Is that pink lemonade or anoxic photosynthesis?

(posted by Jess)

Fayetteville Green Lake, NY, supports the growth of carbonate-depositing microbial communities, much like the stromatolite-forming microbial communities I study in Cuatro Ciénegas, MX.  So, when I got the opportunity to attend the Anoxic Phototrophic Ecosystem Field Workshop this past week in Fayetteville, NY, I jumped at the chance.

Fayetteville Green Lake

Fayetteville Green Lake, NY. Photo by J. Corman.

(Fortunately, Fayetteville is also about two hours from where I grew up, so I welcomed the opportunity to stop by and see my parents, too!)  The discussions during the workshop revolved around studies of ancient and modern microbes that use light to make their own energy (much like plants), but do not produce oxygen in the process (very unlike plants).  To really get an appreciation for this form of life, we spent half a day sampling Green Lake.  Sure enough, we saw numerous carbonate microbialites (or “bioherms”, as they call them there) around the perimeter of the lake.  We were not able to sample these benthic microbes, so we instead made like limnologists, got in row boats, and sampled the water column!  At about 20 m depth, light is still available, but dissolved oxygen is gone.  And there is also a lot of sulfide.  These are exactly the type of conditions under which anoxic phototrophic microbes can grow, particularly those known as purple sulfur bacteria.  Thus, armed with a van dorn and plenty of rope, we pulled up water from 20 m depth.  When the van dorn reached the surface, I was amazed –

Purple sulfur bacteria

This is the water we collected from 20 m deep. It is colored pink because of the purple sulfur bacteria. Photo by J. Glass.

the water looked like pink lemonade!  I suddenly found myself forgetting completely the stromatolite-like microbial communities that were growing around the shoreline and thinking only how spectacular these peculiar bacteria were.

ASU graduate students, Steve, Jess, & Jen, in front of giant bioherms at Dead Man's Point.

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