Great Lakes Environmental Research Laboratory

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In this Jan. 9, 2014 photo provided by the U.S. Coast Guard a convoy of Great Lakes cargo ships line up to follow an icebreaker on the St. Marys River, which links Lakes Superior and Huron. As of Feb. 13, 88 percent of the Great Lakes surface was frozen, according to the federal government’s Great Lakes Environmental Research Laboratory in Ann Arbor. (AP Photo/Lt. David Lieberman)