The first day of June 1988 was sunny, hot and mostly calm — perfect weather for the three young researchers from Canada’s University of Windsor hunting for critters crawling across the bottom of Lake St. Clair. A whining outboard pushed the 16-foot-long runabout carrying Sonya Santavy, a freshly graduated biologist, toward the middle of the lake that straddles the U.S. and Canadian border.
On a map, Lake St. Clair looks like a 24-mile-wide aneurysm in the river system east of Detroit that connects Lake Huron to Lake Erie, and that is essentially what it is. Water rushes quickly through Lake St. Clair because it is as shallow as a swimming pool in most places, except for a roughly 30-foot-deep navigation channel down its middle. The U.S. Army Corps of Engineers carved that pathway more than half a century ago as part of the St. Lawrence Seaway project to allow oceangoing freighters to sail between Lake Erie and the lakes upstream from it.
When water levels were low or sediment high, sometimes that channel still wasn’t deep enough, forcing ships to lighten their loads to squeeze through. This often meant dumping water from the ship-steadying ballast tanks — water taken onboard outside the Great Lakes. Water that could be swarming with exotic life picked up at ports across the planet.
As Santavy and her colleagues puttered over a rocky-bottomed portion of Lake St. Clair, she whimsically dropped her sampling scoop into the cobble below. She was hunting for muck-loving worms, but figured she’d take a poke into the rocks below because — well, to this day, she still doesn’t know. “I can’t even explain why it popped into my head,” Santavy tells me.
