Green Slime in Antarctica Offers Window into the Past

A thin layer of bright green slime at the bottom of an Antarctic lake is giving scientists a glimpse at life on Earth 2.4 billion years ago, according to new research from the University of California, Davis.

The bacteria found in the slime produces a millimeter-thick layer of concentrated oxygen at deep depths that are otherwise devoid of oxygen, or anoxic. These so-called “oxygen oases” reflect a time before photosynthesis was widespread, when oxygen was not yet abundant in Earth’s atmosphere.

Instead, the element was found mainly in small, localized pockets that were produced by a select few organisms — similar to the handful of microbes can survive in harsh Antarctic lakes.

“The thought is, that the lakes and rivers were anoxic, but there was light available, and little bits of oxygen could accumulate in the mats,” UC-Davis professor Dawn Sumner explains in a news release.

That all changed approximately 2.5 billion years ago, however, when evolving bacteria began to photosynthesize. The newly capable organisms introduced oxygen throughout the planet, an event that has since been dubbed the Great Oxidation Event.

The rest, of course, is history!

From Discovery News