Contrary to what you might think, there’s an awful lot of activity going on beneath the surface of our five Great Lakes as freezing temperatures set in and ice forms over parts of or, occasionally, all of them.
It’s not necessarily bad news, either: Strands of filamentous algae known as diatoms swirl around, often attaching themselves to the bottom of the ice that’s formed. To some extent, their presence even helps water freeze just a little more quickly, a phenomenon known as ice nucleation.
Diatoms are cool little critters. According to a U.S. Environmental Protection Agency fact sheet, they convert carbon dioxide in the water into oxygen and are a primary source of food for small fish and invertebrates. Unlike microcystis, planktothrix, and other forms of harmful algae which displace them in the summertime, they don’t produce any toxins.
But, according to information in a webinar presented Monday by noted ice-algae researcher Mike McKay, all is not well because of how Earth’s climate is changing. Endless questions remain about what will happen with lake biology each of the coming winters.
Under-ice research itself is still pretty young.
Mr. McKay, who serves a dual appointment as a Bowling Green State University research professor and as executive director of the University of Windsor’s Great Lakes Institute for Environmental Research, is a wintertime algae hunter.
At times, he was flown by helicopter out on the frozen Great Lakes to drill through ice for core samples.
The U.S. EPA identified the need for a greater understanding of what happens beneath the ice back in the 1980s.
“It’s a great time to be involved in winter science in the Great Lakes,” Mr. McKay said at the beginning of his presentation, titled Life Under Ice: The Rise and Fall of Lake Erie’s Winter Algal Bloom.
It’s one thing to have a better understanding of what’s happening.
But researchers fear they’re chasing a moving target.
The Great Lakes region, as a whole, is producing 70 to 75 percent less ice than it did 40 years ago, Mr. McKay said.
The implications of that changing climate pattern are not entirely known. But whenever there’s less ice, there’s usually more shoreline erosion, he said.
“We may start seeing sediment plumes because of erosion,” Mr. McKay said.
Lake Erie typically has the most ice cover, even though it is the southernmost lake. That’s mostly because of its shallowness, he said.
Mr. McKay, who grew up in Canada, is involved with a joint U.S.-Canadian initiative called Operation Coal Shovel, which began a dozen years ago.
Coast guards from those two nations work to free up ice jams and keep the Great Lakes open for winter navigation as much as possible. While out there doing that, ice and icy water samples are drawn.
Field work is done aboard a Canadian ice-cutter called the Griffon, and an American ice-cutter called the Neah Bay.
The two ships have been retrofitted by Great Lakes scientists to serve as sort of mini-labs. Some samples are kept in coolers for researchers to take back to their own labs, Mr. McKay said.
While aboard the Griffon in 2007, he noticed brown water gushing to the surface.
It wasn’t mud or sediment, but a diatom algal bloom - much different than western Lake Erie’s pea green blooms of microcystis, a color people more often associate with algae.
According to a scientific paper Mr. McKay co-authored, Ecology under lake ice, which was first published in the monthly peer-reviewed trade journal Ecology Letters on Nov. 27, 2016, there has historically been too much focus on summer growing seasons.
Now, with winter conditions rapidly changing worldwide, reduced ice cover on lakes and rivers “highlights an urgent need for research focused on under-ice ecosystem dynamics and their contributions to whole-ecosystem processes,” the paper states.
Mr. McKay’s presentation was part of an ongoing Great Lakes seminar series hosted by the National Oceanic and Atmospheric Administration’s Cooperative Institute for Great Lakes Research and its multiple university and private partners.
First Published December 6, 2021, 11:05 p.m.
