The ‘winter grab’ in the Great Lakes

The ‘winter grab’ in the Great Lakes

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This week, researchers are out “grabbing” samples and measurements from all over the Great Lakes.

Their goal is to better understand the lakes in winter, especially as that season is affected by climate change.

Geosciences Professor Maureen Coleman from the University of Chicago is a part of the Winter Grab effort, and she explains what it’s all about.

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TRANSCRIPT:

MELBA LARA, HOST: This week, researchers are out grabbing samples and measurements from all over the Great Lakes. It’s called the winter grab. Their goal is to better understand the lakes in winter, especially as the season is affected by climate change. Geosciences professor, Dr. Maureen Coleman from the University of Chicago is part of the winter grab effort. She joins us now for our weekly climate conversation and Maureen, welcome.

DR. MAUREEN COLEMAN: Thanks for having me.

LARA: And some of your students are out on the ice today. Right?

COLEMAN: They are I got pictures back, they have successfully collected samples from under the ice in Green Bay, Wisconsin.

LARA: They are brave and probably very cold right now.

COLEMAN: Yes, they are encountering some problems we’ve never had before, like our filtration lines are freezing to solid ice. But I trust they will figure it out. And they’re resourceful and they’ll find a solution.

LARA: So tell us why is something like the winter grab even necessary?

COLEMAN: Well, the winter grab, this giant coordinated effort to study what’s happening under the ice in the Great Lakes, is really, because we have this huge blind spot in our understanding for about six months of the year. From October until March, there are essentially no boats on the Great Lakes. And a lot of the instrumentation like buoys comes off of the lakes as well. And so, everything we know about the Great Lakes is from April through September.

With this blind spot, it’s really hard to predict how climate change will impact the ecosystem. And so by sampling in the winter, we really want to connect the dots throughout the entire year.

LARA: And can you give us more specifics on these blind spots? What exactly are the gaps in our knowledge then of the Great Lakes in the winter?

COLEMAN: Oh, there’s so much we don’t know, from very simple things like how much sunlight penetrates through the ice. Or how nutrients are available in the water. Nutrients like carbon and nitrogen that all life needs to survive, we just don’t know the concentrations in the winter. And in particular, from my perspective, as a biologist, I’m really interested in what organisms are present under the ice. And we have virtually no data on this at all.

LARA: So once the samples are collected, your lab is going to be studying microbes in the water. What are you hoping to learn there?

COLEMAN: So we’re really interested in microbes because they are the base of the food chain, and they recycle all of the elements and nutrients in the water. And so my lab is going to be figuring out which microbes are present through DNA sequencing, and how active they are through some other methods and hoping to get a peek into their world, their tiny world under the ice.

LARA: We’ve been reporting in our climate segment how winter ice coverage in the Great Lakes is kind of trending downward. What could the impact be going forward?

COLEMAN: Ice cover is a huge, huge variable. And it turns out, it’s really important for the biology under the ice. Now naively I would have thought that there’s not much biology happening under the ice in winter, because I would have thought that the ice blocks all of the light, and then it’s so cold. But in fact, quite the opposite is true. We think that when there is ice cover, the biology can be more active under the ice.

In particular organisms that do photosynthesis actually are, in some cases, happier under the ice because the ice shields the wind, and it allows the water to be calmer underneath the ice. And these organisms can really thrive. And so the loss of ice cover is well documented in lakes around the world, including the Great Lakes. And we’re really curious to see how this is going to affect phytoplankton, the base of the food chain and ultimately, the rest of the ecosystem, including fish.


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