As the World Turns: Mat Microbes Dance to the Sun’s Beat Dear AGU,  In a scene reminiscen

As the World Turns: Mat Microbes Dance to the Sun’s Beat

DearAGU, 

In a scene reminiscent of the mat world that prevailed during the first few billion years of life on Earth, a dynamic mosaic of photosynthetic (purple) and chemosynthetic (white) microbial mats flourish today in ground water containing high-sulfur and low-oxygen at the Middle Island Sinkhole in Lake Huron, Thunder Bay National Marine Sanctuary. Daytime dive photos (as shown here in a mid-day image) and nighttime dive photos reveal a diel vertical shift in the workforce of the mat ecosystem – purple cyanobacteria dominate the mat surface during the day, and white sulfur-oxidizing bacteria take over at night. Indeed, these diel sub-millimeter journeys alternately turn the underwater mat scape mostly purple by dusk and white by dawn!

            Might similar vertical mass movements of life have occurred daily in the benthic mats of the Precambrian seas, and continued all the way to the present? Could modern-day microbial mats such as these – wherein photosynthetic cyanobacteria use diel vertical movements to optimize photosynthesis at the surface during the daytime – have shaped the early biosphere by gradually producing net oxygen each day?

— Bopi Biddanda, Ian Stone, Tony Weinke, Janie Cook, Nate Dugener, Davis Fray and Sarah Hamsher, Annis Water Resources Institute, Grand Valley State University (https://www.gvsu.edu/wri/); Phil Hartmeyer, Stephanie Gandulla, John Bright and Russ Green, NOAA-Thunder Bay National Marine Sanctuary (www.thunderbay.noaa.gov); Travis Smith and Steve Ruberg, NOAA-Great Lakes Environmental Research Lab (https://www.glerl.noaa.gov/), Michigan.