Calcification rate and temperature effects on Sr partitioning in coccoliths of multiple species of coccolithophorids in culture

Abstract

Five common placolith-bearing coccolithophorid algae-Gephyrocapsa oceanica, Coccolithus pelagicus, Calcidiscus leptoporus, Umbilicosphaera sibogae (var. sibogae and var. foliosa), and Emiliania huxleyi-were cultured to investigate controls on Sr partitioning in coccolith calcite. For identical temperature and media composition, Sr partitioning varies by more than 30% in exponential phase cultures of the five species and is linearly related to rates of calcite production/cell (q=0.91). Exponential phase culture experiments with three strains of C. leptoporus and six strains of G. oceanica at varying temperatures show variations in Sr partitioning of 20% and 30%, respectively. With C. leptoporus, Sr partitioning is equally correlated with temperature and calcification rate (q=0.8), which themselves are highly correlated; the slope of the relationship between D Sr and calcification rate is comparable to that observed in all species at constant temperature. However, in G. oceanica, increased temperature appears to enhance Sr incorporation by up to 2% to 1.6% jC À1 in the range of 15 to 30 jC. The strong influence of calcification rate on Sr partitioning may be useful for inferring past variations in coccolithophorid productivity from Sr partitioning in coccolith sediments if the influence of temperature on Sr partitioning can be resolved. Because the relationship between calcite production and Sr partitioning is linear, a proportional change in calcification should be expressed much more strongly in the Sr/Ca ratio of large species with rapid calcite production than in smaller species, which produce calcite more slowly. Consequently, it may be possible to separate temperature and calcification influences on coccolith Sr/Ca by separately analyzing Sr/Ca in species that produce calcite rapidly and those that produce calcite slowly, if both undergo comparable relative changes in calcification rates. D

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

“…Mean exponential growth rates for C. braarudii at 15 • C were 0.68 d −1 . These values are well within the ranges reported in other studies carried out at similar temperatures for Calcidiscus (Langer et al, 2006;Buitenhuis et al, 2008;Fiorini et al, 2010Fiorini et al, , 2011Langer et al, 2012;Candelier et al, 2013;Müller et al, 2014) and H. carteri (Stoll et al, 2002;. Exponential growth rates of 0.4-0.5 d −1 signify that roughly half of the culture population undergoes cell division each day.…”

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

“…Yet, cell diameters of Ammonia sp. are small compared to planktonic species, suggesting decreased calcification rates with decreasing size as in coccolithophores (Langer et al, 2006;Stoll et al, 2002). Also, compared to the above labeling experiments, calcification rates determined geometrically from the formation of the ultimate chamber did not take secondary layering of the complete shell into account and thereby underestimated the amount of total calcite precipitated.…”

Coccolith strontium to calcium ratios in Emiliania huxleyi: The dependence on seawater strontium and calcium concentrations

“…Exchange coefficients of coccolith calcite presented in the literature are high compared with values of inorganically precipitated calcite (Stoll et al 2002b). Although kinetic effects can explain part of this offset (Stoll et al 2002b), the origin of this discrepancy is yet not fully understood.…”