Effects of Temperature and Nutrients on Sterol Concentration in Marine Diatoms and Implications for Productivity Reconstructions

Sterols as phytoplankton productivity and community structure proxies have been widely applied for paleo-reconstructions, while quantitative reconstructions using sterols remain understudied. In this study, we aimed to determine the quantitative relationship between sterols and biomass in three species of marine diatoms under different temperature (15℃, 20℃ and25℃) and different nutrient supply (N:P=10:1, 24:1 and 63:1). Brassicasterol is the major sterol in Phaeodactylum tricornutum Bohli, an important species in marginal seas. The effects of temperature on the cellular concentration of brassicasterol is minimum, with values of 1.01×10 -4 ng cell-1 at 15℃, 1.07×10 -4 ng cell-1 at 20℃ and 1.17×10 -4 ng cell-1 at 25℃. Work is underway to evaluate the effects of nutrients on the cellular concentration of brassicasterol. Our preliminary results suggest that brassicasterol could be used to quantitatively reconstruct diatom productivity, and we will report the results of its application in several sediment cores.