ROCHESTER, NY (WXXI) - When the ice melts each spring, the ship visits each of the five lakes to measure basic water quality and sample the “lower food web” -- the tiny animals, plants, and algae that support fish and other aquatic life. The Lake Guardian hits Lake Michigan first in early April, then heads east to Huron and Erie before visiting Ontario. Lake Superior, where the ship was headed on Tuesday, is the last stop because the ice there tends to linger longer. CLICK HERE.