“Big Chill” affects Lake Superior
HOUGHTON – Scientific data and swimmers agree. Lake Superior, always known as a brisk place to bathe, is especially cold this year.
On readings taken throughout the lake, temperatures are about six to eight degrees colder than this time last year, said Guy Meadows, director of the Great Lakes Research Center at Michigan Technological University. What he and colleagues are calling the “Big Chill” is likely to have significant consequences, he noted, though not all scientists agree on what they will be.
Above the deepest eastern and central parts of the lake, where water warms slowly, some surface temperatures are still in the high 30s – not that the cold could keep Keweenaw residents out of the water.
At White City Beach at the south entry to the Portage Canal, students from the BHK Child Development Calumet Great Explorations program swam and played happily in the water Friday.
“It was pretty cold at the beginning of the summer, but it got a lot warmer,” said Great Explorations student Sierra Krock, who said she’s been braving the water regularly since spring.
“I’m a Yooper, I’m always swimming,” added her friend Karilyn Mazurowski. “I’ve been doing it all my life.”
White City Beach was a relatively balmy place to swim. Michigan Tech’s data buoy just a couple of miles away showed 60 degree water temperatures about ten feet below the surface.
Ecologically, “I can’t think of any downside” to the chill, said Meadows, who thinks lower temperatures will favor the lake’s traditional cold-water species, while hopefully slowing the spread of invasives that thrived in water that had been steadily warming over the past few decades.
One of Meadows’ current projects is to research the invasive Eurasian Watermilfoil, an aquatic plant that grows before others in the spring, quickly overshadowing and killing off native underwater vegetation.
Meadows said Watermilfoil have taken over the sea bed in the Les Cheneaux Islands in northern Lake Huron, where they quickly grow to the surface and foul boat propellors. The plant has also spread into Torch Bay and Chassell Bay along the Portage Waterway, where Meadows and others hope to eradicate it before it takes hold.
This spring and summer, “the cold water has delayed its blooming and slowed the spread,” Meadows said.
He also expects to see less severe storms on the lake this fall. The difference in temperature between cold fall air and warmer water leads to waves that can be twice as big in a given wind than if the water had been colder.
Ron Kinnunen, an educator in the Michigan Sea Grant program run by the National Oceanic and Atmospheric Administration, said he’s not sure the cold water doesn’t have a downside.
“I’ve met with wildlife managers, and when we see this cold water, the fish grow more slowly,” he said. “We get a bit more productivity when it’s warmer.”
Salmon, he noted, have been especially affected, with size at a given age decreasing noticeably.
Michigan Tech Professor Colleen Mouw said many of the Big Chill’s effects may be like her own phytoplankton research – the jury is still out on conclusions.
“In spring, we took a survey of scientists on what we thought would happen,” she said. “The only thing the experts agreed on was that it would be colder.”
Research done in the late ’70s when water temperatures were comparable to this summer show results that seem similar to her own – that plankton stratifies, or spreads into deeper water, later in the season and perhaps less overall than when water is warmer.
That’s important, as phytoplankton is the base of the aquatic food chain, but it doesn’t take into account which species of phytoplankton succeed, she said, or the likely negative effects of the cold on invasive species that compete with natives to prey on phytoplankton.
Even Meadows’ seemingly obvious statement that colder temperatures are “just bad for swimming” doesn’t get universal agreement.
Brian Donnelly, who has a camp on Lake Superior’s shore in Stanton Township, said the colder water temperatures didn’t make too much of a difference.
“It’s just the difference between pretty (darn) cold and really (darn) cold,” he said.