Physiological controls on seawater uptake and calcification in the benthic foraminifer Ammonia tepida
- 1Alfred Wegener Institute for Polar- and Marine Research (AWI), Am Handelshafen 12, 27570 Bremerhaven, Germany
- 2Institute of Environmental Science and Technology, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain
Abstract. To analyze the relation between seawater uptake and calcification, we incubated juveniles of the benthic foraminifer Ammonia tepida with various fluorescent probes and visualised them afterwards with confocal laser scanning microscopy. Vesicle membranes, Ca ions and vacuole fluids were followed with various tracers and showed for the first time that endocytosis of seawater is part of the calcification process in Ammonia tepida. Data on the intracellular Ca ion cycling allowed for calculating a preliminary cellular Ca budget during foraminiferal calcification. This showed that the free calcium involved in the production of a new chamber cannot be sufficient and suggests that foraminifera may precipitate their calcite from an amorphous precursor.