The last dive of the trip took us to the Middle Island Sinkholes just north of Alpena Michigan.  I was telling the other divers about this one and that how I was absolutely fascinated with this oddity as the bottom floor is carpeted with a bacteria that thrives off of digesting sulfur and not from the typical offerings lake Huron usually has for its plants, fish, and bacteria. The bacteria itself is maroon in color and survives utilizing a chemosynthesis process instead of other more common processes like photosynthesis

The Karst region and the underwater sinkhole itself is an interesting site as it has spring water coming from deep inside the earth which might provide some evidence of life existing deep inside the earths crust.  This and other sinkholes in the area have these purple bacteria mats believed to be some of the early forms of life on our planet and are studied by NOAA and NASA to learn about how life on other planets might exist.  The reasoning behind this is that the existence of these bacteria mats survive off of the no oxygen high-sulfur content solution at the bottom of this sinkhole. These Extremaphiles have been noted in the mariana trench some 30,000 ft underwater, under a mile of ice in antartic lakes, and here in Lake Hurons Karst region.  The Karst region has been dated back to around 400 million years that started from sediment deposits which formed these karst formations that are enbedded in this region presently. This ultimately has included the existence of the bright yellow sulfur water at the bottom of the sinkhole. There is a lot of these purple cyanobacterical mats that limit themselves to growing within the groundwater re surging from underground and thrive by a chemosynthesis process.

This is my second time visiting the Middle island Sinkhole and I wanted to check out the bed plane section along with taking the other divers to the sink where the yellow sulfur water is located.   As we descend down to a depth of 70 ft we reach the chemocline and the maroon bed planes of the bacteria come into view.

What I found even more fascinating is how the bacteria mats formed a vertical protruding feature reaching up which might be due to some sort of gas coming from the depths.

We continue up the ridge and down into some small cavern like entrances that did not go anywhere yet some of these depressions contained crystal clear yellow sulfur water with dead fish at the bottom which might have been caused by these fish swimming into the sulfur or from natural reasons and just fell into the depression area and are decaying slowly due to the no oxygen solution.

FLICKR: https://www.flickr.com/photos/exploration-worldwide/sets/72157633283833110/

ADDITIONAL INFORMATION: http://www.glerl.noaa.gov/pubs/fulltext/2009/20090012.pdf