An auger is used to drill a hole into Lake Minnetonka to get a water sample.
Photo: Evan Frost | MPR News

Cody Nelson writes for that a team of University of Minnesota-Duluth researchers wanted to know how shortening winters — and less ice cover on lakes — might increase the presence of harmful algae blooms and impact fisheries.

“Aside from people who ice fish, the general assumption is that not much happens in lakes during winter,” said Andy Bramburger, a research associate from U. of Duluth campus. “With climate change, our winters are getting shorter and we’re losing winter, and we really don’t know what the impact of that is.”

To find out, Dr. Bramburger and researchers from the University of Minnesota, the U.S. Geological Survey and the University of Maryland are gathering data from a half-dozen lakes across Minnesota.

The biggest effect of climate change on lakes isn’t necessarily how warm it gets, but how cold it doesn’t get.

These warmer winters are shorter, so more sunlight can reach the water earlier, jump starting algae production and affecting the lake’s biology.

While shorter winters sparking earlier algae production could mean more nutrients cycling up the food chain to fish, it could also mean more of the toxic blue-green algae that has grown in prevalence across Minnesota. These harmful algae blooms, technically cyanobacteria, have been blamed for sickening humans and killing animals — including pet dogs — that drink contaminated water.

For many Minnesotans, this is a major deal. “If you have a cottage and you like to swim or water ski, or further north where people actually take a lot of drinking water for their cottages right out of the lakes, having toxic algae blooms is potentially a big concern,” Dr. Bramburger said.

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