The fundamental niche defined by five ions,NO3 −,PO4 3−, K+, Na+, andCl−, was mapped forChlorella vulgaris(Trebouxiophyceae) andPeridinium cinctum(Dinophyceae) growth rates and maximum cell densities in batch cultures. A five dimensional ion-mixture experimental design was projected across a total ion concentration gradient of 1 to 30 mM to delineate the ion-based, “potential” niche space, defined as the entiren-dimensional hypervolume demarcated by the feasible ranges of the independent factors under consideration. The growth rate-based, fundamental niche volumes overlapped for ca. 94% of the ion mixtures, although the regions of maximal growth rates and cell densities were different for each alga. BothC. vulgarisandP. cinctumexhibited 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 either growth rate or maximal cell density for either alga, although it did play an interactive role with several ions. This study is the first that we are aware of to attempt the mapping of a multivariate, ion-based, fundamental niche volume. The implications of the experimental design utilized and the potential utility of this type of approach are discussed.
ALGAE OIL EXTRACTION FROM FRESHWATER MICROALGAE Chlorella vulgaris
