Great Lake's Sinkholes Host Exotic Ecosystems Akin To Iced-over Antarctic Lakes
Sinkholes penetrating the bottom one of North America's Great Lakes -- Lake Huron -- unexpectedly harbor exotic ecosystems akin to those in permanently iced-over Antarctic lakes and deep-sea, hydrothermal vents and cold seeps. As little as 20 meters (66 feet) below the surface of Lake Huron, the third largest of North America's Great Lakes, peculiar geological formations--sinkholes made by water dissolving parts of an ancient underlying seabed--harbor bizarre ecosystems where the fish typical of the huge freshwater lake are rarely to be seen. Instead, brilliant purple mats of cyanobacteria--cousins of microbes found at the bottoms of permanently ice-covered lakes in Antarctica--and pallid, floating pony-tails of other microbial life thrive in the dense, salty water that's hostile to most familiar, larger forms of life because it lacks oxygen.