Evidence for high iron requirements of colonial Phaeocystis antarctica at low irradiance

摘要: We have carried out field and laboratory experiments to examine the iron requirements of colonial Phaeocystis antarctica in Ross Sea. In December 2003, we performed an iron/light-manipulation bioassay experiment Sea polynya, using algal assemblage dominated by antarctica, collected from surface waters with ambient dissolved Fe concentration ∼0.4 nM. Results this suggest that P. growth rates were enhanced at high irradiance (∼50% incident irradiance) but unaffected addition, elevated mediated a significant decrease cellular chlorophyll content. also conducted dose–response unialgal, non-axenic strain low-iron (<0.2 nM) filtered seawater, both polynya 2003. By rigorous trace-metal clean techniques, iron-addition ∼0°C without organic chelating reagents control levels. At relatively low (∼20 μE m−2 s−1), estimated nitrate-specific rate as function can be described Monod relationship, yielding half-saturation constant respect 0.45 nM iron. This value is compared reported estimates for other Antarctic phytoplankton. Our results seasonal changes availability light play critical roles limiting biomass polynya.