Listen to the podcast from the recent seminar by Merinda Nash.
The Environment Institute’s Sprigg Geobiology Centre presented Merinda Nash from the Electronic Materials Engineering, Research School of Physics, Australian National University on Thursday 21st February 2013.
The talk was titled ‘Conditions constraining biomineralised dolomite in living tropical calcifying red algae offers insight into past environments’ (See Abstract Below)
Merinda Nash is a PhD candidate in the Electronic Materials Engineering group, Research School of Physics, at the Australian National University. Her research is into the physical properties of biogenic carbonates, particularly coral and coralline algae and how these may be impacted by ocean acidification.
Research into effects of ocean acidification on tropical calcifying red algae led to the surprising discovery that these algae precipitate substantial amounts (up to 30% of total carbonate) of dolomite contemporaneously with their living processes. Biomineralised dolomite is found within the cell spaces of living crustose coralline alga and has both rhomb and spheroidal morphologies. Alteration bands of dolomite and aragonite obliterate cell features leaving ghost outlines of original cells. There are many similarities between features of this modern dolomite paleo dolomite. It seems that this bio-dolomite is common in modern coral reefs and is constrained by light, temperature and water energy conditions. Our experiments showed that the presence of dolomite in the coralline algae reduces its rate of dissolution 6-10 times compared to only Mg-calcite coralline algae. This is due to a combination of reduced porosity and stability of the dolomite in-fill. Analysis of reef core coralline algae demonstrated that this bio-dolomite is stable over at least several thousand years and the original cell in-fill morphology is retained. The preferential preservation of dolomite rich red algae demonstrates a process for concentrating dolomite in shallow marine environments in elevated CO2 conditions. Biological ocean acidification experiments on calcifying algae have the potential to answer many questions about how dolomite forms, what is the isotope fractionation of this bio-dolomite and can this information be used to reconstruct past environments. This opens the door to new opportunities for biologists and geologists to collaborate to understand both the past and the future.
Read Merinda’s paper published in Nature that relates to this talk.
Download the podcast from this seminar.