3.1 Dose-response relationship in Fragilariopsis oceanica

After 22 days of seawater cultivation in 1 l glass beakers, brown biofilms of Fragilariopsis oceanica became clearly visible on the bottom and walls of the beakers of both the control (0 mg l −1) and the lowest GeO 2 concentration (0.003 mg l −1) with 27.13 mg DW m −2 and 24.23 mg DW m −2, respectively. In contrast, all GeO 2 concentrations ≥ 0.014 mg l −1 had lower diatom biomass (6.56 mg DW m −2) than the control and 0.003 mg GeO 2 l −1 (P <0.0001, 1-way ANOVA; Figure 2).