A Look Into the Past: Studying Stromatolites in Shark Bay, Australia

Dr. John Stolz, professor of biology and director of the Center for Environmental Research and Education, traveled this spring to Hamelin Pool Marine Nature Reserve in the Shark Bay World Heritage Site of Western Australia to study stromatolites—reef-like structures that form a living community of microorganisms.

The stromatolites are formed in shallow water by the trapping, binding and cementation of sediment by microorganisms. These living organisms provide the most ancient records of life on Earth by fossil remains.

“It’s a window into our past—a living window—in the sense that the living organisms around today are the result of more than three billion years of evolution,” Stolz explained. “The organisms we’re studying today are similar to what existed way back when.”

Stolz partnered with Dr. Pam Reid, professor at the University of Miami’s Department of Marine Geology and Geophysics, whose long-term goal is to map the entire Hamelin Pool to show the diversity and distribution of its stromatolites and the organisms forming them.

The research location is remote. Many of the sites in Hamelin Pool are not readily accessible, and the Australian government requires permits for any sampling. The research itself can be dangerous, with stinging jellyfish and poisonous sea snakes prevalent in the area. “A single bite from a sea snake can be fatal,” cautioned Stolz, who only had one close encounter with a snake during his trip.

Stolz and Reid looked at different microbial communities forming the structures of reefs, which come in various shapes and sizes and thrive at Hamelin Pool because its water has a higher saline content than sea water.

While the stromatolites have been studied by geologists for decades, Stolz said that biologists and ecologists have just begun researching the communities in any detail.

“It’s the ecology that leaves behind this rock record,” Stolz said. “If we can tease apart some of the ecology and the community diversity, we have a better window on what life was like hundreds of millions of years ago.”