Bioavailability of iron speciations and EDTA-iron complexes for Thallassiosira weissflogii (Bacillariophyta)

Abstract

This study aimed to determine the effects of daily and/or initial additions of various amounts of Fe (II) and Fe (III), in combination with or without EDTA, on the growth of Thalassiosira weissflogii cultures. The results reveal that growth parameters were higher in the cultures containing 5000 nM Fe(III) ± EDTA than those of 5 nM Fe(III) and Fe(II). T. weissflogii cells seemed not to have used EDTA-bound iron, but their own released ligand to bind iron when Fe(III) concentration was high, and to have preferred inorganic Fe(II). Cell abundance and chl-a level were higher in daily supplemented cultures, with regard to those supported with iron only initially, evidencing the importance of continuous supply of iron in chl-a synthesis.

Key Words: Thallassiosira weissflogii, iron speciation, EDTA, growth.