Culture experiments on the environmental controls of trace metal ratios (Mg/Ca, B/Ca, U/Ca) recorded in calcareous tests of bipolar deep-sea benthic foraminifera
Final Report Abstract
Comparative experiments in high-pressure and atmospheric pressure aquaria demonstrate that reproduction of palaeoceanographic relevant foraminiferal deep-water species can only be achieved in a high-pressure set-up. However, during the recent experiments it also became clear that the use of Calcein, the fluorescent label commonly used to identify newly precipitated shell material from pre-experimental shell material, affects alkalinity and dissolved inorganic carbon (DIC) content in an unpredictable way. Furthermore, despite progressively reducing the amount of transferred sediments experiment to experiment, reducing the water volume inside the high-pressure aquaria, and sterilizing the inflowing water, it was impossible to achieve a constant carbonate system and pH over an experimental running time of 4-6 months. This made all kind of X/Ca-ratio analyses on foraminiferal shells precipitated during these experiments pointless. Therefore, the research direction changed into two directions: 1) achieving a stable pH over a 6 months period in the experiments running in the existing highpressure aquaria aiming for d11B calibrations on foraminifers; 2) designing new high-pressure aquaria for application under the microscope to avoid a mandatory use of Calcein, and sediments for the identification of experimental offspring and reproduction, respectively. Application of buffers proved the only way to keep the pH in the experiment constant over a 4- 6 months culturing period. The d11B measurements of experimental offspring revealed a positive relationship to pH. New small-sized highpressure aquaria have been designed, patented, and successfully applied.
Publications
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Hochfeste Probenkammer für die Durchlichtmikroskopie und Verfahren zu deren Herstellung. 15.10.2015. Patentnummer 10 2014 018 858
Jutta Wollenburg und Erich Dunker
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(2016). High pressure culturing a major step towards a better understanding on deep sea benthic foraminifers and the geochemical signals recorded in their calcareous shells, Batsheva de Rothschild Workshop Live foraminifera as a new model system for monitoring and reconstructing marine environments, 10-16 September 2016, Eilat, Israel
Wollenburg, J.E.
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(2018) Insight into deep-sea life - Cibicidoides pachyderma environmental and pH-dependent behaviour, International Symposium of Foraminifera, 17-22 June, Edinburgh, Scottland
Wollenburg, J.E., Zittier, Z., Bijma, J.
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(2018) Insight into deep-sea life – Cibicidoides pachyderma substrate and pH dependent behaviour following disturbance, Deep Sea Research Part I: Oceanographic Research Papers, Volume 138, August 2018, Pages 34-45
Wollenburg, J.E., Zittier, Z., Bijma, J.
