Link between light-triggered Mg-banding and chamber formation in the planktic foraminifera Neogloboquadrina dutertrei.
- Author(s): Fehrenbacher, Jennifer S
- Russell, Ann D
- Davis, Catherine V
- Gagnon, Alexander C
- Spero, Howard J
- Cliff, John B
- Zhu, Zihua
- Martin, Pamela
- et al.
Published Web Locationhttps://doi.org/10.1038/ncomms15441
The relationship between seawater temperature and the average Mg/Ca ratios in planktic foraminifera is well established, providing an essential tool for reconstructing past ocean temperatures. However, many species display alternating high and low Mg-bands within their shell walls that cannot be explained by temperature alone. Recent experiments demonstrate that intrashell Mg variability in Orbulina universa, which forms a spherical terminal shell, is paced by the diurnal light/dark cycle. Whether Mg-heterogeneity is also diurnally paced in species with more complex shell morphologies is unknown. Here we show that high Mg/Ca-calcite forms at night in cultured specimens of the multi-chambered species Neogloboquadrina dutertrei. Our results demonstrate that N. dutertrei adds a significant amount of calcite, and nearly all Mg-bands, after the final chamber forms. These results have implications for interpreting patterns of calcification in N. dutertrei and suggest that diurnal Mg-banding is an intrinsic component of biomineralization in planktic foraminifera.