An estimation of calcium carbonate deposition rate in a planktonic foraminifer Globigerinoides sacculifer using 45 Ca as a tracer; a recommended procedure for improved accuracy

Abstract

The amount of calcium carbonate deposited in the shell of Globigerinoides sacculifer during new chamber addition was assessed using 45Ca as a tracer. An improved method is recommended based on the observation that chambers formed during the first 24 h in the labeled seawater medium yield a lower estimate of total calcium carbonate deposited compared to chambers added during the subsequent 24 h intervals. The latter values, moreover, agree substantially with estimates based on laboratory measurements of shell weights from plankton samples. Based on 45Ca incorporation after the first 24 h period in the labeled medium, the mean weight of CaCO, deposited per new chamber was 12.8 pg for organisms with an initial mean length of 457 pm and mean chamber growth of 166 pm; and 20.8 pg for larger organisms with an initial mean length of 519 pm and mean chamber growth of 211 pm. Some hypothetical causes for this enhanced accuracy after the first 24 h in the labeled medium are discussed and guidelines for obtaining improved estimates of calcification using 45Ca as an isotopic tracer are presented.

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

“…They are lower than rates obtained by Ca 2+ labeling experiments of symbiotic planktonic foraminifera (0.04 μg h − 1 (dark) to 0.11 μg h − 1 (light) (Erez, 1983), 0.39 to 0.87 μg h − 1 (light) (Anderson and Faber, 1984), 0.06 μg h − 1 (dark) to 0.32 μg h − 1 (light) (Lea et al, 1995)). Yet, cell diameters of Ammonia sp.…”

“…(Koehler-Rink and Kuehl, 2000). The absence of an overall significant calcium gradient during chamber formation in the microenvironment can be explained in two ways: 1) Ca 2+ was not transported from the external seawater into the DBS via channel-pumping, but supplied via an intracellular calcium pool as shown by Anderson and Faber (1984), ter Kuile and Erez (1988) and ter Kuile et al (1989). 2) Ca 2+ was transported over the complete surface of the shell (Angell, 1979).…”

Biomineralization in perforate foraminifera

“…To determine whether planktonic foraminifera have an internal Careservoir, Anderson and Faber (1984) grew G. sacculifer in artificial seawater spiked with 45 Ca. They showed that calcite formed during the first 24 h contains significantly less 45 Ca than that produced in the second 24 h. These data argue for the existence of an unlabeled intracellular Ca-reservoir that was filled prior to the introduction of the isotopic spike.…”

“…Secondly, chamber addition rates vary over a foraminifera's lifetime, decreasing as the individual ages (Ter Kuile and Erez, 1984). Calcite precipitation rates during chamber addition, on the other hand, are much higher and vary between 0.4 and 0.9 μg/h in the planktonic foraminifera G. sacculifer (Anderson and Faber, 1984), 0.06-0.32 μg/h in O. universa (Lea et al, 1995) and~10 μg/h in the benthic A. tepida (De Nooijer et al, 2009b). Since such rates are rarely quantified, it is difficult to generalize these values to other species or other conditions.…”

Effect of salinity and seawater calcite saturation state on Mg and Sr incorporation in cultured planktonic foraminifera

“…According to Anderson and Faber (1984), Lea et al (1995) and Bijma et al (1999), G. sacculifer has a higher calcification rate than O. universa. The rates at which these two species calcify might thus be responsible for both the difference in Sr/Ca ratios and the different response of foraminiferal Sr incorporation to [CO 3 2− ] changes (Fig.…”