Limitation of Marine Phytoplankton Biomass Yields by Iron
We measured biomass yields of 17 clones of marine phytoplankton in media with different concentrations of iron. The biomass yields of all the clones except two were limited by iron. All cyanobacteria tested were dead at iron concentration of 10−9 M, still limited severely at up to 10−7 M. Coastal dinoflagellates showed evident limitation of biomass yield by iron. Different levels of biomass yield limitations were found among the seven coccolithophorid clones. Among other clones, Micromonas (A2167) was only slightly limited by low concentrations of iron, while Heterosigma akashiwo (OLISTH) showed no growth below 10−10 M. In two oceanic clones, Mantoniella sp. (MC-1) and Umbilicosphaera (A2390), no significant limitation of biomass yields were measured at all the different concentrations of iron.