The chemical microenvironment of the symbiotic planktonic foraminifer Orbulina universa

Köhler-Rink, S; Kühl, M

The chemical microenvironment of the symbiotic planktonic foraminifer Orbulina universa

Köhler-Rink, S Kühl, M

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Publication Type:: Journal Article
Citation:: Marine Biology Research, 2005, 1 (1), pp. 68 - 78
Issue Date:: 2005-03-01

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Field	Value	Language
dc.contributor.author	Köhler-Rink, S	en_US
dc.contributor.author	Kühl, M https://orcid.org/0000-0002-1792-4790	en_US
dc.date.issued	2005-03-01	en_US
dc.identifier.citation	Marine Biology Research, 2005, 1 (1), pp. 68 - 78	en_US
dc.identifier.issn	1745-1000	en_US
dc.identifier.uri	http://hdl.handle.net/10453/14995
dc.description.abstract	Microsensor measurements of CO2, O2, pH and Ca 2+ in the vicinity of the symbiont-bearing planktonic foraminifer Orbulina universa showed major light-modulated changes in the chemical microenvironment due to symbiont photosynthesis, respiration of the holobiont, and precipitation of the calcite shell. Under saturating light conditions, microprofiles measured towards the shell surface showed an O2 increase of up to 220% air saturation, a decrease in CO2 concentration to 4.9 μM, and a pH increase to 8.8 due to symbiont photosynthesis. The Ca2+ concentration decreased to ∼9.6 mM in two specimens, while it increased to 10.2-10.8 mM in three other specimens kept in light. In darkness, the respiration of the community decreased the O 2 concentration to 82% of air saturation, CO2 increased up to 15 μM, the pH decreased to 8.0, and the Ca2+ concentration increased up to 10.4 mM. These data, and derived calculations of the distribution of HCO3- and CO32- near the shell, showed that the carbonate system in the vicinity of O. universa was significantly different from conditions in the surrounding seawater, both in light and darkness, due to the metabolism of the foraminifer and its associated algae. Experimental light-dark cycles indicated a sufficient CO2 supply sustaining high carbon fixation rates of the symbiotic algae via conversion of HCO3- or via CO2 release from calcification and host respiration. Our findings on irradiance-dependent CO 2 and pH changes in the vicinity of symbiont-bearing planktonic foraminifera give direct experimental evidence for the predictions of isotope fractionation models used in palaeoclimatology stating that metabolic processes affect the isotopic carbon signal (δ13C) in foraminifera. © 2005 Taylor & Francis.	en_US
dc.relation.ispartof	Marine Biology Research	en_US
dc.relation.isbasedon	10.1080/17451000510019015	en_US
dc.subject.classification	Marine Biology & Hydrobiology	en_US
dc.title	The chemical microenvironment of the symbiotic planktonic foraminifer Orbulina universa	en_US
dc.type	Journal Article
utslib.citation.volume	1	en_US
utslib.for	0602 Ecology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	closed_access
pubs.issue	1	en_US
pubs.publication-status	Published	en_US
pubs.volume	1	en_US

Abstract:

Microsensor measurements of CO2, O2, pH and Ca 2+ in the vicinity of the symbiont-bearing planktonic foraminifer Orbulina universa showed major light-modulated changes in the chemical microenvironment due to symbiont photosynthesis, respiration of the holobiont, and precipitation of the calcite shell. Under saturating light conditions, microprofiles measured towards the shell surface showed an O2 increase of up to 220% air saturation, a decrease in CO2 concentration to 4.9 μM, and a pH increase to 8.8 due to symbiont photosynthesis. The Ca2+ concentration decreased to ∼9.6 mM in two specimens, while it increased to 10.2-10.8 mM in three other specimens kept in light. In darkness, the respiration of the community decreased the O 2 concentration to 82% of air saturation, CO2 increased up to 15 μM, the pH decreased to 8.0, and the Ca2+ concentration increased up to 10.4 mM. These data, and derived calculations of the distribution of HCO3- and CO32- near the shell, showed that the carbonate system in the vicinity of O. universa was significantly different from conditions in the surrounding seawater, both in light and darkness, due to the metabolism of the foraminifer and its associated algae. Experimental light-dark cycles indicated a sufficient CO2 supply sustaining high carbon fixation rates of the symbiotic algae via conversion of HCO3- or via CO2 release from calcification and host respiration. Our findings on irradiance-dependent CO 2 and pH changes in the vicinity of symbiont-bearing planktonic foraminifera give direct experimental evidence for the predictions of isotope fractionation models used in palaeoclimatology stating that metabolic processes affect the isotopic carbon signal (δ13C) in foraminifera. © 2005 Taylor & Francis.

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http://hdl.handle.net/10453/14995