Microorganisms vital in formation of beachrock

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Microorganisms vital in formation of beachrock

May 31, 2017 - 18:06
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A new study by the University of Queensland (UQ) has revealed that microorganisms play an important role in beachrock formation.

Heron Island, Great Barrier Reef, Australia

Beachrock is consolidated carbonate beach sediment in the intertidal zone that forms naturally on many tropical beaches. Compared to unconsolidated sand, it reduces the erosion rates of these beaches and protects low-lying reef islands from rising sea levels.

“In spite of the critical role beachrock plays in stabilizing some reef cay shores, the mechanism of beach rock formation is still incompletely understood,” said Professor Gordon Southam of UQ's School of Earth and Environmental Sciences.

His team’s findings reveal that microorganisms play a vital role in the formation of beachrock. “These results are of interest because beachrock could be used as a natural coastline stabilisation strategy on sand reef cays, and in turn, protect the unique habitats that reef islands support,” said Professor Southam.

Of all the coastal environments, sandy beaches on low elevation coral reef cays are highly vulnerable due to their susceptibility to erosion. And if the conditions worsened, this would have negative implications for reef cay environments, which may be the sites of sea turtle and bird rookery habitats.

As part of the research, the scientists used beach sand and beachrock samples from Heron Island at Australia’s Great Barrier Reef to synthesise beachrock in the laboratory. They simulated natural beackrock formation conditions, with one experiment influenced by beachrock microbes, and another experiment without them.

They then analysed the resultant materials in the Australian synchrotron in Melbourne, thus confirming the fundamental role these microorganisms have in initiating the formation of beachrock.

The findings gave scientists a better understanding of the role of microorganisms in beachrock generation, and may help to guide future research into this subject.

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