Effect of carbonate ion concentration and irradiance on calcification in foraminifera

Abstract

Abstract. The effect of carbonate ion concentration ([CO32−]) on calcification rates estimated from shell size and weight was investigated in the planktonic foraminifera Orbulina universa and Globigerinoides sacculifer. Experiments on G. sacculifer were conducted under two irradiance levels (35 and 335 μmol photons m−2 s−1). Calcification was ca. 30% lower under low light than under high light, irrespective of the [CO32−]. Both O. universa and G. sacculifer exhibited reduced final shell weight and calcification rate under low [CO32−]. At the [CO32−] expected for the end of the century, the calcification rates of these two species are projected to be 6 to 13% lower than at present conditions, while the final shell weights are reduced by 20 to 27% for O. universa and by 4 to 6% for G. sacculifer. These results indicate that ocean acidification would impact calcite production by foraminifera and may decrease the calcite flux contribution from these organisms.

Photosymbiosis in planktonic foraminifera across the Paleocene–Eocene thermal maximum

“…2,3, Supplementary Material). Environmental differences offer an alternative explanation for variable isotopic patterns among sites, including factors such as the availability of photosynthetically active radiation, temperature, carbonate ion effects, and the extent of water-column stratification (Spero et al 1997; Lombard et al 2009; Henehan et al 2016). This class of explanations is less parsimonious than those invoking changed photosymbiont associations, because variable combinations of environmental changes need to be evoked at each site (Supplementary Table 2).…”

Estimates of Pliocene Tropical Pacific Temperature Sensitivity to Radiative Greenhouse Gas Forcing

“…Previous research has shown Mg/Ca composition and laser ablation profiles are similar between chambers in T. sacculifer (Eggins et al, 2003), so the final chamber is a good approximation for the whole shell chemistry. Additionally, the final chamber of T. sacculifer strongly correlates with SST (Sadekov et al, 2009), and the final chamber represents ~50% of the mass of individuals grown in experimental lab cultures (Lombard et al, 2010). Prior to analysis, individual whole shells were sonicated in deionized water for 20 s and rinsed with methanol.…”