Controls on shell Mg/Ca and Sr/Ca in cultured planktonic foraminiferan, Globigerinoides ruber (white).

Kisakurek, Basak, Eisenhauer, Anton , Böhm, Florian, Garbe-Schönberg, C.-Dieter and Erez, J. (2008) Controls on shell Mg/Ca and Sr/Ca in cultured planktonic foraminiferan, Globigerinoides ruber (white). Earth and Planetary Science Letters, 273 (3-4). pp. 260-269. DOI 10.1016/j.epsl.2008.06.026.

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Abstract

Mg/Ca and Sr/Ca ratios were determined on a single species of planktonic foraminiferan, Globigerinoides ruber (white), collected from the Gulf of Eilat and cultured in seawater at five different salinities (32 to 44), five temperatures (18 to 30 °C) and four pH values (7.9 to 8.4). The Mg/Ca-temperature calibration of cultured G. ruber (with an exponential slope of 8 ± 3%/°C) agrees well with previously published calibrations from core-tops and sediment traps. However, the dependence of Mg/Ca on salinity (with an exponential slope of 5 ± 3%/psu) is also significant and should be included in the calibration equation. With this purpose, we calculated a calibration equation for G. ruber dependent on both temperature and salinity within the 95% confidence limits:

Mg/Ca(mmol/mol)=exp[0.06(±0.02)*S(psu)+0.08(±0.02)*T(°C)−2.8(±1.0)],R2=0.95 The influence of pH on Mg/Ca ratios is negligible at ambient seawater pH (8.1 to 8.3). However, we observe a dominating pH control on shell Mg/Ca when the pH of seawater is lower than 8.0. Sr/Ca in G. ruber shows a significant positive correlation with average growth rate. Presumably, part of the variability in shell Sr/Ca in the geological record is linked to changes in growth rates of foraminifera as a response to changing environmental conditions.

Document Type: Article
Keywords: planktonic foraminifera; Mg/Ca; Sr/Ca; salinity; temperature; pH; growth rate; culturing
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > The Future Ocean - Cluster of Excellence
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2008.06.026
ISSN: 0012-821X
Projects: Future Ocean
Date Deposited: 13 Oct 2010 09:48
Last Modified: 23 Sep 2019 18:20
URI: http://oceanrep.geomar.de/id/eprint/9055

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