We examined the effect of irradiance and growth rate on cadmium : phosphorus ratio in five species of phytoplankton representing four different phylogenetic groups to determine the relative importance of growth rate, irradiance, and taxonomic differences on Cd : P ratios. Irradiance and growth rate are responsible for >2 orders of magnitude variation in the Cd : P of phytoplankton. Diatoms exhibit an increase; cyanobacteria, a...

We analyzed the elemental composition (C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Mo, and Ni) of five marine phytoplankton species representing the four major marine phyla grown over a range of growth irradiances. We found substantial variability in the elemental composition between different species, which is consistent with previously reported differences associated with evolutionary history. We found that many elements...