Concluding Remarks

Abstract

In this book we tried to compile the biological — autecological data on planktonic foraminifera as known by today. During this attempt it became evident that much is still unknown, especially in detail, and that there are quite contradictory results. Stable isotope techniques are widely applied in diverse fields of oceanography and paleoceanography, including bios-tratigraphy, in the interpretation of the evolution of microfossils, to decipher water mass temperatures, climatic influences, sedimentary depositions, and changes in habitat. However, several sources of error may occur when interpreting isotopic data derived from planktonic foraminifera, since not only abiotic factors such as temperature and salinity leave signals in the calcitic shell but to a large extent also biological factors as there are trophic activity, symbiosis, reproductive cycles to name only a few. Berger and Gardner (1975) (and summarized in Berger, 1979b) published a paper “On the Determination of Pleistocene Temperatures from Planktonic Foraminifera”. In this paper they raised for the first time the question “how reliable are such estimates” for paleotemperatures based on the species isotopic composition. If one examines the flood of paleoceanogrphic papers which have appeared during the last decade (all applying the isotopic composition of planktonic foraminiferal shells) they clearly represent a major advance.