Calibration of Sclerosponge Oxygen Isotope Records to Temperature using High-resolution δsup18/supO Data

A revised calibration is presented relating the oxygen isotope composition of the aragonite-secreting sclerosponge Ceratoporella nicholsoni , oxygen isotope composition of seawater, and ambient water temperature. This new relationship has been obtained using high-resolution δ ¹⁸ O data measured in sclerosponges from the Bahamas and Jamaica compared to ambient temperature measurements and δ ¹⁸ O values of seawater from the two locations, both measured and published. New data improve an existing calibration which was determined using measurements of salinity rather than directly measured δ ¹⁸ O values of the seawater and was composed of measurements from different species of sclerosponge and other aragonite-secreting organisms. The updated calibration ( n = 12, r ² = 0.95) is: T(°C)=16.1(±3.1)-[6.5(±1.1)](δarag-δsw),">T(°C)=16.1(±3.1)-[6.5(±1.1)](δarag-δsw), where T is temperature in degrees Celsius, δ _arag is the δ ¹⁸ O value of aragonite normalized to VPDB, and δ _sw is the δ ¹⁸ O value of water normalized to VSMOW. This calibration improves accuracy and precision of Caribbean sclerosponges for reconstructions of temperature as well as δ ¹⁸ O values of seawater.