Great Lakes researchers rush to collect winter data under the ice
TRAVERSE CITY, Mich. – What happens to the Great Lakes during those long frigid months when they are often partially or completely covered in ice? A casual observer – and even experts – might be inclined to say, “Not much.”
Lake scientists have long considered winter to be a season when aquatic activity slows down. Most do their field studies at other times of the year.
But researchers now think there’s more going on in the Bitter Depths than previously thought, including activity influenced by climate change. To learn more, teams will venture to the frozen surfaces of the five lakes this month to collect water samples and other information below the ice.
“We ignored winter on the Great Lakes for so long,” said Ted Ozersky, a lake biologist at the University of Minnesota Duluth, who announced the “Winter Grab” expedition Thursday.
“There are many ways that ice and winter conditions can affect the ecosystem. We don’t fully understand them. We have a general idea of how it should work, but in many cases we don’t have not done the work to see,” Ozersky said.
Crews from more than a dozen US and Canadian universities and government agencies will travel to frozen sections of Lakes Erie, Huron, Michigan, Ontario and Superior during the week of February 14. This is usually around the time of maximum ice cover.
They will take what Ozersky described as a “snapshot” of mid-winter, measuring features such as light levels at different depths, water movement and the presence of carbon, bacteria and nutrients which feed the fish but can also damage the environment.
University of Michigan biogeochemist Casey Godwin will explore Lake Huron’s Saginaw Bay, where phosphorus overload has fueled outbreaks of harmful algae that also plague Lake Erie. He and his colleagues collected lots of data on the bay, but almost none in the winter, he said.
Although algal blooms are generally considered a summer problem, satellite imagery has detected them in Lake Erie’s central basin during cold periods, Godwin said.
“I’m particularly interested in the forms of phosphorus present in water during the winter,” he said. “We have ways to characterize whether this is the type that can sustain the food web or contribute to harmful blooms.”
One of the reasons for the growing interest in the effects of winter on lakes is the evolution of winter itself.
Great Lakes ice cover has declined steadily since the 1970s, and some projections indicate that it may become thinner later this century.
While this may boost the freight transportation industry, the results for lake ecology are unknown.
Ice is “a dramatic physical force,” Ozersky said, influencing everything from the exchange of carbon dioxide between air and water to light penetration and the thermal structure of the water column. . These characteristics can determine the amount of plankton available to fish.
Ice near the shore can protect fish eggs and prevent breaking waves from eroding shorelines.
“We know it’s important, but because we haven’t studied it, there are many areas where we don’t fully understand the effect of having or not having ice,” Ozersky said.
The University of Michigan Cooperative Great Lakes Research Institute, in partnership with the National Atmospheric and Oceanic Administration, is funding this month’s excursion.
The institute sponsored a meeting of specialists in 2019 concerned about the lack of winter data as global warming increases air temperatures, reduces ice cover and alters snow and rain patterns in the gigantic watershed. stretching from Minnesota to the mouth of the St. Lawrence River in Quebec. .
“Winter is the season that is most affected by climate change,” said Marguerite Xenopoulos, an ecosystem ecologist at Trent University in Peterborough, Ont. She will take samples from Georgian Bay of Lake Huron and Bay of Quinte from Lake Ontario during the trip.
Some crews will cross the icy lakes on snowmobiles, all-terrain vehicles, sleds and, in one case, a fan-powered airboat. Others will board icebreaker ships. They will use gas-powered or battery-powered augers to drill holes in the ice, which can be up to three feet (nearly one meter) thick.
Ozersky, who came up with the quest and will visit Lake Superior’s Apostle Islands and Lake Michigan’s Green Bay, said it won’t answer all the questions but should inspire further study. He helped establish a research collaboration called the Great Lakes Winter Network.
His studies could influence practical issues such as upgrading riparian infrastructure and planting winter cover crops to prevent erosion, he said.
“As we gain this information, we will hopefully have a better idea of what the loss of winter will mean and how to adjust management practices to mitigate adverse effects,” Ozersky said.