Use of model and natural phytoplankton to measure iron bioavailability in the southern ocean

摘要

The Southern Ocean is an important region for climate research where primary productivity is iron limited. Despite numerous studies, the role of iron availability in the phytoplankton speciatiou is still poorly understood. In this study, the bioavailability of several organic iron complex was measured using natural phytoplankton and compared to the bioavailability of four strains representing the major taxonomic plankton groups in the Southern Ocean (Bacillariophyta and Prymnesiophytes). Iron bioavailability was measured on filtered (0.2μm) and ultrafiltered (0.02μm) waters collected from three process stations (two at 46°and one at 54°S) south of Tasmania (Australia) during the austral summer. Since trace metal chemical speciation usually best describes its bioavailability, iron-organic speciation will be measured by competitive ligand exchange adsorptive stripping voltammetry (CLE-AdSV). Additional laboratory measurements of growth rate, photosynthetic yield, cellular iron quota for each of the four species studied, provided a quantitative measure of iron bioavailability in the Southern Ocean.