Late Holocene Inter-Annual Temperature Variability Reconstructed From The O-18 Of Archaeological Ostrea Angasi Shells

Two multi-year oxygen isotope (O-18) records were obtained from archaeological Ostrea angasi shells, confirming the potential of this species to provide valuable environmental records for the late Holocene period in southeastern Australia. High-resolution O-18(shell) samples from the O. angasi clearly display a seasonal variability, offering insight into past climate conditions in a region where such information is presently limited. The oxygen isotope record in O. angasi reflects a combined temperature-salinity signal. Observations of O-18(shell) data from modern specimens are used as a point of reference to assist in decoupling these two influences, with the two archaeological samples compared with the O-18(shell) profile of four modern O. angasi. Assuming similar paleo-O-18(water) values at the collection sites, data from these archaeological shells present a record of temperatures during the period of their growth that are consistently lower than modern day, with mean annual temperatures approximate to 2 degrees C cooler.