Oxygen isotope records of the Australian flat oyster (Ostrea angasi) as a potential temperature archive

The response of the oxygen isotope ratio (δ18O) in shells of the Australian native flat oyster Ostrea angasi to changes in water temperature has been assessed using growth experiments conducted for one year at two locations on the east coast of Australia. The analysed δ18O of the oyster shells (δ18Oshell) closely follows the predicted oyster shell δ18O constructed from measured δ18O in the water (δ18Owater) and water temperature. es of freshwater that occur in the estuarine habitats of O. angasi can modify the δ18Owater, and consequently δ18Oshell. Salinity fluctuations can also cause interruptions to shell growth in this species. This can cause overestimated temperatures in O. angasi δ18Oshell temperature reconstructions. shell–temperature calibration was established for O. angasi, yielding the relationship: T°C = 13.97 − (3.57δ18Oshell − δ18Owater) + (0.17δ18Oshell − δ18Owater)2, n = 79, R2 = 0.79, which, within the experimental uncertainties of the data, is similar to other published biogenic carbonate paleotemperature equations.