The Middle Island Sinkhole is 75 to 80 feet deep, underwater off the north shore of the island. It was discovered more than 20 years ago, right around the time the Thunder Bay National Marine Sanctuary was designated.
Further investigation revealed an ecosystem of rich sulfur and low oxygen creating a perfect environment of cyanobacterial mats to survive.
“These mats are very similar to the first oxygen producing organisms on the planet.” said Stephanie Gandulla with the Thunder Bay National Marine Sanctuary.
“Scientists come from all over to study these microbial mats and these microbes to get a better understanding of what the planet was like 400 million years ago.”
Scientists presume microbial mats like this one could be where life first began on Earth.
This tapestry of bacteria is a fusion of purple and red hues scientists dive down toward all that color and collect samples.
As you descend the whole arena opens up.
“You can see this purple cyanobacterial mass at the bottom of the sinkhole," Gandulla said. "It has this rich sulfur smell as you’re bringing up the samples. It’s one of my favorite dive sites.”
Scientists say these kinds of sinkholes could be all over the Great Lakes in hard to find places, especially the deeper parts of Lake Huron.
