Quantification of nutrient-replete growth rates in five-ion hyperspace forChlorella vulgaris(Trebouxiophyceae) andPeridinium cinctum(Dinophyceae)
The effects of five ions, , , K+, Na+ and Cl−, on growth rates were quantified for Chlorella vulgaris (Trebouxiophyceae) and Peridinium cinctum (Dinophyceae) in batch cultures. A five-dimensional, experimental design hypervolume was defined by five-ion mixture vectors projected across a total ion concentration gradient of 1 to 30 mM to quantify growth rates in relation to N:P ratios and primary bulk solution ions. Both C. vulgaris and P. cinctum exhibited very similar, positive responses to cations and negative responses to anions. It was determined that total ion concentration for these five ions, from 1 to 30 mM, did not directly affect growth rate for either alga, although it did play an interactive role with several ions. No truly ‘optimal’ N : P ratio was identified for either alga. Instead, regions of fast growth rates were mapped within the multivariate experimental design space, or ‘hypervolumes’, that encompassed relatively broad ranges of N:P ratios. This illustrates the fact that optimality is ...