Refining C. wuellerstorfi and H. elegans Mg/Ca temperature calibrations

Abstract

We present core top Mg/Ca, Sr/Ca and delta O-18 measurements for Cibicidoides wuellerstorfi and Hoeglundina elegans from the Timor Sea and the Makassar Strait, which span a bottom water temperature (BWT) range from 2 to 18 degrees C In both species Mg/Ca ratios are positively and significantly correlated with BWT, while delta O-18 measurements are significantly anti-correlated with BWT Comparison of calcification temperatures derived from Mg/Ca ratios and delta O-18 measurements yield comparable results and closely match LW-measured temperatures. We integrate our results with previously published data sets from the Atlantic, Indian and Pacific Oceans and provide temperature calibration equations over the temperature range from 2 to 12 degrees C for H. elegans and from 0 to 10 degrees C for C. wuellerstorfi. We found geographical differences in the relation of benthic Mg/Ca ratios to BWT: C. wuellerstorfi shows Mg/Ca sensitivity to BWT of 19% increase in Mg/Ca per degrees C for the Atlantic Ocean and of 15% per degrees C for the Indian and Pacific Oceans. H. elegans shows Mg/Ca sensitivity to BWT of 16% increase in Mg/Ca per degrees C for the Atlantic Ocean and of 14% per degrees C for the Indian and Pacific Oceans. C wuellerstorfi Sr/Ca variability appears to be mainly driven by carbonate ion saturation, whereas H. elegans Sr/Ca variability is closely linked to BWT in the compiled data sets from the Atlantic, Indian and Pacific Oceans. (C) 2015 Elsevier B.V. All rights reserved.