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Ancient Life Form Discovered in Remote Tasmanian Valley

Scientists have uncovered rare, living stromatolites deep within the Tasmanian Wilderness World Heritage Area. The researchers made the discovery during a survey of peat-bound karstic wetlands – an unusual type of swamp that occurs only in peaty soils underlain by limestone and similar carbonate rocks.

Dr Bernadette Proemse of The University of Tasmania says living stromatolites were previously unknown from Tasmania. “The discovery reveals a unique and unexpected ecosystem in a remote valley in the state’s south-west,” Proemse said. “The ecosystem has developed around spring mounds where mineral-rich groundwater is forced to the surface by geological structures in underlying limestone rocks. The find has proved doubly interesting, because closer examination revealed that these spring mounds were partly built of living stromatolites.

“Stromatolites are laminated structures of microorganisms which have created layers of minerals using elements dissolved in the water in which they live. Fossil stromatolites are the oldest evidence for life on Earth – they first appeared 3.7 billion years ago!”

Mr Roland Eberhard of the Department of Primary Industries, Parks, Water & Environment’s Natural and Cultural Heritage Division said that stromatolites are rare because more advanced life forms such as aquatic snails feed on the microorganisms required to form them. “The discovery of living stromatolites in Tasmania is highly significant because stromatolites are rare globally and not previously known from Tasmania except as ancient fossils,” he said. “DNA analysis indicates that the Tasmanian stromatolites are microorganism communities which differ from all other known stromatolites.”

The discovery provides clues to why stromatolites thrived for millions of years but then virtually disappeared from all but a few exceptional places on Earth. The researchers believe that the highly mineralised water flowing from spring mounds is a critical factor in the ability of the stromatolites to survive in the Tasmanian wilderness, because it challenges other forms of life. This became obvious when the researchers noticed that the mounds were littered with the shells of dead freshwater snails.

“This is good for stromatolites because it means there are very few living snails to eat them,” Proemse said. “Fortuitously, these Tasmanian ‘living fossils’ are protected by the World Heritage Area and the sheer remoteness of the spring mounds.”

Further surveys are planned to assess whether spring mounds and stromatolites occur at other sites in the World Heritage Area.

The discovery has been published in Scientific Reports.