Light‐dependent carbon isotope fractionation in the coccolithophorid Emiliania huxleyi

• DOI: 10.4319/lo.2002.47.1.0120
• Publication Date: 2010-06-30T20:23:40Z
• Authors: Björn Rost; Ingrid Zondervan; Ulf Riebesell
• Keywords: Emiliania huxleyi; Total inorganic carbon

The carbon isotopic composition of marine phytoplankton varies significantly with growth conditions. Aqueous CO 2 concentration [CO ] and algal rate (µ) have been suggested to be important factors determining isotope fractionation (ε p ). Here we examine ε the coccolithophorid Emiliania huxleyi in relation light conditions dilute batch cultures. Cells were incubated at different irradiance cycles, photon flux densities (PFDs), ]. Isotope varied between 6.7 12.3‰ under 16 : 8 h dark cycle (L :D) 14.7 17.8‰ continuous light. was largely independent ambient ], varying generally by less than 2‰ over a range from 5 34 mmol L −1 . Instantaneous carbon‐specific rates (µC) PFDs, ranging 15 150 m −2 s , positively correlated This result is inconsistent theoretical considerations experimental results obtained constant conditions, suggesting an inverse relationship µ. In present study effect PFDs on stronger that mand thus resulted positive µ addition, L:D lower values compared Since observed offset about 8‰ could not related daylength dependent changes C this implies direct influence These findings are best explained invoking active uptake E. If representative for natural environment, these complicate interpretation data geochemical paleoceanographic applications.