Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.)

Glas, Martin S., Langer, Gerald and Keul, Nina (2012) Calcification acidifies the microenvironment of a benthic foraminifer (Ammonia sp.) Journal of Experimental Marine Biology and Ecology, 424-425 . pp. 53-58. DOI 10.1016/j.jembe.2012.05.006.

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Abstract

Calcareous foraminifera are well known for their CaCO3 shells. Yet, CaCO3 precipitation acidifies the calcifying fluid. Calcification without pH regulation would therefore rapidly create a negative feedback for CaCO3 precipitation. In unicellular organisms, like foraminifera, an effective mechanism to counteract this acidification could be the externalization of H+ from the site of calcification. In this study we show that a benthic symbiont-free foraminifer Ammonia sp. actively decreases pH within its extracellular microenvironment only while precipitating calcite. During chamber formation events the strongest pH decreases occurred in the vicinity of a newly forming chamber (range of gradient similar to 100 mu m) with a recorded minimum of 6.31 (<10 mu m from the shell) and a maximum duration of 7 h. The acidification was actively regulated by the foraminifera and correlated with shell diameters, indicating that the amount of protons removed during calcification is directly related to the volume of calcite precipitated. The here presented findings imply that H+ expulsion as a result of calcification may be a wider strategy for maintaining pH homeostasis in unicellular calcifying organisms

Document Type: Article
Additional Information: WOS:000306766700008
Keywords: Biomineralization; Calcite; Calcium; Microsensor; pH; SYMBIONT-BEARING FORAMINIFERA; INORGANIC CARBON; ORBULINA-UNIVERSA; INTRACELLULAR PH; BIOMINERALIZATION; PHOTOSYNTHESIS; RESPIRATION; MICROSENSOR; CALCITE; RATIOS
Refereed: Yes
DOI etc.: 10.1016/j.jembe.2012.05.006
ISSN: 0022-0981
Related URLs:
Projects: BIOACID
Date Deposited: 06 Nov 2012 13:51
Last Modified: 05 May 2014 10:35
URI: http://oceanrep.geomar.de/id/eprint/19111

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