Coupling Effects of Silicate, Iron and Other Various Abiotic Variables on Growth of Two Diatoms, Phaeodactylum Tricornutum and Thalassiosira Weissflogii and Their Silicon Utilization

The effects of various Abiotic factors, including concentrations of silicate and iron, temperature, light intensity and salinity of media on two purebred red tide diatoms, Phaeodactylum tricornutum and Thalassiosira weissflogii were investigated through single and full factorial experiments. The single-factor experiments showed diatom Phaeodactylum tricornutum had the fastest growth rate with initial silicate concentration of 200 μmol？L -1, initial iron content of 10 μmol？L -1, environmental temperature of 20 oC, and light intensity of 231.25 μmol photons？m -2？s -1 respectively. Thalassiosira weissflogii grew fastest when initial silicate concentration was 250 μmol？L -1, initial iron concentration was 10 μmol？L -1, temperature of 30 oC light intensity of 231.25 μmol photons？m -2？s -1. From full factorial experiments, the main factors affecting Phaeodactylum tricornutum were iron concentration, temperature, the coupling effect of temperature and light intensity, and the coupling effect of temperature and iron concentration. The main factors affecting Thalassiosira weissflogii were temperature, the coupling effect of temperature and iron concentration, and the coupling interaction of silicate and iron. Silicates, iron ions and the coupling effects of temperature and silicate are the main factors affecting the production of biosilicon in Phaeodactylum tricornutum; and temperature, iron and the coupling effect of silicate and iron ions were the main factors influencing biosilicon produced by Thalassiosira weissflogii. Keywords: coupling effect; Phaeodactylum tricornutum; Thalassiosira weissflogii; silicon utilization