DULUTH, Minn. — Scientists from across the Great Lakes region know a lot about the water in summer, when they can go out in boats and conduct research under a warm sun.
But when it comes to understanding how the lakes function in winter, there's surprisingly little data available.
That's why scientists from 18 institutions in the U.S. and Canada, including universities and government agencies, are fanning out in 12 teams this month across the lakes — toting ice augers and wearing safety float suits — to grab as much data as possible during the coldest, iciest time of year.
They're calling it the "Winter Grab," and it's timed as the lakes generally reach their peak ice coverage, from mid-February into early March.
"Two years ago, we had a workshop at the University of Michigan and collectively came to the realization that, when it comes to understanding what winter looks like in the Great Lakes, there was a huge knowledge gap," said Ted Ozersky, a professor of biology at the University of Minnesota Duluth's Large Lakes Observatory.
Ozersky is coordinating the entire effort, including a local team that walked onto the ice off Red Cliff in Wisconsin's Apostle Islands earlier this week to collect data, using ice augers to bore holes. Another of Ozersky's teams is heading onto Green Bay on Lake Michigan. Teams across the other four Great Lakes and Lake St. Clair also are out this month collecting the exact same data, measuring the same parts of the ecosystems, all using the same methods.
"We don't know the physics of the lakes in winter. We don't know much about water chemistry in winter or fish behavior in winter," Ozersky said.
Researchers won't be collecting fish, but will be looking at many things that impact fish. (Ozersky was part of a team that took a similar look at the winter food chain under the ice of Minnesota's inland lakes in 2018.)
The researchers on the frozen big lakes now are looking at water chemistry, water temperature, oxygen levels, nutrients, toxins and microbes along with zooplankton and phytoplankton, the tiny animals and plants that are the base of the ecosystem, the base of the food chain. The many samples will be analyzed this spring at various labs among the 18 institutions.
The data collected will serve as a benchmark for future work and may help track the changing face of winter on the Great Lakes as winters get shorter and warmer.
It's already known, for example, that winter ice cover on Lake Superior has declined from an average of nearly 80% ice cover in the 1970s to just over 40% in the 2020s. While there are still some very cold winters, and some years with high ice coverage on the lake, like 2014, 2015 and 2019, the average over decades is declining fast.
"Winter is rapidly changing on the Great Lakes, but our ability to understand and predict the consequences of those changes is" restricted by the lack of data, Ozersky noted.
The U.S. and Canadian coast guards are helping take researchers out in boats where there is no ice. But after a slow start to this winter's ice season in December, a colder January and February have allowed ice to build up on some parts of the Great Lakes, allowing researchers to get out to more locations.
"The ice forecasts changed in our favor. Right now, they suggest that more of the locations that we'd like to target might have ice," said Casey Godwin, who studies Great Lakes water quality at the University of Michigan.
For the "Winter Grab," Godwin is part of a University of Michigan team heading onto the ice of Saginaw Bay in an all-terrain vehicle hauling a sled loaded with gear. A crew from the National Oceanic and Atmospheric Administration's Great Lakes Laboratory will ride a fan-powered airboat to collect samples from western Lake Erie.
Scientists already know that what happens in winter can impact what the lakes look like in summer. They just aren't sure yet exactly how or why.
"Winter conditions influence summer events such as harmful algal blooms and episodes of low oxygen," said Ashley Elgin, a scientist with the National Oceanic and Atmospheric Administration.
While the difficulty of getting out to do field work in winter is one reason for the lack of data, there was also a longtime belief by some scientists that winter was when the lakes were mostly dormant, taking a long nap from the unusual biological activity. But recent findings show that's not true. Satellite observations show that monthslong algae blooms occur in Lake Erie's central basin even during the dead of winter, Godwin said.
Of all the winter changes underway on the Great Lakes, the ongoing reduction in ice-cover extent is of paramount importance to these scientists. They call ice cover a "master variable" because it controls many aspects of wintertime lake ecology and impacts lake processes in subsequent seasons, as well.
Minnesota fisheries researchers know, for example, that Lake Superior ciscoes, also called herring, a primary source of food for lake trout, have much better spawning success during years when there is high winter ice coverage. As winter ice has diminished in recent years, herring spawning has declined markedly. In years of no ice, when waves are allowed to thrash shorelines all year, herring spawning success is nil.
Now, if warming trends continue at their current pace, ice cover on the Great Lakes will be a rare occurrence by the end of this century.
"Winter is the season that is altered the most with climate change," said Marguerite Xenopoulos of Trent University in Ontario, who will be collecting samples on Lake Ontario's Bay of Quinte and from Georgian Bay on the Canadian side of Lake Huron.
In addition to the University of Michigan and UMD, participating U.S. colleges and universities include Michigan Technological University, Central Michigan University, Bowling Green State University, Oberlin College, Wright State University, Lake Superior State University, Ohio State University, Clarkson University and the University of Chicago.
Participating Canadian universities are the University of Windsor, Lakehead University and Trent University.
Participating U.S. and Canadian government agencies are the NOAA Great Lakes Environmental Research Laboratory, and Environment and Climate Change Canada. Funding was provided by the Cooperative Institute for Great Lakes Research, which is hosted by University of Michigan's School for Environment and Sustainability.
— The Great Lakes hold over 5,400 cubic miles of water, accounting for about 21% of the world's surface freshwater.
— Lake Superior holds 2,900 cubic miles, or 3 quadrillion gallons, accounting for more than 50% of the water in the Great Lakes.
— The five Great Lakes — Superior, Huron, Michigan, Erie and Ontario — span a total surface area of 94,600 square miles and are all connected by a variety of lakes and rivers, making them the largest freshwater system in the world.
— Lake Superior's deepest point is 1,330 feet. For comparison, If you built the 1,250-foot Empire State Building on the deepest point of Lake Superior, the only thing peeking above the waves would be the antenna.
— There are 88 fish species now swimming in Lake Superior, with 34 of them native to the lake, including lake trout and brook trout. The others, like steelhead rainbow trout, were introduced or are considered invasive species, like smelt, ruffe and goby.
Source: University of Michigan
