Less fish and more algae? Scientists are trying to understand the effects of the historic lack of ice on the Great Lakes

RACINE, Wis. (AP) — Michigan Tech University biologists have been monitoring the fragile wolf population on a remote Lake Superior island every winter since 1958, but had to cut short a planned seven-week survey this season after just two weeks.

The ski plane where they are studying the wolves uses a frozen lake as a landing strip because there is nowhere to go on the island. But this unusually warm winter has left the Great Lakes almost ice-free.

As climate change accelerates, scientists are working to understand how ice-free winters will affect the world’s largest freshwater system. Most of the effects are still theoretical because the lakes are generally too treacherous for data-gathering expeditions in the coldest months and biologists have long thought that little ecological activity still takes place below. of ice. But they say the changes could have serious environmental, economic and cultural impacts, including by harming some fish species, eroding beaches, causing algae blooms and clogging channels. of shipping.

“This year really drives home the point that we need to collect more data,” said Trista Vick-Majors, an assistant biology professor who studies aquatic ecosystems at Michigan Tech. “There’s no way you can predict how an ecosystem will respond to the big changes we’re looking at.”

The planet experienced record heat for an eighth straight month in January, according to the European climate agency. The upper Midwest was no exception, with Chicago enjoying temperatures of around 70 degrees (21 degrees Celsius) late last month and Wisconsin catching up. first tornado in February.

Ice coverage on lakes, with a combined surface area almost the size of the UK, has generally peaked by mid-February over the past 50 years, with up to 91% of lakes covered at one time, according to Great Lakes Ice Tracker website. As of mid-February this year, only 3% of the lakes were covered, which is the lowest figure since 1973, when site records began.

Researchers don’t have much data about how years of ice-free winters can change lakes, but they have several theories.

Ice-free lakes can absorb sunlight more quickly and warm up earlier in the spring. Some biologists think this could lead to earlier and larger blue-greens algae bloomswhich can be toxic to humans and put a damper on summer tourism.

Without ice, the upper levels of lakes tend to warm faster than usual, contributing to thermal stratification, where layers of colder and warmer water form. Less oxygen would reach lower, colder and denser levels, which could cause plankton and other organisms to die, some scientists believe. Whitefish and lake trout typically hatch in the spring and feed on plankton, so less plankton is likely to cause fish populations to decline, potentially leading to tighter fishing quotas and higher prices for fish. grocery stores and restaurants.

Less ice may translate into a longer fishing season, but winter storms can destroy nets and traps and destroy the eggs of whitefish that rely on the ice for protection, said Titus Seilheimer, a specialist in fisheries at the University of Wisconsin-Madison.

Charlie Henrikson runs a small commercial fishing operation off the peninsula of Wisconsin’s Door County. He said his boats set nets in February where they normally don’t start the season until late March. He said he was more concerned about the lack of ice leading to more evaporation, which would cause lake levels to drop and make it difficult for his boats to enter the harbor.

“I’m 71 years old, so of course I prefer it. I want to be able to walk out on the dock here and not have cold conditions. Whatever you want to call it, times are changing. And we get more extreme conditions. It will change our approach and we can think of ways to use it. You always have to adapt.”

Less ice can also lead to longer shipping times on the lake. But if the lakes aren’t covered in ice, strong winter storms can erode shorelines more than usual, which can push more sediment into harbors and make them shallower and more difficult to navigate, he said. Eric Peace, vice president of the Lake Carriers Association, a trade group. Along with lower lake levels due to increased evaporation, ships may need to carry less cargo so they sit higher in the water, he said.

The lack of ice this year has allowed Michigan Tech’s Vick-Majors to launch a project to gather winter-specific data that scientists can compare with summer data. Researchers from around the Great Lakes are participating in sampling this month.

On a recent day, Madeline Magee and Rae-Ann Eifert, lake monitors for the Wisconsin Department of Natural Resources, braved sub-freezing temperatures to retrieve buckets of lake water from a Racine breakwater as part of the Vick-Majors project.

The lake was completely open, an emerald expanse stretching to the horizon, and the wind howled. High waves hit the beach and showered Eifert as he stood on the breakwater, leaving his ski pants covered in ice pellets. Magee said the project was worth it.

“Continuing to collect data going forward will further inform what we know about the Great Lakes and how we can manage the lakes better. … If we lose ice, we’re really changing the fundamental ecosystem of the Great Lakes in ways we don’t really understand today,” she said.