A comment on the proper use of nutrient ratios in microalgal ecology

Repeatable species dominance patterns across nutrient ratio gradients are f ound bath in culture competition experiments and in natural waters. However , the mechanisms behind these similar patterns need not to be identical. In chemostat experiments, such patterns are caused by the two-way competitive interactions between contemporaneously occurring organisms. Nutrient compe tition may be important in situ too, but there is an additional effect of e arly successional species influencing the nutrient environment for later su ccessional species, without being influenced themselves by their successors .