to be analyzed for mercury content.

Back at the Living with Lakes Centre, Kirkwood will do a DNA extraction on the soils and send that for sequencing.

“We can use this information and put it through a database that tells us what kinds of microbes are in each sample. For example, it can tell me whether there are bacteria capable of methylmercury production present,” he said.

“That gives us an idea of what the microbial community looks like and it allows us to compare microbial communities from these different thawed environments.”

Once they know the composition of these microbial communities and how much mercury is in each sample, researchers can “tease out” environments more likely to produce methylmercury.

This information will be useful to inform policy decisions.

“One of the goals of my research is to be able to make a rough map. We should be able to say this area has lots of mercury stored in it and we also show that it has high potential for mercury methylation. Or we might find an area that has lots of mercury but a low potential for mercury methylation,” said Kirkwood.

“By making a map or an estimate of these environments, we can use that to help guide policy. We can say, OK, you really need to avoid development in this area because development and the destruction of the landscape could really lead to accelerated permafrost thaw and the production of methylmercury.”

Permafrost is very sensitive to changes, said Kirkwood. If you build a road over permafrost, for example, the heat from that road can leach into the ground and cause the permafrost to warm.

“Because the Hudson Bay lowlands is already a very southern area of permafrost, it’s very sensitive,” he said.

“Even changing the amount of snow cover on permafrost can lead to the initiation of thaw.”

Any development in the area that is not strategically placed could have negative impacts on the environment.

“Stepping away from microbes for a second and thinking about the bigger picture, permafrost is so important because it is basically the foundation of the north. As it thaws, it has implications for the people who live there,” said Kirkwood.

“In speaking with local communities, they’ve said that in the last 60 or 70 years, things like traveling across the land have become a lot harder because the permafrost is thawing. There are lots more ponds, swamps, and muskegs.”

Kirkwood said that historically, most research on permafrost thaw has been done in the western Canadian Arctic, the High Arctic, and in Nunavik in northern Quebec.

“Not many people have studied the permafrost in the Hudson Bay lowlands until about the last decade or two,” he said.

“There have been a few studies that came out showing pretty quick thawing of the permafrost near the Attawapiskat area. I have looked at air photos of my study area on the Hudson Bay coast from the 1950s until now. You can see that the degradation is quite extensive. We can only assume that’s because this area is warming up significantly.”

Kirkwood, who refers to himself as a veteran student of Laurentian University, completed both his undergraduate and master’s degree at the school.

“If you had asked me five or six years ago if I would be studying permafrost, I would have thought you were crazy – why would I want to study frozen dirt?” he said.

“But I started taking courses on it with my supervisor and something just clicked. I found it very interesting and I love the idea of how large-scale changes to the landscape can lead to such small-scale changes for things like microbes.”

He has been working on his PhD at the Living with Lakes centre for about a year and half.

The COVID-19 pandemic prevented fieldwork last summer, but he’s looking forward to heading north and collecting samples this year.

“What I really love about this work is that I don’t have to just sit in a lab,” he said.

“I actually get to go out there and see how these microbes are changing based on these bigger environmental changes.”

The Local Journalism Initiative is made possible through funding from the federal government.

Twitter: @SudburyStar

Colleen Romaniuk, Local Journalism Initiative Reporter, The Sudbury Star

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