Journal Article

Effect of glucose addition on silica deposition kinetics in natural diatom population

Rychtecky, P, Nedoma, J, Znachor, P

2009

Overview

In July and August 2008, we performed two experiments examining the effect of glucose addition (final concentration 100 kmol l super(-1)) on silica deposition and growth rates of natural diatom population in a eutrophic Rimov Reservoir (Czech Republic). Silica deposition kinetics was measured at four-hour intervals over 24 hours using the incubation with PDMPO, which fluorescence is proportional to silica deposited. Diatoms represented 58 and 37% of total phytoplankton biomass and were dominated exclusively with Fragilaria croto-nensis. There was a linear increase in PDMPO fluorescence over time, slopes of regression lines significantly differed between the experiments. There was no difference in silica deposition between glucose-amended and control variant till 16 super(th) hour of experiment duration but later on, glucose addition significantly increased PDMPO fluorescence indicating diatom growth stimulation. This was confirmed by direct measurement of growth rates (based on cell counts), which almost doubled in glucose-amended variant (k = 0.61 d super(-1)), compared to control (k = 0.35 d super(-1)). Our results indicate that Fragilaria may subsidize its phototrophic metabolism by glucose uptake; however, there is a 16 hour lack required likely for induction of active transport mechanisms.

• Subject: Fragilaria