Influence of Cell Shape and Size on Algal Competitive Ability1

Allometric relations between physiological processes and cell volume and surface area are combined with the variable‐internal‐stores model of growth to predict the ability of hypothetical phytoplankton to compete for phosphorus at equilibrium. The analysis shows that for spherical cells, smaller cells are better competitors than large ones. For cells that are very elongated in shape, however, large cells are often better competitors than small ones. The cells predicted to be the best competitors compare favorably in size and shape with the species observed to dominate in phosphorus‐limited chemostats at equilibrium.