Orbulina universa

Eggins, S. M., Sadekov, a. De Deckker, P. 2004. Modulation and daily banding of Mg/Ca in Orbulina universa tests by symbiont photosynthesis and respiration a comphcation for seawater thermometry Earth and Planetary Science Letters, 225, 411 -419. 

Fig. 5. The species dependencies of the Mg and Ca isotope ratios in a variety of foraminifera. Note Orbulina universa. Some species appear to show a wide variety of values. Mg and Ca isotope ratios of seawater and coral are also given for comparison.

Fig. 1. Light microphotographs of the symbiotic, planktonic foraminifer Orbulina universa (top) and the non-symbiotic species Globigerina buUoides (bottom). After Spero (1998).

Some organism-specific calibrations are shown in Figure 4. They include results from controlled culture experiments with the two planktonic foraminiferal species Globigerinoides sacculifer and Orbulina universa (Sanyal et al. 1996, 2001) and the coral species Porites cylindrica and two species of Acropora (Honisch et al. 2004 Reynaud et al. 2004). 

Fig. 4. Empirical relationships between 8 and culture seawater pH measured in three species of corals (Pontes and Acropora), two species of planktonic foraminifera (Globigerinoides sacculifer and Orbulina universa), and inorganically precipitated calcite. Palaeoceanographic reconstractions use the empirical curves for reconstracting past seawater pH. The upper black sohd, the dotted, and the dashed black line represent the 8"B of B(OH)4 using B3-b4) — 1.019, 1.027, and 1.030 (Kakihana Kotaka 1977 Liu Tossell 2005 Zeebe 2005a). The dot-dashed black line represents the experimental (b3-b4) = 1.0285 of Byrne etal. (2006). Note that 8"B b(OH) and the 8 B in carbonates are two different quantities and that one cannot be deduced from the other (see text).

Kohler-Rink, S. Kuhl, M. 2005. The chemical microenvironment of the symbiotic planktonic foraminifer Orbulina universa. Marine Biology Research, 1, 68—78. 

Fig. 1. (a) Bulk analyses of Mg/Ca ratios in different size classes of Orbulina universa from Atlantic core top samples (open circles) (Elderfield et al. 2002) and culture experiments (filled squares) (Russell et al. 2004). 

Caron, D. A., Faber, W. W. 1. Be, a. W. H. 19876. Growth of the spinose planktonic foraminifer Orbulina universa in laboratory culmre and the effect of temperature on life processes. Journal of the Marine Biological Association of the United Kingdom, 67, 343-358. 

Culture studies of planktic foraminifera have shown that their 8 0 and 8 C values decrease as the carbonate ion concentration and/or pH of their growth medium increases (Spero et al. 1997 Lea et al. 1999 Bjima et al. 1999). The slopes of these isotopic responses were species-dependent, and were approximately three times steeper for 8 C than for 8 0 in the two planktic species studied (d(8 C)/d([CO ]) was -0.006%c/ p,mol/kg for Orbulina universa and approximately... 

Lea, D. W. Spero, H. J. 1992. Experimental determination of barium uptake in shells of the planktonic foraminifera Orbulina universa at 2TC. Geochimica et Cosmochimica Acta, 56, 2673-2680. 

Lea, D. W., Martin, P. A., Chan, D. A. Spero, H. j. 1995. Calcium uptake and calcification rate in the planktonic foraminifer Orbulina universa. Journal of Foraminiferal Research, 25, 14- 23. 

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