Figure 16.2 Competition for the most limiting resource. When raised separately, (a) Asterionella and (b) Synedra diatoms grow rapidly and then persist with population sizes near their carrying capacity. At their carrying capacity, both species dramatically reduce the abundance of silica, although Synedra causes the silica to be driven down to a lower abundance than Asterionella. (c) When combined, the two species again drive down the abundance of silica to the point that there is still enough to meet the minimum requirements of the Synedra population but not enough to meet the minimum requirements of the Asterionella population. As a result, the Asterionella population declines.

Data from D. Tilman et al., Competition and nutrient kinetics along a temperature gradient: An experimental test of a mechanistic approach to niche theory, Limnology and Oceanography 26 (1981): 1020–1033.