TEMPERATURE SENSITIVITY OF PLANKTIC FORAMINIFERA AND ITS INFLUENCE ONTHE OXYGEN-ISOTOPE RECORD

We used oxygen isotope measurements from Holocene surface sediments to infer optimum temperature and temperature sensitivity of the planktic foraminiferal species Globigerinoides ruber (pink) and Globigerinoide s sacculifer. The (isotopic) optimum temperature of G. ruber (pink) is close to 27 degrees C. G. sacculifer seems to have optimum vital cond itions around 22 degrees C and is less temperature sensitive than G. r uber (pink). Our estimations of optimum temperature and temperature se nsitivity are in good accordance with laboratory and field investigati ons. Two simple experiments show that the temperature sensitivity of p lanktic foraminifera, determined from oxygen isotopes, can influence p hase and amplitude of oxygen isotope records, if the temperature distr ibution at the sea surface changes through time. To use this distortio n for paleoceanography, we suggest to derive an 'isotopic transfer fun ction' which allows the calculation of average temperature, temperatur e variability and the isotopic composition of seawater if the oxygen-i sotope differences between at least three species are known. (C) 1998 Elsevier Science B.V. All rights reserved.