(Figure 2 Top)
Samples from inside the Alcove are nearly pure groundwater, fueling growth of purple cyanobacterial mats that then spill over the walls into the Arena. (Image courtesy of Russ Green, Thunder Bay National Marine Sanctuary).
(Figure 2 Bottom)
The Middle Island sinkhole is open to Lake Huron creating a gradient of biological activity. A 9-meter Whaler is also visible in this aerial photo for a since of scale. (Image courtesy of Scott Kendall and Bopi Biddanda, Grand Valley State University).
Related Links
Thunder Bay Sinkholes 2008: Mission Plan
