Cold comfort: Subzero weather is great for Minnesota's lakes

<div dir="rtl" style="text-align: right;" trbidi="on"> <div dir="ltr" style="text-align: left;"> The frigid temperatures this week are keeping Minnesotans indoors — and putting a halt to winter activities, but there's a bright spot.</div> <div dir="ltr" style="text-align: left;"> <a href="http://ra2gnet.ncairo.com/search?q=Minnesota%20weather" target="_blank">Minnesota weather</a></div> <div dir="ltr" style="text-align: left;"> Experts say bitterly cold weather actually can have positive impacts on lakes from curbing the growth of harmful algae to reducing water loss.</div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDdWCbJMIE9H3Pk-pJ0siODsYjATCjm8ce5dMEk1TEjHLaVzbabzth3hjmtTWjTrwGBTrXfOrkg_k43tO0W4ljlAFaifcmhJzkBz5bRz7bmL2OAplsfXj0ErHzsyVQ7kKZkhVEi7EbJrg/s1600/cold-lake.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Minnesota weather" border="0" data-original-height="752" data-original-width="1000" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDdWCbJMIE9H3Pk-pJ0siODsYjATCjm8ce5dMEk1TEjHLaVzbabzth3hjmtTWjTrwGBTrXfOrkg_k43tO0W4ljlAFaifcmhJzkBz5bRz7bmL2OAplsfXj0ErHzsyVQ7kKZkhVEi7EbJrg/s320/cold-lake.jpg" title="Cold comfort: Subzero weather is great for Minnesota's lakes" width="320" /></a></div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> One of the greatest benefits of an extended cold snap is that it helps form a thick ice cover on a lake. When the temperature is 20 degrees below zero — around where it's projected to hover across much of the state on Wednesday — a lake could form 3 or 4 inches of ice per day, said Lee Engel, supervisor of the Minnesota Pollution Control Agency's water quality monitoring unit.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> • Clear ice: Smooth lake ice thrills Twin Cities skaters</div> <div dir="ltr" style="text-align: left;"> • Climate Cast: Climate shifts affecting Great Lakes ice cover</div> <div dir="ltr" style="text-align: left;"> Thicker ice usually means a later ice-out in the spring, Engel said. That slows the growth of plants and algae because the snow-covered ice blocks out the sun from the depths of the lake where they form.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> <img alt="Eleven-year-old Evan Trompeter wades through algae in Little Rock Lake." height="180" src="https://img.apmcdn.org/e629c73e5f92d5915b6451443502a1fc5e3f47c3/uncropped/5c9685-20180627-lake-drawdown-14.jpg" title="Cold comfort: Subzero weather is great for Minnesota's lakes" width="320" /> </div> <div dir="ltr" style="text-align: left;"> "It wouldn't let them get a head start with warm water in the spring," Engel said. "We may see benefits of not having so many harmful algal blooms throughout the summer."</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> Recent studies have linked climate change to the loss of ice cover on lakes across the Northern Hemisphere. A thick ice cover that takes longer to melt in the spring also could help keep the lake's temperature a little cooler.</div> <div dir="ltr" style="text-align: left;">   </div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> That's a good thing: On average, Minnesota's lake temperatures have been on the rise. And some native species of fish do better when a lake's water temperature is cooler. In Lake Superior, that includes lake trout, brook trout and lake herring or cisco, said Cory Goldsworthy, area fisheries supervisor with the Minnesota Department of Natural Resources.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> "That colder weather spell really helps those water temperatures, which are beneficial to those native species," he said.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> On the flip side, some invasive species of fish, like alewife and sea lamprey, don't do as well in colder waters, Goldsworthy said.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> And sport anglers might find that some non-native fish stocked in Lake Superior — such as rainbow and brown trout, coho salmon and Chinook salmon — are tougher to catch in colder years, Goldsworthy said.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> A deep freeze can help curb the growth of other aquatic invaders, but it won't wipe them out.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> Thicker ice near the shore that extends all the way to the bottom of a lake can help slow the growth of invasive species that prefer shallower water, like zebra mussels, said Valerie Brady, an aquatic biologist with the Natural Resources Research Institute at the University of Minnesota Duluth.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> <img alt="Clear, smooth ice has formed on Lake Minnetonka." height="213" src="https://img.apmcdn.org/7d2b3966c04a612b7d3e304d0a9c31fa177c0a7a/uncropped/48b8c1-20190117-clear-ice-01.jpg" title="Cold comfort: Subzero weather is great for Minnesota's lakes" width="320" /> </div> <div dir="ltr" style="text-align: left;"> But some of those invasive species will likely survive in deeper waters over the winter months and recolonize in the spring. The water that's underneath ice stays at about 4 degrees Celsius — about 39 degrees Fahrenheit — Brady said, and most invasive plants and animals in Minnesota do just fine under those conditions.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> "Most of the plants that can make it up here can tolerate these freezing temperatures," Brady said. So, in order for those species to really be disrupted by the cold, she said, "it has to get awfully cold, and ice has to get down into the sediment and actually damage things."</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> Another positive benefit of this intense cold: It might help to slow lakes' loss of water due to evaporation, a phenomenon happening on the Great Lakes thanks to warmer winters and the lack of ice cover.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> "When the Great Lakes ice over, they're capped off. They can't lose their water to evaporation," Brady said. "So it changes the water balance for the whole Great Lakes, depending on how cold the year is and how much of the Great Lakes is covered by ice."</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> Of course, the benefits of this cold could evaporate if warmer temperatures come early this year and melt that ice cover off the lakes.</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> "It really comes down to what happens this spring," Engel said. "Do we get a warm spell that's going to negate this cold temperature and ice that we're forming, or does it stay cool?"</div> <div dir="ltr" style="text-align: left;"> <br /></div> <div dir="ltr" style="text-align: left;"> News source:mprnews</div> </div>

The frigid temperatures this week are keeping Minnesotans indoors — and putting a halt to winter activities, but there's a bright spot...

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