An article published in the journal “Scientific Reports” describes the discovery of modern organisms that create stromatolites, among the most ancient organisms on Earth, in Tasmania, in an area of the so-called Tasmanian Wilderness, considered by UNESCO a World Heritage Site. During the exploration of karst wetlands, a group of researchers came across these rare organisms, the first discovered in Tasmania and thus useful in understanding the evolution and the almost disappearance of organisms that in ancient times were very common.
The microorganisms that generate stromatolites are similar to the ones that in the Precambrian were very common and generated oxygen in the primordial atmosphere of the Earth. Stromatolites are sedimentary structures whose name is a made by the Greek words that mean “mat” and “stone” because they are formed from accumulations generated by microbial mats. Today, however, those organisms are rare, usually in quite extreme environments including the Hamelin Pool area, in Shark Bay, Australia, but so far they were unknown in Tasmania.
A team of researchers led by Professor Allen Nutman of the University of Wollongong (UOW) in Australia believes they found fossil stromatolites dating back to 3.7 billion years ago, which would be the oldest found so far. However, this discovery caused a controversy so results of new studies are needed to better understand the nature of those fossils.
DNA analysis of the organisms discovered in Tasmania shows that it’s a community different from the others known. The bacterial community is dominated by Cyanobacteria, Alphaproteobacteria and an unusually high proportion of Chloroflexi, followed by Armatimonadetes and Planctomycetes. The ecosystem born in a remote valley is unique and depends on particular environmental conditions.
The researchers pointed out that this is an unusual environment for organisms that generate stromatolites with its freshwater and cool temperatures. Water flows with high mineral contents could be a key factor in their survival in that area, also because they are unfavorable to other forms of life that could feed on those organisms.
This discovery suggests new possibilities regarding the environments where the organisms that generate stromatolites can live today. The researchers believe this is a starting point for new investigations into these possibilities to better understand the history of these ancient organisms as well.
