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

The response of the oxygen isotope ratio (delta O-18) 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 delta O-18 of the oyster shells (delta O-18(shell)) closely follows the predicted oyster shell delta O-18 constructed from measured delta O-18 in the water (delta O-18(water)) and water temperature. Influxes of freshwater that occur in the estuarine habitats of O. angasi can modify the delta O-18(water) and consequently delta O-18(shell) Salinity fluctuations can also cause interruptions to shell growth in this species. This can cause overestimated temperatures in O. angasi delta O-18(shell) temperature reconstructions. A delta O-18(shell)-temperature calibration was established for O. angasi, yielding the relationship: T degrees C = 13.97 - (3.57 delta O-18(shell) - delta O-18(water)) + (0.17 delta O-18(shell) - delta O-18(water))(2), n = 79, R-2 = 0.79, which, within the experimental uncertainties of the data, is similar to other published biogenic carbonate paleotemperature equations. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.