Phosphorus forms and zinc concentrations affect the physiological ecology and sinking rate of Thalassiosira weissflogii.

The combined effects of phosphorus (P) forms and zinc (Zn) concentrations on diatom silicification remain unclear. In this study, we investigate the effects of different Zn concentrations on the growth, cellular silicon content and sinking rate of Thalassiosira weissflogii under different P forms. The results showed that under the dissolved inorganic phosphorus (DIP) treatments, the specific growth rate of T. weissflogii in Zn limitation culture was significantly lower than that in Zn-replete culture. However, T. weissflogii cellular silicon content and sinking rate increased. Moreover, the reduced specific growth rate (7 %, p < 0.05), enhanced ALP activity (63 %, p < 0.05), and sinking rate (20 %, p < 0.05) for Zn-deplete T. weissflogii implied that the bioavailability of dissolved organic phosphorus (DOP) was depressed under Zn deplete medium. This study demonstrates that the physiological ecology and sinking rate of the diatom T. weissflogii were affected by both individual and combined changes in P forms and Zn concentrations.