The influence of symbiont photosynthesis on the boron isotopic composition of foraminifera shells

LDEO Publication: 
Publication Type  Journal Article
Year of Publication  2003
Authors  Hoenisch, B.; Bijma, J.; Russell, A. D.; Spero, H. J.; Palmer, M. R.; Zeebe, R. E.; Eisenhauer, A.
Journal Title  Marine Micropaleontology
Volume  49
Issue  1-2
Pages  87-96
Journal Date  Sep
ISBN Number  0377-8398
Accession Number  ISI:000185272300005
Key Words  delta b-11; planktonic foraminifera; vital effects; symbionts; paleo-ph; ionization mass-spectrometry; eastern equatorial pacific; orbulina-universa; globigerinoides-sacculifer; ph control; ocean ph; seawater; carbon; fractionation; productivity

Culture experiments were carried out with the planktonic foraminifer Orbulina universa under high and low light levels in order to determine the influence of symbiont photosynthetic activity on the boron isotopic composition of shell calcite. Under low light (reduced photosynthetic rates) the boron isotopic composition of the tests is 1.5parts per thousand lower compared to shells grown under high light (elevated photosynthetic rates). In terms of inferred pH, the lower boron isotope values correspond to a reduction in pH of approximately 0.2 units. The boron isotopic composition of Orbulina universa from plankton tows is similar to that of shells grown under low light conditions in the laboratory. These data are consistent with reduced symbiont concentrations in recently secreted shells. In addition to laboratory and field grown O. universa, we present the first data for a symbiont-barren foraminifer, Globigerina bulloides. Data obtained for G. bulloides fall similar to1.4parts per thousand below those of the field grown O. universa. Although the plankton tow results are preliminary, they support the hypothesis that respiration and photosynthesis are the key physiological parameters responsible for species-specific vital effects. (C) 2003 Elsevier B.V. All rights reserved.


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URL  <Go to ISI>://000185272300005
DOI  Doi 10.1016/S0377-8398(03)00030-6