Scientists seek to understand impacts of lack in ice of Great Lakes

Michigan Tech University biologists of the United States have been observing a remote Lake Superior island's fragile wolf population every winter since 1958, but they had to cut this season's planned survey.

The Great Lakes in North America, which were always frozen at the time and used as a landing strip by the group of biologists, are left nearly devoid of ice during this warm winter.

As climate change accelerates, scientists are scrambling to understand how iceless winters could affect the world's largest freshwater system.

Ice coverage on the lakes, which have a combined surface area roughly the size of the U.K., has generally peaked in mid-February over the last 50 years, with as much as 91 percent of the lakes covered at times, according to the Great Lakes Ice Tracker website. As of mid-February this year, only 3 percent of the lakes were covered, which was the lowest figure since at least 1973, when the site's records began.

"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 just no way you can predict how an ecosystem is going to respond to the large-scale changes we're looking at."

Researchers don't have much data about how years of iceless winters could change the lakes, but they have plenty of theories.

Iceless lakes could absorb sunlight faster and warm up sooner in the spring. Some biologists speculate that this could lead to earlier and larger blue-green algae blooms, which can be toxic to humans and put a damper on summer tourism.

Without ice, the lakes' upper levels will likely warm even more quickly than usual, contributing to thermal stratification, in which layers of colder and warmer water form. Less oxygen would make it into the 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 would likely cause fish populations to shrink, potentially leading to tighter fishing quotas and higher prices at grocery stores and restaurants.

Longer fishing and shipping season

Less ice could translate to longer fishing seasons, but winter storms could wreck nets and traps and destroy whitefish eggs that rely on the ice for protection, said Titus Seilheimer, a fisheries specialist at the University of Wisconsin-Madison.

Less ice also could lead to a longer lake shipping season. But without ice blanketing the lakes, powerful winter storms could erode shorelines more than usual, which could push more sediment into harbors and make them shallower and trickier to navigate, said Eric Peace, vice president of the Lake Carriers Association, a trade group. Coupled with lower lake levels due to increased evaporation, ships might have to carry less cargo so they would sit higher in the water, he said.

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

(With input from AP)