Near the deepest spot in Lake Michigan, the crew aboard the research vessel Blue Heron lowers a device outfitted with a cluster of 8-liter bottles into the dark blue waters until it disappears from sight.
After a 10-minute descent, the metal-framed contraption known as a rosette finally lands on the muddy bottom roughly 860 feet below the surface. Between Green Bay and Traverse City, Michigan, lies a place devoid of sunlight, deep enough to completely submerge the 74-floor Water Tower Place skyscraper and where temperatures still hover around 39 degrees.
On the trawler’s deck, marine techs reverse the winch, and the rosette lurches upward, deploying canisters to retrieve water samples from the abyss.
While the lake water appears crystal clear, the team of scientists from the University of Chicago know it’s teeming with life. Each drop contains a plethora of species so small that dozens could fit on a speck the width of a strand of human hair.
“When most people look out on the lake, they think about fish,” said Maria Hernandez Limon, a graduate student studying microbiology at U. of C. “But there are orders of magnitude more bacteria.”
Despite their minuscule size, microorganisms — including, bacteria, viruses and algae — are among the most prolific environmental regulators on the planet. These tiny, single-celled species wield the ability to alter the Earth’s climate, spread human disease, regulate the metabolism of animals and some serve as the building block of the aquatic food chain. In the Great Lakes — which provide drinking water for 48 million people and support a $7 billion recreational fishery — researchers know next to nothing about some of the most abundant microbes.