A major marine trade link between Canada and the United States remained closed on Sunday after a ship collided with a lift bridge in Canada's Welland Canal. The canal, which was constructed to link Lake Erie with Lake Ontario and offers a safe detour around Niagara Falls, 10 miles away, has been shut down indefinitely, disrupting traffic on the entire Great Lakes St. Lawrence system. Constable Larry Regnier of the Niagara Regional Police said a freighter was traveling north through the canal at about 9 p.m. on Saturday when the lift bridge started lowering and smashed into the vessel, triggering a blaze; Canada's Transportation Safety Board is currently investigating the accident.